Understanding the Reactivity of Supported Late Transition Metals on a Bare Anatase (101) Surface: A Periodic Conceptual DFT Investigation

The rapidly growing interest for new heterogeneous catalytic systems providing high atomic efficiency along with high stability and reactivity triggered an impressive progress in the field of single-atom catalysis. Nevertheless, unravelling the factors governing the interaction strength between the support and the adsorbed metal atoms remains a major challenge. Based on periodic density functional theory (DFT) calculations, this paper provides insight into the adsorption of single late transition metals on a defect-free anatase surface. The obtained adsorption energies fluctuate, with the exception of Pd, between -3.11 and -3.80 eV and are indicative of a strong interaction. Depending on the considered transition metal, we could attribute the strength of this interaction with the support to i) an electron transfer towards anatase (Ru, Rh, Ni), ii) s-d orbital hybridisation effects (Pt), or iii) a synergistic effect between both factors (Fe, Co, Os, Ir). The driving forces behind the adsorption were also found to be strongly related to Klechkowsky's rule for orbital filling. In contrast, the deviating behaviour of Pd is most likely associated with the lower dissociation enthalpy of the Pd-O bond. Additionally, the reactivity of these systems was evaluated using the Fermi weighted density of states approach. The resulting softness values can be clearly related to the electron configuration of the catalytic systems as well as with the net charge on the transition metal. Finally, these indices were used to construct a model that predicts the adsorption strength of CO on these anatase-supported d-metal atoms. The values obtained from this regression model show, within a 95 % probability interval, a correlation of 84 % with the explicitly calculated CO adsorption energies.

Tin(II) cations stabilized by non-symmetric N,N',O-chelating ligands: synthesis and stability

A series of novel non-symmetric neutral N,N',O-chelating ligands derived from the α-iminopyridine 2-(C(R¹)N(C₆H₃-2,6-iPr₂))-6-(R²R³PO)C₅H₃N (L1: R¹ = H, R² = R³ = Ph; L2: R¹ = Me, R² = R³ = Ph; L3: R¹ = H; R² = Ph, R³ = EtO; L4: R¹ = Me, R² = Ph, R³ = EtO; L5: R¹ = H, R² = R³ = iPrO; L6: R1 = Me, R² = R³ = iPrO) were synthesized. Ligands L1-6 were reacted with SnCl₂ and Sn(OTf)₂ with the aim of studying the influence of different R²R³PO functional groups on the Lewis base mediated ionization of SnCl₂ and Sn(OTf)₂. While all ligands L1-6 provided the corresponding ionic tin(II) complexes [L1-6 → SnCl]⁺[SnCl₃]^- (1-6), only ligands L1, L4 and L6 were able to stabilize tin(II) dications [L1,4,6 → Sn(H₂O)][OTf]₂ (7-9). The auto-ionized compounds [L3-6 → SnCl]⁺[SnCl₃]^- possessing ethylphenyl phosphinate and diisopropylphosphite substituents undergo elimination of EtCl and iPrCl, respectively, yielding compounds 10-13. These can either be interpreted as neutral tin(II)phosphinate chloride (10, 11) and tin(II)phosphonate chloride (12, 13), respectively, containing Sn-O and Sn-Cl bonds, and a PO → SnCl₂ interaction, or as zwitterionic compounds, where the positive charge of the central tin atom is compensated by an [OSnCl₂]^- anion. Finally, DFT studies were performed to better understand the steric and electronic properties of the ligands L1-6 as well as the nature of the bonds in the resulting products, with a particular focus on complexes 10-13.

Influence of time-dependent sampling on fish plasma levels of select pharmaceuticals and per- and polyfluoroalkyl substances (PFASs)

Determining pharmaceutical levels in fish plasma represents an increasingly valuable approach for environmental assessments of pharmaceuticals. These fish plasma observations are compared to human therapeutic plasma doses because of the high evolutionary conservation of many drug targets among vertebrates. In the present study, we initially identified highly variable information regarding plasma sampling practices in the literature and then tested the hypothesis that fish plasma levels of selected pharmaceuticals and per- and polyfluoroalkyl substances (PFASs) would not change with time to process samples from the field. After common carp were placed in a wastewater-fed pond for one month, we immediately sampled fish plasma nonlethally in the field or after transferring fish to clean water and held them under these conditions for either 3 or 20 h. We then quantitated pharmaceuticals in water, and pharmaceuticals and PFASs in plasma by LC-MSMS. Whereas plasma levels of most pharmaceuticals decreased even after 3 h that fish spent in clean water, plasma concentrations of the PFASs examined here remained stable over 20 h. Collectively, our examination of these time-dependent sampling approaches and associated findings highlight the importance of appropriate and consistent sampling for bioaccumulation studies, biomonitoring activities, and aquaculture product safety evaluations.

Water reuse for aquaculture: Comparative removal efficacy and aquatic hazard reduction of pharmaceuticals by a pond treatment system during a one year study

Aquaculture is increasing at the global scale, and beneficial reuse of wastewater is becoming crucial in some regions. Here we selected a unique tertiary treatment system for study over a one-year period. This experimental ecosystem-based approach to effluent management included a treated wastewater pond (TWP), which receives 100% effluent from a wastewater treatment plant, and an aquaculture pond (AP) that receives treated water from the TWP for fish production. We examined the fate of a wide range of pharmaceutically active compounds (PhACs) in this TWP-AP system and a control pond fed by river water using traditional grab sampling and passive samplers. We then employed probabilistic approaches to examine exposure hazards. Telmisartan, carbamazepine, diclofenac and venlafaxine, exceeded ecotoxicological predicted no effect concentrations in influent wastewater to the TWP, but these water quality hazards were consistently reduced following treatment in the TWP-AP system. In addition, both grab and passive sampling approaches resulted in similar occurrence patterns of studied compounds, which highlights the potential of POCIS use for water monitoring. Based on the approach taken here, the TWP-AP system appears useful as a tertiary treatment step to reduce PhACs and decrease ecotoxicological and antibiotic resistance water quality hazards prior to beneficial reuse in aquaculture.

[Temporary Hemiepiphysiodesis in the Correction of Axial Deformities for Genua Valga: Retrospective Assessment and Comparison of Outcomes Achieved with the Use of Eight-Figure Plates and Blount Staples]

PURPOSE OF THE STUDY Axial deformities of the lower limbs of various aetiologies are relatively common orthopaedic diagnoses in paediatric population. Fixed deformity is an indication for correction in order to reduce the pain and to delay the early osteoarthrosis of adjacent joints and pain. Temporary hemiepiphysiodesis is technically a fairly simple method for modulating growth at the level of the growth plate and thus correcting the skeletal axis. MATERIAL AND METHODS 59 patients who underwent axial deformity correction of lower limbs at KDCHOT FN Brno were retrospectively analysed. Group 1 consisted of 21 patients with Blount staples implantation, Group 2 consisted of 38 patients to whom eight-figure plates had been applied. Anthropometric parameters (BMI, age, gender, intermalleolar distance (IMD)), duration of therapy, X-ray parameters (anatomical lateral distal femoral angle (aLDFA), anatomical medial proximal tibial angle (aMPTA)) and complications were recorded. The rate of correction was evaluated as the difference in X-ray parameters before and after surgery with respect to the time interval of the therapy. RESULTS The groups were comparable in terms of anthropometric parameters (BMI (p=0.800), IMD (p=0.334), gender (p=0.87)). The only statistically significant difference was found when comparing the mean age of the groups (p=0.005), with Group 1 (12.7±0.7) containing patients with a higher mean age than Group 2 (11.6±1.5). The groups were also comparable in terms of the average rate of correction over a one-month interval (aLDFA p=0.393; aMPTA p=0.831). The mean correction rate for Group 1 was: aLDFA 0.52±0.20/month, aMPTA 0.12±0.08/month; for Group 2: aLDFA 0.56±0.28/month, aMPTA 0.12±0.20/month. Individual implants differed in the type of complications, but no significant statistical difference in the incidence of complications was found between the analysed groups (p=0.526). DISCUSSION Recently, the system of eight-figure plates has been adopted as a standard method for correction of axial deformities of limbs. Although the benefits of this system are indisputable, when comparing the average monthly correction rate, no significant difference was found between the system of eight-figure plates and Blount staples in our study. Another monitored parameter was the occurrence of complications, which was evaluated fairly strictly. Even in this case, no statistically significant difference was found. We believe that the issue of using eight-figure plates is still open, as evidenced by studies, which often produce different results and conclusions. Therefore, a precise evaluation of the indication for correction, including individual characteristics of patients, is needed. CONCLUSIONS Based on the results, it can be concluded that the use of eight-figure plates in comparison with Blount staples provides neither faster correction of axial deformities nor lesser occurrence of complications. It can therefore be argued that the Blount staples still have their place in the indication of correction of axial deformities. The use of eight-figure plates represents a suitable solution for children of younger age to whom anchoring of the screws of eight-figure plates is a suitable solution in the cartilaginous epiphysis of long bones of younger children. Key words: temporary hemiepiphysiodesis, growth plate, Blount staples, eight-figure plates.

Retrospective analysis of necrotizing pneumonia in children between 2015-2019

INTRODUCTION

An increased incidence rate of cases of complicated pneumonia, reaching up to the stage of necrotizing pneumonia was observed at University Hospital Brno in the past period. The aim of this study was to perform a single-center retrospective analysis of patients with acquired inflammatory lung disease requiring surgical treatment, comprising a long-term follow-up group.

METHODS

Patients hospitalized for community-acquired pneumonia and surgically treated in the years 2015-2019 were analyzed. The rates of necessary chest drainages, decortications and lung resections in relation to the whole group and individual years were monitored. Clinical and X-ray examinations were performed one year after hospitalization and the prognosis was determined for individual types of required treatments. The age, gender and etiological agents were also monitored.

RESULTS

A total of 688 patients were included in the study with the incidence rising until 2018 and decreasing slightly in 2019. A statistically significantly higher number of community-acquired pneumonias and complications was recorded between 2017 and 2018 (p.

[Comparison of Two Minimally Invasive Osteosynthesis Techniques for Radial Head Fractures in Paediatric Patients]

PURPOSE OF THE STUDY Radial head fractures in paediatric patients account for 5-19% of all elbow injuries and approximately 1% of all fractures in children. Non-displaced fractures are treated with plaster cast fixation. If the fracture is displaced, we proceed to closed reduction, or to osteosynthesis in case of unstable fragments. If closed reduction fails, we opt for open reduction and osteosynthesis. The prospective randomised clinical study aims to compare the two methods of minimally invasive osteosynthesis using the pre-bent Kirschner wire or Prévot nail and to identify differences between them. MATERIAL AND METHODS The prospective randomised clinical study was conducted in 2015-2019. The final cohort included 32 patients who met the inclusion criteria. The patients in whom other osteosynthesis implants had been used or in whom open reduction had to be performed were excluded from the study. Also excluded were the patients with serious concomitant injuries of elbow. For patients included in the cohort, demographic data, precise evaluation of the displacement and location of the fracture as well as the duration of plaster cast fixation and osteosynthesis implants used were recorded. In the clinical part, the methods were compared based on the achievement of full range of motion in dependence on the degree of original displacement, use of osteosynthesis implant, and occurrence of early and delayed complications. Clinical and radiological outcomes were compared. In both types of minimally invasive osteosynthesis, Métaizeau surgical technique was used. RESULTS Based on the clinical trial criteria, 26 (81%) excellent, 4 (13%) good and 2 (6%) acceptable outcomes were achieved. In 3 cases the loss of rotation was up to 20°, in 1 case the loss of flexion was up to 10°. In one patient the loss of flexion was 15° and rotation up to 30°. In another patient the loss of rotation was up to 40°. The radiological assessment showed 14 (44%) excellent outcomes, 15 good (47%) and 3 (9%) acceptable outcomes. The statistical analysis of both the groups of the cohort using non-parametric tests revealed no statistically significant differences in individual demographic parameters. The comparisons of both types of osteosynthesis in dependence on the degree of displacement by non-parametric Fisher's exact test showed no statistically significant difference in the radiologic or clinical results. The only statistically significant difference was observed in the duration of metal implant placement. DISCUSSION Comparable studies report excellent or good clinical outcomes in 80-95% of cases (1,13,16). In our cohort, excellent or good clinical outcomes were achieved in 30 patients (94%). In two patients, in whom Prévot nail was used, the outcomes were acceptable. Nonetheless, this fact did not result in any statistical significance when comparing the two methods separately or in comparisons based on the degree of displacement. CONCLUSIONS The comparison of the two methods of minimally invasive osteosynthesis revealed no statistically significant difference, namely not even when both the methods were compared based on the degree of displacement. When Kirschner wire is used, the possibility to remove the metal implant in the outpatient setting is considered to be an advantage. The drawback consists in potential penetration of the sharp Kirschner wire in the radiocapitellar joint, which we did not encounter when the second technique of osteosynthesis was used. The advantage of Prévot nail includes a lower risk of pin-tract infection. Key words: minimally invasive osteosynthesis, radial head, fracture, child.

Sn,P-coordinated Ru cation: a robust catalyst for aerobic oxidations of benzylamine and benzyl alcohol

A stable ionic κ²Sn,P-coordinated Ru complex shows excellent catalytic activity in aerobic oxidations of benzylamine and benzyl alcohol. This complex is stabilized by a stannylene-phosphine peri-substituted naphthalene ligand, which can act as either a reducing agent for a Ru(III) complex or as a κ²Sn,P-chelating ligand for Ru(II) compounds.

N-Donor stabilized tin(II) cations as efficient ROP catalysts for the synthesis of linear and star-shaped PLAs via the activated monomer mechanism

α-Iminopyridine ligands L¹ (2-(CHN(C₆H₂-2,4,6-Ph₃))C₅H₄N), L² (2-(CHN(C₆H₂-2,4,6-tBu₃))C₅H₄N) and L³ (1,2-(C₅H₄N-2-CHN)₂CH₂CH₂) differing by the steric demand of the substituent on the imine CHN group and by the number of donating nitrogen atoms were utilized to initiate a Lewis base mediated ionization of SnCl₂ in an effort to prepare ionic tin(II) species [L^1-3 → SnCl][SnCl₃]. The reaction of L¹ and L² with SnCl₂ led to the formation of neutral adducts [L¹ → SnCl₂] (2) and [L² → SnCl₂] (3). The preparation of the desired ionic compounds was achieved by subsequent reactions of 2 and 3 with an equivalent of SnCl₂ or GaCl₃. In contrast, ligand L³ containing four donor nitrogen atoms showed the ability to ionize SnCl₂ and also Sn(OTf)₂, yielding [L³ → SnCl][SnCl₃] (7) and [L³ → Sn(H₂O)][OTf]₂ (8). The study thus revealed that the reaction is dependent on the type of the ligand. The prepared complexes 4-8 together with the previously reported [{2-((CH₃)CN(C₆H₃-2,6-iPr₂))-6-CH₃O-C₅H₃N}SnCl][SnCl₃] (1) were tested as catalysts for the ROP of L-lactide, which could operate via an activated monomer mechanism. Finally, a DFT computational study was performed to evaluate the steric and electronic properties of the ionic tin(II) species 1 and 4-8 together with their ability to interact with the L-lactide monomer.

Reactivity of Single Transition Metal Atoms on a Hydroxylated Amorphous Silica Surface: A Periodic Conceptual DFT Investigation

The drive to develop maximal atom-efficient catalysts coupled to the continuous striving for more sustainable reactions has led to an ever-increasing interest in single-atom catalysis. Based on a periodic conceptual density functional theory (cDFT) approach, fundamental insights into the reactivity and adsorption of single late transition metal atoms supported on a fully hydroxylated amorphous silica surface have been acquired. In particular, this investigation revealed that the influence of van der Waals dispersion forces is especially significant for a silver (98 %) or gold (78 %) atom, whereas the oxophilicity of the Group 8-10 transition metals plays a major role in the interaction strength of these atoms on the irreducible SiO₂ support. The adsorption energies for the less-electronegative row 4 elements (Fe, Co, Ni) ranged from -1.40 to -1.92 eV, whereas for the heavier row 5 and 6 metals, with the exception of Pd, these values are between -2.20 and -2.92 eV. The deviating behavior of Pd can be attributed to a fully filled d-shell and, hence, the absence of the hybridization effects. Through a systematic analysis of cDFT descriptors determined by using three different theoretical schemes, the Fermi weighted density of states approach was identified as the most suitable for describing the reactivity of the studied systems. The main advantage of this scheme is the fact that it is not influenced by fictitious Coulomb interactions between successive, charged reciprocal cells. Moreover, the contribution of the energy levels to the reactivity is simultaneously scaled based on their position relative to the Fermi level. Finally, the obtained Fermi weighted density of states reactivity trends show a good agreement with the chemical characteristics of the investigated metal atoms as well as the experimental data.

Spatial distribution of native fish species in tributaries is altered by the dispersal of non-native species from reservoirs

Reservoirs are known to alter temperature and flow regimes, shift nutrient cycles, reduce downstream species diversity and enable a predominantly upstream spread of non-native species. However, information about the seasonal dynamics of the spread of non-natives from a reservoir to its tributaries and the further consequences regarding the spatial distribution of native species is rare. We observed the occurrence of fish in the Vltava River and its tributaries (Elbe catchment area, central Europe) upstream of the Lipno Reservoir for five consecutive years. We radio-tagged two non-native and four native species. To detect assemblage spatial variability, we sampled sites in the study area by electrofishing twice per year (spring and autumn). We expected seasonal trends in non-native species appearance in upstream reservoir tributaries and, conversely, low motivation of native fishes to descend to the reservoir. By analysing nearly 3000 individuals of 21 species from the longitudinal profile of the study area, we observed an effect of reservoir distance on the native species ratio in the upper Vltava catchment area, i.e., an increase in distance increased the native species proportion, and the opposite was observed for non-native species. Analyses of 3798 tracking positions of 193 tagged individuals showed massive spring dispersal of non-native species from the reservoir to the main tributary, the Vltava River, and their return to the reservoir for wintering. Their upstream movement positively correlated with an increase in flow rate. Native Salmo trutta showed a specific shift from the Vltava River to smaller streams during the summer, when the presence of non-native species in the Vltava River was most significant. These findings indicate that non-native species repeatedly spread from the reservoir to the upstream river stretch and its tributaries and potentially compete with native species for resources.

De facto reuse at the watershed scale: Seasonal changes, population contributions, instream flows and water quality hazards of human pharmaceuticals

With increasing population growth and climate change, de facto reuse practices are predicted to increase globally. We investigated a longitudinal gradient within the Uhlava River, a representative watershed, where de facto reuse is actively occurring, during Fall and Spring seasons when instream flows vary. We observed human pharmaceutical levels in the river to continuously increase from the mountainous areas upstream to downstream locations and a potable intake location, with the highest concentrations found in small tributaries. Significant relationship was identified between mass flow of pharmaceuticals and the size of human populations contributing to wastewater treatment plant discharges. Advanced ozonation and granular activated carbon filtration effectively removed pharmaceuticals from potable source waters. We observed a higher probability of encountering a number of targeted pharmaceuticals during colder Spring months when stream flows were elevated compared to warmer conditions with lower flows in the Fall despite a dilution paradigm routinely applied for surface water quality assessment and management efforts. Such observations translated to greater water quality hazards during these higher Spring flows. Future water monitoring efforts should account for periods when higher chemical uses occur, particularly in the face of climate change for regions experiencing population growth and de facto reuse.

Changes in microclimate and hydrology in an unmanaged mountain forest catchment after insect-induced tree dieback

Hydrological and microclimatic changes after insect-induced tree dieback were evaluated in an unmanaged central European mountain (Plešné, PL) forest and compared to climate-related changes in a similar, but almost intact (Čertovo, CT) control forest during two decades. From 2004 to 2008, 93% of Norway spruce trees were killed by a bark beetle outbreak, and the entire PL area was left to subsequent natural development. We observed that (1) climate-related increases in daily mean air temperature (2 m above ground) were 1.6 and 0.5 °C on an annual and growing season basis, respectively, and an increase in daily mean soil temperature (5 cm below ground) was 0.9 °C during growing seasons at the CT control from 2004 to 2017; (2) daily mean soil and air temperatures increased by 0.7-1.2 °C on average more at the disturbed PL plots than in the healthy forest; (3) water input to soils increased by 20% but decreased by 17% at elevations of 1122 and 1334 m, respectively, due to decreased occult deposition to, and evaporation from, canopies after tree dieback; (4) soil moisture was 5% higher on average (but up to 17% higher in dry summer months) in the upper PL soil horizons for 5-6 years following the tree dieback; (5) run-off from the PL forest ~6% (~70 mm yr^-1) increased relatively to the CT forest (but without extreme peak flows and erosion events) after tree dieback due to the ceased transpiration of dead trees and elevated water input to soils; and (6) relative air humidity was 4% lower on average at disturbed plots than beneath living trees. The rapid tree regeneration during the decade following tree dieback resulted in a complete recovery in soil moisture, a slow recovery of discharge and air humidity, but a still insignificant recovery in air and soil temperatures.

Psychoactive pharmaceuticals in aquatic systems: A comparative assessment of environmental monitoring approaches for water and fish

Environmental monitoring and surveillance studies of pharmaceuticals routinely examine occurrence of substances without current information on human consumption patterns. We selected 10 streams with diverse annual flows and differentially influenced by population densities to examine surface water occurrence and fish accumulation of select psychoactive medicines, for which consumption is increasing in the Czech Republic. We then tested whether passive sampling can provide a useful surrogate for exposure to these substances through grab sampling, body burdens of young of year fish, and tissue specific accumulation of these psychoactive contaminants. We identified a statistically significant (p < 0.05) relationship between ambient grab samples and passive samplers in these streams when psychoactive contaminants were commonly quantitated by targeted liquid chromatography with tandem mass spectrometry, though we did not observe relationships between passive samplers and tissue specific pharmaceutical accumulation. We further observed smaller lotic systems with elevated contamination when municipal effluent discharges from more highly populated cities contributed a greater extent of instream flows. These findings identify the importance of understanding age and species specific differences in fish uptake, internal disposition, metabolism and elimination of psychoactive drugs across surface water quality gradients.

Organogermanium(II) Hydrides as a Source of Highly Soluble LiH

The reactions of monomeric C,N-chelated organogermanium(II) hydride L(H)Ge⋅BH₃ with organolithium salts RLi yielded lithium hydrogermanatoborates (Li(THF)₂ {BH₃ [L(H)GeR]})₂ . Compound (Li(THF)₂ {BH₃ [L(H)GePh]})₂ was used as a source of LiH for the reduction of organic C=O or C=N bonds in nonpolar solvents accompanied by the elimination of a neutral complex L(Ph)Ge⋅BH₃ . The interaction of (Li(THF)₂ {BH₃ [L(H)GePh]})₂ with the polar C=O bond was further investigated by computational studies revealing a plausible geometry of a pre-reactive intermediate. The experimental and theoretical studies suggest that, although the Li atom of (Li(THF)₂ {BH₃ [L(H)GePh]})₂ coordinates the C=O bond, the GeH fragment is the active species in the reduction reaction. Finally, benzaldehyde was reduced by a mixture of L(H)Ge⋅BH₃ with PhLi in nonpolar solvents.

Effects of Multi-Component Mixtures from Sewage Treatment Plant Effluent on Common Carp (Cyprinus carpio) under Fully Realistic Condition

This study characterized changes in biomarker responses in common carp (Cyprinus carpio) upon exposure to effluent water discharged from a sewage treatment plant (STP) under real conditions. Fish were exposed to contamination in Cezarka pond, which receives all of its water input from the STP in the town of Vodnany, Czech Republic. Five sampling events were performed at day 0, 30, 90, 180, and 360 starting in April 2015. In total, 62 pharmaceutical and personal care products (PPCPs) were detected in the polar organic chemical integrative sampler. Compared to a control pond, the total concentration of PPCPs was 45, 16, 7, and 7 times higher in Cezarka pond at day 30, 90, 180, and 360, respectively. The result of oxidative stress and antioxidant enzyme biomarkers indicated alterations in the liver and intestine tissues of fish from Cezarka pond at day 30 and 360, respectively. High plasma vitellogenin levels were observed in both exposed females (180 and 360 days) and males (360 days) compared with their respective controls. However, only exposed female fish had higher vitellogenin mRNA expression than the control fish in these periods. Exposed female fish showed irregular structure of the ovary with scattered oocytes, which further developed to a vitellogenic stage at day 360. Low white blood cell levels were indicated in all exposed fish. Despite numerous alterations in exposed fish, favorable ecological conditions including high availability of food resulted in a better overall condition of the exposed fish after 1 year of exposure compared to the controls.

Correction to: Effects of multi-component mixtures from sewage treatment plant effluent on common carp (Cyprinus carpio) under fully realistic condition

The original version of this Article unfortunately contained an error. The authors' given and family names were transposed erroneously. It has been corrected now in this Erratum.

Complex effects of pollution on fish in major rivers in the Czech Republic

Monitoring the contamination level in aquatic environments and assessing the impact on aquatic life occurs throughout the world. In the present study, an approach based on a combination of biomarkers and the distribution of various industrial and municipal pollutants was used to investigate the effect of aquatic environmental contamination on fish. Monitoring was performed in ten rivers in the Czech Republic (Berounka, Dyje, Elbe, Lužnice, Odra, Ohře, Otava, Sázava, Svratka, and Vltava rivers, with one or two locations in each river) at the same sites that were regularly monitored within the Czech National Monitoring Program in 2007-2011. Health status, hepatic ethoxyresorufin-O-deethylase (EROD) activity, total cytochrome P450 content, and the plasma vitellogenin concentration were assessed in wild chub (Squalius cephalus) males caught at the monitored sites. The contamination level was the highest in the Svratka River downstream of Brno. Among all measured persistent organic pollutants (POPs), polychlorinated biphenyls and dichlorodiphenyltrichloroethane and its metabolites were the major contributors of POPs in fish muscle. Elbe, Odra, and Svratka rivers were identified as the most polluted. Fish from these locations showed reduced gonad size, increased vitellogenin concentration in male plasma, EROD, and total cytochrome P450 content. These biomarkers can be used for future environmental monitoring assessments. Overall, this study improves our understanding of the relationship between human activities and pollutant loads and further contributes to the decision to support local watershed managers to protect water quality in this region.

Heavier pnictinidene gold(i) complexes

N,C,N-Chelated pnictinidenes ArE [where E = As, Sb or Bi; Ar = 2,6-(tBuN[double bond, length as m-dash]CH)2C6H3] were used as ligands for the coordination of various gold(i) complexes. Thus, the reaction of ArE with [AuCl(Me2S)] gave complexes [AuCl(ArE)] [where E = As (1) or Sb (2)] that exhibited only limited stability in solution. By contrast, the reaction of ArBi with [AuCl(Me2S)] led to the immediate deposition of gold metal and the oxidation of the bismuth atom giving ArBiCl2. The treatment of a tetrameric gold alkynyl complex [Au(C[triple bond, length as m-dash]CPh)]4 with ArAs and ArSb gave ionic compounds [Au(ArAs)2]+[Au2(C[triple bond, length as m-dash]CPh)3]- [denoted as 3+[Au2(C[triple bond, length as m-dash]CPh)3]-] and [Au(ArSb)2]+[Au(C[triple bond, length as m-dash]CPh)2]- [denoted as 4+[Au(C[triple bond, length as m-dash]CPh)2]-], respectively. Finally, the reaction of ArE with the carbene gold(i) complex [Au(IPr)(MeCN)]+[BF4]- [where IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene, MeCN = acetonitrile] produced ionic complexes [Au(IPr)(ArE)]+[BF4]- [for cations: E = As (5+), Sb (6+) or Bi (7+)]. All complexes were characterized using 1H and 13C NMR, high mass accuracy electrospray ionization mass spectrometry (ESI-MS), IR and Raman spectroscopy and (except for 1) by single-crystal X-ray diffraction analysis. Furthermore, the structure and bonding of both neutral and ionic complexes with different coordination patterns have also been investigated in detail using a Density Functional Theory (DFT) computational approach.

The effects of sewage treatment plant effluents on hepatic and intestinal biomarkers in common carp (Cyprinus carpio)

Sewage treatment plants (STPs) are one of the major source of pharmaceuticals and personal care products in the aquatic environment. Generally, the effects of individual chemicals on fish are studied under laboratory conditions, which leads to results that are potentially not realistic regarding the effects of these chemicals under environmental conditions. Therefore, in this study, common carps were held in exposed pond that receive water from STP effluents for 360 days under natural conditions. Elimination of xenobiotics starts in the fish intestine, in which the microbial community strongly influences its function. Moreover, the fish intestine functions as crucial organ for absorbing lipids and fatty acids (FA), with consequent transport to the liver where their metabolism occurs. The liver is the primary organ performing xenobiotic metabolism in fish, and therefore, the presence of pollutants may interact with the metabolism of FA. The catalytic activity of CYP1A and CYP3A-like enzymes, their gene expression, FA composition and intestinal microbiome consortia were measured. The catalytic activity of enzymes and their gene and protein expression, were induced in hepatic and intestinal tissues of fish from the exposed pond. Also, fish from the exposed pond had different compositions of FA than those from the control pond: concentration of 18:1 n-9 and 18:2 n-6 were significantly elevated and the longer chain n-3 FA 20:5 n-3, 22:5 n-3 and 22:6 n-3 were significantly lowered. There were clear differences among microbiome consortia in fish intestines across control and exposed groups. Microbiome taxa measured in exposed fish were also associated with those found in STP activated sludge. This study reveals that treated STP water, which is assumed to be clean, affected measured biomarkers in common carp.

Fate of perfluoroalkyl substances within a small stream food web affected by sewage effluent

The fate of fourteen target perfluoroalkyl substances (PFASs) are described within a small stream affected by a sewage treatment plant (STP) effluent. Concentrations of target PFASs in samples of water, benthic macroinvertebrates and brown trout (Salmo trutta) are presented. Two hundred brown trout individuals originating from clean sites within the same stream were tagged and stocked into an experimental site affected by the STP's effluent. As a passive sampling approach, polar organic chemical integrative samplers (POCIS) were deployed in the water to reveal the water-macroinvertebrates-fish biotransformation processes of PFASs. Bioconcentration/bioaccumulation of target compounds was monitored one, three, and six months after stocking. Twelve of the fourteen target PFASs were found in concentration above the LOQ in at least one of the studied matrices. The compound pattern varied significantly between both the studied species and water samples. Concerning the accumulation of PFASs in fish, the highest concentrations were found in the liver of individuals sampled after three months of exposure. These concentrations rapidly decreased after six months although the water concentrations were slightly increasing during experiment.

Transport of pharmaceuticals and their metabolites between water and sediments as a further potential exposure for aquatic organisms

Although pharmaceuticals are frequently studied contaminants, their fate in the environment is still not completely clear. During a one year study, a complex approach including water, sediment and fish sampling was used to describe the behaviour of pharmaceuticals and their metabolites (PTMs) in the environment. Eighteen pharmaceuticals and seven of their metabolites were determined in a pond used for the tertiary treatment of wastewater effluent. A liquid chromatography-tandem mass spectrometry method was applied to determine the PTMs concentrations in all matrices. Seasonal variations in concentrations were evaluated. The partitioning of contaminants between pond compartments was estimated by means of solid water distribution coefficients (K_d) and bioaccumulation factors (BAF) for the livers of fish. K_d values were almost stable throughout the year, which may be a sign of the continuous transport of PTMs between water and sediment under the experimental conditions. Almost all of the studied compounds, with exception of sertraline (BAF of 6200), were found to not be bioaccumulative in fish livers. The pond removal efficiency was calculated for all PTMs, and favourable conditions for natural pharmaceutical removal were proposed. Further aspects regarding fish pharmaceutical exposure need to be studied.

[Classification Systems to Evaluate the Clubfoot and Their Potential Use to Predict the Course and the Results of the Ponseti Method Treatment]

INTRODUCTION The clubfoot ranks among the most frequent paediatric structural deformities of the lower extremity. Currently, the Ponseti method is considered the gold standard for the treatment. To evaluate the degree and severity of the deformity, clinical classification systems have been developed, commonly used in clinical practice. This study aims to verify whether the Pirani and Dimeglio clinical scoring systems can be used to predict the results of treatment by the Ponseti method. MATERIAL AND METHODS The study included 31 patients. The patients had been referred from the neonatal departments to the Department of Paediatric Surgery, Orthopaedics and Traumatology in Brno with the diagnosed clubfoot deformity, where they were treated by an erudite orthopaedist experienced in this field according to the Ponseti treatment standards. The Pirani and Dimeglio clinical scoring of the deformity were performed always before the commencement of the therapy and after the second plaster cast fixation. The number of plaster cast fixations, the necessity to carry out achillotomy and the relapse rate were set as the parameters of treatment results. In the first stage of statistical analysis, the respective clinical systems were correlated with the treatment results, in the second part of the study the patients were based on the clinical evaluation divided into 3 groups depending on the severity of the deformity, and these groups were subsequently compared. RESULTS 22 patients from the group (71%) underwent percutaneous achillotomy and in 3 patients (9.7%) a relapse occurred. To correct deformities 7.1 corrective casts were used on average. The correlation between the number of plaster cast fixations and classification systems was significant in all the cases, with the strongest dependency shown by the correlation with the Pirani score after the second corrective cast (r = 0.594, p < 0.001). Positive correlation was found also between the necessity to perform achillotomy and both the classification systems. In this case the strongest correlation was established in the case of the Pirani clinical scoring after the second plaster cast fixation (r = 0.488, p = 0.003). Conversely, significant correlation was not established between the relapse rate and the used classification systems, not even in a single case (p ≥ 0.05). In the second stage of the statistical analysis, in the case of the Pirani scoring before the therapy no difference was found between the individual groups with diverse severity of clubfoot deformity during the evaluation of the aforementioned parameters of treatment results. In the Pirani classification after the second plaster cast fixation, a statistically significant difference was established in the number of plaster cast fixations (p = 0.003) and the necessity to perform achillotomy (p = 0.012). When the Dimeglio scoring was applied before the therapy, a statistically significant difference between the groups was found in the number of plaster cast fixations (p = 0.031) and after the second plaster cast fixation in the relapse rate (p = 0.035). DISCUSSION Although the clinical scoring systems belong to key indicators of severity of the deformity and are commonly used in clinical practice, the current literature provides only an inconsistent picture of their application in predicting the course and the results of treatment. Concurrently, the authors opinions on this issue differ. The scoring in later stages of treatment shows a better predictive value than the scoring at the beginning of the treatment, which was confirmed also by the results of our study. CONCLUSIONS Even though the clinical scoring systems show a certain dependency on the parameters of the treatment results, in practice their predictive function can be used to a limited degree only. The complexity of the evaluation of the deformity itself and subsequently of the results of treatment requires also the use of other parameters than the clinical classifications only so that the prediction of the course and results of the treatment of clubfoot according to Ponseti shows a higher degree of reliability. Key words:clubfoot, Ponseti, Pirani classification, Dimeglio classification.

[Comparison of Two Methods of Minimally Invasive Osteosynthesis for Proximal Radius Fractures in Paediatric Patients]

PURPOSE OF THE STUDY The presented study was construed as a retrospective multicentric clinical study focused on paediatric skeletal injuries of the proximal radius. As a general rule, the Type I displaced fractures (Judet classification) are treated conservatively, with no reduction. In the case of Type II-IV displacement, the fracture necessitates reduction or is also transfixed by a Kirschner wire (K-wire) or a Prevot nail (P-nail) where subsequent fragment instability occurs. The comparison aimed to ascertain whether there is a statistically significant difference between the two methods. No difference was expected by the authors, therefore a null hypothesis was set. MATERIAL AND METHODS The patients were treated at the Clinic of Paediatric Surgery, Orthopaedics and Traumatology (CPSOT) of the Faculty of Medicine of the Masaryk University and at the Clinic of Orthopaedics and Traumatology of the Musculoskeletal System of the University Hospital in Pilsen in the period from 2006 to 2015. Two methods of closed reduction and minimally- invasive osteosynthesis were evaluated. The first method was the elastic stable intramedullary nailing (ESIN) with a P-nail, the second method was an osteosynthesis using a K-wire. In the clinical part of the study, comparisons were made based on the monitoring of the same parameters - final restriction of movement, time to full weight bearing of the extremity and incidence of serious complications. RESULTS The final group comprised a total of 31 patients, of whom 7 boys and 24 girls aged 3-16 years with the median of 9-10 years. Some restriction of movement following the treatment occurred in a total of seven patients (44%) with the K-wire and in four patients (27%) with the P-nail. When comparing the movement at 5% level of significance using the Chi-Square tests, no significant difference was found (p = 0.446). When evaluating the serious complications at 5% level of significance using the Chi-Square tests, the difference between the two methods of treatment was again insignificant (p = 0.365). When the full weight bearing was compared (median K-wire 8 weeks, median P-nail 10 weeks), a statistically significant difference was obtained at 5% level of significance using the Fischer exact test (p = 0.003). DISCUSSION In these fractures, usually the metaphysis or the physis are involved in the injury, in which case the fractures are classified according to Salter and Harris, with the most frequent occurrence of SHII epiphyseal separation and rare SHIII and SHIV epiphyseal fractures. The radial head fractures are mostly caused by valgus force. Therefore, the individuals with a higher elbow valgosity are more prone to injuries. The girls strongly prevail (77%) also in our study. In general, our results as well as the literature have proven that as the displacement increases, the necessity of closed reduction and osteosynthesis grows. The post-treatment complications in our group were observed in 35.5% of patients, namely most often in the form of limited movement. The literature refers to complications in 26.5-53% of patients. CONCLUSIONS The clinical results clearly show that when comparing the complications after the radial head fracture in children there is no statistically significant difference between the methods of osteosynthesis. This study shall serve as a starting point for the currently ongoing prospective multicentric study evaluating the modified ESIN technique using a pre-bent Kirschner wire. Key words:children, fracture, radius, proximal, osteosynthesis.

[Verification of the Necessity for the Open Reduction and Tension Band Wiring of the Displaced Olecranon Fracture in Younger Children]

PURPOSE OF THE STUDY Olecranon fractures in skeletally immature patients are rather rare and represent up to 7% of elbow skeletal injuries. Although the majority of olecranon fractures is constituted by undisplaced fractures treated conservatively with good outcomes, a few of them require surgery. The aim of the study was to compare two different approaches of surgical treatment - the open reduction with tension band wiring - cerclage (ORCe) and the closed reduction and percutaneous pinning (CRPP). MATERIAL AND METHODS 37 patients (28 boys, 9 girls) were included in the retrospective multicentric study. The patients were treated at two different institutions (the Clinic of Paediatric Surgery, Orthopaedics and Traumatology, the University Hospital Brno and the Department of Paediatric Surgery and Traumatology, the University Hospital Hradec Králové, Czech Republic). 17 patients underwent the ORCe procedure, while 20 patients were treated using the CRPP method. Different parameters were statistically compared in the groups (demographic data, data concerning the course of the therapy, outcome of the therapy in terms of movements' restrictions and complications such as osteosynthesis failure and infection). RESULTS Both the groups were comparable in terms of demographic data because no statistically significant difference was observed in terms of the age (p = 0.082), the affected site (p = 1.000) and the gender (p = 0.462). Statistically significant difference between these two groups was found in the interval between the implementation and the removal of the osteosynthetic material (p < 0.001) and in the length of cast immobilisation (p = 0.047). The number of patients with movement restriction up to 10° was statistically significantly higher in patients who underwent the CRPP procedure (p = 0.040), but no statistically significant difference was seen between these two groups in terms of movement restriction more than 10° (p = 0.609). One revision surgery was performed in the CRPP group, however with no statistical significance (p = 0.350). DISCUSSION The multicentric study included 37 children, who underwent surgical treatment of a displaced olecranon fracture. Compared to the studies dealing with this topic the number of patients included in this study is relatively high. It advocates the possibility of using the CRPP method as a good alternative to the gold-standard ORCe technique because no difference in terms of the number of revision surgeries and the clinically important movement restriction of more than 10° were seen. It also brings along advantages such as a simple surgical technique, good functional and cosmetic effects, reducing the risk of ischemic insult of growth plate and the possibility of osteosynthetic material removal at an outpatient department with no need for general anaesthesia. The risk of a higher radiation exposure of both the patient and the surgical team should be considered as a disadvantage of the closed method. CONCLUSIONS The mini-invasive CRPP appears to be a good alternative option to the ORCe method for the treatment of isolated olecranon fractures in children offering the advantages such as avoiding extensive open procedure and simple implants removal. Key words:children, olecranon, fracture, tension band wiring - cerclage, percutaneous pinning, elbow.

Bioaccumulation of psychoactive pharmaceuticals in fish in an effluent dominated stream

The treated effluent from sewage treatment plants (STP) is a major source of active pharmaceutical ingredients (APIs) that enter the aquatic environment. Bioaccumulation of 11 selected psychoactive pharmaceuticals (citalopram, clomipramine, haloperidol, hydroxyzine, levomepromazine, mianserin, mirtazapine, paroxetine, sertraline, tramadol and venlafaxine) was examined in Zivny Stream (tributary of the Blanice River, the Czech Republic), which is a small stream highly affected by effluent from the Prachatice STP. Six of the 11 pharmaceuticals were detected in grab water samples and in passive samplers. All pharmaceuticals were found in fish exposed to the stream for a defined time. The organs with highest presence of the selected pharmaceuticals were the liver and kidney; whereas only one pharmaceutical (sertraline) was detected in the brain of exposed fish. Fish plasma and muscle samples were not adequate in revealing exposure because the number of hits was much lower than that in the liver or kidney. Using the criterion of a bioaccumulation factor (BAF) ≥ 500, citalopram, mianserin, mirtazapine and sertraline could be classified as potential bioaccumulative compounds. In combination, data from integrative passive samplers and fish liver or kidney tissue samples were complimentary in detection of target compounds and simultaneously helped to distinguish between bioconcentration and bioaccumulation.

Changes in surface water chemistry caused by natural forest dieback in an unmanaged mountain catchment

Ionic and nutrient compositions of throughfall, tributaries and lake outlet were analysed in the Plešné catchment-lake system (an unmanaged mountain forest in Central Europe) from 1997 to 2016. The aim was to evaluate changes in surface water chemistry after natural forest dieback. In the 2004-2008, 93% of the Norway spruce trees were killed by bark beetle outbreak, and all dead biomass remained in the catchment. Forest dieback changed the chemistry of all water fluxes, and the magnitude, timing, and duration of these changes differed for individual water constituents. The most pronounced decreases in throughfall concentrations occurred for K⁺, dissolved organic carbon (DOC), Ca²⁺ and Mg²⁺, i.e. elements mostly originating from canopy leaching, while concentrations of NH₄⁺ and soluble reactive phosphorus (SRP) remained almost unaffected. In tributaries, the most rapid changes were increases in NO₃^-, K⁺, H⁺ and ionic aluminium (Al_i) concentrations, while terrestrial export of DOC and P forms started more slowly. Immediately after the forest dieback, increase in NO₃^- concentrations was delayed by elevated DOC availability in soils. NO₃^- became the dominant anion, with maximum concentrations up to 346μeqL^-1 within 5-7years after the bark beetle outbreak, and then started to decrease. Terrestrial exports of Al_i, K⁺, H⁺, Mg²⁺, and Ca²⁺ accompanied NO₃^- leaching, but their trends differed due to their different sources. Elevated losses of SRP, DOC, and dissolved organic nitrogen continued until the end of the study. In the lake, microbial processes significantly decreased concentrations of NO₃^-, organic acid anions, H⁺ and Al_i, and confounded the chemical trends observed in tributaries. Our results suggest that terrestrial losses of elements and the deterioration of waters after forest dieback are less pronounced in unmanaged than managed (clear-cut) catchments.

A comparative study of the structure and bonding in heavier pnictinidene complexes [(ArE)M(CO)n] (E = As, Sb and Bi; M = Cr, Mo, W and Fe)

N,C,N-Chelated pnictinidenes ArE [where E = As (1), Sb (2) or Bi (3); Ar = C₆H₃-2,6-(CH[double bond, length as m-dash]Nt-Bu)₂] were used as ligands for the coordination of transition metal carbonyls. Thus, the reaction of 1-3 with [M(CO)₅THF] (where M = Cr, W) or [Mo(CO)₅(Me₃N)] gave complexes [(ArE)M(CO)₅] [where E = As and M = Cr (1a), Mo (1b), W (1c); E = Sb and M = Cr (2a), Mo (2b), W (2c); E = Bi and M = Cr (3a), Mo (3b), W (3c)]. Analogously, the treatment of 1-3 with [Fe₂(CO)₉] resulted in the formation of the complexes [(ArE)Fe(CO)₄] [where E = As (1d), Sb (2d) or Bi (3d)]. All compounds were characterized by ¹H and ¹³C NMR spectroscopy, Raman, IR and UV-Vis spectroscopy. The molecular structures of the majority of the compounds (except 1b and 1c) were also determined by the single-crystal X-ray diffraction analysis. Furthermore, the structure and bonding of the title compounds have also been thoroughly investigated using a computational approach.

Fish fin-clips as a non-lethal approach for biomonitoring of mercury contamination in aquatic environments and human health risk assessment

Muscle tissue and pectoral fins of two important indicator fish species, frequently used in biomonitoring programs, were sampled and analysed for total mercury content (THg) at six localities within the Czech Republic. The relationship between mercury concentration in muscle and in fin-clips was described. Mean values of THg fin-clip concentration correlate significantly (p < 0.01) with those measured in muscle of indicator fish. Concerning comparison among localities, a coefficient of determination (r(2)) of 0.85 and 0.91 was found between studied approaches in the case of chub (Squalius cephalus) and bream (Abramis brama), respectively. THg muscle concentrations (mean, n = 10) varied from 0.181 to 0.491 μg g(-1) wet, depending on indicator species and locality. A concentration-dependent relationship between muscle and fin-clip THg content was found in both species. Based on this finding, a novel method for the prediction of muscle THg concentration from fin-clips analysis was developed. The difference between measured and predicted muscle concentration was below 10% in both indicator species at most sampling sites. Use of fish fin-clips was found as an appropriate nonlethal approach for the evaluation of mercury contamination in aquatic environments as well as for human health risk assessment.

Young-of-the-year fish as a prospective bioindicator for aquatic environmental contamination monitoring

Toxic metals (Hg, Cd, Pb) and fifteen perfluoroalkyl substances (PFASs) were determined in different fish samples at two locations on the Elbe River in the Czech Republic. The muscle tissue of the two adult fish species most commonly used as bioindicators in central Europe and whole body homogenates of various species of young-of-the-year (YOY) fish were used. The purpose of this study was to evaluate the potential to replace adult fish muscle tissue with YOY fish for contamination monitoring. All of the toxic metals and five of the fifteen PFASs were found in the YOY fish samples while only mercury and PFOS were detected in the muscle tissue of adults. The concentration of total mercury (THg) in the YOY fish homogenates ranged between 0.014 and 0.062 μg g(-1). Of the spectrum of analysed pollutants, only the THg concentrations were lower in YOY fish homogenates than in adult muscle tissue. The cadmium concentration varied from 0.004 to 0.024 μg g(-1) and the lead concentration varied from 0.032 to 0.396 μg g(-1) in YOY fish homogenates, while in most of the adult samples, Cd and Pb were below the detection limit of the analytical methods employed. The PFOS concentrations in YOY fish homogenates were comparable to the concentrations frequently found in adult liver tissue. These results show that mixed shoals of YOY fish can be successfully used for aquatic bio-monitoring. Interspecific variability in the concentrations of the target pollutants in YOY fish whole body homogenates is usually lower than the intraspecific variability of the concentrations of the pollutants in adult fish muscle. YOY fish were found to be a suitable bioindicator and have several advantages compared to adult fish.

Spontaneous Double Hydrometallation Induced by N→M Coordination in Organometallic Hydrides of Group 14 Elements

Our attempts to synthesise N→M intramolecularly coordinated diorganometallic hydrides L2MH2 [M=Si (4), Ge (5), Sn (6)] containing the CH=N imine group (in which L is C,N-chelating ligand {2-[(2,6-iPr2C6H3)N=CH]C6 H4}(-)) yielded 1,1'-bis(2,6-diisopropylphenyl)-2,2'-spriobi[benzo[c][1,2]azasilole] (7), 1,1'-bis(2,6-diisopropylphenyl)-2,2'-spriobi[benzo[c][1,2]azagermole] (8) and C,N-chelated homoleptic stannylene L2Sn (10), respectively. Compounds 7 and 8 are an outcome of a spontaneous double hydrometallation of the two CH=N imine moieties induced by N→M intramolecular coordination (M=Si, Ge) in the absence of any catalyst. In contrast, the diorganotin hydride L2SnH2 (6) is redox-unstable and the reduction of the tin centre with the elimination of H2 provided the C,N-chelated homoleptic stannylene L2Sn (10). Compounds 7 and 8 were characterised by NMR spectroscopy and X-ray diffraction analysis. Because the proposed N→M intramolecularly coordinated diorganometallic hydrides L2MH2 [M=Si (4), Ge (5), Sn (6)] revealed two different types of reduction reactions, DFT calculations were performed to gain an insight into the structures and bonding of the non-isolable diorganometallic hydrides as well as the products of their subsequent reactions. Furthermore, the thermodynamic profiles of the different reaction pathways with respect to the central metal atom were also investigated.

Perfluoroalkyl substances in aquatic environment-comparison of fish and passive sampling approaches

The concentrations of seven perfluoroalkyl substances (PFASs) were investigated in 36 European chub (Squalius cephalus) individuals from six localities in the Czech Republic. Chub muscle and liver tissue were analysed at all sampling sites. In addition, analyses of 16 target PFASs were performed in Polar Organic Chemical Integrative Samplers (POCISs) deployed in the water at the same sampling sites. We evaluated the possibility of using passive samplers as a standardized method for monitoring PFAS contamination in aquatic environments and the mutual relationships between determined concentrations. Only perfluorooctane sulphonate was above the LOQ in fish muscle samples and 52% of the analysed fish individuals exceeded the Environmental Quality Standard for water biota. Fish muscle concentration is also particularly important for risk assessment of fish consumers. The comparison of fish tissue results with published data showed the similarity of the Czech results with those found in Germany and France. However, fish liver analysis and the passive sampling approach resulted in different fish exposure scenarios. The total concentration of PFASs in fish liver tissue was strongly correlated with POCIS data, but pollutant patterns differed between these two matrices. The differences could be attributed to the metabolic activity of the living organism. In addition to providing a different view regarding the real PFAS cocktail to which the fish are exposed, POCISs fulfil the Three Rs strategy (replacement, reduction, and refinement) in animal testing.

C,N-Chelated organotin(iv) azides: synthesis, structure and use within click chemistry

Novel organotin(iv) azides were employed as building blocks to prepare various organotin(iv) tetrazolides or triazolides.

Addition of in situ reduced amidinato-methylaluminium chloride to acetylenes

Two ethylene-bridged methylaluminium amidinates and one aluminium amidinate containing three terminal trimethylstannyl-ethynyl groups interconnected by π-coordinated potassium ions were prepared in situ. The re-oxidation of the ethylene-bridged compound by iodine followed by further reduction using the same activation procedure demonstrated the versatility of the approach. The reactivity of an ethylene-bridged methylaluminum amidinate towards HCl was examined to demonstrate the building block concept. DFT calculations were performed to gain insight into the mechanism of the in situ activation of diphenylacetylene.

Non-covalent interactions in coinage metal complexes of 1,2,4-triazole-based N-heterocyclic carbenes

Seven coinage metal(I) complexes bearing two different triazole-based N-heterocyclic carbene (NHC) ligands, [1-tert-butyl-4-{2-[(N,N-dimethylamino)methyl]phenyl}-3-phenyl-1H-1,2,4-triazol-4-ium-5-ide and 1-tert-butyl-4-(4-methylphenyl)-3-phenyl-1H-1,2,4-triazol-4-ium-5-ide], were synthesized and fully characterized in solution by NMR spectroscopy as well as in the solid state by X-ray diffraction techniques. Furthermore, the XRD analysis showed that the bidentate coordination of the amino group substituted NHC ligand, previously observed for rhodium and palladium complexes, does not take place in the solid state structure of Au(I) complexes with various halide ligands. Nevertheless, the formation of sets of two head-to-tail oriented monomers aggregated via a weak metallophilic contact was revealed for both NHC ligands as well as for all three coinage metals with different halides. These experimental data correlate quite well with the previously published theoretical study on related complexes.