Background: The aim of this study was to determine the predictive value of visual evoked potentials (VEPs) in patients with relapsing–remitting multiple sclerosis (RRMS) in achieving no evidence of disease activity-3 (NEDA-3) during up to 10 years of first-line immunomodulatory therapy and to determine whether the lateralization of optic nerve damage may have prognostic significance concerning clinical disability and response to therapy.Methods: In a retrospective study, a total of 83 patients  with RRMS participated. The average age of patients was 38.31 ± 9.01. Patients were followed for 2, 5 or 10 years. VEPs were measured at the beginning of the follow-up and after many years of monitoring. Data on optical neuritis (ON) were obtained from medical history. The degree of disability was estimated by the neurologist (independent rater), and magnetic resonance (MR) imaging of the endocranium was performed with gadolinium contrasts. Achieving NEDA-3 is considered a favorable outcome of treatments.Results: Among those treated, 19 (22.9%) reached NEDA-3, while 64 (77.1%) did not reach NEDA-3. The values of the evoked potential (EP) score for the left eye  = 0.344 (0.156–0.757)) and latency for the left eye ) at the onset of disease were predictive factors for achieving NEDA-3. Conclusions: A normal VEP at the beginning of RRMS increases the chance of reaching NEDA-3 by about six times. Optic neuritis (ON) occurs as the first symptom in 20% to 40% of patients with multiple sclerosis (MS), while about 50% to 70% of such patients have an episode of ON within subsequent relapses ,2,3,4. OThere are numerous studies indicating that optic nerve lesions are closely correlated with the atrophy of white and gray matter in the brain; thus, ON lesions reflect the pathological mechanisms that affect the central nervous system (CNS) in this disease and lead to axon loss ,11.Visual evoked potentials (VEP) are an important tool for the evaluation of patients with clinical and subclinical ON . VEP chaIn recent years, progress has been made in the treatment of MS by using therapy that modifies the course of the disease. Currently, the attitude is to start treatments as soon as possible and thus prevent the development of disability . A new sThe aims of the study are to determine the predictive value of VEP in patients with relapsing–remitting multiple sclerosis (RRMS) in achieving NEDA-3 after up to 10 years of first-line immunomodulatory therapy and also to determine whether the lateralization of optic nerve damage has any prognostic significance for clinical disability and good response to therapy.This research involved 83 subjects with RRMS conducted at the Clinic of Neurology Clinical Centre of Kragujevac. Respondents signed a Good Clinical Practice (GCP) form before any of the study’s procedure.The participants had a clinically definite relapsing–remitting form of multiple sclerosis (RRMS) in whom the diagnosis of the disease was made on the basis of McDonald’s 2017 criteria . ClinicaOn the basis of medical documentation, data were collected on the duration of the disease, its course, the number and frequency of relapses, therapy used and the length of treatment. The degree of clinical disability was determined using the Kurtzke expanded disability status scale (EDSS) .All patients underwent VEP (p100), and the amplitude and latency of the waves were measured. Standard clinical testing involves visual evoked potential recordings in which the visual stimulus was a black-and-white checkerboard that is patterned, has 1 Hz alternation and does not have filters. During recording, the black and white fields occasionally change places. VEPs represent the average response to these changes. Responses are recorded using three electrodes covering the occipital region, with one frontal electrode for comparison. The signal from the middle occipital electrode normally contains a prominent positive component that occurs approximately 100 ms after the stimulus and is called the P100. It is preceded by a smaller negative component with a latency of about 75 ms and is called N75. Waveforms at the lateral electrodes are quite variable; thus, the P100 latency obtained at the middle electrode is taken as a measure of retino-striatal conduction. Cerebral responses are amplified and averaged by a computer. VEPs were generally elicited by the monocular stimulation of each eye. The patient’s distance from the stimulation monitor was 1 m in a sitting position.The findings were scored from 0 to 4 when both eyes were taken into account, where 0 represents normality, 1 represents extended latencies and 2 represents extended latencies and reduced amplitudes in each eye separately . MagnetiThe collected data were processed by obtaining the arithmetical mean, standard deviation, statistically median, quartiles, frequencies and percentages. The normality of the distribution of numerical variables was checked using the Shapiro–Wilk and Kolmogorov–Smirnov tests. The correlation of category variables was examined using the chi-square test for contingency tables and of numerical variables using Spearman’s correlation coefficient. Student’s t-test for independent samples and the Mann–Whitney test were employed to compare the mean values of variables for the two populations, while the analysis of variance and Kruskal–Wallis tests were used for comparing the mean values of variables from several populations. The dependence of the binary variable on the other variables was checked using univariate and multivariate binary logistic regression. The analysis was performed in the SPSS statistical package, version 23.0 .The 83 patients who participated in the study were observed for up to 10 years after initiating interferon beta and glatiramer acetate therapy. All were diagnosed with definitive RRMS according to the revised McDonald criteria . We did p = 0.385).The distribution of patients according to the time period of follow-up is shown in A total of 19 (22.9%) patients reached NEDA-3, while 64 (77.1%) did not. The score for the left eye obtained at the time of diagnosis was associated with a favorable outcome with respect to the treatment of the disease (reaching NEDA-3) (r = 0.024).Among patients with a normal VEP finding (score 0), 15 out of 40 (37.5%) reached NEDA-3, while 2 out of 18 patients (11.1%) with prolonged latency (score 1) reached NEDA-3, and 2 out of 23 patients (8.71%) with prolonged latency and a reduced amplitude (score 2) reached NEDA-3. Both patients (100%) who had unformed waves (score 3) failed to reach NEDA-3. The distribution of the achievement of NEDA-3 after 2-year, 5-year and 10-year monitoring is shown in The difference between the mean latency values obtained in the eye affected by ON between patients who achieved NEDA-3 and those who did not was not statistically significant (r = 0.694). The difference in mean amplitudes obtained in the eye affected by ON between patients who achieved NEDA-3 and patients who did not (r = 0.681) was also not statistically significant.p < 0.05) are shown in The factors for achieving NEDA-3 and factors influencing increases in EDSS using binary logistic regression ). The higher the score on the left eye, the lower the chance of attaining NEDA-3. A score higher by 1 reduced the chance of reaching NEDA-3 by about three-fold. The latency value in the left eye influenced the achievement of NEDA-3 ). The higher the latency value in the left eye, the lower the chance of reaching NEDA-3. A latency value increase of 1 reduced the chance by about 3.4%.Univariate binary logistic regression showed that the values for the score and latency of the left eye obtained at diagnosis were the only two examined factors that influenced the achievement of NEDA-3. Multivariate binary logistic regression indicated that only the score for the left eye affected the achievement of a favorable treatment outcome.A normal finding in the left eye affected the achievement of NEDA-3 ). Patients who had a regular finding were about six times more likely to experience improvements.Left-sided latency affected the EDSS score ). Thus, higher latency values indicated a greater risk of increased EDSS in the further course of the disease. The use of immunomodulatory therapy indicates a risk of increased EDSS ). The initial value for the EDSS affected its increase ). Namely, the higher the initial EDSS value, the greater the risk of a later increase.A normal left VEP score indicated a lower risk of increasing EDSS by about four-fold ).p = 0.020, OR = 0.262 (0.085–0.812)).Univariate binary logistic regression showed that the left-hand score influenced the increase in EDSS by four times  exhibited ON, while 33 (41.8%) never had ON. A total of 24 (52.2%) patients had ON in the left eye, 15 patients (32.6%) had ON in the right eye and 7 patients (15.2%) had ON in both eyes.The VEP score for the left eye at the beginning of the disease showed a normal finding in 40 (48.2%) subjects, prolonged latency in 18 (21.7%), prolonged latency with reduced amplitude in 23 (27.7%) and an unformed wave in 2 (2.4%). The VEP score for the right eye showed a neat finding in 36 (44.4%) subjects, prolonged latency in 23 (28.4%) and prolonged latency with reduced amplitudes in 22 (27.2%) subjects.The current EDSS did not correlate with values for latency in the eye affected by retrobulbar neuritis at the beginning of the disease , nor with values for amplitude in the eye affected by retrobulbar neuritis at the beginning of the disease .EDSS was positively correlated with the total VEP score for both eyes at the beginning of the disease , the VEP score for the left eye , the VEP score for the right eye , latency values for the left eye  and latency values for the right eye .EDSS values were not correlated with amplitude values for the left eye  or for the right eye .The advent of more effective drugs that modify the course of the disease has expanded our choice for the treatment of patients with MS and presents a great challenge for neurologists in deciding on the most appropriate therapy for each individual patient. Everyone agrees that the early initiation of therapy that modifies the natural course of MS is a condition for a favorable outcome with the goal of achieving complete remission. The biggest challenge is to predict the responses to an applied therapy. Early indicators are being sought so that a particular medicament can be replaced by another more effective drug .The expected favorable outcome of treatment NEDA-3 is achieved if the patient shows no worsening of the disease, no progression of physical disability, and no disease activity on the endocranial MRI.As the need to measure the outcome of disease treatment increases, the percentage of patients who manage to reach and maintain NEDA-3 is used to assess the effectiveness of therapy that modifies its natural course . Among oAccording to our results, 58.2% of the patients had ON. It was present in 52.2% of patients in the left eye, 32.6% of patients in the right eye and 5.2% of patients in both eyes. One sign of the demyelination process is the finding of extended VEP latencies with preserved wave amplitudes .When compared to MR, the VEP finding shows greater sensitivity in detecting lesions on the optic nerves. Patients exhibiting ON during the course of MS are more likely to have a pathological VEP finding than the detection of noticeable lesions on the optic nerves by MR . HoweverHowever, the prognostic value of VEP can be assessed using a variety of methods: by predicting the degree of damage to the optic nerve itself and the long-term outcome in terms of visual impairment; by predicting the development of definitive MS in patients with CIS; and by predicting future disability in patients already suffering from MS . CurrentStudies conducted in the 1980s and 1990s indicated a significant association between changes in VEP and the subsequent development of MS, pointing to a 2.5 to 9 times increased risk of developing the disease ,26,27. HAccording to our results, the current degree of disability did not correlate with the values for latency and amplitude in the eye affected by ON at the beginning of the disease nor with the amplitudes in the left and right eye. However, the current degree of disability positively correlated with the total VEP score for both eyes at the beginning of the disease, the VEP score for the left and right eye and latency values for the left and right eye regardless of whether patients had ON or not.The values for the latency and amplitude of VEP in the eye affected by ON at the beginning of the disease were not related to a later higher degree of disability, the frequency of relapse or progression in endocranial MR findings. However, prolonged values of left-sided latency may indicate a higher risk of increased EDSS in the further course of the disease. According to Leocani et al. , the lonSeveral studies that addressed the predictive role of VEP on outcomes in terms of physical disability found a moderate correlation between VEP and subsequent physical disability scores ,31. HerePatients treated with interferon beta 1a had the highest frequency of EDSS score increases (31.8%), while those given interferon beta 1b had the lowest (6.9%). In our previous clinical, observational, cross-sectional study, we showed a lower median value of EDSS in patients treated with interferon beta 1a in comparison with patients treated with interferon beta 1b .A neat left-sided VEP score indicated a four-fold lower risk of increasing disabilities, and the chance of reaching NEDA increased six-fold. Moreover, VEP scores for the left eye as well as latency values for the left eye at the beginning of patient monitoring affected the achievement of NEDA. If the VEP score was higher by 1, the chance of reaching NEDA was reduced three times; if latency values were extended by 1, the chance of reaching NEDA was about 3.4% less.Other studies  suggesteSome Italian authors  showed tIt is difficult at this time to conclude which factors render one of the hemispheres more susceptible to autoimmune damage. Some authors explain this asymmetric distribution of lesions by greater susceptibility for neural and metabolic dysfunctions in the left hemisphere , which mPrevious research has not dealt with variabilities in the findings of left- or right-handed VEP, and this is the first study to address this matter.The findings for VEP can have a significant predictive value for achieving favorable treatment outcomes in patients with RRMS. The VEP score for the left eye, as well as latency for the left eye at the beginning of the disease in patients receiving first-line immunomodulatory therapy, had predictive values for reaching NEDA-3 over several years.


The runoff of the Jiulong River (JLR) is a key parameter that affects the estimation of pollutant flux into Xiamen Bay (XMB). The precise runoff estimation of the JLR can be used to determine the accuracy of the pollutant flux estimation flowing into XMB. In this study, to analyze the hydrological dynamic characteristics and identify the correlation between fixed-site real-time ocean current observations and cross-sectional navigation flow observations, we conducted six navigation observations on two cross-sections of the JLR estuary during the spring tide and neap tide in the normal season, wet season, and dry season in 2020. Simultaneously, we measured hydrological observation data by a fixed-site buoy located in the JLR estuary and collected runoff data that were measured upstream of the JLR. The results showed that the average correlation coefficient between the average velocity of the fixed-point buoy and average velocity of the section was more than 0.90, higher than expected, the minimum average deviation was 4%, and the minimum sample standard error was 5.7%, which was a good result. In this study, we constructed a model for estimating the runoff of the JLR into the sea. The findings demonstrated that Acoustic Doppler Current Profiler (ADCP) online monitoring data were useful to estimate runoff of the JLR with high accuracy, could promote the accuracy of estimated pollutant flux of the JLR’s discharge into XMB, and could provide more scientific and reliable basic data for future load flux estimation research. The environmental pollution of estuaries and bays is an important research topic regarding the interaction between land and sea and is a key issue in the study of global environmental change . In receTotal pollutant control, also known as total pollutant discharge control, total pollution load control, or total pollutant loss control, is a method of pollution control implemented by controlling the amount of pollutants generated by pollution sources within a certain space within an allowable environmental limit, in the comprehensive economic, technological, and social conditions during a specific period of time . This coTotal monitoring is a systematic method that integrates supervision and management, total monitoring, and quantitative evaluation. It has two main parts: water environment quality monitoring and flux monitoring. Conducting research on the online monitoring method of flux into the sea, through real-time monitoring of pollutant discharge and pollutant flux in various regions, this method provides a scientific basis for determining the total amount of pollutant flux in the coastal waters of China. Total monitoring can be used to understand the impact of rivers and other land-sourced pollutants on the coast. The degree of influence of the sea area provides strong technical support for the government in the management of marine environmental protection .The two methods used to calculate pollutant flux are the direct estimation method, based on statistical analysis, and the indirect estimation method, based on numerical simulation. The traditional method calculates the net discharge flow of the exit gate using the monthly average flow of the upstream control station by the corresponding pollutant monitoring concentration to calculate the pollutant flux from the river network into the sea. This statistical method can be used to estimate and analyze the pollutant flux’s changing law and influencing factors. The numerical simulation method includes gridding the study area, simulating physical and biological processes by establishing models, and using the dynamic change process of flow at the estuary. This method uses the water mass obtained from the simulation results of the model to calculate the continuous flux of dynamic changes in real time .The runoff in most estuaries is significantly affected by tides, and the pollutant concentration at the entrance also oscillates back and forth at the estuary with the tide, resulting in obvious changes in pollutant concentration and irregularities. The simple statistical method, of multiplying the net discharge and pollutant concentration, is used to estimate the flux of pollutants into the sea. This method depends on the frequency of water quality monitoring and the frequency of hydrological observations at the estuary.Foster et al. (2000)  observed6, 0.24 × 106, and 0.54 × 106·g km−2·a−1, respectively, which accounted for 14.9%, 24.8%, and 44.9% of the annual carbon flux, respectively. The carbon output during the flood period had a non-negligible contribution to the total annual carbon output of the river. Dong Dehua et al. (1993) [Sun Huiguo et al. (2006)  estimate. (1993)  used samThis previous research showed that the calculation of pollutant flux using traditional statistical analysis methods requires long-term and continuously measured data, the task load and economic cost are significant, and the accuracy and precision of the results obtained are not ideal. The forecasting ability is also limited. Due to the low frequency of routine water quality monitoring at the gate of the Pearl River, the frequency ranges from once in March to once in January, which is similar to European and American countries, and most of the sampling timing is concentrated at low tide. The limitation of frequency means it has been difficult to study the dynamic process of pollutants flowing back and forth under the influence of tides at the entrance through field sampling. Therefore, the pollutant fluxes calculated by traditional statistical methods in previous studies were merely observational. The instantaneous flux at a given time did not represent the true flux into the sea during the entire calculation period.Hu Zhanming et al. 2018)  took the  took thThe discharge of the JLR Estuary into the sea is a key parameter that affects the flux of pollutants in the XMB, and it is an important reference basis for the Xiamen Municipal Government to conduct marine environmental pollution control. Before 2018, the pollutant fluxes into the sea were estimated, based on monthly monitoring data measured at the Beixi and Xixi gauge stations. The contribution of pollution produced in the estuary area and the migration, transformation, and removal process of pollutants during the period were never considered. Therefore, the calculated pollutants in the JLR Basin pass into the sea. This amount reflects a serious error. Wang Weiping (2006) and Zhou Zengrong (2021) ,20 also 8 m3 and an average annual suspended load and sediment content of 0.210 kg/m3. The coordinates of the basin range are between 116°46′55″–118°02′17″ E and 24°23′53″–25°53′38″ N. The basin area is 1.47 × 104 km2, accounting for about 12% of the land area of Fujian Province. Its main stream is composed of Beixi, Xixi, and Nanxi. The Beixi drainage area is 9803 km2 and the Xixi drainage area is 3964 km2. Beixi and Xixi converge in Zhangzhou. Nanxi flows into the Fugong, and finally flows into XMB. XMB mainly includes the west sea area, the estuary of the JLR, the southern sea area, the eastern sea area, and the Tongan Bay area.The JLR is the second-largest river in Fujian, with an average annual runoff of 149 × 10The study area includes the estuary of the JLR, the southern part of the western sea area, and part of the southern sea area. In this study, we carried out observations and collected the ADCP section navigation observation data for two sections along the JLR Estuary, see We took navigation observations once an hour, and it took about 25 min to complete the observation of the two cross-sections each time. The observation time started at 6 o’clock on the observation day. First, we observed and recorded the observation data from point 1 to point 2, completed the observation of section 1 and recorded a set of observation data files of section 1. Then the ship continued to sail from point 2 to point 3, and we recorded the observation data file of section 2. After a break until the next hour, the observation started from point 3 to point 2, and the observation data file for section 2 was recorded. Then, the measuring ship started from point 2 to point 1 and recorded the observation data file for section 1. The ship went back and forth until the end of the same day’s observation work at 18:00. The start time and end time of the hourly navigation observations were generally between 15 min before the hour and 10 min after the hour.The instrument used for cross-section navigation observation was the WHS600 ADCP, by RDI Company . During the measurement, the ADCP was installed on the side of the ship, the sensor probe was placed down about 50 cm below the water surface, and the probe was connected to a notebook computer through the RS232 serial port. We then ran the winRiver software, which is a special software for ADCP navigation flow observation, developed by RDI Company of the United States.ADCP receives and processes the echo signal from the river bottom or the seabed to track the movement of the seabed through “bottom tracking.” As there is no moving suspense on the seabed, the speed measured by “bottom tracking” is the ship speed. The speed measured by ADCP by tracking the movement of suspended particulate matter in the water body is the speed of water flow relative to the ADCP instrument. WinRiver software automatically deducts the ship speed measured by “bottom tracking,” that is, the speed of ADCP’s own movement, which is the absolute speed of water flow movement.The stratification set during ADCP navigation observation was 0.5 m, the time interval of each data ping was 0.65 s, and the effective rate of all data was 98%. Q is flow rate, S is the cross-sectional area of the river mouth, u is velocity vector at a certain point on the river cross-section, ξ is unit normal vector on the track of the observation ship, and ds is the micro-element area on the river cross-section.The ADCP flow calculation method was first proposed by Christensen and Herrick (1982)  and Simpds is determined by the following formula:dz is length of vertical micro-element, dt is time micro-element, bV is vessel speed vector, |bV| is working boat speed , z is vertical coordinate, z is 0 is the river bottom, z is H is the water surface (H is water depth).bV| is determined by the following formula:bxV and byV are the ship’s speed in the x and y directions, and  is the relative position of the ADCP sailing on the horizontal plane, x is in east–west direction, y is in north–south direction.|T is cross-section navigation time, and k is vertical unit vector.The above flow Formulae (1)–(3) can be rewritten as follows:ENSEMBLE is section flow of acoustic wave coverage area at the observation time, ∑Q is sum of flow through the section for flow measurement, The numerical marks on the left section grid are the stratified velocities of each section measured by ADCP flow measurement, and the section without digital marks on the right side is where ADCP did not measure the section. Distance is the straight-line distance of ADCP measured section. The boat in the picture is sailing from left to right. The boat pattern is just a sign, not the direction of sailing. The light beam represents the direction of sound wave sent by ADCP, usually within 20° from the vertical direction. There is no sound wave in the center, and the green color represents the color of the water body.A schematic diagram depicting the principle of ADCP navigation flow observation is shown in In this study, we also monitored and collected fixed-site buoy ADCP online, in the form of hourly current profile velocity and flow direction data. The schematic diagram of the fixed-site buoy ADCP station is shown in The fixed-site buoy was the water quality environmental monitoring buoy of Xiamen Environmental Monitoring Station, which was loaded with Norway AANDERAA Seaguard II-DCP. The main technical indicators were as follows: velocity measurement range 0–3 m/s, accuracy: 0.3 cm/s or ±1.5% FS, resolution 0.2 cm/s. The layer of ADCP current profile was 1 m, the working frequency was 600 kHz, the current measurement accuracy was ±0.25% of the observed value, and the current measurement resolution was 1 mm/s. The time range of the data obtained was from April 2020, to March 2021. In this study, we mainly took data from the same period as the navigation observation for comparative analysis.In 2020, there were six navigation times during which we observed two sections throughout the normal water period, wet season, dry season, spring tide, and neap tide. During the observation period, winRiver software statistically output the observation report, including the main parameters, average velocity, flow direction, total cross-section flow, and cross-section area. In addition, we collected the hourly tide-level data of the Gulangyu marine station, which was 5 km away from the east side of Jiyu Island , and the average value of all profile average velocity in the two sections was 0.37–0.71 m/s (average 0.49 m/s). During the neap tide, the maximum value of all profile average velocity of the two sections observed three times, during the wet, normal, and dry seasons, was 0.44–0.74 m/s (average 0.57 m/s), and the average value of all profile average velocity was 0.28–0.52 m/s (average 0.38 m/s). The maximum value of the section profile average velocity during the spring tide was 1.42 times that during the neap tide, and the average value of the section profile average velocity was 1.29 times that during the neap tide. The velocity was affected mainly by the tidal range. The statistics of the measured tidal level data showed that the ratio of the maximum tidal range of the spring and neap tides was 1.50:1.3/s , and the average value was 13,855–23,268 m3/s . During the neap tide, the maximum discharge of section 1 was 15,226–19,293 m3/s , and the average was 9498–16,113 m3/s . The maximum section discharge during the spring tide was 1.42 times that during the neap tide, and the average section discharge was 1.32 times that during the neap tide.On the basis of the statistical results of the discharge of the section, according to the classification of the spring and neap tides, the maximum value of the discharge of section 1, during spring tide, was 21,784–34,005 mAccording to the classified statistics of the wet, normal, and dry seasons, the maximum velocity of the ebb tide in section 1, during spring, was 0.88 m/s in the wet season (July 2020), 0.95 m/s in the normal season (April 2020), and 0.98 m/s in the dry season (November 2020). The maximum velocity ratio of the spring tide, section 1, in the wet, normal, and dry seasons was 1:1.08:1.11. The tidal range ratio in the corresponding period was 1:0.87:1.19.According to the classified statistics of the wet, normal, and dry seasons, the average value of the maximum velocity of the ebb tide in section 1, during the neap tide, was 0.74 m/s in the wet season (July 2020), 0.62 m/s in the normal season (April 2020), and 0.57 m/s in the dry season (November 2020). The maximum velocity ratio of spring tide, section 1, in wet, normal, and dry seasons, was 1:0.84:0.77. The tidal range ratio in the corresponding period was 1:0.58:0.81.Similarly, the ratio of the average value of the maximum velocity of the spring and ebb tides of section 2 was 1:13:1.04, and the ratio of the average value of the maximum velocity of the neap and ebb tides of section 2 was 1:1:0.87. The ratio of the maximum value of the discharge of spring tide, section 1, was 1:1.10:1.26, and the ratio of the maximum value of the discharge of neap tide, section 1. was 1:0.76:0.70. The ratio of the maximum value of the discharge of spring tide, section 2, was 1:1.13:1.10, and the ratio of the maximum value of the discharge of neap tide, section 2, was 1:0.93:0.78.The statistical data showed that the characteristics of wet, normal, and dry seasons during the neap tide conformed to the general law that the maximum velocity and discharge of the section were greater in the wet season than in the normal season, and greater than in the dry season. No such law applied during spring tide, and the maximum velocity and discharge of the section were larger in the dry season because of the larger tidal range, indicating that the maximum velocity and discharge of the section were affected mainly by tide, rather than by season.The maximum average velocity of the spring tide was 0.76–0.90 m/s (average 0.83 m/s), and the maximum vertical average velocity of the neap tide was 0.49–0.70 m/s (average 0.58 m/s). The maximum vertical average velocity of the fixed-site buoy in the spring tide was 1.43 times that in the neap tide.The maximum velocity in the wet season was 0.76 m/s, the maximum velocity in the normal season was 0.84 m/s, and the maximum velocity in the dry season was 0.90 m/s, which also showed that the velocity was affected mainly by the tide, rather than by the season.2 was greater than 0.90. The correlation formulae and correlation coefficiente between tide level and section area of section 1 and section 2 were as follows:1 is the cross-sectional area of section 1 (m2), S2 is the cross-sectional area of section 2 (m2), and TL is the tide level (cm).We drew the tide level and the section area of section 1 and section 2 into an XY point aggregation diagram in Microsoft Excel software and added the trend line, as shown in 2 was greater than 0.90. The correlation formulae and coefficients between the average velocity of section 1 and section 2 and the discharge of section were as follows:Q1 is the total discharge (m3/s) of section 1, Q2 is the total discharge (m3/s) of section 2, u1 is the average flow speed (m/s) of section 1, and u2 is the average flow speed (m/s) of section 2.We drew the average flow velocity and total discharge of sections 1 and 2 into the XY point aggregation diagram in Microsoft Excel software and added the trend line, as shown in u1 is section 1 average flow speed (m/s), u2 is section 2 average flow speed (m/s), and bV is the vertical average velocity of ADCP current profile of fixed-site buoy (m/s).We drew the vertical average velocity of the fixed-site buoy and the average velocity of the two sections in Microsoft Excel software and added the XY point aggregation diagram with the trend line for correlation analysis, as shown in Method 1:Q1 is section 1 total discharge (m3/s), Q2 is section 2 total discharge (m3/s), bV is the vertical average velocity of the current of the fixed-site buoy (m/s), and TL is the tide level (cm).Using the formula “total discharge of section = average velocity of section × section area”, we replaced relevant Formulae (9) and (10) to calculate the average velocity of both sections and the measured tide level with relevant Formulae (5) and (6) to obtain the tide level and section area of section 1 and section 2, as follows:Method 2:Q1 is section 1 total discharge (m3/s), Q2 is section 2 total discharge (m3/s), and bV is the vertical average velocity of the current of the fixed-site buoy (m/s).By substituting correlation Formulae (9) and (10) between the average velocity of the two sections and the velocity of the buoy ADCP current profile with correlation Formulae (7) and (8) between the average velocity of section 1 and section 2 and the total discharge of section, the following could be calculated:Q1 (the discharge of section 1) was very close to the calculated value of relevant Formulae (11) and (13), and the measured value Q2 (the discharge of section 2) was very close to the calculated value of relevant Formulae (12) and (14). As shown in the figures, the overlap of the two curves was very good. The average values of relative error were section 1 (Formula (11)): 7.4%, section 1 (Formula (12)): 8.4%, section 2 (Formula (12)): 7.6%, and section 2 (Formula (14)): 14.9%. The mean square deviations were 5.7%, 6.3%, 5.7%, and 8.0%, respectively. It can be seen that Formulae (11) and (12) in method 1 had fewer errors and higher accuracy and could be used as the recommended formula for subsequent research and calculation.In this study, we calculated the discharge of the two sections during the observation period using the correlation formula between the fixed-site vertical average velocity and the section discharge. We compared the measured discharge during six observation periods with the calculated discharge, and the relative deviation percentage value was given, as shown in In this project, to study the runoff and circulation of the JLR into the sea, we adopted the method of one representative site in the south of Jiyu Island, combined with the navigation observation of two sections. As this representative site was located in the mainstream area of the waterway in the south of Jiyu Island and had good representativeness, the correlation between the representative vertical average velocity and the discharge on the section was good. Thus, the correlation Formulae (11)–(14) established in this paper can be used. The discharge of the section was calculated according to the vertical average velocity of the buoy observed in real time, and then the real-time pollutant flux of the section was calculated along with the pollutant concentration monitoring data.The tide current reverse period between the north and south sides of Jiyu Island, was different near the high-level and low-level tides. The current direction on the north side of Jiyu Island was still the direction of rising tide, and the current direction on south side of Jiyu Island turned to the direction of falling tide. To improve the calculation accuracy of the discharge of this section, we set a representative observation site on the north side of Jiyu Island for profile current observation. The Haicang port area on the north side of Jiyu Island is a large-scale ship berthing and turning water area, and dredging is often required. Therefore, it was not suitable to set a sea buoy or seabed-based ADCP in the main channel area of the port area to conduct long-term real-time online detection. We did set H-ADCP at an appropriate position along the shore of the wharf berth for horizontal section observation ,23,24,25


The mechanical strength, thermal stability, thermal performance, and microstructure of Qtech T26 blast mitigation polyurea (T26 polyurea) were studied using quasi-static and dynamic mechanical experiments, thermogravimetric experiments, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) experiments, and contact explosion and non-contact explosion experiments with polyurea-coated reinforced concrete slabs. Additionally, the energy dissipation mechanism of the coating was analyzed. The blast mitigation ability and blast mitigation mechanism of T26 polyurea-coated reinforced concrete slabs were investigated by analyzing the macroscopic morphology of reinforced concrete slabs with or without coatings and the contact explosion simulation of polyurea-coated reinforced concrete slabs. The results showed that T26 polyurea exhibited a certain strain rate effect. Its initial thermal decomposition temperature reached 286 °C, and its thermal stability was good. After carbonization, carbon slag can form and adhere to the structural surface. The glass transition temperature Tgs of the soft segment was −44.9 °C, and the glass transition temperature Tgh of the hard segment was 36.5 °C, showing a certain amount of microphase separation morphology. After the explosion test, there was a small pit on the front surface of the coated reinforced concrete plate, and there was no damage on the back surface. The integrity of the plate was good. The uncoated reinforced concrete slab had a large crater on the front of the explosion surface, and the back of the explosion surface experienced explosion collapse, concrete crushing, and an overall loss of stability. The numerical simulation results showed that the failure mode of the coated plate was consistent with the test. The kinetic energy conversion rate of the uncoated reinforced concrete plate was 87.27%, and the kinetic energy conversion rate of the coated reinforced concrete plate was 95.36%. The T26 coating improved the kinetic energy conversion rate of the structure and improved the blast mitigation ability of the reinforced concrete plate structure. Polyurea is a kind of polymer material formed by the rapid cross-linking of isocyanate components and amino compounds that has excellent mechanical properties ,2 and whIn addition, the good blast mitigation effect of polyurea in explosion protection is closely related to its excellent mechanical properties and strain rate effect . ThroughGiven the limitations of the field explosion test, other relevant research is based on the use of ANSYS/LS-DYNA software for numerical simulation. Amini  used numPolyurea protective coating has been studied in terms of anti-explosion, but there is little analysis on the influence of the performance of polyurea material on its blast mitigation. The explosion process is complicated. The explosion will produce high temperatures and strong shock waves that are scattered around. In the explosion protection, the coating material should not only withstand the high temperature and high heat, but also resist the tensile and tearing effects caused by the explosion loads. Therefore, the thermal properties and mechanical properties of coating materials are the basic conditions for their blast mitigation effect. In this regard, for blast mitigation, T26 polyurea was selected in this paper. Starting with the characteristics of the material, the basic mechanical properties and thermal properties of T26 polyurea at different strain rates were studied to understand the molecular stability of T26 polyurea at high temperatures and predict the blast mitigation ability of the material. On this basis, through the contact explosion test and non-contact explosion test of T26 polyurea-coated reinforced concrete slabs and the numerical simulation of reinforced concrete slabs with or without polyurea coating under contact explosion, the damage of reinforced concrete slabs with or without polyurea coating was compared, and the energy absorption and energy dissipation characteristics of T26 polyurea under explosion load were analyzed. The microstructure and the failure mode of the cross-section of T26 polyurea coating after the explosion were observed. The failure mode of the coating under explosion load was studied to verify the blast mitigation ability of T26 polyurea.−3 and has the characteristics of low density, as shown in T26 polyurea is a kind of blast mitigation polyurea material optimized via the traditional polyurea formula. The density of T26 polyurea is below 1 g · cmThe concrete strength grade was C40 with the reinforcement spacing at 150 mm and the diameter at 10 mm, while the protective layer thickness was 15 mm and the size of the reinforced concrete slab was 1000 mm × 1000 mm × 300 mm. The reinforcement was as shown in Good adhesion between the T26 coating and the concrete substrate is crucial. Before spraying, an epoxy-modified polyurethane primer should be applied to the surface of the substrate . The seaReinforcement concrete slabs sprayed with T26 were, after seven days of maintenance, placed on the restraint frame. The explosion pit had a side excavation depth of 0.5 m and a width of 0.7 m on the back explosion surface, and explosives with a TNT dosage of 1.4 kg were placed on the upper surface of the reinforced concrete plate for the explosion test. The schematic of the experimental setup is shown in −1, 0.01 s−1, and 0.1 s−1. The tensile test was carried out until the samples were broken.The T26 polyurea samples were cut into a dumbbell shape using a tablet punching machine  and 1.4 nm (1 kV), the acceleration voltage is 0.1–30 kV, the electron gun uses a tungsten filament lamp, and the magnification is 25–1,000,000 times.ANASYS software was used for the modeling, and LS-DYNA software was used to calculate the model. Calculation models included steel bars, concrete slabs, explosives, air, and polyurea materials. A Lagrange grid and hexahedral element were used in the model grid. The fluid–solid coupling algorithm (ALE) was used in the grid, and the non-reflective normal boundary conditions were set at the boundary. The polyurea material was modeled using a shell element, the steel was modeled using a beam element, and the concrete slab was modeled using a solid element. In addition, the coating and concrete automatically had single-sided contact, and the common node model was used between steel and concrete. The reinforced concrete slab model size was 1000 mm × 1000 mm × 300 mm, and the bottom had fixed support using double reinforcement. The explosive was a cylindrical TNT with a radius of 50 mm and height of 110 mm, and the dosage was 1.4 kg. The air was evenly divided into 1.5 cm grids.After establishing the model of contact explosion between uncoated and T26-coated reinforced concrete slabs in ANSYS, the output file was set as an LS-YDNA file format. The relevant parameters in the output file were modified, including coating thickness and output time, and the coating thickness was 10 mm, the output time was 1000 μs. The modified file was post-processed in LS-YDNA software to obtain the relevant simulation results.For polyurea, the elastic-plastic model named MAT_PIECEWISE_LINEAR_PLASTICITY  was usedJohnson–Holmquist–Cook model  was usedThe reinforcement model was MAT_PLASTIC_KINEMATIC . It is aThe air was described by the MAT_NULL material model and linear polynomial state equation EOS_LINEAR_POLYNOMIAL. The air model parameters are as shown in The explosive model was MAT_HIGH_EXPLOSIVE_BURN, and the EOS_JWL equation of state was selected. The detailed parameters of the above material model can be found in the LS-DYNA user manual . The exp−1 to 0.1 s−1, the stress of the material increased with the increase in the strain rate. Thus, T26 polyurea showed a good strain rate effect at a low strain rate.The stress–strain curves of T26 polyurea at a low strain rate are shown in −1 was higher than that at the strain rate of 11.37 s−1. The accurate stress–strain curves of T26 polyurea were nonlinear at a high strain rate. With the increase in true strain, the true stress increased, and when the strain rate increased, the true stress also increased, indicating that T26 polyurea presented a good strain rate effect. T26 polyurea showed good mechanical strength at a high strain rate. Therefore, during the explosion, the material can continuously improve its strength to resist explosion shock load and enhance the blast mitigation ability of the composite structure with the increase in explosion load strength.The strain rate effect of the material under a high strain rate was further studied. The true stress-strain curve of the material under a high strain rate was obtained by filtering the data collected by the acquisition instrument, as shown in The DSC curve of materials in the temperature range from 30 °C to 700 °C is shown in The explosion environment is a high-temperature environment, which requires the high-temperature adaptability of materials. The TG and DTG curves of T26 polyurea coating are shown in In addition, it can be seen from the DTG curve in The failure modes of uncoated reinforced concrete slabs after contact explosion are shown in The failure modes of the reinforced concrete slabs coated with T26 after contact explosion are shown in The failure modes of the reinforced concrete slab coated with T26 after the explosion with an explosion distance of 50 mm are shown in The T26 polyurea coating after explosion damage was divided into section area I, explosion source center area II, and coating edge area III, and the coatings in the three regions were cut for microscopic morphology observation, as shown in The micro-morphology of T26 polyurea coating was enlarged by 4000 times in different regions after the explosion. The surface of the section area was torn in different degrees, the shape of the damage was scaly, the surface arrangement was disordered and uneven, and there were more tearing layers and a small amount of brittle failure. It can be seen that the polyurea coating melted in some areas under the high temperature caused by the explosion, and the strong shock wave caused the tensile failure of the polyurea coating. At the end of the explosion, the instantaneous decrease in temperature led to the transformation of polyurea from a highly elastic state to a glass state, and the broken polyurea solidified into flakes attached to the surface of the section, as shown in The stress nephograms of the front, back, and side of the uncoated reinforced concrete plate at time t = 1000 μs are shown in The stress nephograms of the front, back, and side of the coated reinforced concrete plate at time t = 1000 μs are shown in In summary, a T26 polyurea coating can improve the blast mitigation ability of reinforced concrete slabs, which played a key role in the blast mitigation protection of reinforced concrete slabs. The numerical simulation and explosion test damage diagram of T26 polyurea are shown in 5 J. Additionally, the kinetic energy change trend of the coated reinforced concrete slab was similar, and when the time t = 29.96 μs, the peak value was 2.12 × 105 J. Compared with the uncoated reinforced concrete slab, the peak of kinetic energy shifted and decreased by 65.42%, indicating that the presence of coating absorbed part of the energy and weakened the kinetic energy of the reinforced concrete slab, as shown in 5 J. Although the internal energy of the coated reinforced concrete slab changed little, showing a trend of increasing first and then decreasing slightly, the maximum absorption of internal energy was 3.26 × 105 J. In summary, the explosion shock energy was greatly attenuated after passing through the T26 coating. The coating can reduce the kinetic energy and internal energy of the reinforced concrete slab by absorbing a large amount of the energy generated by the explosion, and ultimately improved the ability of the reinforced concrete slab to resist the explosion.An explosion can instantly produce high temperatures and strong kinetic energy that is spread around in the form of waves that penetrate reinforced concrete slabs to cause local or overall damage. When the blast wave propagates from the face surface blast of the reinforced concrete slab to the back blast surface of the reinforced concrete slab, the main failure modes of the plate are explosion pits, explosion collapse, explosion penetration, and explosion punching ,24. The In order to further explore the energy absorption of the T26 coating, the kinetic energy, internal energy, and kinetic energy conversion rate of the face surface blast coating, back blast surface coating, and the reinforced concrete slab were shown in (1) Compared with uncoated reinforced concrete slab, the T26-coated reinforced concrete slab had a minor damage degree and higher structural integrity under a 1.4 kg TNT explosion load, and the T26 polyurea had significant explosion protection ability.(2) The explosion protection forms of the coating of the face surface blast and back blast surface were different. The T26 coating on the face surface blast was melted and perforated under explosion load. After melting, the coating formed a surface of carbon slag attachment, which played a role in coating and heat insulation. The T26 coating prolonged the action time and dissipation time of the explosion load by absorbing the energy of the explosion shock wave. By coating the concrete structure, the back blast surface coating restrained the explosive debris to resist the residual shock wave and reduced the secondary damage.(3) In terms of energy conversion and dissipation, the kinetic energy and internal energy of the uncoated slab were larger than those of the coated slab under the same explosive load. The kinetic energy conversion rate of the uncoated reinforced concrete slab was 87.27%, and that of the coated reinforced concrete slab was 95.36%. The T26 coating improved the kinetic energy conversion rate of the structure and dissipated part of the kinetic energy into internal energy, thus weakening the transfer of explosive energy and improving the blast mitigation ability of the reinforced concrete slab structure.


To investigate the high-temperature heat flow’s destructive effect of solid slow-release energetic materials on a steel target, we prepared a sample of solid slow-release energetic materials, eruption devices, and a complete test system to conduct the destruction of high-temperature heat flow on the steel target. In addition, we proposed the energy density to characterise the high-temperature heat flow performance and numerically simulated the destructive effect of the high-temperature heat flow on the steel target. The numerical simulation results were in good agreement with the test results, and the error between them was under 8.5%. Based on the test and simulation results, the steady-state melting model of the steel target was established under the action of high-temperature heat flow. Moreover, a time-varying model of the melting hole shape was found. The results showed that the model of destroying the steel target with the high-temperature heat flow of solid slow-release energetic materials was highly accurate. Therefore, the model could provide theoretical guidance for designing and applying solid slow-release energetic materials in ammunition destruction, metal cutting, the simulation of the laser thermal effect, etc. Solid slow-release energetic materials are a new kind of energetic materials synthesised by the composite treatment of fuel or oxidants . BecauseWhen solid slow-release energetic materials are applied in different fields, some requirements exist for the destructive effect between high-temperature heat flow and the steel target. In the area of waste ammunition destruction, it is required that the melting hole should form quickly when high-temperature heat flow acts on the metal of the projectile body. The gas generated by the combustion of the internal charge can be smoothly discharged so that the ammunition charge’s DDT (deflagration to detonation transition) can be avoided. When disposing of spent munitions, the standard methods used are combustion destruction, explosive destruction, and the decomposition of munitions ,10. Yi JThe focus of the research on the combustion energy release behaviour of solid slow-release energetic materials lies in the study of its formula and manufacturing process, so the destructive effect between the high-temperature heat flow and the target is rarely studied ,19,20,21The eruption device made of 45# steel is shown in 3)2 in tests 1–5 were 22%, 24%, 26%, 28%, and 30%, respectively, and the throat size of the eruption device was 50 mm, aiming at controlling the high-temperature heat flow temperature, velocity, and combustion chamber pressure. The throat diameters in tests 6–10 were 40, 45, 50, 55, and 60 mm, respectively, and the content of Ba(NO3)2 was 26%, aiming at controlling the effective diameter of the high-temperature heat flow.We carried out ten tests in a dedicated test site, and the main instruments were the high-speed camera, thermocouple, manometer and infrared cameras, etc. Based on the previous research basi, and the relevant theories and literature ,20), we , we 20])In Test 3, the beginning time (0 s) of combustion was set when the sample had just ignited and emitted a bright white light. As seen in The high-speed and infrared camera images at the moment of the highest heat flow temperature of Tests 2 and 5 are shown in 3)2 played a dual role as an oxidising and gas-producing agent in the samples, when the content of Ba(NO3)2 increased from 22% to 26%, both the maximum temperature of the heat flow and the maximum pressure of the combustion chamber increased at different degrees. When the content of Ba(NO3)2 was excessive, part of Ba(NO3)2 completely reacted with Al powder, and the remaining Ba(NO3)2 decomposed under high temperature and the pressure to produce more oxygen and nitrogen. In addition, Al powder underwent a combustion reaction with the oxygen released by Ba(NO3)2 and the absorbed heat. As the amount of Ba(NO3)2 and Al powder was fixed in the formula; the higher the content of Ba(NO3)2, the less the proportion of Al powder and the less apparent the endothermic effect. Therefore, when the content of Ba(NO3)2 was under 26%, the combustor pressure and the high-temperature heat flow velocity increased with the rise of the content of Ba(NO3)2. With the increase of Ba(NO3)2 content from 26% to 30%, the maximum temperature, maximum pressure, and maximum velocity decreased to varying degrees. This phenomenon indicated that the mass proportion of Al powder decreased, leading to an insufficiency of the primary energy source of the reaction. There was an optimal allocation ratio of each test in the sample (Al:Ba(NO3)2 = 26:24). Increasing or decreasing the content of any component reduced the heat flow energy. The authors also believed that adjusting the oxide and metal powder content could control the heat flow temperature [The maximum temperature increased from 1845 °C at 22% to 2429 °C at 26%, then dropped to 1987 °C at 30%. These temperature values were similar to those of (about 2000 °C) [To uniformly characterise the performance parameters of the high-temperature heat flow generated by the samples, such as the heat flow velocity, heat flow temperature, and pressure of the combustion chamber, the concept of high-temperature heat flow energy density and calculation Formula (1) were proposed for the first time, representing the internal energy contained in the high-temperature heat flow acting on the unit area within a unit of time.We used energy density to characterise the properties of heat flow. The quantitative calculation of this concept required using three primary parameters: combustor pressure, heat flow temperature, and heat flow propagation velocity, so we considered three points. The maximum heat flow velocity, maximum temperature, maximum combustor pressure, and energy density of 10 tests are shown in The state of the Q235 steel targets before and after the tests is shown in 2), corresponding to the most severe damage to the steel targets. The steel targets of Tests 2 and 4 had different degrees of depression. The steel targets of Tests 1 and 5 only showed a slag hanging phenomenon. Perforations occurred on the steel targets of Tests 6–10. See The thickness of each Q235 steel target was 10 mm, and the diameter was 30 mm. WRN thermocouples were arranged at 0, 30, and 50 mm from the centre of the steel target. In Tests 6–9, the effective heating diameters and the perforations also correspondingly increased with the increase of the throat diameter of the eruption devices. The diameters of the perforations were similar to those of the throat. In Tests 6–10, the diameter of the throat positively correlated with the heat flow’s action range. With the increased action range of heat flow, the effective action area on the target plate also expanded, so the diameter of the weld hole increased. From the images recorded by the high-speed camera, it could be calculated that the time of heat flow melting through the steel targets was about 4.5–6.2 s, so the average penetration speed was about 1.61–2.22 mm/s. However, the perforation’s diameter on the front of the Test 10 steel target was 58 mm, much lower than that of the eruption device’s throat (66 mm). One of the reasons for this was that on the premise of keeping the inlet diameter, the outlet diameter and total length of the nozzle did not change, and the larger the throat diameter, the smaller the convergence ratio and the size of the convergence section. The more the expansion length increased, the greater the loss of high-temperature heat flow energy and the more the energy density decreased. Therefore, as shown in In fluent, we set the metal jet flow and high-temperature gas phase as continuous and the unburned solid particles as discrete. Based on the VOF and DPM models, the numerical simulation of temperature rise, melting, and deformation of solid materials under high-temperature heat flow was realised by stratifying the target plates. The simulation’s initial and boundary conditions were based on the data obtained from the tests, as shown in A numerical simulation was carried out based on the data from Test 8. The temperature distribution of the heat flow is shown in The velocity distribution of heat flow acting on the steel target is shown in Compared with the test results, the front perforation was 54.6 mm, which increased by 8.5%; the back perforation was 50 mm, which increased by 4%. The average penetration velocity was 2.17 mm/s, which increased by 2%. The simulation results were generally in good agreement with the test results. The reason for the error was that the velocity and temperature of high-temperature heat flow were inputted as the maximum value, and the value was constant. Therefore, the numerical simulation results were slightly larger than the test results, and the error was less than 8.5%.mL: the latent heat of melting; mt: the time at which melting started.Assuming that the density of the steel target did not change, the solid-liquid interface condition of the model could be obtained as follows:mU and the position mZ of the solid–liquid interface were obtained as follows:The moving velocity mU: melting rate; A: absorption rate; sC: the specific heat capacity of the steel target; mT: the melting temperature of the steel target; mL: the latent heat of melting; sk: thermal conductivity.Combined with the temperature field of the steel target without phase transition under the action of high-temperature heat flow, the temperature field To obtain the melting hole shape of the steel target at a particular moment was equal to getting the penetration depth of the point whose energy density is higher than the critical energy density at that moment . Then, i0, x data, and y data), where x and y data are the original data points; fun  is the fitting function; x is the coefficient of the fitting function; x0 is the coefficient’s initial guess; and its initial setting may affect the result. If the fitting result is not ideal, the initial value x0 can be changed and then fitted again. Moreover, the relationship between the heat flow and the radial distance of the steel target was obtained as follows:Based on the energy density distribution of Tests 7–9, the centre of the steel target was taken as the coordinate origin, and the energy density of the heat flow was extracted every 5 mm. The distribution of the high-temperature heat flow within its effective diameter is shown in The damage model of heat flow on the steel target mainly included the relationship between penetration depth with time, that is, the penetration velocity of the steel target by heat flow and the change of the melting hole shape over time.The heat flow penetration velocity on the steel target’s central axis in the 7th, 8th, and 9th tests was extracted. The test results were compared with the theoretical results, as shown in The error of the theoretical calculation results was under 8% compared with those of the test results, which proved the accuracy of the theoretical calculation. Therefore, the steady-state melting model could accurately describe the damage process of the steel target caused by heat flow.Based on the energy density distribution obtained in test No. 8, with the centre of the steel target as the coordinate origin, the calculation points were extracted every 2 mm. The penetration depth of these points was obtained at t = 2 s, t = 4 s, t = 6 s, and t = 8 s. Using Matlab, the depth of the melting hole was fitted into the contour maps and compared with the simulation results, as shown in The blue and red lines are the fitting and testing results, respectively. The time-varying melting hole shape obtained by the theoretical calculation was highly consistent with that of the simulation, which proved that the theoretical model had high accuracy.(1)A complete combustion and energy release test system for solid slow-release energetic materials was designed, and the test parameters such as combustion time, combustor pressure, high-temperature heat flow velocity, and temperature were obtained. The high temperature-heat flow performance could be accurately quantified by the energy density and calculation formula proposed in this paper.(2)The high-temperature heat flow had a significant energy loss when the diameter of the eruption device’s throat was larger than 55 mm.(3)The numerical simulation of the heating and deformation process of solid materials under the impact of fluid materials was carried out in fluent, and the model of high-temperature heat flow of gas–liquid–solid coexistence was realised. We simulated the heating and penetration processes of the steel target under the action of high-temperature heat flow. The numerical simulation results were in good agreement with the test results, and the error between them was under 8.5%.(4)Based on the steady-state melting model, we calculated the penetration velocity of high-temperature heat flow on the central axis of the steel target. The results error between the test and model calculation was under 8%. The distribution function of the energy density of the high-temperature heat flow on the radial direction of the steel target was fitted with Matlab to obtain the time-varying model of melting hole shape. The comparison between the calculation results of the model and the simulation results showed that the model’s accuracy was high.


The diverse types of cage-free systems require an understanding of the differences between them in terms of the welfare of the laying hens. One of the methods for assessing the welfare of laying hens is an assessment based on the plumage condition. In the conducted study, the plumage condition of laying hens raised in various types of alternative (non-cage) housing systems was assessed, i.e., in deep litter, free-range, and organic systems. The study included hens of the native Green-legged Partridges (Z-11), Rhode Island Red (R-11) hens covered by a genetic resource protection program, and hybrids of Hy-Line Brown at 20, 36, and 56 weeks of age. The type of cage-free system implemented had an effect on the condition of the plumage in the laying hens. Smaller losses of plumage were found in hens raised in free-range and organic farming conditions than in the litter system. As the age of the birds increased, the condition of the hens' plumage deteriorated. Rhode Island Red hens were characterised by the best plumage condition in litter housing conditions, while the native Green-legged Partridge hens showed the best plumage condition in the free-range and organic systems.2. The study included hens of the native Green-legged Partridge breed (Z-11), Rhode Island Red (R-11) hens covered by a genetic resource protection program, and hybrids of Hy-Line Brown. The plumage of the head, neck, back, tail, and abdomen was assessed on a 5-point scale. The assessment of individual hens' plumage was calculated as the sum of the scores of the head, neck, back, tail and abdomen and could range from 0 (no cover) to 20 points (full plumage). The type of alternative housing system implemented and the age of the laying hens had an effect on the plumage status of all body parts assessed (p < 0.05), while the genotype had an effect on the condition of the neck, back, and tail plumage (p < 0.05). In both the FR and O systems, the plumage status was similar and superior to that in B (p < 0.05). As the age of the birds increased, the condition of the hens' plumage deteriorated. The better state of the plumage in FR and O than in B may indicate improved levels of welfare in housing systems with access to outside runs.The study covered a total of 810 hens in 3 groups (housing systems) of 270 hens each. The plumage condition of laying hens raised in various types of alternative housing systems, i.e., in deep litter (B), free-range (FR), and organic systems (O), was assessed at 20, 36, and 56 weeks of age. The indoor stocking density was 6 hens/m In accordance with the Council Directive 1999/74/EC . ImproviDifferent scoring systems are used to assess the condition of plumage . The resThe prevalence of different types of alternative housing systems in contrast to cage systems raises the question of whether the welfare of laying hens in all types of alternative housing systems is the same. Therefore, the aim of the study was to assess the effect of the type of alternative housing system on the plumage condition of the Z-11 native breed of laying hens, R-11 hens covered by a genetic resources protection program, and Hy-Line Brown commercial hens.As the study did not involve any experimental manipulation or invasive procedures, it did not require the approval of an ethics committee. The study was conducted in Poland (EU) at the Experimental Station of the National Research Institute of Animal Production. The study covered a total of 810 hens, raised in 3 different alternative housing systems: deep litter (B group), free-range (FR group), and organic (O group). In total, 270 hens were allocated to each housing system, including 90 (3 subgroups of 30 pcs.) hens of the native breed of Green-legged Partridge hens (Z-11), 90 (3 subgroups of 30 pcs.) hens of the Rhode Island Red (R-11) breed covered by a genetic resources protection program in Poland, and 90 (3 subgroups of 30 pcs.) commercial Hy-Line Brown hybrids. Hy-Line Brown laying hens had their beaks trimmed at 10 days' age using the hot blade method. 2. FR hens were kept in a henhouse with windows (ratio of window surface to floor surface 1:15) on deep litter with free access to grassy runs. The population in the henhouse was 6 hens/m2, while 4 m2 were allocated for each hen in the run. The hens of the O group were kept in accordance with the provisions on organic farming, i.e., Directive EC 1804/1999 [2) with free access to a grassy run, with a density of 1 hen per 5 m2. In the FR and O henhouses, the hens had free access to the run through 40 × 45 cm openings located on the long wall of the building, from 6:00 to 20:00. The lighting program in the henhouse was the same for all groups and included 16 h of light and 8 h of darkness (16L:8D). During the period when the natural day was shorter than 16 h, daylight was supplemented with artificial light. In each of the assessed raising systems, the henhouses were equipped with round feeders, nipple drinkers, and nests. During the study period, the average temperature inside the henhouse was 15.1 ± 1.8 °C and on the outside run 13.5 ± 2.0 °C at 20 weeks of age, −2.4 ± 4.1 °C at 36 weeks of age, and 22.7 ± 1.9 °C at 56 weeks of age of the hens, respectively. The breeding, hatching, and rearing up to the 16th week was carried out at the Experimental Station. The reared chicks were, in their 17th week, moved from their rearing rooms to the buildings where they were maintained throughout the entire period of use. Hens in each of the studied housing systems  were kept in a separate building belonging to the same experimental farm. Each henhouse was divided into compartments. B birds were kept in a henhouse with windows (window to floor ratio 1:15) on deep litter without access to an open-air run. Hens from the FR and O systems had free access to paddocks from 18 weeks of age. At 20 weeks of age, the average weight of R-11 hens was 1560 g, Z-11 1240 g, and Hy-Line Brown 1650 g. The population in the henhouse was 6 hens/m804/1999  and Regu804/1999 . The henBirds from the B and FR groups were fed ad libitum with a balanced diet for laying hens , and hens from the OS group were fed ad libitum with organic fodder for poultry .2); 2 points for incomplete cover, bare patches ≥ 5 cm2; 1 point for cover with significant losses but with several areas still covered (bare patches >5 cm2); and 0 points for total lack of cover. The assessment of the plumage of the whole body of a single hen was the sum of the ratings of the head, neck, back, tail, and abdomen and could range from 0 (no cover) to 20 (full plumage) points.In total, 30 laying hens (3 subgroups × 10 hens) were randomly selected from each genotype  at 20, 36, and 56 weeks of age from each genotype for the evaluation of plumage status. Layers were 20 weeks old by autumn (September), 36 weeks old in winter (January), and 56 weeks old in early summer (June). At each time point, 270 laying hens (3 systems × 3 genotypes × 3 subgroups × 10 hens) were individually evaluated from each system. The state of the plumage was assessed for hens randomly picked from their individual compartments (subgroups). In order to avoid repeated assessments of the same birds, the assessed layers were placed in a separated part of the compartment for the duration of the assessment using an openwork or mobile partition, which was removed after the assessment of all birds was completed. The plumage condition of the five body parts was assessed on an ordinal 5-point scale developed and modified based on the LayWel project . The folThe assessment of the condition of plumage was carried out by 3 evaluators. All evaluators participating in the study were trained during previous pilot studies. The estimation of the assessor’s level of compliance (inter-rater reliability) was verified by Cohen's kappa coefficient. The compliance rates obtained were above 0.75.p < 0.05.The obtained data were collated and subjected to statistical analysis using Statistica 13.3 . The resData on the effect, housing system, genotype, and age of laying hens on the plumage state were subjected to a multifactorial analysis of variance, and the main effects were determined  as well as the interaction between factors . The influence of the genotype, housing system, and age on the plumage status of hens was analysed using ANOVA, and in the analysis of the results, the following data were taken into account: the 3 systems  × 3 genotypes (Green-legged Partridge hens (Z-11), Rhode Island Red (R-11), Hy-Line Brown) × 3 subgroups × 3 ages of the hens  × 5 body parts  × 10 hens.p < 0.05), while the genotype had an effect on the condition of the neck, back, and tail plumage (p < 0.05).The results of the scoring of the plumage condition  of the hens , aged 20, 36, and 56 weeks, raised in various types of alternative housing systems  are included in p < 0.05) on the quality of the cover at 36 and 56 weeks of age was found, while the effect of the housing system on the state of the cover at 20 weeks of age of the laying hens was not confirmed (p > 0.05). The condition of the plumage in the free-range and organic systems at weeks 36 and 56 was similar and better than in the deep litter hens  or almost full (≥3.77). At the next assessment date, i.e., at 36 weeks of age, larger losses of plumage were recorded in all breeds observed, which to varying degrees covered all assessed areas of the plumage . At the In the initial period in the FR system, i.e., in the 20th week of life, the plumage of the head and neck of the hens of the assessed breeds was full (4 points), while in the area of the tail and back, there were small losses in the Z-11 and R-11 hens, while in the Hy-Line Brown hens, plumage losses were also found on the abdomen. At the next assessment date, i.e., at 36 weeks of age in hens of all observed breeds, the loss of plumage was greater than at 20 weeks. The largest losses of plumage were found in the Hy-Line Brown hens, which covered all the examined areas of the plumage. At week 56, the plumage status of all breeds assessed improved compared to the plumage at week 36 . In the initial period, i.e., in the 20th week of life in the O system, the plumage in hens of all assessed breeds was full or almost full, i.e., with small losses of feathers in the area of the tail (Z-11), or neck, back, and tail (R-11 and Hy-Line Brown). At the next assessment date, i.e., at 36 weeks of age in hens of all observed breeds, the loss of plumage was greater than at 20 weeks. The worst condition of the plumage at week 36 was found in the Hy-Line Brown hens and the best in the Z-11 hens. At week 56, the plumage status of all breeds observed improved compared to the plumage at week 36 . p < 0.05), while in the O system no effect of the genotype was found on the plumage status of the laying hens (p > 0.05). The influence of the age of the laying hens on the condition of the feather cover in all types of housing was noted. The results of the assessment of the whole-body plumage of a single hen  are presented in p < 0.01). The largest losses of plumage were observed in hens raised in the B system , the laying hens were characterised by a good plumage condition, which, however, deteriorated at 36 weeks of age and with further deteriorated at 56 weeks in the laying hens raised on litter. As many authors point out ,76,77,78The better condition of the plumage in free-range and organic system conditions than in the deep litter system without access to a run may indicate a higher level of welfare in the free-range systems than in housing systems without access to an outside run. In both the free range and organic systems, hens of the Z-11 native breed and those of the R-11 breed covered by the genetic resources protection program were characterised by better plumage conditions than the commercial hens, which may indicate their better adaptation to free-range systems.With age, the state of the hens' plumage deteriorated in all systems studied; however, in the free-range and organic systems, the pace of changes was lower than in the housing system on deep litter. The results obtained indicate that prevailing weather conditions or seasons may have indirect effects on the plumage, but this requires more extensive research.


Samples resulting from the heat treatment of the geopolymer paste were subjected to mechanical tests and SEM, EDS and XRD analyses. Samples were obtained using 6 molar and 8 molar NaOH solution with and without the addition of Fe2O3 and MgO. Samples obtained using a 6 molar NaOH solution where Fe2O3 and MgO were added had higher mechanical strengths compared to the other samples.The use of waste from industrial activities is of particular importance for environmental protection. Fly ash has a high potential in the production of construction materials. In the present study, the use of fly ash in the production of geopolymer paste and the effect of Fe The geopolymer acquires its strength by creating long networks of three-dimensional chains, leading to the initial use of a large amount of capillary H2O, followed by its expulsion once a suitable bond can form.“+HWorldwide, in the general study on the production of geopolymer binders, there are still a number of controversies or insufficiently clarified elements, as their mechanical strengths and other physical-mechanical performances are strongly influenced by the oxide composition of the main raw materials and additives, the type and molarity of the alkali activators, the existence or not of heat treatment. From the point of view of the oxide composition and other characteristics of the raw materials, depending on their origin, there is a great heterogeneity, which is the main difficulty in the production of geopolymer binders, the customization of the mixtures by the mass ratio of raw materials and the molarity of the alkaline activator, from case to case, being essential.2O3 and MgO additions and the molarity of the NaOH solution on its mechanical strengths, under the conditions of using a local fly ash, specific for Romanian thermal power plants.The aim of this paper is to analyse the possibility of producing geopolymer binders and the influence of Fe2O3), magnesium oxide (MgO), sodium hydroxide solution  and sodium silicate solution Na2SiO3 34%.The raw materials used in this study for producing alkali-activated geopolymer pastes were selected locally and consisted of fly ash (F.A.), iron trioxide  with Na2O3, MgO and the molarity of the NaOH solution, 1% Fe2O3 and 1% MgO was added to the amount of ash used. This addition of Fe2O3 and MgO was done for both a NaOH solution molarity of 6M and a molarity of 8M.Four geopolymer paste mixtures were prepared and investigated, two with NaOH solution (6M) and two with NaOH solution (8M). The mass ratio of sodium silicate solution to sodium hydroxide solution was set to 2, and the solution mass to dry mass ratio was 0.9. The proportions of substances used for the preparation of the four recipes are shown in The literature indicates the possibility of using NaOH solution for the preparation of alkaline activator, with various molarities, to obtain geopolymeric materials. For economic and environmental impact reasons, but also to create a basis for preliminary analysis for further research, using NaOH solutions with higher molarity, in this study the 6M and 8M variants were chosen.2O3) in relation with mass ratio of fly ash and 6M NaOH solution molar concentration used for the production of the alkaline activator, showed that, in terms of mechanical strengths, as the amount of Fe2O3 increased, they decreased by up to 3.3%. Therefore, for further research, 1%, in relation to the amount of ash, was considered as the optimum addition of Fe2O3.Preliminary investigations carried out only with the addition of 1%, 5% and 10% iron trioxide . Therefore, for further research, 1%, in relation to the amount of ash, was considered as the optimal addition of Fe2O3 and 1%, in relation to the amount of ash, as the optimal addition of MgO.Similarly, for the sodium hydroxide solution with 6M molar concentration, the compressive strength of the samples produced using 1% FeBased on preliminary results obtained for the situation using 6M NaOH solution, the hypothesis of preservation of the trend of evolution of the compressive strength in the variant using 8M NaOH solution was verified. The negative influence of excess addition of oxides was also observed, so the mixtures presented in Crystal structure analysis of the layers was performed by X-ray diffraction (XRD) using a high-resolution Brucker D8 diffractometer with copper anode (CuKα1 = 1.54056 Ǻ). X-ray diffraction (XRD) was used to estimate structural and microstructural properties.Morphological and microstructural characterization was performed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS)). A JEOL JSM 5600 LV  high-resolution scanning electron microscope (SEM) equipped also with an electron back-scattered diffraction detector (EBSD) was used in the present work.The evolution of a three-dimensional shrinkage phenomenon was observed during the 7 days of specimen conditioning, prior to testing in terms of mechanical characteristics, and the shrinkage was evaluated as a volume reduction in relation to the initial volume (40 × 40 × 160 mm). Uniaxial bending and compressive strength were measured using the Advantest 9 testing machine .Flexural strength was determined using the three-point bending test (3PB) in accordance with EN 196-1. A digital flexural strength tester suitable for loads up to 10 kN (±10%) with a loading rate of (50 ± 10) N/s was used. The testing machine is provided with a bending device consisting of two steel support rollers with a diameter of (10 ± 0.5) mm, arranged at a distance of (100 ± 0.5) mm from each other and a third load roller, placed centrally.The compressive strength of the specimens was determined in accordance with EN 196-1, using the compression test of the prismatic specimen halves resulting from the three-point bend test (3PB). The compressive loading rate used was 50 N/s (0.12 MPa/s). Samples were tested at 7, 14 and 28 days of age.Experimental testing was carried out under laboratory conditions, ensuring compliance with repeatability and reproducibility requirements.2O3 and MgO oxides and the molarity of the NaOH solution used for the preparation of the alkaline activator on the physical-mechanical performance of the geopolymer material. From the beginning, a volume shrinkage of the tested specimens between 1.5% and 5.0% was recorded. This can be attributed to the water content in the mixture, which is directly influenced by the molarity of the NaOH solution, water that is removed in the heat treatment process.The experimental results show both the influence of the addition of Fe2O3 and added MgO have a higher strength than the control samples. For example, for a 6M molarity of NaOH solution, the sample (6MX1) containing 1% Fe2O3 and 1% MgO added to the ash used, has a flexural strength of more than 69% compared to the sample (6M) containing no additional elements, at 7 days, over 110% at 14 days and over 80% at 28 days. Similarly, but less obvious, for a molarity of 8M NaOH solution, we have an increase in the bending strength of the 8MX1 sample of 1%, 7% and 12% at 7, 14 and 28 days, respectively. The flexural strength of sample 6MX1 has the highest value compared to the other samples. Although the molarity of the NaOH solution for sample 8MX1 is higher than that of sample 6MX1 the bending strength of sample 6MX1 is higher by more than 15% at 28 days.Analysing The evolution of the compressive strength of the samples obtained at different test intervals is shown in 2O3 and 1% MgO added to the ash used has a compressive strength more than 11% and 15%, respectively, 19% higher than the sample (6M) not containing these additional elements, at the age of 7, 14 and 28 days.It can be seen that the compressive strength for all samples increases with the age of testing. It is also observed that for a molarity of 6M of NaOH solution, the sample (6MX1) containing 1% Fe2O3 and 1% MgO was added or not (increase of less than 1% for ages 14 days and 28 days after casting). The most significant increase in compressive strength due to the addition of iron and magnesium oxides in the case of 8M NaOH solution molarity is recorded early, at the age of 7 days after casting (4%).The evolution of the compressive strength of the samples obtained using a NaOH solution of molarity 8 is almost identical whether 1% Fe2O3 and MgO acting as inactive granular fillers by the presence of unreacted phases  in the geopolymer specimens [The compressive strength of sample 6MX1 at the test age of 28 days has the highest value being more than 37% higher than samples 8M and 8MX1. The increase in compressive strength can also be attributed to the microcrack filling effect of Fepecimens .The increase in mechanical strength, with the increase in molarity of the NaOH solution used in the preparation of the alkaline activator, could be attributed, in addition to the maturation in time and the completion of the geopolymer reactions, to the contribution of Na+ ions and OH- groups provided by the alkaline activator. Thus, in accordance with the literature, with references on the main steps of the geopolymerization mechanism, it is appreciated that both Na+ ions and hydroxyl groups play an important role in the dissolution and hydrolysis processes, breaking the bonds existing in the Si and Al source raw materials, contributing to produce Si-O-Al bonds, bonds known as geopolymer precursors . More spQuantitatively analysing the results obtained in terms of the mechanical strengths, it can be said that they are in agreement with some specifications in the literature and even exceed other reported results, This is due to the fact that geopolymer materials are very sensitive to the physical and chemical characteristics of the raw material, which is the reason why there are situations when mixtures, which although prepared with the same NaOH solution molarity, but using fly ash with different chemical/oxide composition or grain size  or situations where the solution is prepared from NaOH flakes or pearls, the physico-mechanical performances are very different .As can be seen from The SEM micrographs for samples 8M and 8MX1 shown in The literature states that in EDS analysis for Si/Al ratio between 2.39 and 2.84 and for Na/Al between 0.34 and 0.53, respectively, the major reaction product is formed by alkaline hydroaluminosilicates of the zeolitic type in which Ca incorporation is also assumed. Additionally, for sufficiently high Si/Al ratio of 2.49 and a fairly high Na/Al ratio of 2.27, a carbonate variety of sodium and calcium hydroalumino-silicates is obtained . Based o2O3 is unreacted are noticed, which functions as a crack filler, while this could be a possible explanation for both the improvement in compressive strength and the macroscopic reddish colour identified in the tested specimens.Analysing 2O3 and MgO being higher, both for both molarity of the NaOH solution used in the preparation of the alkaline activator. This trend is also considered to be a possible explanation for the higher mechanical strengths in the samples recorded for samples prepared with the addition of oxides.Analysing the ratio of the identified concentration of Fe and Al, respectively, Na, according to the values presented in Analysing the X-ray spectra for samples 6M and 6MX1 in 2O3 and MgO, no major differences in terms of the crystallization angles are identified , periclase (MgO) and forsterite (MgFeSiO4) mineral phases is observed in the X-ray spectrum [Analysing entified . On the spectrum , which iFrom the study, it can be stated that iron trioxide, magnesium oxide and the molarity of the sodium hydroxide solution used in the preparation of fly ash-based geopolymer paste influence the physico-mechanical properties of the obtained heat-treated samples.The bending tensile strength and compressive strength of the 6MX1 sample  had higher values compared to the other samples. This observation can be interpreted as a signal that for the specific case of fly ash with the oxide composition shown in This increase in mechanical strengths can be explained by the action of iron trioxide which causes the formation of ferro-sialate groups and by the action of magnesium oxide which reduces the shrinkage of the sample. Additionally, the lower molarity of the hydroxide solution results in a less energetic reaction and fewer pores in the sample.SEM micrographs reveal areas with fewer pores and fewer cracks for samples obtained with lower molarity of sodium hydroxide solution and smaller pore size, provided, however, that sufficient Na+ and OH− ions are available to allow good dissolution and extraction of Al and Si atoms from the raw material.2O3 and MgO leads to a preferential crystallization directive especially for quartz.XRD analysis shows the presence of quartz, calcite, feldspar and mullite in samples obtained with a molarity of 6 of sodium hydroxide solution, and quartz and feldspar in samples obtained with a molarity of 8M. The formation of these elements is also influenced by the type of ash used and its chemical composition, and the addition of Fe-The hardness of the crystallites as well as the specific crystallization system directly influences the compressive strength of the material;-In the crystallite contact zone, for the crystallite combinations identified in the geopolymer material prepared with 6M NaOH solution, the cohesive energy would be higher than the cohesive energy specific to the intercrystallite contact zone of the geopolymer prepared with 8M NaOH solution.Identifying quartz , mullite , feldspar  and calcite , the following is estimated:The layered EDS images and the provided data reveal that in the case of the studied samples  the majority reaction product is formed by zeolitic-type hydroaluminosilicates and with slight tendencies to form carbonate varieties of sodium and calcium hydroaluminosilicates. Iron trioxide and magnesium oxide are also observed to have a microcrack filling effect, i.e., they act as inactive granular fillers.The mechanical strengths of the samples obtained, comparable to Portland cement, justify the use of these geopolymer pastes in the production of geopolymer concretes and in the production of precast concrete. Results obtained in the current study are in accordance with results previously obtained in the literature, while completing the knowledge about the production of alkaline-activated geopolymer materials ,73,74,752O3 and MgO, respectively, and the influence of the molarity of the NaOH solution used in the preparation of the alkaline activator, on the mechanical strengths of the geopolymer binder prepared using locally sourced fly ash. Based on the obtained results, the following conclusions can be drawn:The compressive and flexural strength of the 6MX1 specimen is higher than the other specimens .SEM micrographs reveal areas with fewer pores and fewer cracks for samples obtained with lower molarity of sodium hydroxide solution and smaller pore size.XRD analysis shows the presence of quartz, calcite, feldspar and mullite in samples obtained with a molarity of 6M of sodium hydroxide solution, and quartz and feldspar in samples obtained with a molarity of 8M.The EDS data show that the major reaction product is formed of zeolitic-type hydroaluminosilicates with slight tendencies to form carbonate varieties of sodium and calcium hydroaluminosilicates.2O3 and MgO to a geopolymer improves its physico-mechanical properties.The addition of FeThe aim of this experimental study was to investigate the influence of the addition of Fe-The chemical, oxidic and mineralogical composition of the raw material used (flz ash) is specific only to the main source from which was provided and, according to the literature, has a major influence on the physico-mechanical characteristics of the geopolymer matrix;-The NaOH solution used to prepare the alkaline liquid was prepared with local raw materials;-Although some specifications in the literature analyse the influence of Fe and Mg oxides on the performance of geopolymer materials, in this case, these oxides do not represent the input of the basic raw material (fly ash), but are introduced as a controlled addition;-The mix-design ratio and production technology are obtained following the analysis of literature but customized to the availability of resources and equipment. It is known that reproducibility is strongly influenced by the particularities of the materials and production techniques.This paper contributes to the research developed so far worldwide on alkali-activated geopolymer materials with the following:All these specific elements represented both challenges and risks, but also elements of novelty in the development of the experimental programme.In the future, it is important to determine the optimum molar concentration of the NaOH solution used for the preparation of the alkaline activator and the optimal temperature range for obtaining samples with higher mechanical strengths.