Deschampsia caespitosa L., the microbial activity, and the soil’s capacity to retain nutrients. The measured basal respiration and dehydrogenase activity values confirm the significant effect of drought on microbial activity. These values were demonstrably higher in the period before drought simulation by more than 60%. On the other hand, significant differences between microbial activities in the rhizosphere and non-rhizosphere soil were not found. We did not find a clear effect of drought on the formation of soil water repellency.This work presents results from a field experiment which was focused on the impact of the drought period on microbial activities in rhizosphere and non-rhizosphere soil. To demonstrate the effect of drought, the pot experiment lasted from 2012 to 2015. Fifteen lysimeters (plastic containers) were prepared in our area of interest. These lysimeters were filled with the subsoil and topsoil from this area and divided into two groups. The first group consisted of two variants: V1 (control) and V2 (84 kg N/ha), which were not stressed by drought. The second group consisted of three variants, V3 (control), V4 (84 kg N/ha), and V5 (84 kg N/ha + 1.25 L lignohumate/ha), which were stressed by drought every year of the experiment for 30 days. Changes in the soil moisture content caused by drought significantly affect the growth of  Drought is currently regarded as a new phenomenon, but it is a natural part of the climate ,2 and anRhizosphere and rhizosphere soil are the most important soil parts where significant processes take place, which affect not only the soil fertility but the entire soil ecosystem, i.e., the ability to retain nutrients, resistance to erosion, or soil filtration capacity . RhizospThe direct impact of drought on microbial activity in the soil environment and consequently also on soil fertility, health, and quality can be expressed by the presence of microbial enzymes in the soil  or by thThe reason for using enzyme activities and soil respiration as indicators of drought impact on the soil environment is the fact that, according to Borken et al.  and Sanar), i.e., oxidized, reduced, and organic forms of N. If the input of Nr into the soil is higher than the soil can utilize , the soil environment and soil microorganisms become saturated with this Nr [min  [The significance of rhizosphere as being a unique environment in which processes take place that are indispensable for the natural functioning of the soil has been confirmed by a number of scientific studies. Rhizosphere soil has a key influence on the soil’s capacity to retain nutrients, namely reactive N  ,18 where.e., Nr) .Changes in microbial activities as well as changes in the composition of microbial communities due to drought may be reflected in the shifted values of soil hydrological limits. The contents of hydrophobic and hydrophilous substances in the soil strongly affect the soil potential of accepting water molecules . Soil waDeschampsia caespitosa L. and microbial activity (soil respiration) in rhizosphere and non-rhizosphere soil. Furthermore, the effect of drought was studied on the formation of soil hydrophobicity and the washing out of Nmin from the soil. For the purpose of studying the above-mentioned objective, the following hypotheses were tested: zero hypothesis (H0) and alternative hypothesis (H1). H0: changes in the soil water content caused by extreme climatic phenomena have no influence on the development of the model plant, soil microbial activities, or a loss in nutrients from the soil, do not influence the level of soil hydrophobicity, and their action cannot be mitigated by the method of farmland fertilization. H1: changes in the soil water content caused by extreme climatic phenomena adversely affect the model plant development, microbial activities, and a loss in nutrients from the soil. They also show a change in soil hydrophobicity. In the case of agricultural land, the negative effects can be corrected using the method of fertilization.The aim of this study was to evaluate the direct effect of drought stress on the development of The above hypothesis was tested in a lysimetric experiment  which wamin). The other group was at all times covered with a roof once a year  for 30 days during the growing season. This group contained three variants: control, variant fertilized with mineral nitrogen, and variant fertilized with mineral nitrogen combined with lignohumate (LG).The period of drought was simulated using plastic rooves. Five experimental variants were prepared to test the effect of drought, which were divided into two groups . The firmin dose for extensive grass stands, i.e., 84 kg N/ha. Treatment V5 was fertilized with the combination of mineral fertilizer and auxiliary preparation Lignohumate B , a mixture of humic and fulvic acids and their salts. Based on the recommendation of the manufacturer, a dose for garden lawns was chosen, watering after the establishment, i.e., 12.5 mL/100 m2. This dose was completed with the above-mentioned dose of Nmin. Dates of fertilizer applications are presented in Treatments V2 and V4 were fertilized with the mineral fertilizer DAM 390 , a liquid nitrogenous fertilizer with the content of 30% (w) nitrogen in various forms, of which ½ was amide-N, ¼ was ammonium-N, and ¼ was nitrate-N. These variants were applied using 60% of the recommended N2 production for 24 h in a 7-day period, three times before and after drought simulation. The soda lime granules were stored in a plastic container. Before use, the container was opened and inserted into a metal ring. Each lysimeter had two metal rings (see 2 (Equation (1)). The results of cumulative CO2 production were expressed in g of C per m2 and day.Basal respiration (BR) was measured according to Keith and Wong  using soings see ; part C.The calculation of basic respiration based on the weight increment of natrocalcite according to the Keith and Wong  equationBR was measured every year in three cycles; one cycle always consisted of a min. of two dates of natrocalcite application . Each ap3, 1 mL of TTC, and then 2.8 mL of distilled water. The prepared samples were incubated at 37 °C for 24 h. After this procedure, triphenyl formazan (TPF—product of the reaction) was extracted using 60 mL of methanol and the resultant solution was filtered. The presence of TPF in the filtrate was indicated by the intensity of a reddish color which was determined using a spectrophotometer  at the wavelength of 485 nm. DHA was expressed as µg of TPF per 1 g of dry soil matter.Dehydrogenase activity (DHA) was determined using triphenyltetrazolium chloride (TTC) as an acceptor of charged particles released via the oxidation of organic compounds, in accordance with the original method developed by Casida et al. . Accordimin from the soil was monitored through its leaching in the soil eluate (SOEL) and quantified on the basis of its concentration in SOEL. The amount of SOEL leaked from the lysimeters was measured directly in the control shaft  to the solution. The product of the reaction is NH3, which was determined according to the same principle as ammonium ions.The loss in Nol shaft  and recos et al.  and thens et al.  was devemin was calculated as a sum of these basic Nmin forms. The analysis was performed on the distillation–titration instrument Behr S3 Stream Distillation Unit .The total amount of NKr; cm/s) as an indirect indicator of SWR [Kr value was calculated based on measuring cumulative water infiltration . The field measurements of I were taken using a Mini Disk Infiltrometer  was adjusted to the value of 2 cm. MDI was always placed on the soil surface so that maximum contact with the soil could be ensured. Prior to starting the measurements, the initial water volume in the instrument and at the time of t = 0 was recorded; then, the MDI was placed on the measured surface. The loss in water amount was recorded in regular time intervals selected with respect to the rate of infiltration from 30 s to 120 s. The minimum number of readings at each measuring point was 12. The measurements were taken before and after drought simulation in each experimental year in the rhizosphere and non-rhizosphere zones of soil. rK was calculated according to Lichner et al. [Changes in the content of hydrophobic and hydrophilous substances responsible for soil water repellence (SWR) are expressed in the presented study using the value of unsaturated hydraulic conductance Kr.The measured data of individual parameters were assessed using exploratory data analysis to verify the homogeneity and normality of their selection. Potential differences in the activity of dehydrogenase and basal respiration were analyzed using the analysis of variance (one-way ANOVA) in combination with the post-hoc Tukey honestly significant difference (HSD) test. Furthermore, regression analysis was performed to analyze the correlations of selected parameters. All significant differences were detected at The production of plant biomass (expressed in DM) was variable both within the individual years of the experiment and between the years . The higIn 2013 and 2015, the control variant without drought stress (V1) exhibited significantly higher values of plant biomass production than the control variant stressed by drought (V3). In 2013–2014, the application of fertilizers in the drought-stressed variants  resulted in a demonstrably higher production of plant biomass as compared with the control variant stressed by drought (V3). However, the values were at all times demonstrably lower than those in the fertilized variant with no drought stress V2. In general, all experimental variants reached the demonstrably highest production of plant biomass during the first year of the experiment (2013).Basal respiration was monitored in the rhizosphere and non-rhizosphere soil before and after drought simulation in three years . Average BR values for three years of the experiment (2013–2015) are presented in 2-C/m2∙24 h before drought simulation and of 1.45 g CO2-C/m2∙24 h after drought simulation. Similarly, variants only exposed to the impact of natural weather conditions (V1–V2) exhibited a demonstrably higher level of BR (4.61 and 5.28 g CO2-C/m2∙24 h) in the first period than in the second period (2.2 g CO2-C/m2∙24 h). Thus, a BR decrease by more than 50% occurred in the second period of measurement again.In general, microbial activity can be evaluated using the average cumulative COSimilarly, as in the case of BR, DHA was always measured in two periods before and after drought simulation , i.e., iIf we focus only on the period before drought simulation (I) in 2014, we can see that the DHA values ranged from 9.38 to 20.62 µg TPF/g∙h, without making a difference between the R or NR soil. Significant differences were recorded between the variants that were not stressed by drought (V1 and V2) as compared with the other variants (V3–V5) stressed by drought both in 2014 and already in 2013. Other differences were detected in the values of DHA between the R and NR soil of variants with no drought stress (V1 and V2). Compared with the NR soil, DHA was about 60% higher in the R soil. In contrast, differences in DHA between the R and NR soil of other variants were not detected.A similar behavior of values was also apparent in the second period of 2014, i.e., after drought simulation (II), where the same significant differences were recorded as in the preceding period. As compared with the other variants , the highest level of enzymatic activity was demonstrably exhibited by V1(R soil) and V2(NR soil). The drought-stressed variants exhibited no significant differences even when comparing the R and NR soil.In 2015, the most significant differences were determined again in the period before drought simulation (I) . The ranThe second period of DHA monitoring (II), i.e., after drought simulation in 2015, showed that microbial activity decreased in the R soil of all drought-stressed variants. Among other things, a significant decrease in DHA values was recorded in Variant V2 (NR soil) which was not stressed by drought. The demonstrably highest DHA values were once again detected in the R soil of Variants V1 and V2 as compared with the remaining variants. Furthermore, significant differences in DHA between the R and NR soil were recorded in Variants V1, V2, and V5. In the variants stressed by drought, a significant effect of drought on DHA decrease was recorded as being more than 60%.min in SOEL before and after drought simulation are shown in The leaching of mineral nitrogen through the soil eluate (SOEL) was monitored for three years (2013–2015). Although the experiment was already established in October 2012, we had to wait until the end of the year to let conditions in the lysimeter stabilize so that actual soil conditions could be simulated as faithfully as possible. The concentrations of Nmin (>15 mg/L) were recorded before drought simulation. The lowest values were detected after drought simulation and ranged around 5 mg/L. Significant differences among the variants were observed only in the period after drought simulation (min was recorded in the control variant (V1 = 1.90 mg/L) and the second lowest one was in the variant with 84 kg N/ha (V2 = 3.67 mg/L). These variants were not exposed to drought stress, and the loss in Nmin recorded in them was approximately 60% lower than in the drought-stressed variants. Differences among the drought-stressed variants were detected only between Variant V4 (application of 84 kg N/ha) and Variants V3 (control) and V4 (combined application of Nmin and Corg).In 2013, the highest losses in Nmulation . The sigmin was again detected in SOEL from Variant V1, both in the period before drought simulation and in the period after drought simulation. It is important to follow differences (a) among the variants within the individual groups of the experiment , and (b) between the groups (stressed and unstressed by drought). Compared with the unfertilized controls, variants fertilized with 84 kg N/ha (V2 and V4) exhibited that Nmin losses increased by min. 20% both in the group unstressed by drought (V1) and in the drought-stressed group (V3). Variant V5 fertilized with a similar N dose as V2 and V4, but with the addition of LG (1.25 l/ha), exhibited that demonstrably lower values of Nmin leached from the soil as compared with Variant V4 . Moreover, this variant reached the same level of Nmin loss in 2014 as Variant V2 which was not stressed by drought and Variant V3 (unfertilized control) which was stressed by drought.In 2014 and 2015, the lowest concentration of Nmin from the soil using regression analysis  and 2015 . The results of the regression analysis are significant and indicate that the lowest level of microbial activity was found in variants with the highest concentrations of Nmin in SOEL in the rhizosphere soil. The intertwining of individual measured parameters is illustrated by the scheme in min and Corg) and weather conditions affect the production of plant biomass  before drought simulation, i.e., in the first half of the model plant growing season, and (II) after drought simulation, i.e., in the second half of the model plant growing period. Measured values are therefore divided into these two groups even in the variants (V1 and V2) that were exposed to the impact of natural weather conditions only. In the first year of the experiment (2013), no significant differences were found among the individual variants either before or after drought simulation, nor were any significant differences detected between the periods before and after drought simulation within the individual variants.rK indicating an increased degree of SWR were found in the R soil of variants stressed by drought V3(R)–V5(R) in the period after drought simulation. The highest value was recorded in the NR soil of Variant V5(NR), which was significant in relation to V2(NR) and V3(R). No significant differences were found within the individual variants between the rhizosphere and non-rhizosphere soil. In this period, significant differences were recorded only between the rhizosphere and non-rhizosphere soil across the variants, for example between V3(R) and V2(NR). Thus, the degree of SWR was affected primarily by soil moisture content , in the period after drought simulation. The lowest values of  content  which warK. In the second period of 2015, i.e., after drought simulation, the lowest rK values were detected in the rhizosphere soil of drought-stressed variants (V3–V5) as compared with the control Variant V1 and the variant with applied Nmin. In this period, the absolute highest rK value was recorded in Variant V1(NR). The only significant difference between the two periods of measurements (I and II) was found in Variant V2 in which a significant increase in the rK value was detected. No significant differences in the rK values were found in the individual variants between the periods before and after drought simulation.A similar course of values was also observed in 2015 when significant differences were found in the period before drought simulation only between Variants V1(NR), V5(NR), and V2(NR). Variants V1(NR) and V5(NR) exhibited the highest values of rK values were also evaluated for the whole 3-year period of the lysimetric experiment  and the alternative hypothesis (H1). These hypotheses are discussed in detail in the below sub-chapters.A prerequisite in the presented experiment  was thatmin, which significantly increased the biomass production of the model plant. The highest biomass yield was always recorded in Variant V2 (no drought stress) and Variant V4 (drought stress), where 84 kg N/ha was applied  or in combination with Corg in the form of humates (V5) acted positively on the mitigation of drought impact. The application of fertilizers was the second most important factor which affected the development of Deschampsia caespitosa L. and mitigated the negative effect of drought. It follows that the H0 hypothesis was disproved and the alternative H1 hypothesis was confirmed. Thus, if we wanted to adapt grass ecosystems to climate change, we would have to increase their species diversity and adopt a suitable regime for the nutrition of these stands. This means supplementing N-substances and ensuring the supply of Corg. Similar conclusions were also arrived at by Zhang et al. [It is also very important to mention that the decrease in the production of plant biomass was demonstrably lower in 2013 and 2014 than in the unfertilized control. This indicates that the application of Ng et al. .The data of BR presented in Therefore, the BR values indicate a repeated effect (simulation) of drought on the microbial activity in the soil, which showed a pronounced decrease in BR values. The effect of drought on the decrease in microbial activity in the soil was confirmed . On the It should also be taken into account that total precipitation amounts during the second half of the vegetation period  were mucAs mentioned above, there is a presumption that the records of microbial activity were due to the local meteorological situation. Total precipitation amounts for the first cycle of BR measurement in 2013, 2014, and 2015 were 111.3 mm, 88.8 mm, and 31.3 mm, respectively. Total precipitation amounts measured in the third cycle of BR measurement (after drought simulation) in 2013, 2014, and 2015 were 99.5 mm, 95.5 mm, and 18.2 mm, respectively. BR values after the third cycle of measurements in variants without roofing (V1 and V2) were at a similar level in 2013 and 2014, but a clear drop was recorded in 2015. According to Bloem et al.  and EngeNot even in one experimental period in the individual years  were sigmin on microbial activity in the soil expressed by DHA compared with the control variant; it is, however, necessary to point out that the origin and character of nutrients play a decisive role. In contrast, Luo et al. [min always increased values of all tested enzymatic activities in the soil. Contrariwise, Jahangir et al. [Dehydrogenases belong to basic microbial enzymes and are referred to as enzymes of the respiratory chain ,55. The o et al. , for exao et al.  and Chu o et al.  point tor et al.  found ouBased on the values measured before and after drought simulation in 2015, it can be deduced that DHA could have been affected by the method of fertilization. The reason for this is a situation whereby the highest values of DHA in the individual periods were determined in Variant V2 fertilized with mineral fertilizer. When the other values recorded in the following period after drought simulation are included, the effect of the stress of the soil and plants due to a shortage of monture is apparent. Results from 2014 and 2015 indicate not only the actual effect of drought on the enzymatic activity in the soil, but also its long-term negative effect on the overall microbial activity in the soil, because in both experimental years the lowest DHA values were measured, which reflect the overall potential oxidation activity of microorganisms in the soil  in variamin in SOEL, a combined influence of drought, meteorological phenomena  compared with the same period in the following years . The increased precipitation caused the formation and leakage of soil eluate from individual lysimeters and hence the increased leaching of Nmin from the soil in the individual lysimeters. The amounts of captured SOEL are presented in min concentration in SOEL were probably affected by the process of the stabilization of biochemical reactions in the soil of the buried lysimeter. Nendel et al. [min could have been affected by its content in the collected homogenized soil and insufficient formation of optimal soil structure. This fact is also confirmed by the high values of ±SE  of the experiment confirm the assumed hypothesis of the mediated effect of drought on the loss in Nmin, which was also corroborated by Bimüller et al. [min concentration in the captured SOEL in individual variants (V3–V5) in the period of drought stress because the increased Nmin concentration was always demonstrated in the preceding period in 2013–2015.As mentioned above, the measured values of Nr et al. . An indir from the soil to be not only evidence of damage to soils but also evidence of negative anthropogenic action on the soil ecosystem. This state is also indicated by BR values that were the lowest in variants with the greatest loss in Nmin in the periods of drought stress in 2013 and 2015, and exhibited negative dependence on the values of Nmin loss from the soil. The mentioned authors Bloem [min from the soil and its reduced availability to plants.Various scientific works such as those by Bloem , Sutton rs Bloem , Sutton rs Bloem , and Kinrs Bloem  confirm min in the soil, as well as a possibility to mitigate the impacts of drought by the application of supporting substances, namely those which can support microbial activity in the soil and the resistance of plants to drought stress. The method of fertilization and type of applied fertilizer were other factors which affected the loss in Nmin from the soil as variants fertilized by DAM 390 fertilizer—84 kg N/ha (V2 and V4)—showed that Nmin losses increased by min. 20% as compared with unfertilized controls both in the group unstressed by drought (V1 vs. V2) and in the drought-stressed group (V3 and V5 vs. V4).The presented results further indicate the significance of the fertilization effect on retaining Nmin leaching from the soil. Thus, the values measured in Variant V5 indicate a positive influence of the combined application of DAM 390 and Lignohumate LG B on the reduction in Nmin leasing from the soil. The LG B fertilizer that was applied to Variant V5 represents a liquid humic preparation with the content of salts of humic and fulvic acids (concentration 12%) in a ratio of 1:1. Simplified, this preparation can be an artificially prepared, partly dissolved organic matter. Based on its composition, LG B is likely to affect processes in the rhizosphere, particularly fulvic acids, which it contains and which readily dissociate and become involved in the exchange of C and O2, thus representing, according to Zsolnay [min loss from the soil detected using regression analysis. Variants with a low loss in Nmin demonstrably exhibited the highest level of microbial activity in 2013 and 2015, and a negative dependence on the Nmin loss  exhibited demonstrably lower values of N Zsolnay , a potenmin loss . The varmin loss .I; mL) was measured and unsaturated hydraulic conductance  was calculated in the conditions of lysimetric experiment in 2013–2015, with the measurements made only in the soil zone affected by the root system of the model plant (R soil) in 2013. In 2014 and 2015, the measurements were also taken in the soil zone not directly affected by the root system of the model plant (NR soil). The reason for this was a modified methodology and the extension of monitored parameters, i.e., potential difference in the formation of SWR between the rhizosphere (R) and non-rhizosphere (NR) soil (Cumulative infiltration (NR) soil .rK value was used to express the level of SWR as based on scientific studies and experiments of Cosentino et al. [rK values [The o et al. , Wang eto et al. , Robichao et al. , and Diao et al. . It can o et al.  and Licho et al. . More pro et al. , the volr values ,39.rK values were characterized by the absence of significant differences both in the period before drought simulation and in the period after drought simulation. In the following year (2014), significant differences were recorded only in the period after drought simulation. The rK value was with great probability affected by soil moisture content . On the other hand, the course of rK values in 2014 (period after drought stress) signaled a decreased rate of water infiltration into the rhizosphere. Thus, the state indirectly indicates increased hydrophobicity in the soil affected by roots. The presented results suggest that there is a relation between physical–chemical soil properties and the level of SWR, which was confirmed by Mataix-Solera et al. [In the first year of measurements (2013), the measured  content , which ga et al. . The siga et al. .rK values were found among the individual variants again. Based on Mao et al. [rK, indicating increased SWR in the upper layer of the soil, but it was not significant with the preceding period before drought simulation. The reason for this was probably a short time of drought stress to which model plants were exposed. The significance of the length of drought periods on changes in the SWR formation and in the distribution of SWR-causing substances was confirmed by Mao et al. [0 on the basis of measured rK values because the effect of drought on the formation of SWR was not statistically demonstrated in all experimental variants.In the last experimental year (2015), only partial significant differences in o et al. , Schramao et al. , and Sáno et al. , there wo et al.  and Sándo et al. . It is tDeschampsia caespitosa L., microbial activities in the rhizosphere and non-rhizosphere soil, and Nmin loss from the soil (soil capacity to retain this key nutrient). The main goal of the study was a general evaluation of the direct effect of drought on the plant–soil complex and the indirect effects of drought on the degree of soil hydrophobicity. In the performed lysimetric experiment, a zero hypothesis (H0) and an alternative hypothesis (H1) were formulated: H1: changes in the soil water content caused by extreme climatic phenomena adversely affect the model plant development, microbial activities, and loss in nutrients from the soil. They also show changed soil hydrophobicity. In the case of agricultural land, the negative effects can be corrected by the method of fertilization. The hypothesis was confirmed in terms of drought effect on the model plant, microbial activity in the soil, and loss in Nmin from the soil, and based on which the effect of drought on the selected soil parameters was confirmed, however with different statistical probability and measured intensity of the effect. In the case of the effect of drought on the formation of soil hydrophobicity, no influence was demonstrated and H1 was rejected.The presented paper is to contribute to studying the effect of drought on the growth of the model plant Deschampsia caespitosa L., microbial activity in the soil, and the soil’s capacity to retain nutrients. The measured BR and DHA values confirm the significant effect of drought on microbial activity in the soil both from a current and long-term point of view. The results of the field lysimetric experiment confirm the high significance of drought effect on microbial activity in both rhizosphere and non-rhizosphere soil. Our lysimetric experiment demonstrated only partly that adverse impacts of drought can be eliminated using the application of fertilizer with C available in the form of lignohumates.Based on the research results, it is possible to state that changes in the soil moisture content caused by drought significantly affect the growth of min itself having a negative influence on the loss in mineral N forms from the soil. In contrast, the application of LG B fertilizer in the period after soil stress by drought demonstrably reduced the loss in Nmin as compared with the control variant that was stressed by drought as well.Furthermore, a demonstrable influence of drought was detected on the loss in Nmin from the soil environment. Drought-stressed variants always exhibited the loss in Nmin via leaching as being greater than variants unstressed by drought. Based on the above measured data, it is possible to state that the loss in Nmin in the field experiment was affected by the combined action of drought and the fertilization method with the application of DAM mineral fertilizer, with the content of N


With the nanopowder mixing, the size of the parent nanoparticles in the composite remains practically unchanged in the range of 50–100 nm. The impregnation composites consist of 70 nm In2O3 nanoparticles with ZnO nanoclusters < 30 nm in size located on its surface. The nanoparticles in the hydrothermal composites have a narrow size distribution in the range of 10–20 nm. The specific surface of hydrothermal samples is five times higher than that of impregnated samples. The sensor response of the impregnated composite to 1100 ppm H2 is 1.3–1.5 times higher than the response of the mixed composite. Additives of 15–20 and 85 wt.% ZnO to mixed and impregnated composites lead to an increase in the response compared with pure In2O3. In the case of hydrothermal composite, up to 20 wt.% ZnO addition leads to a decrease in response, but 65 wt.% ZnO addition increases response by almost two times compared with pure In2O3. The sensor activity of a hydrothermal composite depends on the phase composition of In2O3. The maximum efficiency is reached for the composite containing cubic In2O3 and the minimum for rhombohedral In2O3. An explanation is provided for the observed effects.The influence of the method used for synthesizing ZnO-In This makes it possible to use such oxides as sensors for monitoring environmental composition. It has been shown that sensors based on nanoparticles of semiconductor metal oxides with particle sizes of about 100 nm have the greatest efficiency [The electrical resistance of nanostructured semiconductor metal oxides such as SnOParticles of such a size generally have a large specific surface area and high energy. The presence of such surface energy in the system contributes to the sensor phenomenon, allowing it to overcome the activation energy of reactions . It is aSensors based only on one metal oxide have insufficiently high efficiency and selectivity in the detection of multicomponent gas mixtures. It has been established that in order to obtain effective sensors, the systems must comprise a mixture of oxides, one of which has a high concentration of conduction electrons and the other a high catalytic activity in oxidation and dissociation reactions ,4,5,6.The conductive and sensor properties of binary metal oxide composites largely depend on the synthesis method, which can affect the type of interaction between the nanoparticles of the system  and ZnO , the particle sizes of which ranged from 50 to 100 nm. The necessary amounts of metal oxide nanopowders were thoroughly ground with water in a ball mill for 1–2 h. This synthesis method produced binary metal oxide nanocomposites containing separate crystals of each of the constituent metal oxides [Systems of ZnO-Inl oxides .3)2·6H2O (purity ≥ 99%) and kept at room temperature for 24–48 h. As a result of such prolonged treatment, the salt solution completely and evenly wetted the surface of indium oxide. Concurrently, the zinc nitrate molecules were adsorbed not only on the surface of the powder but also diffused into the near-surface layer. Subsequent removal of water at temperatures of about 70–80 °C and heating the sample for several hours to 300 °C resulted in an impregnated composite consisting of indium oxide particles with small particles of zinc oxide embedded on their surfaces [To obtain composites by the impregnation method, a commercial indium oxide nanopowder was placed in an aqueous solution of zinc nitrate Zn3·4H2O (≥99.5%) and zinc nitrate Zn(NO3)2·6H2O (≥99%) were used as precursors. For hydrolysis, aqueous solutions of these salts were kept in a medium with a large excess NaOH, which allowed the pH value of the medium to be maintained constant during the entire process. The zinc and indium hydroxides formed were separated in a centrifuge at a speed of 4000 rpm for 15 min and then thoroughly washed with distilled water. For hydrothermal treatment, the resulting product was placed in a 25 mL Teflon-lined stainless-steel autoclave and kept at a temperature of 180 °C for 1 h. To convert the hydroxides processed in the autoclave into the corresponding individual oxides or the ZnO-In2O3 composite, they were heated in air at 500 °C until a constant resistance was achieved. The three methods described above were used to prepare samples of ZnO-In2O3 composites containing from 5 to 85 wt.% zinc oxide. The samples were subsequently used for microstructural and compositional characterization and the measurement of conductivity and sensor properties.In the preparation of ZnO-InThe phase composition, structure, and morphology of the composites were determined by X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM and SEM), energy dispersive X-ray spectroscopy (EDX) and low-temperature gas adsorption. XRD spectra were recorded on a Rigaku Smartlab SE X-ray diffractometer using Cu Kα radiation with a wavelength of 1.5406 Å. The average size of nanoparticles was determined from XRD spectroscopy data according to the Debye-Scherrer formula: D = 0.9λ/(βcosθ), where λ is the wavelength of X-ray radiation, β is the half-width of the peak, and θ is the diffraction angle corresponding to this reflex.The morphology of particles in the composites and the distribution of metal ions between the components of the composite were determined by SEM on the Prisma E device and TEM and EDX, on the Tecnai Osiris FEI equipped with energy-dispersion analysis The dot is system. The specific surface area and average pore size were determined by low-temperature nitrogen adsorption on the NOVA Series 1200e Quantachrome (USA) device.To determine the conductivity and sensor properties, the synthesized composites were mixed with distilled water. The resulting paste was applied to a special chip equipped with a platinum heater and contacts for recording the corresponding electrophysical characteristics, gradually raising the temperature to 550 °C until a constant resistance of the resulting film was achieved.o/Rg were determined from these data, where Ro is the initial resistance of the sensor  and Rg is the minimum value of the sensor resistance achieved after the introduction of the analyzed gas.The sensor resistance change was recorded using the Digital Multimeter Keysight, the signal from which was transmitted to the computer. The installed computer program was used to obtain the kinetic curve of the change in resistance. The sensor responses S = R2 was studied using the device developed in the temperature range of 280 to 520 °C. The accuracy of maintaining the temperature was within 1 °C. The chip with the applied sensitive layer was located in a special chamber with a volume of about 1 cm3 into which purified air or a calibration gas mixture containing 0.1% H2 was supplied. The gases were pumped through the chamber at a rate of 200 mL/min.The sensor response of the prepared films to H2O3 composites obtained by the three approaches described in the previous section were determined by modern physicochemical methods. The analysis of these data enables the determination of the effect of the synthesis method on the phase composition, structural characteristics, as well as the conductive and sensor properties of the composites.The structure, morphology, conductivity, and sensor response to hydrogen of ZnO-In2O3 composites obtained by the three synthesis methods are presented in 2O3. Diffraction peaks at 21.5, 30.6, 35.5, 37.7, 41.8, 45.7, 51.0, 55.9, and 60.7° correspond to planes (211), (222), (400), (411), (332), (431), (440), (611), and (622) of indium oxide, respectively. Peaks at 31.7, 34.1, 36.1, 47.3, 56.5, 62.7, and 67.7° can be attributed to the (100), (002), (101), (102), (110), (103), and (112) planes of the oxide zinc, respectively. For composite ZnO-In2O3 obtained by mixing powders and impregnation methods, all diffraction peaks correspond to the cubic structure of bixbyite In2O3 (JCPDS no. 06-0416) and hexagonal ZnO with a wurtzite structure (JCPDS no. 36-1451).The XRD spectra of ZnO-In2O3 composites synthesized by the hydrothermal method, peaks were recorded that relate to both the cubic and rhombohedral phases of In2O3 . The compositions of zinc oxide in these composites, calculated by the Rietveld method, are 9.7, 29.5, 64.9, and 100%. Note that the concentration calculated from the XRD data corresponds to that used for synthesis only for the 65%ZnO-35%In2O3 composite. It can be assumed that the ZnO-In2O3 heterostructure is formed only at this concentration. At other concentrations of zinc, one component is introduced into the structure of another. The absence of any extraneous peaks indicates the high purity and crystallinity of the samples synthesized by the three methods used in this study.In the spectra of ZnO-In2O3  in hydrothermal samples is located in the region of large angles compared with the situation in pure In2O3 see . The obsThe particle size of zinc oxide calculated by the Debye-Scherrer formula is 45–50 nm in mixed composites and 10–30 nm in impregnated samples. The size of these nanoparticles in mixed composites does not depend on the zinc oxide concentration. On the contrary, the particle size of ZnO in impregnated composites decreases from 30 to 10 nm as its concentration in the mixture with indium oxide increases. It is probable that with an increase in the concentration of zinc salt, a large number of crystallization centers appear in the process of impregnation, which prevent the growth of embryos and, consequently, the formation of large crystals. In addition, the size of indium oxide nanoparticles in samples prepared by these two methods was calculated from the data from X-ray diffraction analysis. Calculations have shown that the size of indium oxide particles is approximately 70 nm and does not depend on the zinc oxide concentration in such samples.2O3 structure hinders crystal growth. In composites containing from 20 to 85 wt.% zinc oxide, the particle size of ZnO is almost three times larger than that of In2O3 and decreases from 72 to 25 nm. The observed difference in the sizes of nanoparticles of zinc oxide and indium oxide may indicate that zinc oxide completely covers the surface of indium oxide during the formation of crystalline zinc oxide in hydrothermal composites, resulting in the formation of a core-shell structure.According to XRD data, an increase in the concentration of zinc oxide in hydrothermal composites is accompanied by a decrease in the size of indium oxide nanoparticles from 25 to 9 nm. This result indicates that during synthesis, Zn atoms replace In atoms in the lattice, which creates deformations in the composites . Thus, t2O3 nanocomposites are a mixture of nanocrystals of the corresponding oxides, have a diverse shape, and are characterized by a wide particle size distribution from 50 to 100 nm, which practically coincides with the particle sizes of the initial commercial nanopowders  is observed for the hydrothermal composite containing 65% ZnO. A higher specific surface area and a smaller average pore size of hydrothermal composites compared with mixed and impregnated composites facilitate the adsorption of O2 and the analyzed gas, which should lead to an acceleration of the response-recovery processes during gas detection.The surface area calculated by the BET method was 25 m samples . To studn-type semiconductors. In all the cases considered, the temperature dependence of the resistance of synthesized composites is not described by the Arrhenius law. The deviation from the Arrhenius law is obviously due to the fact that an increase in temperature leads to the desorption of chemisorbed active oxygen particles located on the surface of the sensitive layer.The temperature dependence of the conductivity in air of composites obtained by the various methods investigated exhibits the same characteristics. In the range of 300 to 520 °C, the conductivity of all synthesized systems increases with rising temperature, which is typical for 2O3 composite conductivity on the concentration of zinc oxide is largely determined by the synthesis method.At the same time, as can be seen from the experimental data shown in 2O3 systems when a heterojunction occurs [The nature of the change in the resistance of the impregnated composite, depending on the composition, differs little from the situation observed for the mixed composite. Specifically, the resistance in these systems increases sharply with an increase in the ZnO concentration. An increase in resistance is also observed in ZnO-Inn occurs ,34. Impr2O3 and ZnO , electrons are transferred from In2O3 to ZnO nanocrystals at contacts between nanocrystals of these oxides. This circumstance should be taken into account when considering the conductivity process in this system using the percolation model [Due to the large difference in the values of the electron work function between Inon model .2O3 particles in the composites investigated differ even more.As a result of the percolation transition, the path of the current flow changes. The conducting particles become nanoparticles of zinc oxide rather than indium oxide nanoparticles. Such a transition causes a sharp decrease in conductivity. It is important to note that the percolation transition in the systems investigated depends on the method used for sample preparation and occurs at different concentrations of zinc oxide. While in order to change the current path, the impregnated composite must contain 40 wt.% ZnO, the percolation transition in a composite formed by mixing nanopowders is observed at a concentration of at least 65 wt.% zinc oxide. This difference is mainly because the size of ZnO nanoclusters formed on the surface of indium oxide does not exceed 10–30 nm. This size is several times smaller than that of ZnO nanoparticles in a mixed composite, the average size of which is approximately 70 nm. The specific surface area of ZnO and, consequently, the contact area between ZnO and In2O3 nanocrystals.All this implies that the transition of electrons from indium oxide to zinc oxide in contact with it occurs more efficiently in an impregnated composite than in a mixed composite. As a result of such a transition of conduction electrons, the current in the system will flow through aggregates of zinc oxide molecules with much lower conductivity. This trend also explains the observed decrease in the conductivity of the impregnated composite at a lower concentration of ZnO than in the mixed composite. With ZnO concentrations above 40%, the conductivity of the impregnated composite becomes significantly less than that of a mixed composite of the same composition in which current flows through In2O3 composites formed by mixing nanopowders and impregnation .The sensor properties of ZnO-Inchnology  is nearl– on this surface. The formation of O– oxygen centers occurs during the dissociation of chemisorbed oxygen on the surface oxygen vacancies of a metal oxide nanoparticle. In the ZnO–In2O3 composites investigated, oxygen dissociation with the formation of chemisorbed oxygen atoms occurs mainly on the surface of ZnO nanoparticles. This is because ZnO has a higher catalytic activity than In2O3. The electrical current in both mixed and impregnated composites containing up to 80% ZnO flows through electron-rich In2O3 nanoparticles. The current flow path is determined not only by the ratio of component concentrations in the composite but, in accordance with the percolation theory, also depends on the size of oxide particles [According to the current generally accepted model of sensor processes in the detection of reducing compounds, the sensor response is determined by two processes: the adsorption of oxygen and the analyzed gas on the surface of the sensor layer and the reaction of adsorbed compounds with oxygen centers Oarticles ,35.2O3 and ZnO nanoparticles, oxygen atoms formed on the surface of ZnO nanoparticles pass to the surface of In2O3 nanoparticles, capturing conduction electrons and transforming into anion radicals, O-. These anion radicals participate in the detection reaction of reducing compounds, in particular H2. The ZnO also catalyzes the dissociation of adsorbed H2. Consequently, these nanocrystals are chemical sensitizers of the sensor reaction in the ZnO-In2O3 composite. The effect of ZnO on the sensor response in the ZnO-In2O3 nanocomposite can be attributed to the flow of H atoms from ZnO into In2O3 nanocrystals, where they react with O− and return electrons to the In2O3 conduction band. The chemical sensitization of the process is most effective in the composite when conducting aggregates of In2O3 are in contact with ZnO nanocrystals along the entire current path.Upon contact between In2O3 system is also observed at 20% ZnO [On the curve of the dependence of the maximum response of mixed and impregnated composites to 1100 ppm of hydrogen on composition, there are two maxima at zinc oxide concentrations of 15–20 and 85 wt.%. Note that the maximal response to ethanol in the ZnO-In 20% ZnO . The max2O3 nanoparticles during impregnation. The low bond strength in the lattice of such clusters and their developed surfaces contribute to a decrease in the energy required for the formation of active oxygen vacancies. As a result, the concentration of active centers in the cluster significantly increases, which causes a higher sensor response when detecting hydrogen with an impregnated composite. The role of contacts between zinc and indium oxide nanoparticles having different electronic structures and morphologies was also observed in the detection of ethanol [The main reason for the different sensor activity of the composites, as well as their structural characteristics discussed above, is that the size of zinc oxide nanoparticles in the mixed composite is several times larger than the size of ZnO nanoclusters deposited on the surface of In ethanol ,25,28.2O3: 0–20 wt.%, 20–85 wt.%, and above 85 wt.% ZnO. These sites differ in the effect of zinc oxide on the sensor response of the composite. Note that a similar pattern was previously observed in SnO2-In2O3 composites [In contrast to mixed and impregnated systems, several characteristic areas can be distinguished on the curve of the dependence of the maximum sensor response on the composition of hydrothermal composites ZnO-Inmposites . The sen2O3 composites containing up to 20% zinc oxide is significantly influenced by the fact that during the synthesis of such composites, a change in the phase composition of In2O3, namely the transition of the cubic to the rhombohedral phase, occurs. Earlier, we found that the introduction of cerium into indium oxide, leading to its phase changes, causes a sharp drop in the sensor response to hydrogen compared with pure indium oxide [2 compared with the undoped sample [The magnitude of the sensor response of hydrothermal ZnO-Inum oxide . The intd sample .2O3 and, on the other, to a decrease in the proportion of the rhombohedral phase of indium oxide.An increase in zinc oxide concentration from 20 to 85 wt.% leads to a rise in the sensor response to hydrogen by almost two times. In this case, the formation of crystalline zinc oxide particles and the return of a stable cubic phase of indium oxide are already taking place. It should be noted that in mixed and impregnated composites, indium oxide has an exclusively cubic structure. That is, an increase in the sensor response to hydrogen in hydrothermal composites containing from 20 to 85% zinc oxide is due, on the one hand, to the formation of a heterojunction between ZnO and In2O3 during hydrothermal synthesis and, at such a concentration, completely cover the surface of indium oxide. Accordingly, the sensitivity of the nanocomposite decreases, approaching the sensitivity of nanocrystalline ZnO.Note that the composite containing 65% ZnO has the maximum sensor activity. According to the data obtained, only two phases  are formed in such a system, and an increase in the sensory response is associated with chemical sensitization. A decrease in the sensor response of composites containing more than 85% zinc oxide is associated with the interruption of the flow of current between indium and zinc oxides. This is because nanoparticles of crystalline ZnO are formed on In2O3 composites, the temperature dependence of the sensor response of hydrothermal composites to hydrogen passes through the maximum. The maximum temperatures (Tmax) in the detection of 1100 ppm of hydrogen for composites obtained by the hydrothermal method and the impregnation method are 100 and 125 °C, respectively, which are higher than for the mixed composite  contained in mixed composites. This happens because of oxygen dissociation on the surface of nanoparticles, resulting in a large concentration of defects with catalytic activity. Such defects contribute to the formation of oxygen adatoms. The bond of the resulting atoms with defects leads to an increase in the energy required for oxygen desorption and its transition from ZnO particles to In2O3 particles, which determines the conductivity of the composite. Therefore, the sensitization of the sensor response by ZnO nanoparticles is manifested in such composites at higher temperatures than in mixtures of commercial nanopowders and is more effective due to the high concentration of defects [The observed difference in T defects .2O3 composites on their selectivity in the detection of H2 with respect to CO. 2 and CO.The main disadvantage of metal oxide sensors is their insufficient selectivity with respect to cross-sensitive gases. In this regard, we studied the influence of the method of obtaining ZnO-InH2/SCO ratio, significantly exceeds the selectivity of composites obtained by mixing oxide nanopowders or by the impregnation method. Such a difference in the selectivity of the samples obtained by different methods is probably due to the change in the structures of the resulting composites and, as a consequence, the sorption activity of the metal oxides included in their composition. The high selectivity of the hydrothermal composite may also be associated with the formation of p-type defects [The data presented show that although the composite synthesized by the hydrothermal method has the smallest value of the maximum response to both gases, its selectivity, i.e., the S defects .2O3 composites indicates a significant influence of the method of their formation on the phase composition, structural characteristics, conductivity, and sensor properties in the detection of hydrogen with such materials. The methods of mixing commercial nanopowders and impregnation lead to the formation of two-phase crystalline composites, regardless of the concentration of the components.The analysis of the properties of nanostructured ZnO-In2O3 nanoparticles and their capture of electrons from these nanoparticles work in the sensor process.In the impregnated composites, the particle size of zinc oxide was smaller than in mixed systems. In turn, in hydrothermal composites, the phase composition is significantly influenced by the concentration of zinc oxide in the composite. Obviously, with any method of composite preparation, the dissociation of oxygen molecules on catalytically active ZnO nanoparticles coupled with further transfer of oxygen atoms to electron-rich InA very important role is played by the interaction between the components of composites due to specific contacts in the process of their synthesis. This factor concerns hydrothermal synthesis to the greatest extent. Specifically, this factor refers to the doping of nanoparticles—the transition of metal ions of one component into nanoparticles of another component with the embedding of metal ions of one oxide into the crystal lattice of another metal oxide.2O3 composites we investigated, contacts between nanoparticles of the oxides led to electron transfer from In2O3 to ZnO and a gradual increase in the resistance of the composites with a rise in the ZnO concentration in the system. Along with this, in hydrothermal composites containing up to 20 wt.% ZnO, the interaction of nanoparticles leads to a change in the phase composition and structure of In2O3 particles as a result of the embedding of zinc ions into In2O3. The maximum resistance in this case is achieved in the system containing 20 wt.% ZnO.In the mixed and impregnated ZnO-In2O3 to a rhombohedral form. This transition probably has a significant effect on the interaction between metal oxides and, consequently, on the sensor process.The change in the structure of composites, as well as the different particle sizes, result in the composites formed by the impregnation method having the maximum sensor response to hydrogen. The reason for the relatively low response of hydrothermal composites may be a change in the phase state of indium oxide during hydrothermal synthesis. Unlike mixed and impregnated composites containing only the cubic form of indium oxide, hydrothermal synthesis results in the transition of the cubic form of In


The separation of trivalent actinides and lanthanides is a key step in the sustainable development of nuclear energy, and it is currently mainly realized via liquid–liquid extraction techniques. The underlying mechanism is complicated and remains ambiguous, which hinders the further development of extraction. Herein, to better understand the mechanism of the extraction, the contributing factors for the extraction are discussed  by combing molecular dynamics simulations and experiments. This work is expected to contribute to improve our systematic understanding on a molecular scale of the extraction of lanthanides and actinides, and to assist in the extensive studies on the design and optimization of novel ligands with improved performance. In recent years, there has been a transition of the energy strategy worldwide from non-renewable fossil fuels to renewable resources. This transition is also considered necessary in order to minimize the release of carbon dioxide to alleviate the greenhouse effect and environmental pollution. Nuclear energy is considered one of the most promising alternatives to fossil fuels. According to statistics, in 2022, the nuclear power plants in China generated 417.786 billion kW∙h, accounting for 4.98% of the total national power generation. This is equivalent to 118 million tons of standard coal, which is deemed to release substantial carbon dioxide, nitrogen oxides, and sulfur dioxide, demonstrating the advantage of nuclear energy as a highly efficient, clean, and sustainable energy solution.3+ than Ln3+; thus, they are considered to be potential ligands for the extraction and separation of An3+ from Ln3+. Many groups have improved the understanding of the solution dynamics of lanthanides, actinides, and their complexes with ligands toward the design and optimization of ligands for Ln/An separation via liquid–liquid extraction.With the growth of nuclear power generation, a large amount of nuclear waste needs to be disposed of ,2. The dIn this work, recent studies on the solution dynamics of phosphinic and thiophosphinic ligands and their complexes with lanthanide and actinide ions are reviewed to provide peer scientists with an understanding of the status of this issue.3+ has higher affinity for ligands containing N or S atoms than Ln3+; thus, these soft donor ligands exhibit selectivity for An3+ and can be used in the separation of An3+ from Ln3+. The ligands containing O atoms are commonly used for group extraction and chelation of lanthanides and actinides, but can hardly distinguish them.The ligands used for Ln/An separation generally contain O, N, or S as ligating sites. The intrinsic conformational and electronic properties of the ligands determine their behavior in the extraction and exhibit different kinetics and selectivity. According to the hard–soft acid–base (HSAB) principle ,9, the sThe geometric structures of ligands govern their behavior in the condensed phase, including their coordination modes with metal ions and their migration in homogeneous and heterogeneous media. Many factors can influence the solution dynamics of lanthanide and actinide ions, such as the concentration of ligands, their protonation states (pH), and the type of solvent.Owing to the difficulty in conducting experimental studies of actinides, molecular dynamics (MD) simulations have been employed to explore the extraction mechanism, including the key issues of, e.g., the coordination structure and the migration in the extraction. Below the recent advances in the understanding of the factors influencing the dynamics of actinides in the condensed phase are surveyed.3+ and Cyanex301  governs the protonation state of ligands and the hydrolysis of metal ions, as well as affects their complexation mode and distributions and the complexes formed between them. Thus, the solution dynamics of lanthanides and actinides ions is strongly affected by the pH of solution. Wipff and coworkers  reported3+ using molecular dynamics simulations, and both their intact and deprotonated forms were surface-active and populated at the interface, with the latter being more surface-active. Dwadasi and coworkers 2+) and 1:2 complex with Y3+ ([Y(NO3)2(H2O)7]+). The slope analysis studies in the laboratory, combined with the molecular dynamics simulations, revealed that two and one ligands from the D2EHPA phosphoric acid extractant were required for the complete extraction of lanthanum and yttrium ionic complexes, respectively.Lastly, the ability of ligands to coordinate with metal ions influences the extraction. In 2020, Xiao et al.  studied y D2EHPA  23], th, th−, NO2 (SC-CO2) in the extraction of uranyl ion using molecular dynamics simulations. The most significant difference between the two types of media was the lower solubility of water in chloroform and the higher mobility of the molecules in the SC-CO2.The dilute phase used in the liquid–liquid extraction provides a medium to accommodate the ligand-bound metal ion species. Wipff et al.  investig3+ by BTP solvated in hexane + octanol, hexane, nitrobenzene, or chloroform using molecular dynamics simulations. BTP dispersed well in chloroform and nitrobenzene, but aggregated in hexane and hexane + octanol. In the biphasic systems of water with the former two solvents, BTP was distributed at the interface with its molecular plane parallel with the interface; in the biphasic system of water with the latter, at the interface, BTP could orientate itself with its molecular plane parallel to the interface or with its nitrogen atoms pointing toward the dilute phase. Liu et al. [Wipff and co-workers  exploredu et al.  added oc3+ cation in the butylmethylimidazolium bistriflimide ([BMIM][NTf2]) ionic liquid. For both Am:L (1:1) and Am:L2 (1:2) complexes, it was found that the secondary solvation environment was influenced by the imidazolium arms of the ligands attracting NTf2 anions near the metal ion. As a result, the binding free energy for the second ligand was twice that for the first ligand, which resulted in the Am:L2 complex being more stable than the Am:L complex. The preorganized ligands with charged functional groups could be tuned to enhance the selectivity in ion extraction efficiency.Ionic liquids, as “green” solvents with low volatility, high thermal stability, and wide liquid temperature range, can be used in the liquid–liquid extraction of lanthanide and actinide ions, with potential application prospects ,31,32,33Efficient separation of trivalent lanthanides and actinides is the key to establishing an advanced nuclear fuel cycle, which remains a challenge owing to their similar chemical and physical properties in the condensed phase . AccordiAs potential candidates to separate actinides and lanthanides, sulfur donor ligands display high selectivity for actinides over lanthanides, and the separation factor (SF) of An/Ln in the liquid–liquid extraction can be up to, depending on the dilute phase and the pH of the aqueous phase, SF = 5900  , 6000 d. These v3+ from trivalent lanthanides by Cyanex301; in the next year, they reported that the SF value of Am3+ and Eu3+ could be up to 5900 [3) were obtained for micro and macro concentrations of Ln(III) at pH 3–4. In 2002, Chen et al. [3+ from lanthanides.Bis dithiophosphinic acid (Cyanex301) is a representative sulfur donor ligand to selectively separate lanthanides and actinides. In 1995, Zhu et al.  selectiv to 5900 . In 1998 to 5900  reportedn et al.  used purThe growing attention toward the potential of Cyanex301 to be used in the selective separation of trivalent lanthanides and actinides calls for an extensive understanding of the origin of its selectivity, which remains controversial. There are three main opinions, emphasizing the coordinating structures of complexes, the dehydration of lanthanides and actinides, or the covalency of the coordinated bonds. Below, we briefly survey the studies related to these three opinions.3 complexes with Nd, Sm, and Cm using visible absorption spectroscopy and X-ray absorption fine structure (XAFS) measurements, as shown in 3+, Nd3+, and Eu3+) and actinides (Am3+) , while eight sulfur atoms from four Cyanex301 ligands were coordinated with Am with no aqua ligand, HML4 (L = C301). In 2007, Bhattacharyya et al. [3+ and Eu3+ complexes with Cyanex301 in nitric acid. At a low concentration of Cyanex301 (less than 0.3 mol/L), the coordinated complexes took the form of AmL3 and EuL2NO3 (L = C301), respectively. In the concentrated Cyanex301 systems, the complex of Eu3+ changed into Eu(C301)3.In 2002, Jensen et al.  found ths (Am3+) , wherebya et al.  reportedThese results show that the coordinated structures of lanthanides and actinides extracted by Cyanex301 are different and influenced by the concentration of Cyanex301 and the property of the solvent, resulting in a complicated mechanism underlying the distinctly different selectivity of Cyanex301 for lanthanides and actinides.When using Cyanex301 to extract lanthanides and actinides, depending on the properties of the metal ions, both inner-sphere complexes a and out3+ by Cyanex301, and they found that, when 10% of HC301 was neutralized, the inner coordination shell of Nd3+ in the organic phase was occupied by sulfur atoms from Cyanex301 and there was no formation of a W/O microemulsion. As the system was further neutralized, more HC301 was deprotonated, and a W/O microemulsion could be observed in the system. In a follow-up study, they [In 2016, Chen et al.  investigdy, they  found thdy, they  also rep3  by density functional theory, and reported that the complex with C301 as a bidentate ligand and the metal cation coordinated by six sulfur atoms were likely the most stable extraction complexes. They proposed that the higher selectivity of Cyanex301 for actinides may originate from the different hydration Gibbs free energies with the hydration Gibbs free energies of Eu3+ being higher than those of Am3+ and Cm3+, resulting in the complex of Eu3+ being less stable in the aqueous solution. Similar results were reported in a recent density functional theory study of the coordination of Eu(III) and An(III) with N-donor ligands, and their distinct ability to be dehydrated was proposed to govern their selective separation in liquid–liquid extraction [Cao and coworkers  investigtraction .3+ over Nd3+. In a later density functional theory study, Cyanex301 was identified to combine with Am3+/Cm3+ to form ML3 complexes (L = C301), and the binding strength was stronger than with Eu3+ ions [First-principles studies have attributed the selectivity of Cyanex301 for actinides to the covalent feature of the interaction between them. In 2011, Bhattacharyya et al.  found thu3+ ions . The extu3+ ions , which bIn addition to the controversy on the origin of the selectivity of Cyanex301, the mechanism of extraction of lanthanides and actinides by Cyanex301 is under debate. At present, the widely accepted extraction mechanism is the cation-exchange mechanism [As discussed above, liquid–liquid extraction is a complicated process in the condensed phase, which can be influenced by multiple factors, e.g., the aggregate of ligands, the ratio of metal ions and ligands in the complexes, the saponification of ligands, and the dilute phase. In practice, two methods are commonly used to improve the extraction of lanthanides and actinides by phosphinic ligands, i.e., the modification of the substituent and the addition of synergistic reagent to the dilute phase.3+ and Eu3+ compared to native Cyanex301. In a later study [3 substituent was introduced into dithiophosphinic acids (DPAH, 3+ than Eu3+ could be attributed to the stronger covalency of Am–S bonds. In another combined experimental and computational study by the same group [o-CF3 were found to have a stronger interaction with Nd3+, and the improved ability to extract Nd3+ ions was proposed to be due to steric hindrance of the o-CF3 substituent, which benefited the dehydration of metal ions. Xu et al. [3+ and Eu3+; they found that the branched alkyl chain substituent and aromatic substituent exhibited better selectivity in the separation of Am3+ and Eu3+, which was attributed to the enhancement of the acidity of the ligands [The substituents can affect the hydrophilicity and hydrodynamics of the ligands, which impose an influence on the extraction ability of the ligands. In 2013, Chen et al.  reporteder study , the –CFds DPAH, , and theme group , the ligu et al. ,73 modif ligands ,72,74.3+ and Eu3+ more efficiently, with the SF being up to 6000 higher than the value when using only Cyenax301. The difference may mainly originate from the different coordinated structures of the extracted complexes, as shown in 3+ by Cyanex301 and D2EHPA performed better than when only using Cyanex301, as well as by Ionova et al. [3+ and Eu3+ with the effective charge of oxygen atoms in the neutral oxygen-containing ligands.In liquid–liquid extraction, it is a common operation to add synergistic reagents to improve the extraction. Hill et al.  reporteda et al. , who evaAt present, synergistic extraction is a potential way to improve the separation of lanthanides and actinides. However, the underlying mechanism is complicated and remains to be clarified to assist in the optimization of synergistic extraction in a specific extraction system.To achieve the sustainable development of nuclear energy and eliminate the concerns regarding its threat to human beings, it is of significance to understand the extraction of ligands and ligands coordinating with lanthanides and actinides. Soft sulfur-donating ligands display significant selectivity for the trivalent actinides compared to lanthanides, and they are considered among the potential extractants in Ln/An separation. In order to provide a systematic view of the state of the art to promote extensive studies, we summarized herein the contributing factors that influence the solution dynamics and the extraction of trivalent lanthanides and actinides, i.e., the concentration of ligands, the pH, the type of salt ion, the type of dilute phase, and the specifics revealed by studies of sulfur-containing ligands.Among these sulfur-donating ligands, Cyanex301 is a successful sulfur-based extractant and shows good performance in the separation of trivalent actinides and lanthanides. This review discussed the possible origins of selectivity of Cyanex301 for the actinides to contribute to an understanding of the mechanism underlying the selectivity of Cyanex301 and to assist in the design of Cyanex301 analogues with optimal performance for the extraction of actinides.This work is expected to enrich our understanding of the extraction and the dynamics of ligands combined with actinides and lanthanides, and to optimize the extraction of lanthanides and actinides.


Coughing is common in dogs with tracheal collapse (TC). Inhaled corticosteroids are the standard of care in humans, but their use in dogs is less widespread than oral corticosteroids. This study compared the efficacy, adherence, and tolerance to treatment of inhaled versus oral corticosteroids in 30 dogs with cough and TC, randomized to each treatment. Responses were monitored in the hospital (enrolment and weeks 2 and 4) and at home (weeks 1 to 4) using a semiquantitative clinical scale based on four key clinical parameters . Both treatments provided comparable clinical improvements, with significantly greater improvements at the end in the fluticasone group. Adherence and tolerance were equivalent, but thirst and the frequency of urination increased in those taking prednisone. In conclusion, inhaled fluticasone is effective in controlling cough in dogs with TC without side effects, which encourages its use to be extended compared to prednisone.p < 0.05). Adherence and tolerance were comparable. From weeks 2 to 4, OG dogs were significantly thirstier and urinated more frequently than IG dogs. In conclusion, fluticasone provided good tolerability and efficacy in controlling cough in dogs with TC, and they showed a lower incidence of signs of hypercortisolism compared to prednisone. These data encourage the use of inhaled fluticasone in dogs with cough and TC.Coughing is common in dogs with tracheal collapse (TC). The use of inhaled corticosteroids is less widespread than oral ones. This study aims to compare the effects of oral and inhaled corticosteroids in dogs with cough and TC. Thirty dogs were prospectively included and randomized to the prednisone oral group  or fluticasone inhaled group . A clinical score (CS) based on four clinical parameters  was monitored at the hospital (enrolment and weeks 2 and 4). Water intake, urination habits, and adherence and tolerance to treatments were monitored weekly. Significant improvements in clinical parameters were identified in both groups throughout the study. Between-group (OG–IG) comparisons revealed no significant differences, indicating equivalent improvement. At the study’s endpoint, the IG dogs had a significantly lower CS (5.69 ± 0.79) than OG dogs (6.43 ± 1.02,  Tracheal collapse (TC) in dogs is a degenerative structural disorder of the tracheal wall, resulting in the excessive  dynamic collapse of the tracheal lumen ,2 whenevThe complete etiology has not been established. A multifactorial origin, including congenital anomalies  and acquired conditions , seems to be implicated ,5,6,7,8.In predisposed breeds, the diagnosis of TC is very often presumptively established based on the case history, clinical signs, physical examination and radiography of the neck and thorax. One of the most common signs of TC is a dry, harsh and persistent cough, sometimes described as a “goose-honking” cough, which can progress to a wheezing noise and difficulty breathing. Radiography is a definitive indication in the first-step evaluation of dogs with suspicion of TC, and allows one to discard other possible etiologies and to identify concomitant cardiorespiratory diseases. Complementary techniques such as fluoroscopy, computed tomography, endoscopy, and ultrasonography contribute to the diagnosis and evaluation of the severity of the process ,2,3,7,10The concurrence of coughing and increased sensitivity to palpation of the trachea may indicate the presence of associated tracheal inflammation, whose treatment may provide general improvements in the patient by interrupting the vicious circle of airway collapse–inflammation–cough. In these cases, an indication for the use of corticosteroids may exist. In humans and cats with airway disease, inhaled corticosteroids have shown proven efficacy for cough control and are considered the standard of care in place of oral corticosteroids ,13,14,15The use of inhaled corticosteroids has recently demonstrated its efficacy in the treatment of dogs with TC and other causes of cough . The inhDespite the theoretical clinical benefits, no prospective studies have compared the therapeutic effects of inhaled versus oral corticosteroids in dogs with cough and TC. The availability of these data is timely and necessary in seeking to improve penetrance among specialists and general practitioners. The goal of this study was to evaluate the comparative efficacy of oral versus inhaled corticosteroids parallel to the appearance of polyuria–polydipsia as markers of iatrogenic hyperadrenocorticism and differences in tolerance and adherence to each treatment regimen over a 4-week period. We hypothesized that inhaled corticosteroids would provide positive responses comparable to oral ones, with less concurrence of polyuria–polydipsia, and good tolerance and adherence to treatment.Client-owned dogs presented to the Cardiorespiratory Service of the Veterinary Teaching Hospital of the University of Murcia and the Veterinary Hospital “7 Vidas” for evaluation of cough were considered candidates for inclusion in this prospective observational randomized study. Owners provided informed consent, and the Institutional Animal Care and Use Committee at the University of Murcia approved all procedures . Dogs presenting with cough and diagnosed with TC were eligible for the study if an indication for the use of anti-inflammatory therapy was found. Tracheal collapse was diagnosed based on the objective verification of changes in tracheal diameter on radiographs, fluoroscopy and computed tomography, or the identification of tracheal collapse during endoscopy. When endoscopy could not be performed, the diagnosis was based on a combination of the following criteria: lack of clinical or radiographic evidence of an aspiration-related foreign body or neoplastic disease, and the observation of luminal changes in the tracheal diameter on radiographs or fluoroscopy. A 13-point grading system was established to quantify the severity of the clinical signs and to objectify the indication for the use of anti-inflammatory therapy. This system was based on four key clinical parameters  whose variations were standardized according to a predetermined semiquantitative scale . The sumThe treatment regimen for each group is specified in -Use of a self-manufactured face mask made from plastic bottles, so that the lip corners are covered, the eyeballs are excluded, and 2–3 cm is maintained from the nose to the opening hole of the mask .-Pediatric or veterinary commercial valved holding chamber (VHC).-Once the metered-dose inhaler (MDI) dispenser, VHC and mask had been coupled, it was recommended to hold the animal minimally during administration. Once the indicated dose had been released, the system had to be kept coupled until 7–10 respiratory cycles had been completed.Regardless of the assigned therapeutic scheme, the following general treatment guidelines were applied to all dogs: avoid the use of collars in favor of harnesses, weight control and avoid exposure to tobacco smoke  as well as sudden changes in behavior and environmental temperature. Dogs that were taking antitussives for more than one month prior to study entry were allowed to continue taking them as long as no contraindications  were identified during the diagnosis investigation. The use of additional medications was not allowed during the study period. The method of oral medication administration was free, and adhered to the previous habits of the owner in relation to their own animal. In the case of the inhalation therapy, owners were instructed to standardize their administration, following these guidelines:The research team conducted a personal training session with the owners of each dog included in the study to teach them the correct method of use of the inhaled medication. The owners were instructed to progressively acclimate the dog to the facemask before activating the MDI.After inclusion and random assignment to one study group (OG or IG), the animals were scheduled for face-to-face veterinary control on weeks 2 and 4 of treatment, while on weeks 1 to 4, the owners had to complete the home control form. The data collected in the veterinary controls were formalized by completing an inclusion form and another for follow-up . LikewisA power calculation was performed before enrolment based on a 13-point clinical grading system. A conservative assumption determined that a standard deviation (SD) of 1.3 (10%) would capture the greatest changes on this scale. The null hypothesis was defined as no significant change on the 13-point scale between study groups, and the alternative hypothesis was that there would be a change of at least 1.8 points in the total score. By performing a bilateral t-test using a power calculator , a samplIndividual scores for each clinical variable included in the grading system as well as the FCS constituted the semiquantitative variables analyzed in the study. Body weight and age were analyzed as quantitative variables. Quantitative data are presented as the mean ± standard deviation and categorical data are expressed as proportions and percentages. Differences between checkpoints for the scores of each clinical variable and FCS were explored by means of the Wilcoxon test for paired data. The internal percentage distribution of clinical variables between control points and between treatment groups was also analyzed by the comparison of proportions using a chi-squared test and column-paired analysis using Z-tests. p < 0.05.Statistical analyses were performed using the commercially available statistical software package IBM SPSS Statistics 28.0.1.1 (14) and significance was set at A total of 32 dogs were enrolled in the study. However, two dogs in the OG were excluded from the study due to a lack of owner compliance. Finally, the study included 30 dogs, 14 in the OG and 16 in the IG. The mean age of the 30 dogs was 7.0 ± 3.84 (1–16) years. Fourteen dogs were male (eight castrated) and sixteen were female (ten spayed). The weight range for all dogs was between 1.8 and 15 kg , and the 5-point body condition score ranged between 2 and 5 . Represented breeds included Yorkshire terrier (9), mixed breed dogs (9), Maltese (3), Poodle (4), Chihuahua (3), and Pomeranian (2). At the time of enrolment, no significant differences between the two study groups in demographic variables or clinical parameters  were found , Table 3p < 0.05). The cough episodes were paroxysms in 93.8% of dogs at inclusion, and this percentage was significantly lower at weeks 2  and 4 . Cough frequency was also reduced from persistent and very frequent to frequent and sporadic. It is striking that none of the dogs in the group presented cough sporadically at inclusion and week 2, while at week 4, 75% presented this cough frequency category. The differences in the inner distributions of tracheal sensitivity categories followed a similar trend, although they became more evident and significant when observing the difference in the percentage of dogs with hyperreactive tracheas at the time of inclusion (43.8%) compared to weeks 2 (6.3%) and 4 (0%). At inclusion, 75% of dogs were in the severe score class, but at the end of the study, 100% of them were in the mild score class. Scores of each of the clinical variables monitored at the hospital  as well as FCS were significantly reduced from the inclusion checkpoint compared with the week 2 and week 4 checkpoints . ReductiWater consumption and urinary frequency did not significantly change during the study in this group . The adhThe group of dogs that was randomized to receive oral corticosteroid therapy showed overall favorable results equivalent to those described for the IG . The scoAt week 1, the perceptions of the owners of 35.7% of the dogs from this group were that water consumption and urinary frequency increased compared to the inclusion point . This peAdherence to the treatment was excellent, with 92.9% of owners declaring that they were always able to administer the prescribed dosages during the study. Tolerance was also excellent, with mild differences during the study .p < 0.05; As previously mentioned, significant improvements in the clinical study parameters were identified in both groups throughout the study. However, between-group  comparisons at each checkpoint revealed no statistically significant differences, thus indicating that the improvements provided by both regimens tested for the treatment of cough in these groups of dogs with TC were equivalent. However, the only significant difference between the groups was that the FCS in the IG was lower (5.69 ± 0.79) than in the OG , and very good tolerance to the inhaled administration protocol. These data support and encourage using inhaled fluticasone to treat cough in dogs with TC.