• Klíčová slova
• EXPERIMENTAL LAB STUDY *, LIVER CYTOLOGY *, MICROSCOPY, ELECTRON *, RADIATION EFFECTS *, RADIATION INJURY, EXPERIMENTAL *, RATS *,
• MeSH
• cytoplazma * MeSH
• elektronová mikroskopie * MeSH
• elektrony * MeSH
• experimentální radiační poranění * MeSH
• hepatocyty * MeSH
• játra cytologie   MeSH
• krysa rodu Rattus MeSH
• mikroskopie * MeSH
• radiační poranění * MeSH
• radiační účinky * MeSH
• rentgenové záření MeSH
• výzkum * MeSH
• Check Tag
• krysa rodu Rattus MeSH
• Publikační typ
• časopisecké články MeSH

The great potential of scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) is in detection of unusual chemical elements included in ancient human dental calculus to verify hypotheses about life and burial habits of historic populations and individuals. Elemental spectra were performed from archeological samples of three chosen individuals from different time periods. The unusual presence of magnesium, aluminum, and silicon in the first sample could confirm the hypothesis of high degree of dental abrasion caused by particles from grinding stones in flour. In the second sample, presence of copper could confirm that bronze jewelery could lie near the buried body. The elemental composition of the third sample with the presence of lead and copper confirms the origin of individual to Napoleonic Wars because the damage to his teeth could be explained by the systematic utilization of the teeth for the opening of paper cartridges (a charge with a dose of gunpowder and a bullet), which were used during the 18th and the 19th century AD. All these results contribute to the reconstruction of life (first and third individual) and burial (second individual) habits of historic populations and individuals.

• Klíčová slova
• Napoleonic Wars, SEM-EDX, ancient dental calculus, human habits, the Great Moravian Empire,
• MeSH
• lidé MeSH
• mikroskopie elektronová rastrovací metody   MeSH
• spektrometrie rentgenová emisní metody   MeSH
• zkameněliny * MeSH
• zubní kámen chemie   ultrastruktura   MeSH
• zvyky * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

This study reports application of monitoring and characterization protocol for particulate matter (PM) deposited on tree leaves, using Quercus ilex as a case study species. The study area is located in the industrial city of Terni in central Italy, with high PM concentrations. Four trees were selected as representative of distinct pollution environments based on their proximity to a steel factory and a street. Wash off from leaves onto cellulose filters were characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy, inferring the associations between particle sizes, chemical composition, and sampling location. Modeling of particle size distributions showed a tri-modal fingerprint, with the three modes centered at 0.6 (factory related), 1.2 (urban background), and 2.6μm (traffic related). Chemical detection identified 23 elements abundant in the PM samples. Principal component analysis recognized iron and copper as source-specific PM markers, attributed mainly to industrial and heavy traffic pollution respectively. Upscaling these results on leaf area basis provided a useful indicator for strategic evaluation of harmful PM pollutants using tree leaves.

• Klíčová slova
• Air pollution, EDX, Human health, Particulate matter, SEM, Urban trees,
• MeSH
• dub (rod) chemie   MeSH
• látky znečišťující vzduch analýza   MeSH
• listy rostlin chemie   MeSH
• mikroanalýza elektronovou sondou MeSH
• monitorování životního prostředí metody   MeSH
• pevné částice analýza   MeSH
• průmysl MeSH
• spektrometrie rentgenová emisní MeSH
• velkoměsta MeSH
• znečištění ovzduší statistika a číselné údaje   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Itálie MeSH
• velkoměsta MeSH
• Názvy látek
• látky znečišťující vzduch MeSH
• pevné částice MeSH

Haloalkane dehalogenase (HLD) enzymes employ an SN 2 nucleophilic substitution mechanism to erase halogen substituents in diverse organohalogen compounds. Subfamily I and II HLDs are well-characterized enzymes, but the mode and purpose of multimerization of subfamily III HLDs are unknown. Here we probe the structural organization of DhmeA, a subfamily III HLD-like enzyme from the archaeon Haloferax mediterranei, by combining cryo-electron microscopy (cryo-EM) and x-ray crystallography. We show that full-length wild-type DhmeA forms diverse quaternary structures, ranging from small oligomers to large supramolecular ring-like assemblies of various sizes and symmetries. We optimized sample preparation steps, enabling three-dimensional reconstructions of an oligomeric species by single-particle cryo-EM. Moreover, we engineered a crystallizable mutant (DhmeAΔGG ) that provided diffraction-quality crystals. The 3.3 Å crystal structure reveals that DhmeAΔGG forms a ring-like 20-mer structure with outer and inner diameter of ~200 and ~80 Å, respectively. An enzyme homodimer represents a basic repeating building unit of the crystallographic ring. Three assembly interfaces (dimerization, tetramerization, and multimerization) were identified to form the supramolecular ring that displays a negatively charged exterior, while its interior part harboring catalytic sites is positively charged. Localization and exposure of catalytic machineries suggest a possible processing of large negatively charged macromolecular substrates.

• Klíčová slova
• DhmeA, Haloferax mediterranei, catalysis, cryo-EM, haloalkane dehalogenase, multimerization, x-ray crystallography,
• MeSH
• elektronová kryomikroskopie metody   MeSH
• hydrolasy * chemie   MeSH
• krystalografie rentgenová MeSH
• substrátová specifita MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• haloalkane dehalogenase MeSH Prohlížeč
• hydrolasy * MeSH

OBJECTIVE: To characterize the microstructure of two zinc phosphate cement formulations in order to investigate the role of liquid/solid ratio and composition of powder component, on the developed porosity and, consequently, on compressive strength. METHODS: X-ray powder diffraction with the Rietveld method was used to study the phase composition of zinc oxide powder and cements. Powder component and cement microstructure were investigated with scanning electron microscopy. Small angle neutron scattering (SANS) and microfocus X-ray computed tomography (XmCT) were together employed to characterize porosity and microstructure of dental cements. Compressive strength tests were performed to evaluate their mechanical performance. RESULTS: The beneficial effects obtained by the addition of Al, Mg and B to modulate powder reactivity were mitigated by the crystallization of a Zn aluminate phase not involved in the cement setting reaction. Both cements showed spherical pores with a bimodal distribution at the micro/nano-scale. Pores, containing a low density gel-like phase, developed through segregation of liquid during setting. Increasing liquid/solid ratio from 0.378 to 0.571, increased both SANS and XmCT-derived specific surface area (by 56% and 22%, respectively), porosity (XmCT-derived porosity increased from 3.8% to 5.2%), the relative fraction of large pores ≥50μm, decreased compressive strength from 50±3MPa to 39±3MPa, and favored microstructural and compositional inhomogeneities. SIGNIFICANCE: Explain aspects of powder design affecting the setting reaction and, in turn, cement performance, to help in optimizing cement formulation. The mechanism behind development of porosity and specific surface area explains mechanical performance, and processes such as erosion and fluoride release/uptake.

• Klíčová slova
• Acid-base cements, Small angle neutron scattering, X-ray micro-computed tomography, X-ray powder diffraction, Zinc oxide, Zinc phosphate cements,
• MeSH
• difrakce rentgenového záření MeSH
• fosforečnany vápenaté MeSH
• kostní cementy MeSH
• maloúhlový rozptyl MeSH
• mikroskopie elektronová rastrovací MeSH
• pevnost v tlaku MeSH
• počítačová rentgenová tomografie * MeSH
• testování materiálů MeSH
• zinkfosfátový cement * MeSH
• zubní cementy * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fosforečnany vápenaté MeSH
• kostní cementy MeSH
• zinkfosfátový cement * MeSH
• zubní cementy * MeSH

This study presents an X-ray computed nanotomography (nano-CT) based, high-resolution imaging technique. Thanks to a voxel resolution of 540 nm, this novel technique is suitable for observing the 3D morphology of soft biopolymeric scaffolds seeded with stem cells. A sample of highly porous collagen scaffold seeded with contrasted mesenchymal stem cells (MSC) was investigated by using lab-based nano-CT. The whole volume of the sample was analysed without its destruction. To evaluate the potential of nano-CT, a comparison measurement was done using a standard microscopy technique. Scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX) established an extension and local accumulation of the contrasting agent - heavy metallic osmium tetroxide. The presented imaging technique is novel as it will help to understand better the behaviour of cells while interacting with three-dimensional biomaterials. This is crucial for both experimental and clinical tissue engineering applications in order to limit the risk of uncontrolled cell growth, and potentially tumour formation. LAY DESCRIPTION: Biomaterials play a crucial role in tissue engineering by serving as 3D scaffolds for cellular attachment, proliferation, and in growth ultimately leading to new tissue formation. Cell morphology and proliferation inside the 3D scaffold are necessary to know for assessing cell viability. However, these studies are usually negatively affected by the limitations of imaging techniques. We demonstrate that X-ray computed nanotomography (nano-CT), based on high-resolution imaging technique providing voxel resolution of 540 nm, is a suitable method for observing the 3D morphology of soft biopolymeric scaffolds seeded with stem cells. A sample of highly porous collagen scaffold seeded with contrasted mesenchymal stem cells (MSC) was investigated by using a lab-based nano-CT. The whole volume of the sample was analysed without its destruction. To evaluate the potential of nano-CT, a comparison measurement was done using a standard microscopy technique. Scanning electron microscopy in a combination with energy dispersive X-ray analysis established an extension and local accumulation of the contrasting agent - heavy metallic osmium tetroxide. The presented imaging technique is novel as it will help to understand better the behaviour of cells while interacting with three-dimensional biomaterials. This is crucial for both experimental and clinical tissue engineering applications in order to limit the risk of uncontrolled cell growth, and potentially tumour formation.

• Klíčová slova
• Biopolymeric scaffold, SEM/EDX, X-ray computed nanotomography, mesenchymal stem cells, tissue engineering,
• MeSH
• biokompatibilní materiály MeSH
• buněčné kultury MeSH
• kolagen chemie   MeSH
• králíci MeSH
• kultivované buňky MeSH
• mezenchymální kmenové buňky ultrastruktura   MeSH
• mikroskopie elektronová rastrovací metody   MeSH
• poréznost MeSH
• rentgenová mikrotomografie metody   MeSH
• tkáňové podpůrné struktury * MeSH
• viabilita buněk MeSH
• zobrazování trojrozměrné metody   MeSH
• zvířata MeSH
• Check Tag
• králíci MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• biokompatibilní materiály MeSH
• kolagen MeSH

This paper provides an overview of analytical methods frequently used to identify terrestrial radionuclides in samples. While radioactivity is normally measured through the ionising radiation produced during the spontaneous decay of unstable atoms, selected radionuclides or their chemical elements can be quantified with instrumental techniques based on stimulated emission or counting of atoms. The advantages and disadvantages of these analytical methods are discussed. Particular attention is paid to X-ray fluorescence analysis of materials containing uranium and thorium. It is also possible to determine the area distributions of these chemical elements in samples with the use of scanning X-ray fluorescence systems.

• MeSH
• hmotnostní spektrometrie MeSH
• mikroanalýza elektronovou sondou MeSH
• neutronová aktivační analýza MeSH
• poločas MeSH
• radiační pozadí * MeSH
• radioizotopy draslíku analýza   MeSH
• radiometrie metody   MeSH
• radionuklidy analýza   MeSH
• spektrometrie rentgenová emisní * přístrojové vybavení   MeSH
• thorium analýza   MeSH
• uran analýza   MeSH
• Země (planeta) * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• radioizotopy draslíku MeSH
• radionuklidy MeSH
• thorium MeSH
• uran MeSH

An unusual mechanism of formation of a parasitophorous vacuole as a result of interaction between an invasive stage of a parasite (merozoites of a protozoon, Mattesia dispora) and defense response of an insect host, Galleria mellonella is reported. The entire ontogenesis of parasitophorous vacuole can be divided into five morphologically clearly discernible stages. They differed, e.g., in the contents and distribution of elements at subcellular level, as determined by direct in situ elemental analysis of single organelles (electron microprobe X-ray analysis). The method was used in conjunction with electron microscopy to investigate the relationship between the host and the parasite.

• MeSH
• Apicomplexa růst a vývoj   imunologie   ultrastruktura   MeSH
• interakce hostitele a parazita MeSH
• mikroanalýza elektronovou sondou MeSH
• můry imunologie   parazitologie   ultrastruktura   MeSH
• transmisní elektronová mikroskopie MeSH
• vakuoly chemie   parazitologie   ultrastruktura   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

We report the first observation of single-shot soft x-ray laser induced desorption occurring below the ablation threshold in a thin layer of poly (methyl methacrylate)--PMMA. Irradiated by the focused beam from the Free-electron LASer in Hamburg (FLASH) at 21.7 nm, the samples have been investigated by atomic-force microscope (AFM) enabling the visualization of mild surface modifications caused by the desorption. A model describing non-thermal desorption and ablation has been developed and used to analyze single-shot imprints in PMMA. An intermediate regime of materials removal has been found, confirming model predictions. We also report below-threshold multiple-shot desorption of PMMA induced by high-order harmonics (HOH) at 32 nm. Short-time exposure imprints provide sufficient information about transverse beam profile in HOH's tight focus whereas long-time exposed PMMA exhibits radiation-initiated surface ardening making the beam profile measurement infeasible.

• MeSH
• elektrony MeSH
• laserová terapie metody   MeSH
• lasery * MeSH
• mikroskopie atomárních sil MeSH
• polymethylmethakrylát MeSH
• povrchové vlastnosti MeSH
• rentgenové záření * MeSH
• sloučeniny boru účinky záření   MeSH
• spektrofotometrie MeSH
• uhlík účinky záření   MeSH
• ultrafialové záření MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• polymethylmethakrylát MeSH
• sloučeniny boru MeSH
• uhlík MeSH

Urolithiasis is a frequent and in many cases serious disease. Proper analysis of kidney stone composition is crucial for appropriate treatment and prevention of disease recurrence. In this work, scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy was applied for a study of 30 samples covering the most common types of human kidney stones. The results are analyzed and evaluated in terms of applicability of the method for both routine kidney stone analysis as well as collecting of specific data. The method provides complex information about studied samples including morphology of the stones and of the present crystals or their aggregates. It also brings information on elemental composition of the phases. After application of standardization, quantitative microanalysis with detection limits of 400 ppm (Mg, P, S, Cl, K, Ca), 500 ppm (Na) and 1200 ppm (F) was obtained. Compositional mapping with EDS shows the elemental distribution within a sample. This study demonstrated that information on morphology and chemistry acquired by these methods was highly reliable for identification of phases, even when present in small amounts. It provided information on kidney stone structure, relationships between phases, major and minor element content, and variations in chemical composition related to the growth of the stones. SEM represents a powerful tool in urinary stone analysis, since a single facility can produce a wide spectrum of information. It can be suggested as a basic method used for routine urinary stone identification, whilst bringing additional detailed information that cannot be obtained by other methods.

• Klíčová slova
• Urolithiasis, electron probe microanalysis, energy-dispersive X-ray spectroscopy, renal calculi, scanning electron microscopy,
• MeSH
• apatity chemie   MeSH
• fosforečnany vápenaté chemie   MeSH
• lidé MeSH
• mikroskopie elektronová rastrovací * MeSH
• močové kameny ultrastruktura   MeSH
• spektrometrie rentgenová emisní MeSH
• šťavelan vápenatý chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• apatity MeSH
• calcium phosphate, dibasic, dihydrate MeSH Prohlížeč
• fosforečnany vápenaté MeSH
• šťavelan vápenatý MeSH
• whewellite MeSH Prohlížeč