Selectivity Coefficients Research Articles

Cation exchange parameters for Opalinus Clay and its confining units

The knowledge of cation exchange parameters is important to understand and model the porewater chemistry in clayrocks. The Opalinus Clay (OPA) is a well-studied formation in view of its importance as host rock for radioactive waste repositories, but uncertainties exist regarding its cation exchange parameters, in particular its selectivity coefficients (Kc). In fact, porewater chemistry models for OPA have so far been based on generic selectivity coefficients.Thanks to a recent extensive siting programme, involving eight vertical deep boreholes in northern Switzerland, a large number of porewater and cation exchange data from the OPA and its clay-rich confining units could be analysed. Thus, from the combination of porewater compositions (obtained from high-pressure squeezing and advective displacement), and exchangeable cation data (obtained from Ni ethylenediamine extraction), reliable selectivity coefficients could be derived. The values for KcNa/K, KcNa/Ca, KcNa/Mg are consistent with those obtained in parallel from the Mont Terri underground rock laboratory although the scatter is somewhat larger in the latter dataset. The derived selectivity coefficients indicate no dependency on ionic strength or in-situ temperature. Minor differences in Kc values between OPA and confining units can be attributed to differences in clay mineralogy. The validity of a two-site cation exchange model including illite and smectite for estimating exchangeable Na, Ca and Mg from measured porewater compositions could be shown, while this simple model underpredicts the share of exchangeable K. The exchangeable cation extraction procedure induces the dissolution of Sr-bearing minerals whose amount is in the same range as exchangeable Sr, thus not enabling the derivation of selectivity coefficients for Sr.Finally, derived selectivity coefficients confirm results of previous studies, thus providing confidence in the applied experimental and modelling protocols on the one hand and in the outcome of those studies on the other hand.

Application of ionic liquid extractant in enhanced separation of 2-propanol-n-hexane azeotrope system

2-Propanol and n-hexane are widely used (as) chemical reagents in electronic, pharmaceutical, and chemical industries. An efficient separation of the azeotropic system of 2-propanol-n-hexane is of profound practical significance. By using the conductor-like screening model for real solve (COSMO-RS) predictive model, ionic liquids as extractants for separating the azeotropic system of 2-propanol-n-hexane were evaluated with selectivity coefficients (S) and capacity (C) as the evaluation indexes. Based on the evaluation results, one high-performance extractants named hydroxylamine Cl (C8A19) was selected from 435 kinds of ionic liquids designed by combining 29 kinds of anions and 15 kinds of cations. Moreover, the reliability of the model in predicting the vapor–liquid phase equilibrium behavior of 2-propanol-n-hexane system was verified. Then, the effect of C8A19 on the vapor–liquid phase equilibrium of the 2-propanol-n-hexane system was investigated theoretically and experimentally. The results show that the azeotrope of the system can be broken when the molar fraction of C8A19 is 0.02, denoting that C8A19 can be used for enhanced separation of 2-propanol-n-hexane system. On the basis of the aforementioned study, the selectivity mechanism of the extractant was analyzed from the perspective of microscopic molecular interactions by using the descriptor (σ-profiles) of COSMO-RS. This study provides both theoretical and data support for further designing high-performance ionic liquid extractants and extraction process.

Research on the mechanism of coal adsorption of CO2 hindering oxygen

This paper investigates the inhibitory effect of CO2 on oxygen adsorption during the low-temperature oxidation of coal. Taking the example of Tingnan coal, the physical adsorption barriers of CO2 during coal oxidation at different temperatures were analyzed in terms of competitive adsorption curves, adsorption capacity, adsorption selectivity and diffusion coefficients using a combination of indoor experiments and molecular simulations. It is proposed that the competitive adsorption advantage of CO2 is significantly greater than that of O2, and it is negatively correlated with temperature. Additionally, the variations of aliphatic gas-phase products are evident during the pre-oxidation temperature stages. When the pre-oxidation temperature exceeds 70 °C, the amounts of CH4 and C2H4 released increase with the pre-oxidation temperature, and the inhibitory effect of injected CO2 deteriorates. The simulation results validate the experimental conclusions and are in line with the actual situation, providing auxiliary optimization and guidance for coal mine fire prevention work.

Magnetic field assistant method for synthesizing imprinted photocatalytic membrane with highly exposed ZnFe2O4@PoPD heterojunction for efficient selective degradation

Although the phase inversion method has been widely used for the preparation of the photocatalytic polymer membrane, the embedding of photocatalytic powder in the inside of the polymer membrane seriously blocks the active site and limits the photocatalytic efficiency. In this work, we demonstrate that using a magnetic photocatalyst to prepare the photocatalytic membrane can solve the above challenges with the help of magnetic field assistant method. Moreover, a ZnFe2O4@Poly(o-phenylenediamine) core-shell heterojunction (I-ZnFe2O4@PoPD) with imprinted layer is employed as the photocatalyst to prepare the highly exposed imprinted photocatalytic membrane (IM-ZnFe2O4@PoPD), which provides recognized site to selectively capture the specific pollutants and facilitate the charge transfer by formed built-in electric field between ZnFe2O4 and PoPD. In addition, the photodegradation efficiency of the imprinted molecule, such as tetracycline (TC), over the as-prepared IM-ZnFe2O4@PoPD membrane reaches to 75.76%. Inversely, the photodegradation efficiency of unimprinted molecules, like ciprofloxacin (CIP), is only 20.28% in the same condition. The selectivity coefficient of IM-ZnFe2O4@PoPD relative to UIM-ZnFe2O4@PoPD can reach 2.6. Briefly, our work throws light on the preparation of membranes with more exposed active sites and high photocatalytic selectivity.

How territoriality and sociality influence the habitat selection and movements of a large carnivore.

While territoriality is one of the key mechanisms influencing carnivore space use, most studies quantify resource selection and movement in the absence of conspecific influence or territorial structure. Our analysis incorporated social information in a resource selection framework to investigate mechanisms of territoriality and intra-specific competition on the habitat selection of a large, social carnivore. We fit integrated step selection functions to 3-h GPS data from 12 collared African wild dog packs in the Okavango Delta and estimated selection coefficients using a conditional Poisson likelihood with random effects. Packs selected for their neighbors' 30-day boundary (defined as their 95% kernel density estimate) and for their own 90-day core (defined as their 50% kernel density estimate). Neighbors' 30-day boundary had a greater influence on resource selection than any habitat feature. Habitat selection differed when they were within versus beyond their neighbors' 30-day boundary. Pack size, pack tenure, pup presence, and seasonality all mediated how packs responded to neighbors' space use, and seasonal dynamics altered the strength of residency. While newly-formed packs and packs with pups avoided their neighbors' boundary, older packs and those without pups selected for it. Packs also selected for the boundary of larger neighboring packs more strongly than that of smaller ones. Social structure within packs has implications for how they interact with conspecifics, and therefore how they are distributed across the landscape. Future research should continue to investigate how territorial processes are mediated by social dynamics and, in turn, how territorial structure mediates resource selection and movement. These results could inform the development of a human-wildlife conflict (HWC) mitigation tool by co-opting the mechanisms of conspecific interactions to manage space use of endangered carnivores.

Development of a Highly Selective Chloride Ion Potentiometric Sensor Utilizing a Novel N, N-Ethylene-bis-(Salicylideneaminato) Zinc (II) Molecule for Clean Environment

The present study focuses on the advancement of a chloride ion potentiometric sensor that exhibits high selectivity. This sensor employs a novel molecule, namely N, N-Ethylene-bis-(Salicylideneaminato) zinc (II), in order to achieve accurate measurements in the pursuit of maintaining a clean environment. N, N′-Ethylenebis( salicylideneaminato) nickel (II) ionophore has been generated as well as evaluated using analysis of NMR, IR and C, H, N. Subsequently, membranes incorporating the ionophore (I) were developed utilizing poly(vinyl chloride) (PVC) as a matrix, with plasticizing solvent mediators including Dioctyl phthalate (DOP), chloronapthalene (CN), Dibutyl phthalate (DBP), and tri-n-butylphosphate (TBP). Additionally, catalyzed cation discriminator, hexadecyltrimethylammonium bromide (HDTMA) was employed to enhance membrane formation. This sensor performed better than all other variants. Its membrane composition was 5 mg ionophore, 32 mg PVC, 60 mg DBP, and 3 mg HDTMA. Notably, the sensor exhibited an extended operational range of 2.0×10−6 to 1.0×10−1 M, in addition to Nernstian compliance (58.8 mV/Decade) within pH span of 2.3–9.3, and an impressive response time of 19 s. A detection range as low as 1.64×10−6 was attained, indicative of its high sensitivity. Furthermore, the sensor exhibited remarkable selectivity for chloride ions, as confirmed by selectivity coefficient measurements obtained through fixed interference technique (FIM). The sensor demonstrated a satisfactory three-month shelf life and acceptable repeatability. In practical application, the sensor demonstrated effectiveness in quantifying chloride ions in wastewater samples. This work addresses important sustainability issues while contributing to an improved comprehension of the underlying concepts of self-assembled behavior and setting up an option for the generation of efficient sensors with potential uses in photonics and microelectronics.

THE INFLUENCE OF EMPLOYEE SELECTION ON WORK PRODUCTIVITY AT REYHAN SQUARE HOTEL SELAYAR ISLANDS DISTRICT

HR development is not just about recruitment and training, but also involves career management, performance management, rewards, and inter-employee relations. Organizations that successfully build an inclusive culture and focus on employee development will create an environment where every individual feels valued and has opportunities to grow.The main objective of this study is to analyze the effect of employee selection on work productivity in the hotel industry. By analyzing the factors that influence employee selection as well as their impact on productivity, this research is expected to provide useful insights for HR practitioners in improving employee selection and management strategies. In addition, this research is also expected to contribute to the development of HR management theory. The population in this study was employees of the Reyhan Square Hotel which amounted to 40 people. The population used was also a sample in this study. Where the sampling technique used is saturated sampling. Saturated sampling is a sampling technique when all members of a population are used as samples. The method used in this study is quantitative, quantitative data that focuses on measuring and analyzing statistical number-based data. By using a survey method approach to find the cause and effect. The conclusion of this study, Variable X, namely Selection, has a positive and significant effect on the work productivity of Reyhan Square Hotel with a Selection coefficient (X) value of 0.437 and a calculated t value of 2,824 t table 2,024 with a significant value of 0.008 0.05.

Selective dissolution of zinc and lead from duplex β-phase brasses in low and high conductivity water

This study provides insights regarding the selective metal leaching of brass in various tap water conditions, which benefits water utilities to predict the potential of metal released from brass water meters. The long-term time-dependent selective metal dissolution of brass with various β phase fractions have not previously been investigated. In this study, a 201-d immersion experiment was carried out in low and high conductivity tap water (LCTW and HCTW, respectively). Three commercialized brass samples in different β phase fractions (β = 51%, β = 43%, β = 39%), named brass 51, brass 43, and brass 39, respectively, were used. The results showed that brass 51 had the most negative corrosion potential (−0.17 V) and the lowest polarization resistance (8.5 kΩ) compared to brass 43 and brass 39 (−0.04 V and 10.1−14.7 kΩ, respectively) in LCTW. This trend was verified by the 201-d immersion experiment in which brass 51 exhibited the highest zinc leaching rate (21−30 μg L−1 cm−2 d−1), followed by brass 43 and brass 39 (16−23 μg L−1 cm−2 d−1) in both waters. The leaching amounts of lead and copper were extremely low compared to zinc. In LCTW, the uniform corrosion (UC) mechanism dominated from day 1 to day 120. Afterwards, UC was replaced by the galvanic corrosion (GC) mechanism, with the selective leaching coefficient of Zn over Cu (SZn/Cu) increasing from 10 to 25 to 40−80. In HCTW, however, the SZn/Cu reached 300−1000, and the transition of UC to GC occurred earlier on day 30 due to the rapid formation of the ZnO layer on the brass surface that hindered the ion attack.

High-efficiency selective enrichment of U(VI) from aqueous solutions by amidoxime-functionalized siliceous mesocellular foams

Siliceous mesocellular foams (MCFs) with high surface area, large pore volume and ordered mesoporous structure have a great potential in the capture of pollutants. To achieve the sorption of U(VI) with enhanced capacity and selectivity, amidoxime groups were modified on MCFs by optimizing the molar ratio of (2-cyanoethyl) triethoxysilane (CPTES) in silicon source from 0% to 30%. CPTES promoted the grafted amounts of amidoxime group (0–1.85 mmol/g) while resulted in the collapse of mesopores of amidoximated MCFs from 426.5 to 136.3 m2/g. Sorption behaviors of U(VI) at the interface of amidoximated MCFs and solutions were systematically investigated under various hydrochemical conditions. Amidoximated MCFs could capture U(VI) rapidly (4.0 h) with superior maximum sorption capacity (446.6 mg/g at pH 5.0 and T 298 K), and favorable reusability (67.8% of capacity remained after six recycles). Selective enrichment of U(VI) from artificial nuclide wastewater (201.5 mg/g of capacity, 16.08–33.61 of selectivity coefficients) and seawater (179.3 mg/g of capacity, 5.08–20.48 of selectivity coefficients) against the interference of heavy metals and nuclides were presented. This study provided a valuable reference for the preparation of sorbents with surface amidoximation and advanced porosity as well as a meaning option for the extraction of nuclides from aqueous solutions.

Classification of Blood Cells with Convolutional Neural Network Model

Among the blood cells, white blood cells (WBC), which play a crucial role in forming our body's defense system, are essential components. Originating in the bone marrow, these cells serve as the fundamental components of the immune system, shouldering the responsibility of safeguarding the body against foreign microbes and diseases. Insufficient WBC counts may compromise the body's skill to resist infections, a status known as leukopenia. White blood cell counting is a specialty procedure that is usually carried out by qualified physicians and radiologists. Thanks to recent advances, image processing techniques are frequently used in biological systems to identify a wide spectrum of illnesses. In this work, image processing techniques were applied to enhance the white blood cell deep learning models' classification accuracy. To expedite the classification process, Convolutional Neural Network (CNN) models were combined with Ridge feature selection and Maximal Information Coefficient techniques. These tactics successfully determined the most important characteristics. The selected feature set was then applied to the classification procedure. ResNet-50, VGG19, and our suggested model were used as feature extractors in this study. The categorizing of white blood cells was completed with an amazing 98.27% success rate. Results from the experiments demonstrated a considerable improvement in classification accuracy using the proposed CNN model.

A molecular extraction process for vanadium based on tandem selective complexation and precipitation

Recycling vanadium from alternative sources is essential due to its expanding demand, depletion in natural sources, and environmental issues with terrestrial mining. Here, we present a complexation-precipitation method to selectively recover pentavalent vanadium ions, V(V), from complex metal ion mixtures, using an acid-stable metal binding agent, the cyclic imidedioxime, naphthalimidedioxime (H2CIDIII). H2CIDIII showed high extraction capacity and fast binding towards V(V) with crystal structures showing a 1:1 M:L dimer, [V2(O)3(C12H6N3O2)2]2−, 1, and 1:2 M:L non-oxido, [V(C12H6N3O2)2] ̶ complex, 2. Complexation selectivity studies showed only 1 and 2 were anionic, allowing facile separation of the V(V) complexes by pH-controlled precipitation, removing the need for solid support. The tandem complexation-precipitation technique achieved high recovery selectivity for V(V) with a selectivity coefficient above 3 × 105 from synthetic mixed metal solutions and real oil sand tailings. Zebrafish toxicity assay confirmed the non-toxicity of 1 and 2, highlighting H2CIDIII’s potential for practical and large-scale V(V) recovery.

Quality-by-design ecofriendly potentiometric sensor for rapid monitoring of hydroxychloroquine purity in the presence of toxic impurities

Hydroxychloroquine (HCQ) is prescribed to treat malaria and certain autoimmune diseases. Recent studies questioned its efficiency in relieving COVID-19 symptoms and improving clinical outcomes. This work presents a quality-by-design approach to develop, optimize, and validate a potentiometric sensor for the selective analysis of HCQ in the presence of its toxic impurities (key starting materials), namely 4,7-Dichloroquinoline (DCQ) and hydroxynovaldiamine (HND). The study employed a custom experimental design of 16 sensors with different ion exchangers, plasticizers, and ionophores. We observed the Nernstian slopes, correlation coefficients, quantification limit, response time, and selectivity coefficient for DCQ and HND. The computer software constructed a prediction model for each response. The predicted responses strongly correlate to the experimental ones, indicating model fitness. The optimized sensor achieved 93.8% desirability. It proved a slope of 30.57 mV/decade, a correlation coefficient of 0.9931, a quantification limit of 1.07 × 10–6 M, a detection limit of 2.18 × 10–7 M, and a fast response of 6.5 s within the pH range of 2.5–8.5. The sensor was successfully used to determine HCQ purity in its raw material. The sensor represents a potential tool for rapid, sensitive, and selective monitoring of HCQ purity during industrial production from its starting materials.

Estimation of thermodynamics properties as a measure of the extent of interference in a conducting polymer based electrochemical aqueous ion sensor

Background: Interference of other ions towards the target analyte in an electrochemical sensor is typically estimated utilizing the peak reduction (PR) technique and the selectivity coefficient technique, both of which have limitations. In our earlier works, a scale of interference was developed using the barrier width (BW) technique based on Simmon’s model utilizing a conducting polymer-based sensor for the detection of Cd2+ by square wave voltammetry (SWV). Also, a new scale of interference was generated with higher resolution by incorporating the BW technique along with adsorption isotherms and the PR technique. Methods: The present work takes the investigation further at the electrode-electrolyte interface to explain the interference effect using thermodynamic parameters such as the partition coefficient, enthalpy and reorganization energy. The length of the reaction site for Cd2+ can also measure interference effect. In this work, SWV for Cd2+ detection in presence of interfering species at different temperatures were conducted, -ΔGad values were extracted and all the thermodynamic parameters were evaluated. The novelty of this work lies in incorporation of these thermodynamic parameters along with BW values (d) to explain the interference phenomena. Results: The variation of the thermodynamic properties for Cd2+ in presence of interfering species were examined. Correlation coefficients were developed from the thermodynamic parameters and the d values to explain the extent of interference. Conclusions: This study can provide information on the thermodynamic properties which can be predicted from BW technique. The correlation coefficients would help obtain an estimate of the interference with the need of lesser number of experiments.

Fe3O4/biochar modified with molecularly imprinted polymer as efficient persulfate activator for salicylic acid removal from wastewater: Performance and specific recognition mechanism

In this study, a novel Fe3O4-based biochar coupled surface-imprinted polymer was constructed via simple hydrothermal route for salicylic acid recognition and degradation in advanced oxidation processes. The material exhibited excellent adsorption capability, up to 118.23 mg g−1, and efficient degradation performance, 87.44% removal rate within 240 min, based on integrating the advantages of both huge specific surface area as well as abundant functional groups from biochars and specific recognition sites from imprinted cavities. Moreover, high selectivity coefficient (11.67) showed stable recognition in single and binary systems. SO4•− and •OH were confirmed as reactive oxygen species in catalytic reaction according to quenching experiments and EPR analysis. The degradation mechanism and pathway were unraveled by DFT calculations and LC-MS. Furthermore, the results of toxicity evaluation, stability and reusability demonstrated application potential in the field of water environment restoration. This study confirmed that molecular imprinting provided a promising solution to targeted removal of emerging environmental pollutants by degrading after the enrichment of pollutants to the composites surface.

Role of zeolite content on the sorption properties of analcime-rich rocks from the Abinky Formation (Niger)

The Abinky formation, composed of analcimolites (i.e., rocks with <70 wt% analcime), underlies Tchirezrine II, which hosts the Imouraren (Niger) uranium deposit. A potential mining project is under consideration to recover U by in situ acid leaching. Analcimolites are uncommon rocks, and assessing their ion-exchange properties is the first step to understand and predict the mobility of aqueous species in these formations. The objective of this study is then to understand the link between the Cation Exchange Capacities (CEC) of analcimolites as a function of their analcime content and associated crystal chemistry. Mineral quantification was performed by Rietveld refinement constrained by local chemical analysis with scanning electron microscopy coupled with Energy Dispersive Spectrometry. CEC were obtained at neutral pH by performing NH4+-for-Na+ exchange (CECNa/NH4), and Na+/H+ ion exchange experiments were performed with 4 analcimolites.Results showed that the analcime crystal chemistry deduced from Rietveld refinement was in good agreement with that obtained from SEM analysis (1.99 < Si/Al < 2.53). The results showed that all samples had a positive correlation between CECNa/NH4 and analcime content until ~30 meq/100 g for a sample containing ~85wt%Riet. of analcime, and that ~6 % of the total amounts of Na+ present in the analcime could be exchanged by NH4+ and H+. Based on Si and Al aqueous measurements, results showed that exchange with Na+ is the main process consuming H+ during Na+/H+ exchange when pH > 3.5. These experimental data were then interpreted by considering a single site equal to the CECNa/NH4 value, specific for each analcimolite, and a selectivity coefficient equal to log KNa/H = 1.3 (Gaines Thomas convention) being equal for all samples investigated. Finally, these data were used to assess the role played by Na+/H+ exchange in the pH evolution of the pore water of an analcime-rich rock subjected to dynamic acidification.

Nitrogen-doped carbon nanotube encapsulated Co9S8 composite cathode for high-selective capacitive extraction of uranium (VI) from radioactive wastewater

Selective extraction of uranium [U(VI)] from uranium containing nuclear wastewater is of great significance in alleviating the uranium resources shortages and eliminating the radioactive radiation. Benefited by the merits of cost-effectiveness and environment-friendliness, capacitive deionization (CDI) shows a great promise towards selective removal of U(VI). However, exploring novel electrode materials with high intrinsic affinity rather than the excessive assistance of external means faces challenges. Herein, a nitrogen-doped carbon tube encapsulated Co9S8 composite (CS-NCNT) was developed as a Faradic cathode for selective electrosorption of U(VI) from radioactive wastewater. This work mainly emphasized on these following results: (i) The electrochemical redox activity and high surface-controlled ratios endowed the optimized CS-NCNT-2 electrode a maximum electrosorption capacity (189 mg g−1) towards U(VI). (ii) Except that CS-NCNT-2 exhibited excellent selective electrosorption performance in U(VI)-containing spiked real seawater, an ultrahigh selectivity coefficient of 707 (UO22+ over Na+) was also achieved at a Na+: UO22+ molar ratio of 200. (iii) The valence state analysis and molecular dynamic simulation revealed the essence of the reversible electrosorption-desorption process and the preferable extraction towards UO22+ compared with Na+ ions, respectively. Overall, this work can be potentially expanded to other metal chalcogenides-based electrode materials for selective removal of UO22+ even other radionuclide in U(VI)-containing radioactive wastewater.

Homogenization spin coating strategy for synthesizing IM-BTO photocatalytic membrane aims to tetracycline selectively degradation

Photocatalytic membrane technology is a promising technology for advanced water treatment. However, as a simple, fast, and stable spin coating method for photocatalytic membrane preparation, the spin coating solution often used in spin coating can cause the pore plugging on the membrane surface and encapsulates photocatalysts, which seriously affects the flux of the membrane and the exposure of the photocatalytic active site. Here, this work adopted a homogenization spin coating strategy, using polyvinylidene difluoride (PVDF) solution as the spin coating solution to prepare the highly exposed imprinted bismuth titanate porous photocatalytic membrane (IM-BTOM). Due to the same composition of PVDF solution as the PVDF substrate membrane, IM-BTOM basically retained the good porous structure of the membrane. The homogenization spin coating strategy not only endowed IM-BTOM with high flux (4545.45 L m-2h−1 bar−1), but also prevented the encapsulation of IM-BTO powder materials, fully exposing the photocatalytic active sites, thereby obtaining better photocatalytic ability and selectivity. The degradation rate of tetracycline with IM-BTOM was nearly three times that with the conventional cellulose acetate spin coating membrane. Meanwhile, the existence of imprinting cavities also endowed IM-BTOM with high selectivity for the target pollutant, with a selectivity coefficient of up to 2.66. This work provides a new idea for preparing high-efficient photocatalytic membrane by spin coating.

Sorption of picolinic acid by Cu(II)-containing sulfocationite KU-2-8

Objectives. To study the equilibrium distribution of components between KU-2-8 sulfocationite and an aqueous solution containing picolinic acid and Cu(II); to show the possibility of immobilization of cations of picolinic acid and Cu2+ in sulfonic cation exchanger KU-2-8; to calculate the component compositions of the equilibrium solution, in order to obtain the required ionic composition of the KU-2-8 sulfonic cation exchanger according to the selectivity coefficients of binary ion exchange, and the constants of formation of such complexes in water.Methods. The concentrations of the individual components in multicomponent solutions were calculated using the HySS 2009 program (Hyperquad Simulaton and Speciation). The calculation of the equilibrium ionic compositions of KU-2-8 sulfocationite was performed using the selectivity coefficients of binary ion exchanges and the formation constants of complexes of picolinic acid with Cu2+ and H+ cations. Experimental study of the equilibrium distribution of components between aqueous solutions of picolinic acid, copper nitrate, and KU-2-8 sulfocationite was carried out by means of the dynamic method at a temperature of 298 K. Fourier-transform infrared spectroscopy and electron paramagnetic resonance spectroscopy were used, in order to determine the ionic forms of the components contained in the sulfocationite.Results. It was shown that the equilibrium solution contains H+ protons, Cu2+ cations, LH picolinic acid molecules, protonated picolinic acid cations [H2L]+, deprotonated picolinic acid anions L-, Cu2+ complexes with the deprotonated picolinic acid anion [CuL]+, and Cu2+ complexes with two anions of deprotonated picolinic acid [CuL2]. The concentration of H+, Cu2+, and [H2L]+ cations in the solution significantly exceeds the concentration of other components at pH values from 0 to 0.5. The content of [CuL]+ cations and neutral complexes [CuL2] increases significantly in the solution, while the [H2L]+ cations disappear at pH greater than 1. It was experimentally established that the concentrations of picolinic acid and copper in the polymer phase are many times higher than the concentrations of these components in an aqueous solution. The partition coefficients are about 24 and 210 for picolinic acid and Cu(II), respectively. The calculated dependencies of the concentrations of Cu2+, [H2L]+, H+, [CuL]+ cations in the polymer vs pH of an equilibrium solution containing picolinic acid were obtained. The experimental data on the concentrations of all cations in the ion exchanger is in the intervals of the calculated compositions within the limits of measurement errors.Conclusions. KU-2-8 sulfocationite is proposed as a container for obtaining drugs based on picolinic acid and Cu2+ cations. It was shown that the selectivity coefficients of binary ion exchanges and the formation constants of [H2L]+, [CuL]+ complexes can be used to precalculate the ionic compositions of the equilibrium solution, in order to obtain the required compositions of the sulfocationite.

Background Selection From Unlinked Sites Causes Nonindependent Evolution of Deleterious Mutations.

Background selection describes the reduction in neutral diversity caused by selection against deleterious alleles at other loci. It is typically assumed that the purging of deleterious alleles affects linked neutral variants, and indeed simulations typically only treat a genomic window. However, background selection at unlinked loci also depresses neutral diversity. In agreement with previous analytical approximations, in our simulations of a human-like genome with a realistically high genome-wide deleterious mutation rate, the effects of unlinked background selection exceed those of linked background selection. Background selection reduces neutral genetic diversity by a factor that is independent of census population size. Outside of genic regions, the strength of background selection increases with the mean selection coefficient, contradicting the linked theory but in agreement with the unlinked theory. Neutral diversity within genic regions is fairly independent of the strength of selection. Deleterious genetic load among haploid individuals is underdispersed, indicating nonindependent evolution of deleterious mutations. Empirical evidence for underdispersion was previously interpreted as evidence for global epistasis, but we recover it from a non-epistatic model.

Predicting Functional Consequences of Recent Natural Selection in Britain.

Ancient DNA can directly reveal the contribution of natural selection to human genomic variation. However, while the analysis of ancient DNA has been successful at identifying genomic signals of selection, inferring the phenotypic consequences of that selection has been more difficult. Most trait-associated variants are noncoding, so we expect that a large proportion of the phenotypic effects of selection will also act through noncoding variation. Since we cannot measure gene expression directly in ancient individuals, we used an approach (Joint-Tissue Imputation [JTI]) developed to predict gene expression from genotype data. We tested for changes in the predicted expression of 17,384 protein coding genes over a time transect of 4,500 years using 91 present-day and 616 ancient individuals from Britain. We identified 28 genes at seven genomic loci with significant (false discovery rate [FDR] < 0.05) changes in predicted expression levels in this time period. We compared the results from our transcriptome-wide scan to a genome-wide scan based on estimating per-single nucleotide polymorphism (SNP) selection coefficients from time series data. At five previously identified loci, our approach allowed us to highlight small numbers of genes with evidence for significant shifts in expression from peaks that in some cases span tens of genes. At two novel loci (SLC44A5 and NUP85), we identify selection on gene expression not captured by scans based on genomic signatures of selection. Finally, we show how classical selection statistics (iHS and SDS) can be combined with JTI models to incorporate functional information into scans that use present-day data alone. These results demonstrate the potential of this type of information to explore both the causes and consequences of natural selection.