The objectives of the study were to compare the effects of the composting and the vermicomposting processes on the distribution of particles into three size fractions, and to assess the agrochemical properties of the size fractions of the composts and the vermicomposts. Three different mixtures of biowaste were subjected to two thermophilic pre-composting, and then the mixtures were subsequently subjected to 5months composting and vermicomposting under laboratory conditions. Vermicomposting was able to achieve the finer and more homogeneous final product compared to composting. For compost, the highest portion of the finest fraction was achieved from products which originated from kitchen waste containing used paper, followed by digestate with straw, and finally sewage sludge with garden biowaste. In most cases, compost particles which were less than 5mm exhibited the better agricultural potential than coarser compost. However, agrochemical properties of the finest vermicompost exceeded classical compost.

• Klíčová slova
• Agrochemical properties, Compost, Particle size fractions, Vermicompost,
• MeSH
• biodegradace MeSH
• odpadky - odstraňování metody   MeSH
• odpadní vody chemie   MeSH
• Oligochaeta MeSH
• papír MeSH
• půda chemie   MeSH
• velikost částic MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• odpadní vody MeSH
• půda MeSH

Flowability is among the most important properties of powders, especially when fine particle size fractions need to be processed. In this study, our goal was to find a possibly simple but accurate mathematical model for predicting the mass flow rate for different fractions of the pharmaceutical excipient sorbitol for direct compression. Various regression models derived from the Jones-Pilpel equation for the prediction of the mass flow rate were investigated. Using validation with experimental data for various particle and hopper orifice sizes, we focused on the prediction accuracy of the respective models, i.e., on the relative difference between measured and model-predicted values. Classical indicators of regression quality from statistics were addressed as well, but we consider high prediction accuracy to be particularly important for industrial processing in practice. For individual particle size fractions, the best results (an average prediction accuracy of 3.8%) were obtained using simple regression on orifice size. However, for higher accuracy (3.1%) in a unifying model, valid in the broad particle size range 0.100-0.346 mm, a fully quadratic model, incorporating interaction between particle and orifice size, appears to be most appropriate.

• Klíčová slova
• flow equation, hopper, interaction term, mass flow rate, multilinear regression, orifice diameter, particle size, powders properties,
• Publikační typ
• časopisecké články MeSH

Flowability of powder excipients is directly influenced by their size and shape although the granulometric influence of the flow and shear behaviour of particulate matter is not studied frequently. In this work, the influence of particle size on the mass flow rate through the orifice of a conical hopper, and the cohesion and flow function was studied for four free-flowable size fractions of sorbitol for direct compression in the range of 0.080-0.400 mm. The particles were granulometricaly characterized using an optical microscopy; a boundary fractal dimension of 1.066 was estimated for regular sorbitol particles. In the particle size range studied, a non-linear relationship between the mean particle size and the mass flow rate Q10 (g/s) was detected having amaximum at the 0.245mm fraction. The best flow properties of this fraction were verified with aJenike shear tester due to the highest value of flow function and the lowest value of the cohesion. The results of this work show the importance of the right choice of the excipient particle size to achieve the best flow behaviour of particulate material.Key words: flowability size fraction sorbitol for direct compaction Jenike shear tester fractal dimension.

• MeSH
• fraktály * MeSH
• pevnost ve smyku MeSH
• pomocné látky * MeSH
• prášky, zásypy, pudry MeSH
• sorbitol * MeSH
• velikost částic MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• pomocné látky * MeSH
• prášky, zásypy, pudry MeSH
• sorbitol * MeSH

Non-isothermal differential scanning calorimetry was used to study the influences of particle size and mechanically induced defects on the recrystallization kinetics of amorphous Enzalutamide. Enzalutamide prepared by hot melt extrusion and spray-drying was used as a model material. The recrystallization rate was primarily accelerated by the presence of the processing-damaged surface of the powder particles. The actual surface/volume ratio associated with decreasing particle size fulfilled only a secondary role. Interestingly, higher quench rate during the extrusion led to a formation of thermally less stable material (with the worse stability being manifested via lower activation energy of crystal growth in the amorphous matrix). This can be the consequence of the formation of looser structure more prone to rearrangements. The recrystallization kinetics of the prepared Enzalutamide amorphous materials was described by the two-parameter autocatalytic kinetic model. The modified single-curve multivariate kinetic analysis (optimized for the data obtained at heating rate 0.5 °C•min-1) was used to calculate the extrapolated kinetic predictions of long-term isothermal crystal growth. The predictions were made for the temperatures from the range of drug shelf-life and processing for each particle size fraction. By the combination of the mass-weighted predictions for the individual powder fractions it was possible to obtain a very reasonable (temperature-extrapolated) prediction of the crystallization rate for the as-prepared unsieved powdered amorphous Enzalutamide.

• Klíčová slova
• Amorphous drug, Enzalutamide, Particle size, Prediction, Recrystallization,
• MeSH
• benzamidy MeSH
• diferenciální skenovací kalorimetrie MeSH
• fenylthiohydantoin MeSH
• kinetika MeSH
• krystalizace MeSH
• nitrily MeSH
• stabilita léku MeSH
• velikost částic MeSH
• vysoká teplota * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• benzamidy MeSH
• enzalutamide MeSH Prohlížeč
• fenylthiohydantoin MeSH
• nitrily MeSH

The 2017-2019 hourly particle number size distributions (PNSD) from 26 sites in Europe and 1 in the US were evaluated focusing on 16 urban background (UB) and 6 traffic (TR) sites in the framework of Research Infrastructures services reinforcing air quality monitoring capacities in European URBAN & industrial areaS (RI-URBANS) project. The main objective was to describe the phenomenology of urban ultrafine particles (UFP) in Europe with a significant air quality focus. The varying lower size detection limits made it difficult to compare PN concentrations (PNC), particularly PN10-25, from different cities. PNCs follow a TR > UB > Suburban (SUB) order. PNC and Black Carbon (BC) progressively increase from Northern Europe to Southern Europe and from Western to Eastern Europe. At the UB sites, typical traffic rush hour PNC peaks are evident, many also showing midday-morning PNC peaks anti-correlated with BC. These peaks result from increased PN10-25, suggesting significant PNC contributions from nucleation, fumigation and shipping. Site types to be identified by daily and seasonal PNC and BC patterns are: (i) PNC mainly driven by traffic emissions, with marked correlations with BC on different time scales; (ii) marked midday/morning PNC peaks and a seasonal anti-correlation with PNC/BC; (iii) both traffic peaks and midday peaks without marked seasonal patterns. Groups (ii) and (iii) included cities with high insolation. PNC, especially PN25-800, was positively correlated with BC, NO2, CO and PM for several sites. The variable correlation of PNSD with different urban pollutants demonstrates that these do not reflect the variability of UFP in urban environments. Specific monitoring of PNSD is needed if nanoparticles and their associated health impacts are to be assessed. Implementation of the CEN-ACTRIS recommendations for PNSD measurements would provide comparable measurements, and measurements of <10 nm PNC are needed for full evaluation of the health effects of this size fraction.

• Klíčová slova
• Aerosols, Air quality, Atmospheric particulate matter, Nanoparticles, Particle number concentrations, Urban environment,
• MeSH
• látky znečišťující vzduch * analýza   MeSH
• monitorování životního prostředí MeSH
• pevné částice analýza   MeSH
• saze MeSH
• velikost částic MeSH
• velkoměsta MeSH
• výfukové emise vozidel analýza   MeSH
• znečištění ovzduší * analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa MeSH
• velkoměsta MeSH
• Názvy látek
• látky znečišťující vzduch * MeSH
• pevné částice MeSH
• saze MeSH
• výfukové emise vozidel MeSH

Today, it is proven that the contaminated urban soils are hazardous for the human health. Soil substrates of playgrounds call for special research as they are places where children are directly exposed to soil contaminants. Therefore, the objective of this work was to measure the pseudo-total contents and bioaccessibility of several metals and metalloids (As, Bi, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Sn, V, Zn) in two grain sizes (< 150 μm and < 50 μm) of playground soils in Bratislava city (the capital of Slovakia). The content of metal(loid)s in the soils was controlled by a number of factors, with their increased contents (above 75% percentile or higher) at sites influenced by point sources of pollution (industry and agriculture) or at old sites located in the city centre. Cobalt, Cr, Fe, Mn, Ni and V had relatively uniform contents in soils compared to the other elements. As regression modelling with a categorical variable confirmed, the age of urban areas influenced the accumulation of As, Bi, Cd, Cu, Hg, Pb, Sb and Sn in playground soils. Exploratory statistical techniques with compositionally transformed data (principal component analysis, cluster analysis and construction of symmetric coordinates for correlation analysis) divided trace elements into the two main groupings, Co, Cr, Fe, Mn, Ni, V and Bi, Cd, Cu, Hg, Pb, Sb, Sn, Zn. Median concentrations of the elements in smaller soil grains (< 50 μm) were significantly higher than in coarser grains (< 150 μm). Cobalt, Cu, Mn, Pb, Sn and Zn had significantly higher bioaccessible proportions (% of the pseudo-total content) in < 50 μm soil size than in < 150 μm; however, the same order of bioaccessibility was achieved in both grain sizes. The highest bioaccessibility had Cd, Cu, Pb and Zn (~ 40% and more), followed by Co, As, Mn, Sb (18-27%), Hg, Ni, Sn (10-12%) and finally Cr, Fe and V (less than 4%). The hazard index and carcinogenic risk values were higher in < 50 μm than in < 150 μm and significantly decreased in the two soil sizes when the bioaccessibility results were included in the health hazard calculation.

• Klíčová slova
• Bioaccessibility, Contamination, Health risk assessment, Metal(loid)s, Urban soil,
• MeSH
• biologická dostupnost MeSH
• dítě MeSH
• karcinogeny analýza   MeSH
• kovy analýza   farmakokinetika   MeSH
• látky znečišťující půdu analýza   farmakokinetika   toxicita   MeSH
• lidé MeSH
• monitorování životního prostředí metody   MeSH
• polokovy analýza   farmakokinetika   MeSH
• půda chemie   MeSH
• stopové prvky analýza   farmakokinetika   toxicita   MeSH
• velikost částic MeSH
• velkoměsta MeSH
• veřejné parky MeSH
• vystavení vlivu životního prostředí škodlivé účinky   analýza   MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Slovenská republika MeSH
• velkoměsta MeSH
• Názvy látek
• karcinogeny MeSH
• kovy MeSH
• látky znečišťující půdu MeSH
• polokovy MeSH
• půda MeSH
• stopové prvky MeSH

The management of an increasing amount of municipal waste via incineration has been gaining traction. Fly ash as a by-product of incineration of municipal solid waste is considered a hazardous waste due to the elevated content of various elements. The enrichment and distribution of 24 elements in fly ash from three wastes incinerators were evaluated. Two coarse (>100 μm and <100 μm) and five sub-sieve (12-16, 16-23, 23-34, 34-49, and 49-100 μm) particle size fractions separated on a cyclosizer system were analyzed. An enhancement in the enrichment factor was observed in all samples for the majority of elements in >100 μm range compared with <100 μm range. The enrichment factor of individual elements varied considerably within the samples as well as the sub-sieve particle size ranges. These variations were attributed primarily to: (i) the vaporization and condensation mechanisms, (ii) the different design of incineration plants, (iii) incineration properties, (iv) the type of material being incinerated, and (v) the affinity of elements.

• Klíčová slova
• Enrichment, Fly ash, Incineration, Particle size distribution, Wastes,
• MeSH
• popel uhelný chemie   MeSH
• spalování odpadů MeSH
• tuhý odpad analýza   MeSH
• velikost částic * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• popel uhelný MeSH
• tuhý odpad MeSH

The present study focused on investigating the differences in properties between calcined and milled aluminosilicates with different particle size distributions. Two types of clay, i.e., kaolin and kaolinitic claystone, were subjected to calcination at 750 °C, and subsequent milling to obtain different fractions with distinct particle size distributions. These fractions were then combined with a potassium alkaline activator and quartz sand in a 50:50 weight ratio to form a geopolymer composite. The geopolymer binders were then characterized using a mercury intrusion porosimeter (MIP), scanning electron microscopy (SEM), and a rotary rheometer. Mechanical tests were conducted on the geopolymer composites prepared from aluminosilicates with varying particle size distributions. The findings indicated that aluminosilicates with a finer particle size distribution exhibited higher levels of dissolved aluminum (10,000 mg/kg) compared to samples with coarser particle size distributions (1000 mg/kg). Additionally, as the particle size distribution decreased, the dynamic viscosity of the geopolymer binders increased, while the average pore size decreased. Finally, the mechanical properties of the geopolymer composites derived from both tested aluminosilicates demonstrated a decline in performance as the mean particle size increased beyond 10 µm.

• Klíčová slova
• characteristics, claystone, geopolymer, mechanical properties, metakaolin, metakaolinite, particle size,
• Publikační typ
• časopisecké články MeSH

Ambient air pollution, namely exposure to air particulate matter (PM), has been shown to be connected with a number of adverse health effects. At least part of the effects can be caused by organic pollutant mixtures associated with PM, which can elicit a wide range of specific toxic potentials. These potentials could be affected by seasonal variation of pollutant mixtures and PM size fraction. To examine this, six size subfractions of PM10 were collected at rural and urban site in the Czech Republic in a year-long sampling campaign. The samples were assessed for aryl hydrocarbon (AhR)-mediated activity, estrogenicity and anti-androgenicity using mammalian cell models. The concentrations of detected toxic potentials differed among seasons. The greatest levels were observed in samples collected during winter when AhR-mediated effects and estrogenicity were at least 10-times greater than in summer. While the observed potentials were mostly less pronounced in samples from rural area, during winter, their AhR-mediated activity was twice as great as at the urban site. This was probably caused by the low-quality of fuel used for heating at the rural site. Assessed toxic potentials were associated mainly with PM size fractions with lesser aerodynamic diameters (<1 μm). Toxic potentials were compared with data from chemical analyses covering 102 chemicals from different pollutant groups to model their contribution to the observed effects. For AhR-mediated activity, chemical analyses explained on average 44% of the effect and the main identified effect-drivers were polycyclic aromatic hydrocarbons. For estrogenicity and anti-androgenicity, detected chemicals were able to explain on average less than 1.6% and 11% of the potentials, with their highest explicability reaching 13% and 57%, respectively. This was affected by the lack of data on specific toxic potency of some detected air pollutants, but also indicates a possible role of further not analyzed chemicals in these effects.

• Klíčová slova
• AhR-mediated toxicity, Ambient air, Anti-androgenicity, Estrogenicity, PM size Fractions,
• MeSH
• látky znečišťující vzduch analýza   MeSH
• monitorování životního prostředí MeSH
• pevné částice analýza   MeSH
• roční období MeSH
• znečištění ovzduší * MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• látky znečišťující vzduch MeSH
• pevné částice MeSH

The influence of powder size of chosen pharmaceutical powder excipients on drained angle as well as the correlation between drained angle and the mass flow rate of certain powder size fractions were investigated in this work. A method of the indirect estimation of the three-dimensional drained angle from the mass of the residual powder was used experimentally to study the influence of powder size fractions in range of 0.200-0.630 mm for sodium chloride, sodium citrate, potassium chloride, and potassium citrate. Failures of flow significantly increased the drained angles for powder size fraction of 0.200-0.250 mm. For the uniformly flowable powder size fraction of 0.400-0.500 mm, the faster the flow rate, the smaller drained angles were observed for excipients investigated. To estimate parameters of the flow equation, the measurement of material flow rates from the hopper of different orifice sizes is needed, while the estimation of drained angle is much easier needing only one hopper. Finally, the increase of the hopper wall angle of the standard conical hopper to 70 degrees could be recommended to achieve uniform mass flow and to reduce the adverse effect of powder gliding along the hopper walls.

• MeSH
• algoritmy MeSH
• kinetika MeSH
• pomocné látky MeSH
• prášky, zásypy, pudry * MeSH
• příprava léků MeSH
• velikost částic MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• pomocné látky MeSH
• prášky, zásypy, pudry * MeSH