A set of 69 concentration-response curves from 5 acute ecotoxicity assays was fitted with a 2-parameter logistic equation. High correlation between values of regression parameters suggested similar slopes of the curves. This enabled derivation of the empirical single-parameter logistic equation with the sole median effective concentration (EC50) parameter. Such an equation might be useful in the evaluation of lower-quality (preliminary) experimental data and for the reduction of the number of test organisms and of testing costs.

• Klíčová slova
• Acute ecotoxicity assays, Concentration-response slope, EC50 calculation, Logistic model,
• MeSH
• Aliivibrio fischeri účinky léků   MeSH
• Chlorophyta účinky léků   MeSH
• Daphnia účinky léků   MeSH
• dvojchroman draselný toxicita   MeSH
• látky znečišťující životní prostředí toxicita   MeSH
• logistické modely * MeSH
• referenční standardy MeSH
• testy akutní toxicity * normy   MeSH
• živorodka MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• dvojchroman draselný MeSH
• látky znečišťující životní prostředí MeSH

The structured population LPA model is studied. The model describes flour beetle (Tribolium) population dynamics of four stage populations: eggs, larvae, pupae and adults with cannibalism between these stages. We concentrate on the case of non-zero cannibalistic rates of adults on eggs and adults on pupae and no cannibalism of larvae on eggs, but the results can be numerically continued to non-zero cannibalism of larvae on eggs. In this article two-parameter bifurcations in LPA model are analysed. Various stable and unstable invariant sets are found, different types of hysteresis are presented and abrupt changes in dynamics are simulated to explain the complicated way the system behaves near two-parameter bifurcation manifolds. The connections between strong 1:2 resonance and Chenciner bifurcations are presented as well as their very significant consequences to the dynamics of the Tribolium population. The hysteresis phenomena described is a generic phenomenon nearby the Chenciner bifurcation or the cusp bifurcation of the loop.

• Klíčová slova
• Chenciner bifurcation, LPA model, Population dynamics, Strong 1:2 resonance, Two-parameter bifurcations,
• MeSH
• biologické modely * MeSH
• chování zvířat MeSH
• kanibalismus MeSH
• matematické pojmy MeSH
• nelineární dynamika MeSH
• populační dynamika statistika a číselné údaje   MeSH
• Tribolium růst a vývoj   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Based on Kedem-Katchalsky formalism, the model equation of the membrane potential (Δψs) generated in a membrane system was derived for the conditions of concentration polarization. In this system, a horizontally oriented electro-neutral biomembrane separates solutions of the same electrolytes at different concentrations. The consequence of concentration polarization is the creation, on both sides of the membrane, of concentration boundary layers. The basic equation of this model includes the unknown ratio of solution concentrations (Ci/Ce) at the membrane/concentration boundary layers. We present the calculation procedure (Ci/Ce) based on novel equations derived in the paper containing the transport parameters of the membrane (Lp, σ, and ω), solutions (ρ, ν), concentration boundary layer thicknesses (δl, δh), concentration Raileigh number (RC), concentration polarization factor (ζs), volume flux (Jv), mechanical pressure difference (ΔP), and ratio of known solution concentrations (Ch/Cl). From the resulting equation, Δψs was calculated for various combinations of the solution concentration ratio (Ch/Cl), the Rayleigh concentration number (RC), the concentration polarization coefficient (ζs), and the hydrostatic pressure difference (ΔP). Calculations were performed for a case where an aqueous NaCl solution with a fixed concentration of 1 mol m-3 (Cl) was on one side of the membrane and on the other side an aqueous NaCl solution with a concentration between 1 and 15 mol m-3 (Ch). It is shown that (Δψs) depends on the value of one of the factors (i.e., ΔP, Ch/Cl, RC and ζs) at a fixed value of the other three.

• Klíčová slova
• Kedem–Katchalsky equations, concentration Rayleigh number, concentration polarization, membrane potential, membrane transport, polymeric membrane,
• Publikační typ
• časopisecké články MeSH

The presented study is devoted to the investigation of the micellization-induced liquid-liquid fluctuations in sodium decanoate (NaD) aqueous solutions, based on the vibrational spectroscopic study of NaD and the determination of critical micelle concentration (CMC) of this system. At the same time, we focused on monitoring the effect of the addition of decanol to this system and changing its basic parameters from the point of view of CMC. CMC is an important parameter from a practical point of view and a characteristic feature of each micelle-forming compound. Upon analyzing the spectroscopic data we focus our attention mainly on the intensity and band position variations of both the symmetrical and antisymmetrical vibrational modes of CH2 groups situated in the high-frequency part of the spectrum. The study used normal (non-enhanced) Raman spectroscopy with excitation wavelength 785 nm, surface-enhanced Raman spectroscopy (SERS) on large-scaled gold-coated SERS-active substrates and infrared spectral measurements. The results of spectroscopic measurements were supported by tensiometry and potentiometry.

• Klíčová slova
• Critical micelle concentration, Raman spectroscopy, Sodium decanoate, Vibrational spectroscopy,
• Publikační typ
• časopisecké články MeSH

Concentration of 16 polycyclic aromatic hydrocarbons (PAHs), 7 polychlorinated biphenyls (PCBs), and 11 organochlorine pesticides (OCPs) in sewage sludge from 40 wastewater treatment plants (WWTPs) was investigated. Relationship between pollutant sludge contents, main WWTP parameters and type of sludge stabilisation was carefully evaluated. Average load of PAHs, PCBs, and OCPs in different sludges from Czech Republic was 3096, 95.7 and 76.1 μg/kg dry weight, respectively. There were moderate/strong correlations among the individual tested pollutants in sludge (r = 0.40-0.76). Relationship between total pollutant contents in sludge, common WWTP parameters and sludge stabilisation was not evident. Only individual pollutants such anthracene and PCB 52 correlated significantly (P < 0.05) with biochemical oxygen demand (r = -0.35) and chemical oxygen demand removal efficiencies (r = -0.35), suggesting recalcitrance to degradation during wastewater treatment. When sorted according to the design capacity, a linear correlation between WWTP size and pollutant contents in sludge was evident with growing WWTP capacity. Our study indicated that WWTPs with anaerobic digestion are prone to accumulate a statistically higher content of PAHs and PCBs (P < 0.05) in digested sludges compared to aerobically digested ones. The influence of anaerobic digestion temperature of treated sludge on tested pollutants was not evident.

• Klíčová slova
• Biosolids, Concentration, Organic contaminants, Screening, Wastewater management,
• Publikační typ
• časopisecké články MeSH

Electrodialysis is an electric-field-mediated process separating ions exploiting selective properties of ion-exchange membranes. The ion-exchange membranes create an ion-depleted zone in an electrolyte solution adjacent to the membrane under DC polarization. We constructed a microfluidic system that uses the ion-depleted zone to separate ions from the processed water solution. We tested the separation performance by desalting a model KCl solution spiked with fluorescein for direct observation. We showed both visually and by measuring the conductivity of the output solutions that the system can work in three modes of operation referred to as continuous desalination, desalination by accumulation, and unsuccessful desalination. The mode of operation can easily be set by changing the control parameters. The desalination factors for the model KCl solution reached values from 80 to 100%, depending on the mode of operation. The concentration factor, given as a ratio of concentrate-to-feed concentrations, reached zero for desalination by accumulation when only diluate was produced. The water recovery, therefore, was infinite at these conditions. Independent control of the diluate and concentrate flow rates and the DC voltage turned our system into a versatile platform, enabling us to set proper conditions to process various samples.

• Klíčová slova
• cation-exchange membranes, desalination, ion concentration polarization, ion separation, microfluidics,
• MeSH
• chlorid sodný izolace a purifikace   MeSH
• čištění vody metody   MeSH
• elektrická vodivost MeSH
• elektrody MeSH
• iontová výměna MeSH
• odpadní voda chemie   MeSH
• salinita * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chlorid sodný MeSH
• odpadní voda MeSH

40 adult White Californian rabbits were monitored for serum levels, soft tissue concentrations, and biological half-life of technical chlorotetracycline (Aureovit 12 C40 -- SPOFA), chlorotetracycline chloride (Farmitalia substance), tetracycline chloride (tetramyocine tablets for veterinary use -- SPOFA), and oxytetracycline chloride (oxymycoine in powder form for solution for veterinary use -- SPOFA), following application of 20 micrograms.kg-1. All tetracyclines tested were orally administered by gavage, following dissolution or suspension (Aureovit 12 C40). Statistically significant differences were found to exist among serum levels of various tetracyclines, with the 1st to 11th hours from administration, whereafter differences turned minimal between the 11th and 24th hours. Differences were found to exist also among concentrations in various organs.

• MeSH
• aplikace orální MeSH
• chlortetracyklin aplikace a dávkování   farmakokinetika   MeSH
• králíci metabolismus   MeSH
• oxytetracyklin aplikace a dávkování   farmakokinetika   MeSH
• poločas MeSH
• tetracyklin aplikace a dávkování   farmakokinetika   MeSH
• zvířata MeSH
• Check Tag
• králíci metabolismus   MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH
• Názvy látek
• chlortetracyklin MeSH
• oxytetracyklin MeSH
• tetracyklin MeSH

The difference between weekly measurements and the annual arithmetic mean of radon indoor concentration CRn,Indoor was studied in the Czech Republic. The deviations were analysed for 1537 weekly measurements which were consecutively obtained in 29 rooms over a period of 1 year and the annual arithmetic mean was calculated for each particular room. The relationship of the deviations to three meteorological parameters (i.e. outside temperature, atmospheric pressure, and weekly rainfall) and to the sequential number of a calendar week was studied. The effect of atmospheric pressure and weekly rainfall was not significant. The deviation between a weekly measurement and the annual arithmetic mean depended significantly on outside weekly average temperatures. If the average outside weekly temperature was below 10 degrees C, the radon concentration was systematically higher than that of the annual arithmetic mean. The deviation variability was lower up to a temperature of 10 degrees C. If the weekly average outdoor temperature was higher than 10 degrees C, the uncertainty of a weekly measurement of radon concentration was also higher.

• MeSH
• algoritmy MeSH
• dávka záření MeSH
• hodnocení rizik metody   MeSH
• kalibrace normy   MeSH
• počasí MeSH
• radiační ochrana metody   normy   MeSH
• radioaktivní látky znečišťující vzduch analýza   MeSH
• radiometrie metody   normy   MeSH
• radon analýza   MeSH
• reprodukovatelnost výsledků MeSH
• řízení kvality MeSH
• roční období * MeSH
• senzitivita a specificita MeSH
• statistické modely * MeSH
• statistika jako téma MeSH
• studie případů a kontrol MeSH
• znečištění vzduchu ve vnitřním prostředí analýza   statistika a číselné údaje   MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• srovnávací studie MeSH
• validační studie MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• radioaktivní látky znečišťující vzduch MeSH
• radon MeSH

Transthoracic echocardiography (TTE) has become an important modality for the assessment of cardiac structure and function in animal experiments. The acquisition of echocardiographic images in rats requires sedation/anesthesia to keep the rats immobile. Commonly used anesthetic regimens include intraperitoneal or inhalational application of various anesthetics. Several studies have compared the effects of anesthetic agents on echocardiographic parameters in rats; however, none of them examined the effects of different concentrations of inhalational anesthetics on echocardiographic parameters. Accordingly, the aim of this study was to examine the effects of different concentrations of isoflurane used for anesthesia during TTE examination in rats on basic echocardiographic parameters of left ventricular (LV) anatomy and systolic function. TTE examinations were performed in adult male Wistar rats (n=10) anesthetized with isoflurane at concentrations of 1.5-3 %. Standard echocardiograms were recorded for off-line analysis. An absence of changes in basic echocardiographic parameters of LV anatomy and systolic function was found under isoflurane anesthesia using concentrations between 1.5-2.5 %. An isoflurane concentration of 3 % caused a small, but statistically significant, increase in LV chamber dimensions without a concomitant change in heart rate or fractional shortening. For the purpose of TTE examination in the rat, our results suggest that isoflurane concentrations

• MeSH
• anestetika inhalační farmakologie   MeSH
• echokardiografie MeSH
• funkce levé komory srdeční účinky léků   fyziologie   MeSH
• isofluran farmakologie   MeSH
• krysa rodu Rattus MeSH
• potkani Wistar MeSH
• srdeční komory diagnostické zobrazování   účinky léků   MeSH
• systola MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• anestetika inhalační MeSH
• isofluran MeSH

Comparative studies of ionic composition, osmolality, protein concentration and pH of seminal plasma along with spermatozoa concentrations were carried out in stellate sturgeon, Acipenser stellatus, and Russian sturgeon, Acipenser gueldenstaedtii. Analysis of A. gueldenstaedtii sperm showed significantly higher concentrations of Na(+) (34.58 ± 4.61 mm), Ca²(+) (0.35 ± 0.12 mm), Mg²(+) (0.70 ± 0.25 mm), Cl(-) (13.50 ± 4.04 mm) and proteins (0.60 ± 0.29 mg/ml) in the seminal plasma than did seminal plasma of A. stellatus: Na(+) (20.08 ± 10.75 mm), Ca²(+) (0.28 ± 0.06 mm), Mg²(+) (0.29 ± 0.05 mm), Cl(-) (7.50 ± 3.00 mm) and 0.30 ± 0.11 mg/ml proteins. Significantly higher concentration of K(+) (5.42 ± 1.06 mm) was observed in A. stellatus compared to A. gueldenstaedtii K(+) (2.29 ± 0.50 mm). Concentration of Na(+) was positively correlated with osmolality (r = 0.819), levels of Cl(-) (r = 0.922) and Mg²(+) (r = 0.727) and pH (r = 0.848). The concentration of Mg²(+) was positively correlated with protein concentration (r = 0.774), Na(+) (r = 0.727), Cl(-) (r = 0.872) and Ca²(+) (r = 0.801). A positive relationship was also found between concentration of K(+) and spermatozoa concentration (r = 0.709). Results revealed strong inter-species differences in several parameters. The data should be useful for artificial fertilization and for cryopreservation of sturgeon sperm.

• MeSH
• draslík analýza   MeSH
• hořčík analýza   MeSH
• ionty chemie   MeSH
• koncentrace vodíkových iontů MeSH
• ohrožené druhy MeSH
• osmolární koncentrace MeSH
• ryby fyziologie   MeSH
• sodík analýza   MeSH
• sperma chemie   cytologie   fyziologie   MeSH
• spermie chemie   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• draslík MeSH
• hořčík MeSH
• ionty MeSH
• sodík MeSH