The water footprint values obtained were compared with other mines with similar operations. These results generate a baseline for decision making, providing elements for environmental strategic planning, regulations and showing the great environmental pressure that gold activity exerts on water resources and the territories.This research deepens the analysis of the mineral water footprint, especially that of gold, in regions that are understudied and where mining has been an intensified extractive activity since the colonial era, as is the case in the northern part of department of Cauca in Colombia. Thus, the purpose was to estimate the water footprint indicators in gold mining in Suárez , to quantify the impacts generated by the non-returned water in the production process and the levels of pollutants in the wastewater, aimed to strength public policies, control strategies and mitigation that generates reductions in the impacts from mining activities on the environment. The blue water footprint was estimated in 79.91 m •Assessment of water footprint of gold production in Suárez .•3 per kg of gold extracted.Gray water footprint was found to be in the range of 272,125.39 to 404,825.11 m•The gold production had much larger gray water footprint than blue water footprint.•Gold mining activity requires important management by environmental authorities and polluting agents. Cyanide, Mercury, Mining, Water use. However, the distribution of water is not homogeneous across the Colombian territory, and the outlook is troubling due to excessive human pressure from population growth and, above all, by the recent specialization of Colombia's economy towards primary sector production, which uses water intensively [Seventy-one percent of the earth's surface is covered by water; however, less than 1% of the planet's potable water is suitable for human consumption , and firensively .In Colombia, the largest water consumers are the agricultural, energy and livestock sectors, which constitute 76.6% of the domestic total water use. According to official records, the mining sector demands 1.8% of total domestic water consumption. Considering that 82% of gold production is alluvial-type exploitation (direct exploitation of the riverbed), of which 95% corresponds to illegal mining , and thabarequeo (panning) and the remaining 4.4% came from special reserve areas and scrap recovery. The production level in 2017 was 34% lower than that in 2016, which may be explained by the implementation of control measures by the Colombian authorities on illegal mining [The productive dynamics of the gold mining sector in Colombia increased approximately 6% annually on average from 2000 to 2017, driven by an increase in the international price of gold. In 2017, production totaled 46.2 tons, of which 48.5% was reported to have been mined from areas with mineral titles, 47.1% was reported as production from There does not seem to be any indication that gold will cease to play a key role in the medium- or long-term as an international source of value, nor is there a viable substitute for its role as an essential component in new technological industries, which is why a constant demand persists for this scarce resource , implyinwww.ejatlas.org), Colombia is also one of the countries with the most reported cases of environmental conflicts, where mining, and especially gold mining, stands out. This situation is explained by the promotion of an extractive model by recent governments, particularly since 2000, accompanied by the increase in international gold prices that have generated a boom and uncontrolled exploitation to the detriment of the environment [In fact, Colombia's water sources have one of the highest levels of mercury contamination in the world . Accordiironment .In this sense, to quantify the impact generated by human activity on water and in the context of such concepts as ecological footprint, carbon footprint and virtual water flows, the concept of the water footprint (WF) emerges , 15, whiENA-National Water Study 2014" [3/year, with a projection of 948.3 Mm3/year by 2022. Unfortunately, this study did not apply the methodology of the water footprint for this sector, with only the blue water footprint indicator being estimated for the petroleum mining subsector, which yielded a value of 6.6 Mm3/year [In the "dy 2014" , it was Mm3/year .3/year up to 3,650.06 Mm3/year [water is more valuable than gold” in non-monetary standards of value [Detailed studies on the analysis of the mineral water footprint are scarce in Colombia. One of the few existing studies was conducted in the mining municipality of Segovia , where a gray water footprint indicator was estimated for the gold mining activity in various scenarios, yielding values from 870.45 MmMm3/year . The ordof value .Therefore, it is appropriate to deepen the analysis of the mineral water footprint, especially that of gold, in regions that are understudied and where mining has been an intensified extractive activity since the colonial era, as is the case in the northern part of department of Cauca (Colombia). Thus, the present study estimates the water footprint indicator for gold mining in the municipality of Suárez , referencing the Water Footprint Assessment Manual  and the 2The article is based on data retrieved from primary sources. It is inevitable that any error in these sources may influence the outcome of this analysis. However, the data has been checked with other sources  and is sufficiently consistent for the analysis.The information base used for the research was consulted in the Colombian Mining Information System , which c2.13/s average flow rate at La Salvajina dam discharge), with annual precipitations in the zone that varies between 2000 and 3000 mm.The mining district of El Tambo-Dovio, which includes a large part of the department of Valle del Cauca and part of the north of the department of Cauca, is located in the south-western part of Colombia. In this district, mining products are extracted, such as limestone, construction materials, coal, gold, silver, platinum, among others . Specifi2 [The geographical scope of the study was limited to the area of gold mining in Suárez , where the exploitation of gold is mainly done in primary deposits. In the case of alluvial mining, data from the deposits in the Ovejas river, Cauca river, Inguitó river, Quebrada Saladito and Quebrada San Martin , 22, 24 From the geological point of view, the gold in Suárez (Cauca) is in the stock of Pasobobo-Damián which has hydrothermal deposits associated with copper and gold porphyries of dacitic and andesitite composition  emplaced in oceanic affinity basaltic rocks . The allIn 2.1.1In the inventory of mineral processing plants, 24 plants or processing sites were identified, of which 19 correspond to plants located in the primary deposits and 6 are sites of alluvial mineral exploitation . It shouAmalgamation with mercury is a process where the concentrated mineral is mixed with mercury to form an amalgam . Subsequently, the amalgam is burned to evaporate the mercury and recover the gold and silver in its metallic form. This process is highly inefficient because only a fraction of the gold, approximately 30% of the potential to be extracted, is recovered. In small-scale mining, the owners of the independent gold processing sites typically retain the wastes from the amalgamation as payment from the miners for the use of the equipment; these wastes or tailings are subsequently cyanided to extract the remaining gold .The cyanidation process consists in a leaching stage, where the cyanide dissolves the metallic gold in the form of a gold-cyanide complex, thus allowing it to be separated from sand, rocks and other minerals. Subsequently, two techniques may be used to reverse the process in the liquid solution, converting gold from its concentrated gold-cyanide form to metallic gold. The first consists of the precipitation of metallic gold promoted by the addition of zinc, a technique that is widely used in Colombia; the second is the electrodeposition of gold in an electrolytic cell that requires other prior processes of concentration and a higher technological degree, and although this technology is the most widely used worldwide, it is not applied in Colombia .For the exploitation of alluvial ores, it was considered that the extraction was done with mini dredges or backhoes; the crushing and sorting was carried out manually without mechanical aids, and the refinement of the gold was carried out by artisanal techniques (gravimetric concentration) and mercury amalgamation in channels or buckets.The inventory was provided by the Colombian Geological Services, and the database is considered a secondary source, thus the possibility of measurement, misclassification or selection bias are not excluded. Onsite verification of the mines operation was not possible due to public order problems in the zone. Is recommend for future studies to obtain a remote sensing analysis for small-scale gold mining of the region.2.2The water footprint (WF) methodology is widely used in the study of hydrographic basins or specific geographic areas in a defined time scale, accounting for water consumption and pollution throughout different anthropogenic activities. The methodology of this study is based on the four phases described in the "The Water Footprint Assessment Manual"  and the The WF of a product is composed of: i) Direct WF (DWF), which refers to water consumed and contaminated in all the production stages and; ii) Indirect HH (IWF), which refers to water consumed and contaminated in the production of goods and services used in the production stages . Where wIn this case, the indicators were calculated with the water flows and pollutant quantities estimated from the inventory described in The calculations and assumptions used for each of the variables studied are explained in the following lines.2.2.1In the primary ore extraction plants, the number of tons per day of crushed or primary material in a mine was calculated, considering that 1 hydraulic hammer has a crushing capacity of 2.5 ton/day and 1 drum of 0.4 ton/day . With thIn the case of alluvial deposits, data from the Corporación Autónoma Regional del Cauca (2006a)  were use2.2.2The amount of gold extracted with a purity of 75%  was calculated by multiplying the crushing capacity of each mine by the average grade, which for alluvial deposits is 10 g/ton and for primary deposits is 15 g/ton . The resIn the case of alluvial deposits, data from the Corporación Autónoma Regional del Cauca (2006a) were used, where the grams of gold extracted per day for each location are reported.2.2.3The amount of gold reported in the official records of the Mining and Energy Information System  correspo2.2.4Water inflow at the mine was estimated by multiplying the specific water consumption required by each type of beneficiation process  by the t2.2.5The water outflow or discharge rate was calculated considering that for the different types of beneficiation process, most of the processing water is returned to the natural water source from which it is collected, and there is a percentage of water that does not return, remaining contained in the moisture of the sludges and sands processed in the primary ore mines. These sands are accumulated in piles with a water content between 9 and 17% , 24, 29.For the alluvial mines, where the processed sands and sludge are discharged back into the river, the discharge rate is equal to the inflow rate.2.2.6In the amalgamation process of primary ore mining, an average of 27.5 g of mercury  per gram of recovered gold are used .For the alluvial deposits, the reported use value of 20.0 g of mercury per gram of gold recovered was used, using the backhoe extraction method and beneficiation by amalgamation in open-flow gutters .2.2.7Method 1 considered the study by Ruíz Solano (2016), where the discharges were characterized and a material balance for mercury was performed in a small-scale primary ore mining plant in Cauca, where gold is extracted through an amalgamation process in a semi-closed cycle. In this study, a discharge was estimated in the liquid effluent of 3.38% of the mercury used in each cycle. Likewise, there are losses due to volatilization of 1.64% of the initial mercury in each cycle, which evaporates during the burning of the amalgam and constitutes a source of air pollution .For the alluvial deposits, the reported value of 0.31 g of mercury released to the soil, atmosphere or water per gram of gold recovered in alluvial mines in the semi-closed cycle for the mining area of the municipalities of Buenos Aires and Suárez was used . This va2.2.8For the primary deposits, the reported value of 7.7 g of mercury released to the soil, atmosphere or water per gram of gold recovered in the open cycle for the mining area of Buenos Aires and Suárez was used .For the alluvial deposits, the reported value of 15.5 g of mercury released to the soil, atmosphere or water per gram of gold recovered in alluvial mines in the open cycle for the mining area of Suárez was used .These values were corrected with a factor of 66%, considering that of the total mercury emissions, approximately 66% corresponds to the discharge in the liquid effluent .2.2.93 of solution is used. To calculate the use of CN, an average value of 3.75 kg of sodium cyanide per m3 of solution was used. This value was multiplied by the volume (in m3) of the cyanidation tanks of each plant.According to the Mining-Environmental Assessment of the Suárez Mining District , in the 2.2.10A cyanide analysis performed by the Colombian Geological Service on cyanide-poor solutions at three mineral processing plants in Buenos Aires and Suárez showed that on average, this effluent had a concentration of free cyanide of 1.5 g/l . This va2.2.113/year; 3/year; and BWF is an indicator of the consumptive use of water, which corresponds to fresh water extracted from a surface water body or from groundwater for the development of a productive or extractive activity . In this2.2.123/year; 3; 3/year; 3; 3; 3; and GWF is an indicator of the degree of contamination of fresh water associated with the productive or extractive process. It is defined as the volume of fresh water (from an uncontaminated source) required to dilute the pollutant loads produced by the production process until the concentration of water contaminants reaches the natural conditions of the source and the existing water quality standards . In thisIn the case of pollutants such as cyanide or mercury, which do not come from the water entering the mine as all discharge is due to the activity performed inside the mine, the GWF may be calculated according to the following modification of The maximum allowable concentration of CN discharge is 1 mg/l, and Hg is 0.002 mg/l for gold extraction activity, according to Resolution 0631 of the Ministry of the Environment and Sustainable Development.For the calculation of the GWF of each processing plant or site of exploitation, it was considered that the CN and the Hg discharges were performed in independent effluents even if a mine had both cyanidation and amalgamation processes.Note that one of limitations of the water footprint methodology applied to highly polluting activities such as mining can lead to gray footprint calculation to be infinite due to strict maximum allowable discharge concentration of pollutants.3Based on the mine sample from 3.13/kg of gold, which is higher than the values reported in Segovia (Antioquia) – 58.69 m3/kg of gold [3/kg of gold [3/kg of metal production was calculated for a plant in South Africa with large-scale mining operations that extracted precious metals from the platinum group . For the BWF indicator, there is a greater incorporation of water in the production processes in large-scale mining operations compared to small- and medium-scale mining operations due to modernization, which includes a greater number of refining stages and auxiliary services, such as refrigeration, cleaning and hydraulic transport, among others, that increase the water consumption per kg of metal produced.The BWF indicator was estimated at 79.9 m of gold  – and in of gold . Both mi3/year; however, these estimations are only comparable between mines or mining sectors with an equal or similar capacity of gold production and with similar extraction technologies; due to the limited number of studies on the subject, these results could not be extrapolated at the national level.2) and a population  similar to the municipality of Suárez , a BWF in the domestic sector of 40 m3 per inhabitant per year is equivalent to a total of 644,040 m3/year. The BWFs of other sectors in Colombia, such as the hydroelectric (24 Mm3 per year), livestock (12 Mm3/year) and agricultural (14 Mm3/year) sectors, are reported for the total Porce river basin. A study by Pérez et al. (2017), which estimated the BWF for fish farming in Colombia, reported the following BWF for three types of fish farms in the department of Valle del Cauca: 2.0 m3/kg for tilapia, 0.8 m3/kg for Blackfin Pacu and 0.1 per kg for trout. From the analysis of the different BWFs, it can be inferred that gold mining, compared to some of the cases observed in other sectors, is an activity that retains a relatively high quantity of blue water. Thus, the extraction of 1 kg of gold retains two times more water than the domestic use of one person in a year, and between 4 to 14 times the amount of water required to obtain 1 kg of farmed fish.Given the lack of estimates of water footprint indicators at municipality level in the department of Cauca, we proceeded to compare measurements with values of BWFs reported for other sectors in other municipalities in Colombia. For example, the evaluation of the Water Footprint in the Porce river basin  reported3.23/kg of gold was estimated for method 1 and 404,825.1 m3/kg of gold with method 2. In method 1, the amalgamation stage is performed in a semi-closed process with a higher percentage of recycled mercury; therefore, mercury contamination (Hg) represents only 7% of the GWF and the balance is due to cyanide (CN). In method 2, mercury is not it is not reused, thud 37% of the GWF corresponds to mercury contamination.For the base case GWF indicator , two metThe amalgamation process is prohibited in Colombia due to the toxic and bioaccumulable nature of this heavy metal, which damages the brain, kidneys and testes, causes neurodevelopmental and behavioral delays, subtle damage to visual memory, attention and speed deficits in visual responses, attention deficit, hearing and psychomotor damage, severe skin inflammation, irritation of the gastrointestinal tract, severe hepatic damage and progressive and generalized paralysis of the extremities, among other problems . The ColThe contamination by cyanide contributes the most to the calculation of the GWF because the cyanidation technique is used in the Suárez plants with greater crushing capacity. It is important to note that cyanide contamination has a short-term effect and is not bioaccumulable (with the exception of some complexes) because it can be partially degraded by the sun's ultraviolet radiation ; howeverIn general, tailings from the gold industry may be classified into the following types of waters: (1) waters with mercury due to hauling of amalgam, elemental mercury and other chemical compounds formed with mercury during processing; (2) residual cyanide waters from the process of precipitation with zinc and acid waters; and (3) products from the dissolution of metals and other compounds washed away by rainwater in excavation piles and debris. In most cases, this last type of water is mixed during the extraction process. In the present study, the first two types were calculated.3 of water per kg of gold extracted for the processes of amalgamation and cyanidation in small- and medium-scale mining operations in Segovia, Amalfi, Anorí, Remedios and Zaragoza (Antioquia). This difference is explained by the fact that in Suárez, 50% of the processing plants base their production exclusively on gravimetric methods without using toxic chemicals such as cyanide or mercury, whereas for the group of municipalities in Antioquia, the estimations were performed with the use of mercury in all gold extraction plants, which helps explain the fact that municipalities such as Segovia have the greatest number of cases of mercury poisoning in Colombia [The values estimated in this study are lower than those of the study by the CTA (2013), which calculated the GWF of gold mining to be 1.5 MmColombia .3/kg of extracted metal. Thus, it is important to highlight that the legal nature of large-scale mining implies the enforcement of environmental regulations is more rigorous and greater controls are placed on the discharge of effluents.In contrast, when comparing the GWF reported for a large-scale mining plant in South Africa (of platinum)  the GWF 3/year), resulting in values on the order of tens of Mm3/year. This does not consider the impact generated after the closure of a mine and the subsequent management required for the tailings or wastes of the mining process, which contain a high concentration of toxic substances that are not included in the GWF calculations of the large-mining sector because they are discharged and stored inside the mine and not discharged to external bodies of water. This is known in legal-environmental language as environmental liabilities.However, in large-scale mining operations, the quantities of extracted metal are measured in tons per year, in contrast to kg per year for small- and medium-scale mining operations; this results in a large impact when calculating the annual GWF , which yielded GWF values between 870.45 Mm3/year and 3,650.06 Mm3/year. However, gold production in this municipality was in the range of 1.7–5.5 tons for the years of the study, which represents an order of magnitude higher than the gold production in Suárez.3/s [3/year) required to dilute contaminated gold production water to a comparative quality of the water flowing in the Cauca river; in other words, for the highest values estimated in methodologies 1 and 2, 15% and 22% of the total river flow rate, respectively, is required to dilute the pollutants to safe levels . This constitute a red flag alert for cities like Cali (2.5 millions of inhabitants) and other municipalities (approximately 10 millions of inhabitants) downstream Suárez, whose drinking water source is mainly the Cauca river, where mines discharge their tailings.The annualized GWF values in Suárez, using both methodologies, represent a critical environmental situation due to the large quantity of clean water  a BWF of 303.9 Mm3.3•Implement strategic environmental planning throughout the country to limit and, in many cases, prohibit gold mining activities in territories and areas that are highly fragile, of ecosystemic importance and culturally diverse as well as areas that provide water for human consumption such as tropical dryland forests, mangroves, wetlands and, in general, ecosystems and strategic territories for the conservation of biodiversity, and health of the population and that provide environmental and cultural services.•Implement the mercury elimination plan in Colombia. Effectively controlling sources of illegal importation of mercury into the country.•Take advantage of new trends in consumer awareness for cleaner processes that result in lower environmental impacts but acknowledging that "green gold" is not feasible in any of the cases.•Support technological conversion processes through mining training centers in those populations involved in this economic activity. Facilitate the transformation of medium-scale mining, from amalgamation plants to cyanidation plants, with adequate tailings management, thus achieving reductions in GWF.•Encourage unions and associations between small-scale miners by developing models that support coexistence between organized groups of small-scale miners and medium- and large-scale mining stakeholders and allowing productive synergies such as the processing of material collected by small-scale miners in medium- and large-scale industrial plants.•Carefully implement gravimetric concentration processes, which, although they do not use toxic inputs, can lead to an increase in suspended solids in water that, upon reaching rivers or other bodies of water, can decrease the availability of food for fish and reduce the absorption capacity of light in riverbeds, generating imbalances in aquatic ecosystems . Future •Promote a green tax on gold extraction that applies to exports or the extractive activity itself. This should be aimed at financing technological conversion, promote research in this field and the construction of wastewater treatment plants.From the results obtained, strategies and proposals for the gold mining sector were formulated, which may be applied in areas influenced by small- and medium-scale mining operations, such as Suárez. The proposed strategies and recommendations are as follows:43/kg of gold extracted and the GWF ranges between 272,125.39 and 404,825.11 m3/kg of gold extracted. These values confirm the high impact of gold mining on water bodies caused predominantly by contamination from cyanide (93–63%) and mercury (7–37%), whereas the incorporation of water in the mining process (BWF) is moderately high compared to other productive sectors.In this study, an approximation was made to calculate indicators of the water footprint of gold mining in the municipality of Suárez , determining that the BWF is 79.91 mMeasurements of the water footprint of gold mining in this small population of Colombia enlighten an analysis of the environmental impacts and true economic importance of this precious metal, in which a process for replacing the current demand for gold in all its markets must be identified, either as a sumptuary good, store of value or raw material for new technologies. Only a paradigm shift will permit societies to assign greater importance to the conservation of environmental heritage over uncontrolled exploitation by the mining industry. In the process of such changes, this analysis allows strategies and proposals to be formulated for the gold mining sector, among which are the implementation of strategic environmental planning throughout the country gold mines and advancing the technological conversion for total elimination of the use of mercury.Christian E. Alvarez-Pugliese: Conceived and designed the experiments; Performed the experiments; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data; Wrote the paper.Fiderman Machuca-Martínez: Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data; Wrote the paper.Mario Pérez-Rincón: Conceived and designed the experiments; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data; Wrote the paper.Minciencias (669/2014).This work was supported by Data included in article/supplementary material/referenced in article.The authors declare no conflict of interest.No additional information is available for this paper.


Enterobacter sp. UOM 3 and Pseudomonas hunanensis IB C7 led to an increase in the length and mass of roots and shoots and the leaf surface index, and an improvement in some parameters of the elements of the crop structure, which were suppressed by the pollutant. The most noticeable effect of bacteria on the plant hormonal system was a decrease in the accumulation of abscisic acid. The data obtained indicate that the introduction of microorganisms weakened the negative effects on plants under abiotic stress caused by the presence of oil. Plant-bacteria associations were more effective in reducing the content of hydrocarbons in the soil and increasing its microbiological activity than when either organism was used individually.Much attention is paid to the relationship between bacteria and plants in the process of the bioremediation of oil-contaminated soils, but the effect of petroleum degrading bacteria that synthesize phytohormones on the content and distribution of these compounds in plants is poorly studied. The goal of the present field experiment was to study the effects of hydrocarbon-oxidizing bacteria that produce auxins on the growth, biochemical characteristics, and hormonal status of barley plants in the presence of oil, as well as assessing the effect of bacteria and plants separately and in association with the content of oil hydrocarbons in the soil. The treatment of plants with strains of  Enterobacter sp. UOM 3 and Pseudomonas hunanensis IB C7 to stimulate the growth and development of barley plants against the background of oil pollution and reduce the content of oil hydrocarbons in the soil, will remain in field conditions.The industrial process of petroleum extraction and refinery leads to the global pollution of ecosystems with hydrocarbons. In comparison with water and air, the soil environment is the most susceptible to the negative impact of these pollutants, which causes a decrease in the biological activity of the soil and a loss of its main quality, i.e., fertility ,2,3. TheP. hunanensis IB C7 strain, the length of the roots increased in comparison with the plants untreated with bacteria and grown in oil-contaminated soil. Inoculation with Enterobacter sp. UOM 3 and P. hunanensis IB C7 resulted in a 12–13% increase in shoot elongation. A similar trend was noted when analyzing the fresh weight of roots and shoots .One of the most important criteria indicating the success of oil biodegradation is the survival rate of the introduced hydrocarbon-oxidizing bacteria, i.e., their ability to maintain high numbers for a long time. As in the case of heterotrophic microorganisms, the density of the population of hydrocarbon-oxidizing bacteria in the soil with oil without plants remained stable throughout the experiment. The addition of The number of oligonitrophilic microorganisms in contaminated soil without plants and bacterization slightly increased over time. When both strains were used in the experiments without plants, the number of microorganisms in this group increased between 4.6 and 5.3 times. In the soil with barley plants, this indicator was higher than in the soil with the absence of plants. By the end of the experiment, the number of oligonitrophils increased between 2.4 and 3.5 times with the introduction of oil-degrading bacteria into the soil with plants compared to the experiments with plants but without bacterial treatment.Enterobacter sp. UOM 3 and P. hunanensis IB C7, IAA content in plant roots was 1.6 and 1.9 times lower than in the control, respectively. In the experiments without oil, IAA was significantly higher in the roots than in the barley shoots. In the presence of the pollutant, the level of this hormone in the aboveground and underground parts of the plants leveled off. Compared to the control, the IAA content in the shoots of barley grown in soil with the pollutant increased approximately 3 times.No significant differences were found in the content of auxin, indole-3-acetic acid (IAA), in barley roots either without oil or in its presence . In the The content of abscisic acid in the shoots in all variants of the experiment was lower than in the roots . Against the background of oil pollution, an increase in the abscisic acid (ABA) level was found only in non-inoculated plants . This waP. hunanensis IB C7 strain by an increase in the free form of zeatin in the roots. The content of zeatin and zeatin riboside in the shoots was lower than in the roots in all variants of the experiment .The content of all three analyzed forms of cytokinin in the roots of barley plants was approximately 14–19 ng/g fresh weight in the control . Under tperiment , with thTen days after the emergence of seedlings, the content of chlorophyll in barley shoots measured in plants growing in the presence of oil was 2 times lower than in the control . The samThe minimum level of flavonoids was found in the control plants . The preP. hunanensis IB C7 , which is an indicator of changes in the C/N ratio in leaves. In the control plants, it was in the range of between 49.2 and 62.7 conventional units during the measurement period; ten days after the emergence of seedlings under stress conditions, it decreased to between 18.1 and 20.9, and later increased to between 24.7 and 30.5. The highest NBI value was reached in the variant with the inoculation of plants with is IB C7 .P. hunanensis IB C7, the proline content was 35.5 μg/g, while the use of Enterobacter sp. UOM 3 decreased its level down to the control value. In the course of the experiment, the proline level increased in all variants of the experiment by an average of between 1.5 and 2.3 times. At the same time, in cases where bacterial treatment was carried out against the background of oil pollution, its amount, as before, was significantly lower than in the variant with oil without the introduction of microorganisms (by between 30% and 47%).At the initial stage of the growing season, the content of proline in the barley shoots of the control plants was 26.4 μg/g fresh weight . In the Poaceae family [The process of seed germination in oil-contaminated soil is known to differ significantly in different plant species ,17. In te family ,24. The introduction of microorganisms partially compensated for the adverse effect of the pollutant. The positive effect of bacterization was likely due to both the accelerated degradation of the pollutant and the bacterial production of substances promoting the growth and development of plants ,25.Enterobacter sp. UOM 3 and P. hunanensis IB C7 to increase the length and mass of shoots and roots detected in laboratory experiments against the background of hydrocarbon stress [The capacity of bacteria to produce hormones is considered one of the most important mechanisms of their effect on plant growth and development ,27,28. Tn stress ,15 was ain planta. The importance of bacterial effects on the hormone content in plants was demonstrated under salinity [Plant inoculation with growth-stimulating bacteria has been shown to increase plant growth and resistance to stressful influences such as toxic metals , salinitsalinity  and soilsalinity . Howeversalinity ,37. In tsalinity ,39. Conssalinity  since thsalinity . The abssalinity ,29 on thsalinity .Enterobacter sp. UOM 3  [The presence of oil in the soil inhibited root growth to a lesser extent than shoot growth. The redistribution of biomass in favor of roots is a characteristic growth response to a deficiency of water and mineral nutrients ,42. Sincp. UOM 3 . Shoot gtrients) . BacteriThe inhibition of shoot growth under conditions of water shortage resulting from oil pollution leads to the formation of smaller leaves, which is reflected in a decrease in the leaf surface index by 2.4 times compared with control plants grown in clean soil . This isIt has been shown that hydrocarbons have an inhibitory effect on photosynthesis ,47 and tP. hunanensis IB C7 may be due to its nitrogen-fixing ability [Plants use an increase in the synthesis of flavonoids and proline as mechanisms of adaptation to stressful environments ,53,54,55 ability , but thiOne of the early adaptive reactions of plants to unfavorable environmental conditions is an increase in the synthesis of various low-molecular compounds, e.g., proline. It participates in the regulation of the osmotic potential of cells, stabilizes the cell structure, and removes excess ROS, thereby increasing the resistance of plants to stress . Data onThe introduction of hydrocarbon-oxidizing bacteria significantly increased the decomposition of the pollutant , which ip ≤ 0.5). An increase in the pool of oligonitrophilic microorganisms was noted over time, most noticeable in variants with the introduction of strains. Obviously, this was due to a decrease in the toxicity of the soil brought about by a decrease in the oil content in it , since this group of microorganisms is sensitive to contamination with various pollutants, including hydrocarbons [A significant contribution to the number of heterotrophic microorganisms in the soil was made by hydrocarbon-oxidizing microorganisms . This isocarbons ,67.Hordeum vulgare L.), variety Chelyabinskiy 99, adapted to the climatic conditions of the Ural region, in which the territory of the Republic of Bashkortostan is located. Barley was chosen, out of seven plant species, as relatively oil-resistant and highly sensitive to inoculation with hydrocarbon-oxidizing bacteria [Enterobacter sp. UOM 3 and Pseudomonas hunanensis IB C7, synthesizing IAA [Enterobacter sp. UOM 3 (isolated by the authors from a sample of urban soil from Jebra Island (Tunisian Republic)) and P. hunanensis IB C7  were stored in the collection of microorganisms of the Ufa Institute of Biology, RAS  [2 plots. Commercial oil of the Urals brand is heavy (density 860–871 kg/m3), sulfurous (sulfur content 1.2–1.3%) oil, which is a mixture of light West Siberian oil and heavy high-sulfur oil from the Ural and Volga oil fields. The contamination was caused by a small oil leak from the oil pipeline. Samples for chemical analysis were taken from the top layer (0–20 cm) of the soil two months after the oil spill. The average content of the pollutant was 27 g/kg of soil. The experiment was carried out in seven variants with three replications of each:Clean soil + barley plants without bacterial treatment (control);Oil-contaminated soil;Oil-contaminated soil + barley plants without bacterial treatment;Enterobacter sp. UOM 3;Oil-contaminated soil + Enterobacter sp. UOM 3 + barley plants;Oil-contaminated soil + P. hunanensis IB C7;Oil-contaminated soil + P. hunanensis IB C7 + barley plants.Oil-contaminated soil + The study was carried out in the territory of the Ufa district of the Republic of Bashkortostan (Russia) from the 2 June to 8 September 2020. Weather indicators during this period were within the average statistical parameters for the previous five years. In our work, we used barley plants  ,29. The 6 CFU per seed (CFU: colony-forming units) took place immediately before sowing. Unbacterized seeds were moistened with water. After treatment, the seeds were planted either in clean or contaminated soil (600 pcs m−2) to a depth of 4–5 cm. After that, the plots of variants 4 to 7 were immediately watered with 250 mL of a liquid culture of bacteria (titer 2 × 109 CFU/mL) diluted in 5 L of water. The laboratory seed germination rate was 92%. The inoculation of seeds with a liquid culture of bacteria in the amount of 10Ten and thirty-four days after the emergence of seedlings, the growth characteristics of the plants were measured. The leaf surface index was assessed by analyzing photographs using ImageJ software . At the end of the experiment, the analysis of individual elements of the crop structure was carried out. Since plants were considered only as agents of bioremediation, the use of plant products as food for humans and animals was not envisaged. In accordance, the qualitative and quantitative indicators of grain were not measured.The content of chlorophyll (a + b) and flavonoids in the leaves was measured using a DUALEX SCIENTIFIC+ device  according to the manufacturer’s recommendations, and free proline—according to the Bates method , using tEnterobacter sp. UOM 3 and P. hunanensis IB C7 were cultured for 72 h in a meat-peptone broth (g/L): peptone–5, NaCl–5 [Bacteria 4NO3–2.0, MgSO4 × 7H2O–0.2, KH2PO4–2.0, Na2HPO4–3, CaCl2 × 6H2O–0.01, Na2CO3–0.1, agar-agar–15, pH–7.0) [2HPO4–0.2, MgSO4 × 7H2O–0.2, NaCl–0.2, K2SO4–0.1, CaCO3–5, agar-agar–15 [In order to estimate the microbial counts in soil, a serial dilution of soil suspension was used. The number of heterotrophic microorganisms was measured by application to the nutrient agar (see above). For measuring the number of petroleum degrading bacteria, we used Raymond agar (g/L): NH pH–7.0) , supplem-agar–15   until a final volume of 2 mL was reached. The concentrated solution was poured into a pre-weighed glass beaker and dried until a constant weight was reached. The total petroleum hydrocarbons present in the samples were then quantified by gravimetric analysis with a weighing accuracy of up to 0.1 mg.Total petroleum hydrocarbons in the soil samples were measured using the EPA 3540C method. Then, 10 g of soil samples were packed in filter paper and extracted in a Soxhlet extractor with 300 mL of hexane for 8 h at six extraction cycles per hour. The extraction product was transferred to a glass column filled with glass wool and NaTen days after the emergence of shoots, the concentration of hormones in the shoots and roots was assessed. IAA and abscisic acid (ABA) were extracted according to ,75. Purip ≤ 0.05). The data were processed using Statistica (Statsoft) software (version 10). In figures and tables, data are presented as mean ± standard error. The significance of differences was assessed by ANOVA followed by Duncan’s test (P. hunanensis IB C7 and Enterobacter sp. UOM 3 and barley plants contributed to a more significant reduction in the content of hydrocarbons in the soil compared to the use of bacteria and plants separately. A good survival rate of introduced bacteria in oil-contaminated soil and a positive effect of bacterization on the growth of barley plants have been established. Treatment with microorganisms mitigated the negative effects of abiotic stress caused by the presence of oil in the soil for plants due to the influence exerted on the hormonal status of plants, as well as on the systems of osmoregulation and photosynthesis.During the field experiment, it was shown that, against the background of oil pollution, the simultaneous use of auxin-producing bacterial oil destructors


Alzheimer’s disease (AD) is one of the most common neurodegenerative diseases in the elderly. The aim of this study was to explore the effects of AD on cardiac function and autonomic nervous function, and the feasibility of electrocardiogram (ECG) in monitoring the development of AD. APP/PS1 double transgenic mice were used in the Morris water maze (MWM) experiment to evaluate the changes of cognitive ability of AD mice, then the non-invasive ECG acquisition system was used and the changes of ECG intervals and heart rate variability (HRV) were analyzed. AD mice already had cognitive dysfunction at the age of 5 months, reaching the level of mild dementia, and the degree of dementia increased with the course of disease. There were no significant changes in ECG intervals in the AD group at each month. The mean square of successive RR interval differences, percentage of intervals >6 ms different from preceding interval, and normalized high frequency power component in the AD group were decreased and low-to-high frequency power ratio and normalized low frequency power component were increased. Combined with the results of the MWM, it was shown that the regulation mechanism of sympathetic and parasympathetic nerves in mice was already imbalanced in early stage AD, which was manifested as the increase of excessive activity of sympathetic nerves and the inhibition of parasympathetic activities. Therefore, ECG-based analysis of HRV may become a means of daily monitoring of AD and provide an auxiliary basis for clinical diagnosis. Alzheimer’s disease (AD) is in one of the most common neurodegenerative diseases in the elderly, which has two pathological hallmarks. One is senile plaques formed by the excessive extracellular accumulation of β-amyloid (Aβ) protein and the other is the neurofibrillary tangles formed by the hyperphosphorylation of tau protein inside neurons . AD is mCurrently, there is no single detection method for AD, and doctors usually use multiple methods for diagnosis, including a detailed medical history and family medical history provided by the patient and family members, family opinions on the patient’s thinking skills and behavioral changes, cognitive testing combined with clinical examinations, etc. The clinical examinations include mostly blood tests, magnetic resonance imaging, cerebrospinal fluid biomarker detection, and positron emission computed tomography -7. HowAn electrocardiogram (ECG) is a relatively simple, inexpensive, commonly used test. Heart rate variability (HRV) obtained from ECG signals refers to the changes in differences between successive ECG cycles, which can be used to quantitatively and noninvasively evaluate autonomic nervous function reliably, and can be obtained almost without the cooperation of patients with dementia . Low HRVIn this study, the APP/PS1 double transgenic mice, which were hybridized between PRP-HAPPK595N/M596L single transgenic dementia model mice and PRP-HPS1DE9 single transgenic dementia model mice, were used as the AD model. The Morris water maze (WMW) test was used to evaluate AD severity in mice at different months of age, and the ECG was obtained with a non-invasive method. The purpose was to study the changes of cardiac function and autonomic nerve function during AD progression, and to explore the feasibility of ECG monitoring of the progression of AD.The APP/PS1 double transgenic mice and C57BL/6J wild type (WT) mice were purchased from Beijing Huafukang Biotechnology Co., Ltd. (China). All mice were raised in an SPF animal laboratory with a photoperiod of 12-h light/dark and free access to water and food. The mice were divided into 5-, 7-, 10-, and 12-month-old groups, in which APP/PS1 mice were the AD group and C57BL/6J mice were the WT group for control, with 10 mice in each group. The procedures for this study were approved by the Biomedical Ethics Committee of Hebei University of Technology (report number: HEBUTaCUC2020003).The MWM video analysis system  was used to assess the cognitive ability of AD mice. The system is composed of a circular pool, a mobile platform, and an image acquisition and processing system. The circular pool was divided into four quadrants: Northeast (NE), Northwest (NW), Southeast (SE), and Southwest (SW). Stickers of different shapes were attached to the center of the pool wall, slightly above the water surface, in each quadrant as position and direction references for the mouse. The platform was placed in the center of the NW quadrant and 1 cm below the water surface.The experiment was carried out for 6 consecutive days. Each mouse was trained 4 times a day with an interval of 10 min between each test. All mice were placed in the SE quadrant for the first and fourth times, and randomly in the SW and NE quadrants for the second and third times. During each trial, mice were placed facing the wall of the pool and monitored for 60 s.The index recorded in the experiment was the escape latency referring to the time from entering the water to landing on the platform. Mice that remained on the platform for 2 s were recorded as successful platform searches. After successful search, mice were left on the platform for 30 s to familiarize themselves with the platform. Mice that failed to find the platform within 60 s were recorded as escape latency of 60 s, and these mice were guided to the platform and left in the platform for 60 s. The average of four trainings per day was taken as the score for that day. The average escape latency of all mice for the 6 days in the WT group was the reference value, and the final score of each mouse in the AD group was the average score of 6 days. The percent difference between the final score of each mouse in the AD group and the reference value of the final score of the WT mice was calculated. When >20%, the mouse was considered demented, from 20 to 30% mild dementia, >30-40% moderate dementia, and >40% severe dementia.ECGenie awake non-invasive ECG analysis system  was used to obtain the resting ECG of mice. The system included a data acquisition computer, acquisition platform, and signal amplifier. Mice were placed on the acquisition platform with feet in contact with the electrodes to form bipolar lead ECG. Then, the ECG signal was processed by the biological signal amplifier, so that the waveform of ECG changes could be displayed on the computer. ECG was recorded by LabChart software . The sampling rate was 2 kHz.After the ECG, the e-MOUSE physiological waveform analysis software was used to analyze the collected data, and the ECG interval durations and HRV parameters of mice were obtained. The signals containing excessive noise or error waveform were pruned or removed. Stable ECG signals of the mice in the resting state were intercepted manually, and the data of mice whose resting heart rate could be affected by trauma  were excluded.The ECG parameters of AD mice evaluated were heart rate (HR), PR interval duration, QRS complex duration, and QT dispersion (QTd). QTd is the difference between the longest QT and the shortest QT interval.The analysis of HRV mainly includes time domain analysis and frequency domain analysis . Time dot-test was used to compare the difference in escape latencies between the AD group and the WT group in the MWM test. One-way analysis of variance was used to analyze ECG parameters and HRV indexes in the multiple groups of the same strain, and t-test was used to analyze the differences between the AD group and the WT group at the same month of age. Statistical significance was set at P<0.05.Data are reported as means±SE. The In the MWM experiment, escape latency progression during training is a very important indicator , and itsThe reference values of 5-, 7-, 10-, and 12-month-old mice were calculated, and the values were 21.41, 22.14, 26.51, and 25.85 s, respectively. The percent difference between the final score and the reference value of each AD mouse was calculated, and results showed that the ratios of mice in the 5-month-old AD group were mainly distributed between 20 and 30%, the ratios of mice in the 7-month-old AD group were mainly distributed between 30 and 40%, and the ratios of mice in the 10- and 12-month-old AD groups were above 40%, indicating that the 5-month-old AD mice had mild dementia, 7-month-old AD mice had moderate dementia, and 10- and 12-month-old AD mice had severe dementia.No difference was found in HR, PR interval duration, QRS interval duration, and QTd between AD and WT groups at any month of age . Age hadvs WT5=7.81±1.27 ms, AD7=2.91±0.45 vs WT7=4.63±0.20 ms; P<0.05), and the PNN6 in 5-month-old AD group was significantly decreased compared with the 5-month-old WT group .In the time domain indexes of HRV, both RMSSD and PNN6 reflect the intensity of parasympathetic activity. The effect of age on RMSSD and PNN6 was statistically significant (P<0.05). Compared with 5-month-old mice, RMSSD and PNN6 in 7-, 10-, and 12-month-old mice were significantly decreased . CompareIn the frequency domain index of HRV, LF/HF reflects the modulation balance of sympathetic and parasympathetic nerves , LFn refIn order to explore the level of condition in AD mice, the MWM experiment was used. Mice had mild dementia at the age of 5 months, moderate dementia at the age of 7 months, and severe dementia at the age of 10 and 12 months. The results were consistent with previous studies, which showed that the cognitive ability of APP/PS1 mice decreased gradually with the prolongation of AD course .PSEN1) and presenilin 2 (PSEN2) genes associated with familial AD have been found in patients with dilated cardiomyopathy (Protein misfolding plays a key role in the pathogenesis of neurodegenerative diseases, especially in AD . Past stmyopathy . Furthermyopathy ,22. Thatmyopathy , the nonIn order to explore the effect of AD on ECG parameters, the resting HR, PR interval, QRS complex duration, and QTd of mice were analyzed. HR is controlled by the sinoatrial node that is controlled by the autonomic nervous system and body fluid. HR is accelerated when a sympathetic nerve is excited and slowed down when the vagus nerve is excited. Our results showed that there was no significant difference in HR between the AD group and the WT group, but compared with 5-month-old mice, HR of 7-, 10-, and 12-month-old mice increased significantly, which indicated that sympathetic nerve activity increased the ageing of mice.PR interval duration is an important indicator of heart conduction block and abnormal heart conduction, which reflects the time between atrial fibrillation and ventricular depolarization. The results of this study showed that compared with WT mice of same age, the duration of PR interval in AD mice of 7, 10, and 12 months of age was slightly prolonged, which indicated that there was a phenomenon of prolonged atrioventricular conduction in AD mice. There was no significant change in the QRS group reflecting the ventricular depolarization among each group. The difference between the longest QT interval and the shortest QT interval is called QTd. In past studies, the QTd was considered an indicator of uneven ventricular repolarization, and a significant increase in QTd represented a deepening of the disorder at the ventricular repolarity, which was associated with an increased risk of cardiovascular disease and was a sign of sudden cardiac death and ventricular fibrillation . High QTThe autonomic nervous system mainly includes sympathetic nerves and parasympathetic nerves, which jointly regulate body balance. Autonomic nerve function and cognitive function are closely related , and preIn conclusion, the autonomic nervous function of mice in the early stages of AD was abnormal, showing that the sympathetic overactivity was enhanced and the parasympathetic activity was inhibited. This is reflected in the HRV parameters that change with the development of the disease course. Therefore, it can be speculated that HRV may be a non-invasive physiological marker for early understanding of AD severity, but further studies are required to reveal the effect and mechanism of HRV on the changes of AD severity of patients.


Parameter tuning of PID controller for liquid level control of beer filling machine was studied in this paper, which can meet the demand of accurate controlling in beer production and improve the rapidity under the same conditions. Firstly, an improved genetic algorithm was proposed which has been verified by eight kinds of test functions. Simulation results revealed that, in comparation with other modified particle swarm optimization algorithm and modified genetic algorithm, the algorithm proposed in this work is not only capable to improve the convergence speed and precision under the same experimental conditions but also to improve the probability to converge to the optimal value. Finally, the proposed algorithm was applied to the parameter tuning of the PID controller of beer filling machine for liquid level control. Superior property had been obtained, which implied an effective improvement in the rapidity with the premise of steady-state error exclusion. Usually, in order to improve the performance of the control systems, various measures need to be taken , 2. PID The quantization factor and scaling factor were iteratively optimized in the offline state by using particle swarm optimization algorithm approach to adjust the fuzzy PID parameters rapidly, and the control system was simulated and analyzed by MATLAB, which has been reported in pervious literature . FurtherThe improved genetic algorithm refers to the random division of variable interval according to the setting interval number, while the initial population is generated according to the fitness value of the midpoint of the interval and roulette wheel selection. In the iterative process of the algorithm, the PSO algorithm was introduced into the crossover operation according to the probability. The individual with the lowest fitness value would be substituted by random individuals generated via the same method in developing the population.Step 1: setting the parameters in the improved genetic algorithm, including population numbers, interval numbers, maximum iterations, crossover probability, mutation probability, introduction probability of particle swarm optimization algorithm, learning factor, maximum inertia weight, minimum inertia weight, allowable error, etc.Step 2: dividing the variable intervals randomly according to the interval number settings in Step 1 and substituting the midpoint of the intervals into the fitness function of the algorithm to estimate the fitness value. On this basis, according to the algorithm parameters set in Step 1 and the roulette selection, the initial population of the algorithm has been generated.Step 3: calculating the fitness value of each individual among population to evaluate each individual and to complete the selection operation.Step 4: executing the crossover operation according to the crossover probability and the introduction probability of the particle swarm optimization algorithm which has been set in Step 1. The particle swarm optimization algorithm updates the speed and position abiding to equation .where the optimum algorithm population, global optimum, speed, and position of population size were denoted as ω, which diminished with four different strategies associated to the probability to enhance the optimization ability during the iterative process in improved genetic algorithm, as revealed in equations (The inertia weight has been labeled as quations –5) 22] [22]ω, w [22]ω, wωmax and ωmin, where maxe and era represented the maximum and the current number of iterations in the improved genetic algorithm, respectively.The maximum and minimum of inertia weights were marked as Step 5: executing mutation operation according to the mutation probability set in Step 1.Step 6: calculating the fitness value for each individual in population and generating a random individual with the same method in generating the initial population of the algorithm described in Step 2, which would be used to substitute the individual with the lowest fitness value at present.Step 7: determining whether the termination condition of the algorithm has been met based on the number of iterations and the allowable error of the algorithm. And the algorithm would terminate or skip to Step 3 for cyclic calculation.−15 in the allowable error, 0.5 in the introduction probability of particle swarm optimization algorithm, and 0.90 and 0.10 in the maximum and minimum inertial weight, respectively, had been set. Different algorithms had been run 100 times each.In order to verify the performance under the same experimental conditions, the improved genetic algorithm had been applied to the optimization of eight different kinds of typical test functions. The simulation experimental environment is MATLAB R2009 B version, in which numbers including 50 in the population of the algorithm, 12 in the number of intervals, 200 in the maximum number of iterations, 0.90 in the crossover probability, 0.01 in the mutation probability, 2 × 10The expressions of the eight kinds of test functions had been demonstrated in equations –13), an, an13), Among them, the improved genetic algorithm proposed in this paper was presented as algorithm 1, while algorithm 2 was the modified particle swarm optimization algorithm based on interval algorithm and modified elite strategy, and algorithm 3 belonged to the improved genetic algorithm promoted in literature .−11, 4.9460 × 10−2, and 4.3543 × 10−2 with the average convergence algebras of 77, 155, and 159 and average probability of converging to the optimal value of 98.8750%, 61.7500%, and 59.3750%, respectively.As revealed from Tables 1It is concluded that compared with algorithms 2 and 3, the improved genetic algorithm proposed in this paper improves the convergence accuracy, the convergence speed, and the probability of convergence to the optimal value of algorithm effectively, which is also implied in H), the cross-sectional area of the liquid storage tank (A), and the inflow (Q1) and outflow (Q2) liquid obey the equation as follows [Considering of the balance between inflow and outflow volume of liquid, the height of liquid level To simplify the mathematical model of the control system, we assumed that the outflow increment was proportional to the liquid level increment and was inversely proportional to the valve resistance of the load valve, which has been shown in the following equation , 24:(16)Based on equations  and 16)16),(17)RBy using Laplace transformation, we getK, T, and τ are defined as 5, 160, and 3 in this paper.Considering the hysteresis of liquid level changes in realistic engineering problems, the liquid level control system can be approximately seen as a first-order inertial hysteresis system with the transfer function shown in the following equation , 24:(19)Stability laid the foundation for the operation of the control system. Hence, it is a priority to determine the stability of a certain control system. Since the control system consisted of a nonlinear delay part, the analysis of stability has to be realized via the observation of the unit step response curves and calculation of the amplitude and phase angle margin of a control system, instead of the Routh–Hurwitz stability criterion. The unit step response curve of the control system is shown in X represented the variate of proportional coefficient (KP), integral coefficient (KI), and differential coefficient (KD) of the PID controller. ts, σ% were denoted as the adjustment time and overshoot of the control system, respectively. P(X) referred to the penalty function. Thus, the expression is shown in the following equation:ess is the steady-state error of the control system.In order to improve the performance of the control system, algorithms 1, 2, and 3 have been employed to correct PID controller parameters, and the fitness function is shown in the following equation:The convergence curves of algorithms 1, 2, and 3 are presented in ess) of the control system had been eliminated effectively and the adjustment time (ts) of the control system was reduced after PID correction, which were elucidated in both The steady-state error  can be modified, which will reduce the accuracy requirements simultaneously.The overshoot of the control system corresponding to the optimal results for algorithms 1, 2, and 3 was 14.3807%, 20.2146%, and 19.1002%, respectively. For higher requirements in stability of the control system, the penalty function Under the same experimental conditions, an improved genetic algorithm was proposed in this work to improve the convergence speed, accuracy, and the probability to converge to the optimal value. The performance of the proposed algorithm had been verified by eight different kinds of typical test functions. Furthermore, the improved genetic algorithm had been applied to the parameter tuning of PID controller for liquid level controlling of beer filling machine, which revealed the superiority in effectively improving the rapidity of the control system with the premise of steady-state error elimination.


The selection of material solutions is a basic decision-making problem that occurs in engineering issues. It affects the entire life cycle of a building structure, its safe use, maintenance costs, and a need to meet requirements for sustainable development, including recycling. This paper aims at selection of the optimum composition of HPC designed for monolithic girder structures of post-tension bridges. For the analysis, a set of 12 new-generation concretes (HPC) was designed, made, and tested. A full-scope set of evaluation criteria was created and then the optimal alternative was selected. For this purpose, an advanced hybrid algorithm combining EA FAHP  and FuzzyTOPSIS  methods was used. The obtained results indicate a possibility for the practical application of the proposed algorithm by decision-making engineering staff. It can also be the basis for further research on application compared to other material and design solutions and, depending on the issue, different combination of aggregated methods. Problems with selection of material and structural solutions are one of the fundamental decision-making issues in technical fields, including bridge construction. It is a complex issue, requiring experience and interdisciplinary knowledge. Its complexity increases along with the requirements imposed on modern cement-based materials. Bridges made of prestressed concrete are an excellent example, where the quality of the embedded material is of great importance for the durability of the structure. The production of concrete is nowadays a great design and execution challenge, and the choice of the optimum material solution is a fundamental decision-making problem in engineering terms. It is crucial and affects the entire service life of a bridge, from its design, through its use, up to its demolition, and recycling.Despite certain difficulties associated with erection, post-tensioned girder bridges have many advantages over classical reinforced concrete (RC) bridges, including the ability to transfer significant loads, achieve longer spans, reduce the height of cross-sections and span deflections, and have relatively high fatigue strength. These parameters showed a slight improvement due to the implementation of HPC with strength classes ranging from C50 to C100 and even C120 ,4,5.The first applications of HPC in prestressed bridges were recorded in the 1980s, e.g., the East Huntington Bridge over the Ohio River or the Tower Road Bridge in the state of Washington . The ter2 nano silicon dioxide used as a nanopowder is best known [The high-performance concrete, unlike the ordinary concrete, has a compact and tight microstructure and a low water-to-cement ratio (w/c ~ 0.2). Furthermore, it is a ecological material and thus not hazardous to human health ,10,11,12st known ,20,21,22The most numerous group of publications on the subject are research papers, combined with theoretical verification, e.g., ,24,25. TFollowing a survey of literature it was found that implementation of new solutions (formulas) of HPCs to be used for post-tensioned bridges is still a topical issue. The following trends can be observed: increasing durability of new bridges and associated reduction in maintenance costs, creating lighter, more cost-effective structures, increasing span limits, and reducing a number of girders.The character and complexity of the decision-making process in civil engineering is influenced by at least several factors. The first one is that design and execution conditions are never the same, which is characteristic for construction projects. The second one is the occurrence of many criteria, often contradictory, conditioned by factors that are difficult to measure, contractual, or which cannot be precisely defined. The need to take into account group ranks generated by appointed decision makers is also a difficulty. These problems are particularly evident with regard to issues undertaken by the authors in this paper and associated with the selection of concrete material solutions for advanced post-tensioned bridge span structures.Until now, the choice of structural materials has most often been determined by standard requirements together with cost minimization. Nowadays, despite the increased number of evaluation criteria and the importance of selection of optimal material solutions, this process, in most cases, is still solved only on the basis of knowledge and experience of the decision-making civil engineers. The reason for this state of affairs is the lack of a flexible, systematized assessment model that allows an unambiguous qualification of materials. The issue is also not solved by methods that have emerged in recent years, which are used to evaluate the environmental impact of materials and construction elements. They may be divided into two main groups: those which apply a qualitative approach with a system of criteria and scoring using a simple mathematical algorithm, and a quantitative approach based on LCA (Life Cycle Assessment) and guidelines set forth in ISO 14040. Methods that are better known are: BREEAM —Giudice et al.  and KeysIn the authors’ opinion, implementation of multi-criteria analysis methods referred to as MCDA , in particular the sub-group of FGDM (Fuzzy Group Decision Making) methods allowing for the application of fuzzy values, is far more promising. There are few publications only on the application of this type of MCDA methods in the material analysis. These are works on a variety of topics and with a different scope of analysis. Paper  comparesSimilar studies on the selection of material solutions for repairs of concrete structures can be found in ,46,47. TThe analysis of the literature indicates that the methods applied do not show flexibility, which would allow for a quick implementation of the algorithm to any decision-making problem in the selection of material and design solutions. In most cases, the application of only basic methods entails limitations associated with them in terms of analysis, e.g., the possibility for free shaping of the levels of the decision tree, a number of applied criteria/sub-criteria or analysed alternatives. The presented difficulties clearly indicate the necessity to apply computational methods, which at the same time allow to systematize the decision-making process, take into account the required set of evaluation criteria, and which have a relatively simple procedure algorithm.Being aware of the deficiency resulting from the literature review, this paper presents an original application of the MCDA methodology in the analysis of material solutions for HPC intended for spans of post-tensioned girder bridges.A procedure algorithm for the proposed analysis is presented in Despite the higher cost incurred during the erection of HPC post-tensioned bridges, the advantages indicated above may cause these structures to be more cost-effective than traditional ones made of reinforced concrete in the long-term operation. For that reason, a representative road viaduct over a main railway line, being a concept for a two-lane bypass of Bąków as a part of the DK-11 main road (Poland), was adopted for the analysis.A monolithic HPC structure was adapted for that purpose, with a cross-section in the form of a post-tensioned box girder with a total width of 15.00 m and a height of 2.2 m a. The stSupports are designed as reinforced concrete structures in the form of abutments and pillars supported on direct foundations  and on two rows of piles . Pillars have a deep beams structure, with a separate openwork upper part in the form of inclined, short columns. Pillar heights range from 6.4 m to 11.00 m.Properties of the concrete for the construction of monolithic post-tensioned bridges should be selected based on the following basic criteria: strength, tightness, and long-term deflections. Apart from the features mentioned, the actual execution conditions and possibilities as well as the economic criterion should also be taken into account.Requirements for the compressive strength of concrete depend primarily on the value of internal forces that occur in the structure. Application of higher strength concrete for prestressed concrete bridges than for RC bridges results from better utilization of concrete properties in prestressed structures, as compression occurring there is transferred by the entire cross-section of concrete. In addition, concretes with higher performance parameters are less prone to deformation and therefore losses of prestress force due to the elastic shortening of the concrete also being lower. Another argument to support the use of high-performance concrete in prestressed structures is the possible safe introduction of concentrated prestress forces and anchorage of tendons. Thus, in the case of post-tensioned bridges, the concrete must have as high of a compressive strength as possible when prestressed . For theA requirement for concrete tightness is an important parameter for any bridge structure as they are exposed to a direct impact of precipitation and large temperature fluctuations. Tight concrete can effectively protect, e.g., prestressing the steel against corrosion, which directly affects the durability and reliability of the bridge. Another important, but not the most important parameter of concrete in post-tensioned bridges, is a sufficiently high tensile strength of the concrete, as it ensures good adhesion to steel in case of elements where the post-tensioning force is transferred directly to the concrete (this applies to post-tensioned structures with adhesion). In concretes used for prestressed structures, it is also important to ensure the quality of technological processes following preparation of the concrete mix, which includes, among others, transport, pouring, compaction, and curing.Favourable technological properties of the concrete mix and a rapid increase in the concrete early strength;Favourable mechanical properties, in particular high compressive strength (after 28 days);High durability and resistance to environmental impacts.For the purposes of the analysed issue, 12 sets of concrete with different composition were designed and made. Design assumptions for concrete composition were focused to obtain:Such a material, in terms of its application in the building industry in the form of concrete products, should meet the requirements for its safe use in various environmental conditions, while ensuring occupational health and safety of users. These conditions are fulfilled when the concrete is designed and made of safe waste ingredients, i.e., that meet the acceptance criteria with regard to radioactivity and a content of heavy metals and hazardous compounds. These are requirements generally adopted for the raw materials used, guaranteed by manufacturers and included in their technical specifications. In addition, concrete as a product can already be tested for leachability of hazardous components. Such action is advisable and required when its production involves the content of unknown waste . However, in case of the tests performed in this study, the ingredients used for concrete come from known suppliers and have the manufacturers’ technical data sheets, which guarantee their safe use and influence on health and environment-related factors. Therefore, the paper focuses on the determination of physical and mechanical properties of the concretes tested, which, when used in structural products, will guarantee a long service life of the structure without any repairs, as well as high durability and safety for the environment (immobilisation of compounds coming from waste in the form of silica fumes).The economic aspect has been considered in two ways: directly, through the development of concrete sample composition, and indirectly, through evaluation of the bridge structures durability that has the impact on the environment through the extended life and reduction of maintenance and repair works.Tests were performed for concrete mixes and hardened concretes made of Portland cement CEM I 42.5R without and with an aqueous solution of hydrophilic nanosilica (HI) and hydrophobic nanosilica colloid (HF). Nanoadditives were used in an amount of 1.5% by weight to the weight of cement. Silica fume (D) was additionally added to concretes in the amount of 8% by mass. Whereas a 40% solution of polycarboxylic superplasticizer (SP) was used as a chemical admixture in the amount of 2% by mass of cement. Consistency of concrete mixes was adjusted by the amount of water (w/c ratio from 0.23 to 0.33).The composition of the designed concretes (S1–S12) is given in 3), according to PN-EN12350-6; air content by a water column method (with a measurement uncertainty of ±0.5%), according to PN-EN12350-7.Properties of fresh concrete mixes and hardened concrete were tested in the accredited Construction Material Laboratory of the Faculty of Civil Engineering and Architecture at the Opole University of Technology. A scope of tests performed was adequate to satisfy the requirements for the analysed post-tensioned bridge structure. Testing included the determination of concrete mix properties in terms of: a consistency class expressed by a slump test method (with a measurement uncertainty of ±1 cm), according to PN-EN 12350-2; density (with a measurement uncertainty of 10 kg/m3) according to PN-EN 12390-7, water penetration depth into concrete at a pressure of 0.5 atm (expanded uncertainty ±4 mm) according to PN-EN 12390-8, water absorption (expanded uncertainty ±0.36%) and freeze-thaw resistance in water (expanded uncertainty ±0.46%), both according to PN-B-06250. The repeatability of a given test, the quantity of concrete mix, as well as dimensions and a number of cubic specimens of hardened concrete were each time in accordance with the specified standards, and the analysis of the results took into account the extended uncertainty of measurement that the test results were subject to.The purpose of hardened concrete testing was to determine the early compressive strength (after 1 day of testing) and the final compressive strength (after 28 days of curing). Tests were performed according to the guidelines of PN-EN 12390-3 standard. The expanded uncertainty of measurements was ±2.9 MPa). Cubic specimens with dimensions of 100 × 100 × 100 mm were used for testing. In addition, after 28 days of concrete curing, the density was determined for cubes with the size 150 × 150 × 150 mm  and M2.2 ;-s4 for mixture M3.3 (1% by mass of polycarboxylate superplasticizer SP and 1.5% by mass of hydrophobic nanosilica HF);-s5 for mixes: M3.2 (1% by mass of polycarboxylate superplasticizer SP and 1.5% by mass of hydrophilic nanosilica HI), M4.2  and M4.3 .This caused a change in the consistency class from s1 determined for M1.1 reference mix and: M1.2, M2.1, M2.3, M3.1, and M4.1 mixes—modified by the nanoadditive content in an amount of 1.5% by mass to class:3 for mix M3.1, then by 100 kg/m3 for M3.2, and by 70 kg/m3 for M3.3 compared to M1.1. In addition, M4.1 mixes containing silica fume D and superplasticizer SP, as well as mixes with an additional 1.5% by mass of hydrophilic nanosilica HI (M4.2) or hydrophobic nanosilica HF (M4.3) showed an increased density compared to M1.1 reference mix.The addition of 1.5% by mass of hydrophilic nanosilica HI in M1.2, as well as hydrophobic nanosilica HF in M1.3 increased the density of mixes tested compared to density of M1.1 reference mix made of CEM I 42.5R cement. Whereas in mixes containing the addition of silica fume D (M2.1), as well as silica fume D and hydrophilic nanosilica HI (M2.2) or hydrophobic nanosilica HF (M2.3), a decrease in density was observed compared to the reference mix . On the The introduction of nanoadditives (HI and HF) to concrete mixes generally reduced the air content compared to the reference mix M1.1 made of CEM I 42.5R cement. Only M2.3 (with silica fume) and M3.3  mixes showed an increased air content compared to the M1.1 reference mix.3 was shown compared to the reference concrete (C1.1). A similar relation was also observed for the concretes: C2.1 (with 8% by mass of D) and concretes: C2.2 (with 8% by mass of D and 1.5% by mass of HI nanosilica) and C2.3 (with 8% by mass of D and 1.5% by mass of HF nanosilica). Concretes modified with superplasticizer SP (C3.1), as well as those containing 1% by mass of superplasticizer SP and 1.5% by mass of nanosilica HI (C3.2) and with 1% by mass of SP and 1.5% by mass of HF (C3.3) showed the increase in density compared to the C1.1 concrete by, respectively: 40 kg/m3 for C3.1, by 20 kg/m3 for C3.2 and by 40 kg/m3 for C3.3 concrete. Concretes C4.2 and C4.3, which apart from the superplasticizer and nanosilica also contained silica fume showed increased density compared to the reference concrete. On the other hand, C1.1 reference concrete and C4.1 concrete modified with 8% by mass of D fume and 1% by mass of superplasticizer SP had the same density value equal to 2390 kg/m3.It was found that the introduction of hydrophilic nanosilica HI to the concrete composition did not cause any changes in its density (in C1.2), other than under the influence of hydrophobic nanosilica HF in C1.3, where the decrease in density by about 20 kg/mSimultaneous application of both nanosilica HI and HF, silica fume D, and superplasticizer SP in concretes C4.2 and C4.3, allowed for proper reduction of the w/c ratio to 0.27, which had a beneficial effect on increasing their compressive strength compared to the reference concrete C1.1. However, application of nanosilica led to a slow increase in the early strength by 180% for C4.2 concrete with HI and by 169% for C4.3 concrete with HF, respectively.After 28 days of curing, the highest strength was demonstrated by C3.2 concrete containing polycarboxylate superplasticizer SP and hydrophilic nanosilica HI. The above indicates a compatible interaction of components used, both in terms of their quantity and type. This is also confirmed by test results of water absorption, which for C3.3 concretes (1% by mass of SP superplasticizer and 1.5% by mass of HI) was 3.9%, and for C4.2  was 3%, and for C4.3  was 2.6% and was considerably lower than water absorption of C1.1 reference concrete C1.1 made of cement CEM I 42.5R (5.4%). The introduction into the composition of concretes  of the polycarboxylate superplasticizer in C4.2 with HI and in C4.3 with HF resulted in the best tightness among the samples tested, which was confirmed by the lowest values of their water absorption and penetration depth of water supplied under the pressure of 0.5 atm. Those concretes also showed increased resistance to frost, determined by both the lowest reduction in weight and strength compared to the reference concrete (C1.1). The samples of those concretes subject to freezing did not show any cracks or visible wastage, and the average mass loss did not exceed 5% compared to the reference samples. Those concrete types reached a F100 frost resistance level. Only in the case of concrete containing 1.5% by mass of hydrophilic nanosilica (C4.2) was the strength reduction after 100 freeze/thaw cycles greater than for the reference concrete made of pure CEM I 42.5R cement .Samples of those concretes subject to freezing did not show any cracks or visible mass loss, and the average mass loss did not exceed 5% compared to reference samples. Those concrete types reached a F100 frost resistance level.The increased tightness of concretes was also confirmed by results of water absorption tests, which showed values below 5%, which, according to the requirements of the standard, allows the use of concretes with those additives in practical applications for the production of elements exposed to the direct impact of weather conditions.The structure of the hierarchical model includes the identification of a set of criteria that are components of the issue being analysed. The next step is to group them into thematically unified sets and to place them on appropriate levels of the hierarchical tree depending on the relations between them. A properly defined hierarchical model should enable a comprehensive assessment of the set of analysed alternatives leading to their ranking. The proposed set of criteria/sub-criteria is presented in -Structure safety is met a priori;-The aggregate type and particle size distribution are identical for all alternatives being analyzed;-Production of concrete and its transport are carried out by means of generally available equipment of concrete batching plants;-The mix is placed in the formwork while observing the technological regime (rheology of HPCs).The following assumptions were adopted during construction of the hierarchical tree:During evaluation of the destimulants, the highest ranks were assigned to alternatives with the lowest values of parameters analyzed.i+d and id−) and in finding values of the components of the ranking vector iS. By using the hybrid method, system evaluation measures can be obtained that take into account different aspects of the issue, allowing a more precise definition of the so-called utility function, leading to identification of conditions and the analysis of their intensity.In order to carry out the computational analysis of the issue, a hybrid algorithm consisting of two basic methods was proposed. The EA FAHP method  by entering them into the FuzzyTOPSIS calculation procedure. Calculations in the analysed issue based on results of the design and research part (Section 4) were carried out by means of the computational procedure developed according to the algorithm presented in Section 6. Both in the case of the pairwise comparison of criteria and sub-criteria in the EA FAHP method, as well as in the ranking of analyzed alternatives S1–S12 in terms of criteria/sub-criteria in the FuzzyTOPSIS method, the evaluation process was conducted by a team of DM (decision makers). The team consisted of persons with a long-term experience in civil engineering, as well as in the technology of building and cement-based materials. Based on the ranks obtained, differences were found only in nine cases , and the discrepancy was by 1 unit in each case. Discrepancies in the final ranks were determined by aggregation of individual judgements.When analysing the obtained pairwise comparison results for criteria/sub-criteria using the EA FAHP method, the value of the CR coefficient was within the range 0.0000–0.0616. Matrices of ranking obtained in the result of pairwise comparisons for main criteria A–D and sub-criteria A, C, and D in EA FAHP method using TFN  are shown in In the case of the C2 criterion, ranking of alternatives was estimated based on predicted parameters of the designed structure, i.e., its target technical condition. The mean values from the measurements were adopted as ranks of the alternatives determined by features tested with laboratory methods, and the standard deviation was approximated by fuzzy ranks.iE with (marked with *) obtained by means of EA FAHP method.Final ranking of alternatives (Si) of selected material solutions for concretes S1–S12 is presented in In result of the analysis performed, the highest rank was obtained by S11 sample, then concretes marked as S8 and S12, with ranks 0.865, 0.829, and 0.808, respectively . It can The highest rank obtained for S11 concrete is mainly due to its very good technical parameters, confirmed by tests. The use of additives in the form of silica fume, hydrophilic nanosilica, and a polycarboxylate superplasticizer resulted in high early and final strength, reduced water absorption, and increased freeze-thaw resistance compared to other samples. Simultaneous application of nano- and microsilica has proved to be a very beneficial solution, leading to densely packed spaces around cement grains and accelerated concrete curing . Such an effect is caused by an additional C-S-H phase, obtained in the pozzolanic reaction of silica fume and calcium hydroxide, in the form of a gel filling the micropores. Its presence causes better sealing of the cement matrix and a visible increase in the final strength of the concrete. The technical parameters obtained also indicate its increased durability.To make results (ranking) more clear in the context of HPC applications for post-tensioned girder bridges, three rating ranges (ranges I–III) were distinguished, i.e., 0–33%, 33–67%, and 67–100%, which can provide a convenient reference scale for designers and administrator . The higConcretes marked as S7, S10, S3, S2, and S5 in the ranking order are in range II and on the basis of analyses  it can bOn the basis of the performed tests and multi-criteria analysis, as well as previous experience in the use of HPCs for post-tensioned bridge structures, it can be assumed that this material also has ecological and economic potential for the projects implemented .It should also be noted that the rational detailed specification of criteria and the use of linguistic variables in the procedure  allow for a clear evaluation of the analysed samples, regardless of their design composition and mechanical properties. This is favoured by the establishment of interdisciplinary teams of DMs, recommended due to the complexity of the issue.The algorithm allows to consider various decision-making factors affecting the selection of the most favourable concrete and, ultimately, the quality of the execution and durability of post-tensioned girder bridges, taking into account economic and ecological factors;The results obtained confirmed the correctness of the algorithm and its application potential—it can be used as a tool supporting the development of new material solutions in bridge construction;The algorithm, unlike the methods used so far , allows for the mapping of real concrete quality assessment processes, taking into account uncertainty, incomplete information, as well as subjective and group ranks ;The practical aspect of the proposed model is the possibility of its relatively free adaptation to the specific character of the problem, without limiting a number of analysed alternatives (concrete samples) and the possibility for almost free shaping of the hierarchical tree;Modification of concrete composition by the simultaneous combination of silica fume and polycarboxylate superplasticizer added in the presence of hydrophilic or hydrophobic nanosilica proved to be a solution that allows for a significant reduction of the water-cement ratio, which has a beneficial effect on the improvement of physical parameters of concrete mixes and mechanical properties of hardened concretes. The above solution guarantees tight placing and compacting of mixes in moulds, their proper curing, as well as obtaining increased durability of hardened concretes demonstrated by a quick increase of early and final strength, high tightness, and very good resistance to weather conditions (temperatures below zero).Research on high-performance concretes for post-tensioned bridges, lasting for three decades, indicates the importance of the problem. At the same time, the presence of many criteria and almost unlimited design possibilities for the composition of concretes, cause the occurrence of considerable difficulties in obtaining an unambiguous solution in the selection of optimum material. Noting the lack of similar publications, this paper presents a computational and decision-making model for the evaluation and ranking of this type of concrete. The aggregated algorithm, which involves the EA FAHP and FuzzyTOPSIS methods, has been verified on a group of 12 samples of concretes designed for this purpose. On this basis, the following conclusions have been specified:It shall be also noted that the method has certain shortcomings, i.e., it is not possible to take into account a long-term dependence of the criteria ranks, e.g., associated with fluctuation of market conditions. Therefore, it seems necessary to improve the computational model by implementing the mathematical optimisation technique to support the analysis of multi-criteria decision-making problems, taking into account specific constraints and requirements. Other directions for further research should also consider the setting of precise ranges of final ranks depending on such factors as the technological, ecological, or economic aspects depending on the adopted criteria of sustainable development . Despite over 30-year experience in implementation of HPC, it should be noted that there is relatively little data on the durability and recycling of this material applied for bridge structures. In the current state of knowledge, these data can only be estimated.To sum up, the proposed hybrid MCDA method enables the identification of dominant criteria (sub-criteria) and selection of the most advantageous solution (concrete) for the application in question. The analysis is based on technical parameters of selected HPCs obtained in lab testing. The proper selection of structural material is particularly important in the case of post-tensioned bridges using HPC, as many parameters can have a decisive impact on the quality of execution, as well as the durability of the structure.The obtained results, as the outcome of a large spectrum of decision-making processes, indicate a possibility for popularization of the methodology proposed, provided that supplementary research is done . This may improve the technical level of the execution of post-tension girder bridges made of HPC.