A method of numerical calculation of the fourth virial coefficients of the mixture of additive hard spheres is proposed. The results are compared with an exact analytical formula for the fourth partial virial coefficient B4[1] (i.e., three spheres of diameters sigma1 and one sphere of diameter sigma2) and a semiempirical expression for B4[2] (i.e., two spheres of each kind). It is shown that the first formula is nonanalytic and the implication to the equations of state for hard-sphere mixtures is discussed.

• MeSH
• algoritmy * MeSH
• chemické modely * MeSH
• komplexní směsi chemie   MeSH
• počítačová simulace MeSH
• reologie metody   MeSH
• roztoky chemie   MeSH
• statistické modely * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• komplexní směsi MeSH
• roztoky MeSH

We describe an ultrasonic instrument for continuous real-time analysis of the fractional mixture of a binary gas system. The instrument is particularly well suited to measurement of leaks of a high molecular weight gas into a system that is nominally composed of a single gas. Sensitivity < 5 × 10(-5) is demonstrated to leaks of octaflouropropane (C3F8) coolant into nitrogen during a long duration (18 month) continuous study. The sensitivity of the described measurement system is shown to depend on the difference in molecular masses of the two gases in the mixture. The impact of temperature and pressure variances on the accuracy of the measurement is analysed. Practical considerations for the implementation and deployment of long term, in situ ultrasonic leak detection systems are also described. Although development of the described systems was motivated by the requirements of an evaporative fluorocarbon cooling system, the instrument is applicable to the detection of leaks of many other gases and to processes requiring continuous knowledge of particular binary gas mixture fractions.

• MeSH
• analýza selhání vybavení MeSH
• chemické techniky analytické přístrojové vybavení   metody   MeSH
• design vybavení MeSH
• komplexní směsi analýza   MeSH
• mikrochemie přístrojové vybavení   metody   MeSH
• plyny analýza   MeSH
• ultrasonografie přístrojové vybavení   metody   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• komplexní směsi MeSH
• plyny MeSH

Neonicotinoids are increasingly and widely used systemic insecticides in agriculture, residential applications, and elsewhere. These pesticides can sometimes occur in small water bodies in exceptionally high concentrations, leading to downstream non-target aquatic toxicity. Although insects appear to be the most sensitive group to neonicotinoids, other aquatic invertebrates may also be affected. Most existing studies focus on single-insecticide exposure and very little is known concerning the impact of neonicotinoid mixtures on aquatic invertebrates at the community level. To address this data gap and explore community-level effects, we performed an outdoor mesocosm experiment that tested the effect of a mixture of three common neonicotinoids (formulated imidacloprid, clothianidin and thiamethoxam) on an aquatic invertebrate community. Exposure to the neonicotinoid mixture induced a top-down cascading effect on insect predators and zooplankton, ultimately increasing phytoplankton. Our results highlight complexities of mixture toxicity occurring in the environment that may be underestimated with traditional mono-specific toxicological approaches.

• Klíčová slova
• Aquatic invertebrates, Community-levels, Mixture, Neonicotinoid insecticides, Trophic interactions,
• MeSH
• bezobratlí MeSH
• chemické látky znečišťující vodu * analýza   MeSH
• dusíkaté sloučeniny toxicita   MeSH
• insekticidy * analýza   MeSH
• neonikotinoidy toxicita   MeSH
• sladká voda MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chemické látky znečišťující vodu * MeSH
• dusíkaté sloučeniny MeSH
• insekticidy * MeSH
• neonikotinoidy MeSH

Chemicals in the environment occur in mixtures rather than as individual entities. Environmental quality monitoring thus faces the challenge to comprehensively assess a multitude of contaminants and potential adverse effects. Effect-based methods have been suggested as complements to chemical analytical characterisation of complex pollution patterns. The regularly observed discrepancy between chemical and biological assessments of adverse effects due to contaminants in the field may be either due to unidentified contaminants or result from interactions of compounds in mixtures. Here, we present an interlaboratory study where individual compounds and their mixtures were investigated by extensive concentration-effect analysis using 19 different bioassays. The assay panel consisted of 5 whole organism assays measuring apical effects and 14 cell- and organism-based bioassays with more specific effect observations. Twelve organic water pollutants of diverse structure and unique known modes of action were studied individually and as mixtures mirroring exposure scenarios in freshwaters. We compared the observed mixture effects against component-based mixture effect predictions derived from additivity expectations (assumption of non-interaction). Most of the assays detected the mixture response of the active components as predicted even against a background of other inactive contaminants. When none of the mixture components showed any activity by themselves then the mixture also was without effects. The mixture effects observed using apical endpoints fell in the middle of a prediction window defined by the additivity predictions for concentration addition and independent action, reflecting well the diversity of the anticipated modes of action. In one case, an unexpectedly reduced solubility of one of the mixture components led to mixture responses that fell short of the predictions of both additivity mixture models. The majority of the specific cell- and organism-based endpoints produced mixture responses in agreement with the additivity expectation of concentration addition. Exceptionally, expected (additive) mixture response did not occur due to masking effects such as general toxicity from other compounds. Generally, deviations from an additivity expectation could be explained due to experimental factors, specific limitations of the effect endpoint or masking side effects such as cytotoxicity in in vitro assays. The majority of bioassays were able to quantitatively detect the predicted non-interactive, additive combined effect of the specifically bioactive compounds against a background of complex mixture of other chemicals in the sample. This supports the use of a combination of chemical and bioanalytical monitoring tools for the identification of chemicals that drive a specific mixture effect. Furthermore, we demonstrated that a panel of bioassays can provide a diverse profile of effect responses to a complex contaminated sample. This could be extended towards representing mixture adverse outcome pathways. Our findings support the ongoing development of bioanalytical tools for (i) compiling comprehensive effect-based batteries for water quality assessment, (ii) designing tailored surveillance methods to safeguard specific water uses, and (iii) devising strategies for effect-based diagnosis of complex contamination.

• Klíčová slova
• Combined effect, Effect-based methods, Mixture toxicity, Water contamination, Water framework directive, Water monitoring,
• MeSH
• biologické modely * MeSH
• biotest * MeSH
• chemické látky znečišťující vodu * analýza   toxicita   MeSH
• kultivované buňky MeSH
• vystavení vlivu životního prostředí analýza   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chemické látky znečišťující vodu * MeSH

Antibacterial coatings on biomedical instruments are of great interest because they can suppress bacterial colonization on these instruments. In this study, antibacterial polymeric thin coatings were deposited on teflon substrates using atmospheric pressure plasma polymerization from a propane-butane mixture. The plasma polymerization was performed by means of surface dielectric barrier discharge burning in nitrogen at atmospheric pressure. The chemical composition of plasma polymerized propane-butane films was studied by energy-dispersive X-ray spectroscopy (EDX) and FTIR. The film surface properties were studied by SEM and by surface energy measurement. The EDX analysis showed that the films consisted of carbon, nitrogen and oxygen from ambient air. The FTIR analysis confirmed, in particular, the presence of alkyl, nitrile, acetylene, imide and amine groups. The deposited films were hydrophilic with a water contact angle in the range of 13-23°. The thin film deposited samples were highly active against both S. aureus and E. coli strains in general. On the other hand, the films were cytocompatible, reaching more than 80% of the cell viability threshold compared to reference polystyrene tissue.

• Klíčová slova
• antibacterial thin films, plasma polymer, propane–butane mixture,
• MeSH
• antibakteriální látky farmakologie   MeSH
• atmosférický tlak MeSH
• butany MeSH
• dusík MeSH
• Escherichia coli MeSH
• propan * MeSH
• Staphylococcus aureus * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antibakteriální látky MeSH
• butany MeSH
• dusík MeSH
• propan * MeSH

One of the main goals of the Spanish and Portuguese-Speaking Group of the International Society for Forensic Genetics (GHEP-ISFG) is to promote and contribute to the development and dissemination of scientific knowledge in the field of forensic genetics. Due to this fact, GHEP-ISFG holds different working commissions that are set up to develop activities in scientific aspects of general interest. One of them, the Mixture Commission of GHEP-ISFG, has organized annually, since 2009, a collaborative exercise on analysis and interpretation of autosomal short tandem repeat (STR) mixture profiles. Until now, six exercises have been organized. At the present edition (GHEP-MIX06), with 25 participant laboratories, the exercise main aim was to assess mixture profiles results by issuing a report, from the proposal of a complex mock case. One of the conclusions obtained from this exercise is the increasing tendency of participating laboratories to validate DNA mixture profiles analysis following international recommendations. However, the results have shown some differences among them regarding the edition and also the interpretation of mixture profiles. Besides, although the last revision of ISO/IEC 17025:2017 gives indications of how results should be reported, not all laboratories strictly follow their recommendations. Regarding the statistical aspect, all those laboratories that have performed statistical evaluation of the data have employed the likelihood ratio (LR) as a parameter to evaluate the statistical compatibility. However, LR values obtained show a wide range of variation. This fact could not be attributed to the software employed, since the vast majority of laboratories that performed LR calculation employed the same software (LRmixStudio). Thus, the final allelic composition of the edited mixture profile and the parameters employed in the software could explain this data dispersion. This highlights the need, for each laboratory, to define through internal validations its criteria for editing and interpreting mixtures, and to continuous train in software handling.

• Klíčová slova
• Collaborative exercise, DNA analysis, Forensic genetics reporting, Mixture interpretation, Spanish and Portuguese-Speaking Working Group, Statistical evaluation,
• MeSH
• DNA fingerprinting normy   MeSH
• laboratoře statistika a číselné údaje   MeSH
• lidé MeSH
• mikrosatelitní repetice * MeSH
• pravděpodobnostní funkce MeSH
• software MeSH
• soudní genetika normy   MeSH
• společnosti vědecké * MeSH
• výzkumná zpráva normy   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Body-focused repetitive behavior disorders (BFRBs) include Trichotillomania (TTM; Hair pulling disorder) and Excoriation (Skin Picking) Disorder (SPD). These conditions are prevalent, highly heterogeneous, under-researched, and under-treated. In order for progress to be made in optimally classifying and treating these conditions, it is necessary to identify meaningful subtypes. 279 adults (100 with TTM, 81 with SPD, 40 with both TTM and SPD, and 58 controls) were recruited for an international, multi-center between-group comparison using mixture modeling, with stringent correction for multiple comparisons. The main outcome measure was to examine distinct subtypes (aka latent classes) across all study participants using item-level data from gold-standard instruments assessing detailed clinical measures. Mixture models identified 3 subtypes of TTM (entropy 0.98) and 2 subtypes of SPD (entropy 0.99) independent of the control group. Significant differences between these classes were identified on measures of disability, automatic and focused symptoms, perfectionism, trait impulsiveness, and inattention and hyperactivity. These data indicate the existence of three separate subtypes of TTM, and two separate subtypes of SPD, which are distinct from controls. The identified clinical differences between these latent classes may be useful to tailor future treatments by focusing on particular traits. Future work should examine whether these latent subtypes relate to treatment outcomes, or particular psychobiological findings using neuroimaging techniques.

• Klíčová slova
• Classification, Mixture modeling, Skin picking disorder, Subtypes, Treatment, Trichotillomania,
• MeSH
• dospělí MeSH
• lidé MeSH
• trichotilomanie * diagnóza   epidemiologie   terapie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• multicentrická studie MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

Neonicotinoid insecticides represent nearly a quarter of the global insecticide market and are widely used in agriculture but also for lawn, garden care, and pest control. They are highly water-soluble, persistent in soil, may enter the aquatic compartment via spray drift, runoff, or leaching, and contribute to downstream aquatic toxicity. Although insects appear to be the most sensitive group to neonicotinoids, other groups, such as crustaceans, may also be affected. Furthermore, most studies focus on single-insecticide exposure and very little is known concerning the impact of neonicotinoid mixtures on aquatic invertebrates. The present study was designed to test potential toxicological effects of an environmentally relevant mixture of imidacloprid, clothianidin, and thiamethoxam on populations of Ceriodaphnia dubia and Daphnia magna under controlled conditions. Chronic toxicity tests were conducted in the laboratory, and survival and reproduction were measured for both species under environmentally relevant, 'worst-case' concentrations for each compound separately and in combination as pesticides are often detected as mixtures in aquatic environments. The neonicotinoids did not appear to affect the survival of C. dubia and D. magna. Reproduction of C. dubia was affected by the mixture whereas all three individual insecticides as well as the mixture caused a significant reduction in the reproduction of D. magna. Our results highlight the complexity of pesticide toxicity and show that traditional toxicological approaches such as, acute mortality studies and tests with single compounds can underestimate negative impacts that occur in the environment.

• Klíčová slova
• Aquatic invertebrates, Mixture, Neonicotinoids, Sublethal effects,
• MeSH
• chemické látky znečišťující vodu * toxicita   MeSH
• Cladocera * MeSH
• Daphnia MeSH
• dusíkaté sloučeniny toxicita   MeSH
• insekticidy * toxicita   MeSH
• neonikotinoidy toxicita   MeSH
• thiamethoxam farmakologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chemické látky znečišťující vodu * MeSH
• dusíkaté sloučeniny MeSH
• insekticidy * MeSH
• neonikotinoidy MeSH
• thiamethoxam MeSH

Herbicides and their metabolites are often detected in water bodies where they may cause adverse effects to non-target organisms. Their effects at environmentally relevant concentrations are often unclear, especially concerning mixtures of pesticides. This study thus investigated the impacts of one of the most used herbicides: S-metolachlor and its two metabolites, metolachlor oxanilic acid (MOA) and metolachlor ethanesulfonic acid (MESA) on the development of zebrafish embryos (Danio rerio). Embryos were exposed to the individual substances and their environmentally relevant mixture until 120 hpf (hours post-fertilization). The focus was set on sublethal endpoints such as malformations, hatching success, length of fish larvae, spontaneous movements, heart rate and locomotion. Moreover, expression levels of eight genes linked to the thyroid system disruption, oxidative stress defense, mitochondrial metabolism, regulation of cell cycle and retinoic acid (RA) signaling pathway were analyzed. Exposure to S-metolachlor (1 μg/L) and the pesticide mixture (1 μg/L of each substance) significantly reduced spontaneous tail movements of 21 hpf embryos. Few rare developmental malformations were observed, but only in larvae exposed to more than 100 μg/L of individual substances (craniofacial deformation, non-inflated gas bladder, yolk sac malabsorption) and to 30 μg/L of each substance in the pesticide mixture (spine deformation). No effect on hatching success, length of larvae, heart rate or larvae locomotion were found. Strong responses were detected at the molecular level including induction of p53 gene regulating the cell cycle (the pesticide mixture - 1 μg/L of each substance; MESA 30 μg/L; and MOA 100 μg/L), as induction of cyp26a1 gene encoding cytochrome P450 (pesticide mixture - 1 μg/L of each substance). Genes implicated in the thyroid system regulation (dio2, thra, thrb) were all overexpressed by the environmentally relevant concentrations of the pesticide mixture (1 μg/L of each substance) and MESA metabolite (1 μg/L). Zebrafish thyroid system disruption was revealed by the overexpressed genes, as well as by some related developmental malformations (mainly gas bladder and yolk sac abnormalities), and reduced spontaneous tail movements. Thus, the thyroid system disruption represents a likely hypothesis behind the effects caused by the low environmental concentrations of S-metolachlor, its two metabolites and their mixture.

• Klíčová slova
• Embryotoxicity, Environmental concentration, Metabolite, Pesticide mixture, Sublethal effects, Zebrafish embryo,
• MeSH
• acetamidy metabolismus   toxicita   MeSH
• chemické látky znečišťující vodu metabolismus   toxicita   MeSH
• dánio pruhované metabolismus   MeSH
• embryo nesavčí účinky léků   metabolismus   MeSH
• embryonální vývoj účinky léků   MeSH
• herbicidy metabolismus   toxicita   MeSH
• larva MeSH
• štítná žláza účinky léků   embryologie   MeSH
• synergismus léků MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• acetamidy MeSH
• chemické látky znečišťující vodu MeSH
• herbicidy MeSH
• metolachlor MeSH Prohlížeč

Methacrylated vegetable oils are promising bio-based polymerizable precursors for potential material application in several fields, such as coating technologies or 3D printing. The reactants' availability for their production is an enormous advantage, but the modified oils also exhibit high apparent viscosity values and poor mechanical properties. This work focuses on a way to produce oil-based polymerizable material precursors in a mixture with a viscosity modifier in a one-batch process. The required methacrylic acid for the modification of epoxidized vegetable oils can be obtained as a secondary product of the methacrylation of methyl lactate forming a polymerizable monomer along with the acid. This reaction results in a yield of over 98% of methacrylic acid. Epoxidized vegetable oil can be added into the same batch using acid for oil modification which results in the one-pot mixture of both methacrylated oil and methyl lactate. The structural verifications of products were provided via FT-IR, 1H NMR, and volumetric methods. This two-step reaction process produces a thermoset mixture with a lower apparent viscosity of 142.6 mPa·s in comparison with methacrylated oil exhibiting a value of 1790.2 mPa·s. Other physical-chemical properties of the resin mixture such as storage modulus (E' = 1260 MPa), glass transition temperature (Tg = 50.0 °C), or polymerization activation energy (17.3 kJ/mol) are enhanced in comparison with the methacrylated vegetable oil. The synthesized one-pot mixture does not require additional methacrylic acid due to the use of the one formed in the first step of the reaction, while the eventual thermoset mixture exhibits enhanced material properties compared to the methacrylated vegetable oil itself. Precursors synthesized in this work may find their purpose in the field of coating technologies, since these applications require detailed viscosity modifications.

• Klíčová slova
• methacrylated methyl lactate, modified lactate, polymerizable precursors, resin, thermoset mixture, viscosity modification,
• Publikační typ
• časopisecké články MeSH