Identification/quantification of multiple pesticide residues in food plants by ultra-high-performance liquid chromatography-time-of-flight mass spectrometry

In this study, the potential of ultra-high-performance liquid chromatography coupled with the time-of-flight mass spectrometry (UHPLC–TOF MS) to enable rapid and comprehensive analysis of 212 pesticide residues in QuEChERS extracts obtained from four plant matrices has been investigated. Method optimization is discussed in detail. In addition to molecular adducts, also fragment ions were provided for all target pesticides, thus obtaining at least three identification points required by European Decision 2002/657/EC was achieved. To get maximum information on analytes present in the extracts, each sample was examined within two injections, the first in a positive and the next one in a negative ionization mode. Under UHPLC conditions, both analyses were completed within 24 min. For more than 96% of pesticides involved in this study, the limit of quantification was ≤10 μg/kg. As a part of the work, strategy enabling screening of non-target pesticides and their metabolites is demonstrated on analysis of real-life samples.     

Preparation of Bragg mirrors on silica optical fibers and inner walls of silica capillaries by employing the sol–gel method,and titanium and silicon alkoxides

Journal of Sol-Gel Science and Technology - The paper presents results on sol–gel preparation and characterization of multilayered coatings, Bragg mirrors, on silica slides, silica fibers,...     

Biosynthesis of Quantum Dots (CdTe) and its Effect on Eisenia fetida and Escherichia coli

Biosynthesis belongs to one of the new possibilities of nanoparticles preparation, whereas its main advantage is biocompatibility. In addition, the ability of obtaining the raw material for such synthesis from the soil environment is beneficial and could be useful for remediation. However, the knowledge of mechanisms that are necessary for the biosynthesis or effect on the bio-synthesizing organisms is still insufficient. In this study, we attempted to evaluate the effect of quantum dots (QDs) not only on a model organism of collembolans, but also on another soil organism—earthworm Eisenia fetida—and in also one widespread microorganism such as Escherichia coli. Primarily, we determined 28EC₅₀ as 72.4 μmol L^?1 for CdTe QDs in collembolans. Further, we studied the effect of QDs biosynthesis in E. fetida and E. coli. Using determination of QDs, low-molecular thiols and antioxidant activities, we found differences between both organisms and also between ways how they behave in the presence of Cd and/or Cd and Te. The biosynthesis in earthworms can be considered as its own protective mechanism; however, in E. coli, it is probably a by-product of protective mechanisms.     

On Toeplitz localization operators

We present a unified approach to study properties of Toeplitz localization operators based on the Calderón and Gabor reproducing formula. We show that these operators with functional symbols on a plane domain may be viewed as certain pseudo-differential operators (with symbols on a line, or certain compound symbols).     

Volume fluctuations in potassium silicate glass studied by molecular dynamics

Potassium-silicate glass, 0.05K₂O·0.95SiO₂, was prepared by molecular dynamics under three different regimes (cooling rates, simulating box sizes) to study their influence to temperature regimes of volume fluctuations. Partial volume fluctuations (VF) were introduced with the help of Voronoi polyhedra tessellation. Dynamic and static fluctuations were suggested as a measure for time- and space-related fluctuations. Separation of the dynamic and static VFs anticipates glass transition. The glass transition was related with the change of the temperature course of the static VFs. The dynamic VFs changed their temperature regimes well below the glass transition and the transition temperature was related with the change of the transport regime. Glass transition cages the atoms but Voronoi polyhedra are definitely shaped well below the glass transition temperature.     

Optical Properties of Micro-patterned Silver Nanoparticle Substrates

In this paper, we describe a novel technique for depositing metal nanoparticles (NPs) on a planar substrate whereby the NPs are micro-patterned on the surface by a simple stamp-printing procedure. The method exploits the attractive force between negatively charged colloidal metal NPs and positively-charged polyelectrolyte layers which have been selectively deposited on the surface. Using this technique, large uniform areas of patterned metal NPs, with different plasmonic properties, were achieved by optimisation of the stamping process. We report the observation of unusual fluorescence emission from these structures. The emission was measured using epifluorescence microscopy. Fluorescence lifetime behaviour was also measured. Furthermore, the μ-patterned NPs exhibited blinking behaviour under 469 nm excitation and the fluorescence spectrum was multi-peaked. It has been established that the fluorescence is independent of the plasmon resonance properties of the NPs. As well as optimising the novel NP μ-patterning technique, this work discusses the origin and characteristics of the anomalous fluorescence behaviour in order to characterise and minimise this unwanted background contribution in the use of metal NPs for plasmonic enhancement of fluorescence for optical biochip applications.     

Fabrication of micro-patterned substrates for plasmonic sensing by piezo-dispensing of colloidal nanoparticles

Analytical and Bioanalytical Chemistry - In this work we describe a very fast and flexible method for fabrication of plasmon-supporting substrates with micro-patterning capability, which is...     

MALDI MSI Reveals the Spatial Distribution of Protein Markers in Tracheobronchial Lymph Nodes and Lung of Pigs after Respiratory Infection

Respiratory infections are a real threat for humans, and therefore the pig model is of interest for studies. As one of a case for studies, Actinobacillus pleuropneumoniae (APP) caused infections and still worries many pig breeders around the world. To better understand the influence of pathogenic effect of APP on a respiratory system—lungs and tracheobronchial lymph nodes (TBLN), we aimed to employ matrix-assisted laser desorption/ionization time-of-flight mass spectrometry imaging (MALDI-TOF MSI). In this study, six pigs were intranasally infected by APP and two were used as non-infected control, and 48 cryosections have been obtained. MALDI-TOF MSI and immunohistochemistry (IHC) were used to study spatial distribution of infectious markers, especially interleukins, in cryosections of porcine tissues of lungs (necrotic area, marginal zone) and tracheobronchial lymph nodes (TBLN) from pigs infected by APP. CD163, interleukin 1β (IL-1β) and a protegrin-4 precursor were successfully detected based on their tryptic fragments. CD163 and IL-1β were confirmed also by IHC. The protegrin-4 precursor was identified by MALDI-TOF/TOF directly on the tissue cryosections. CD163, IL-1β and protegrin-4 precursor were all significantly (p < 0.001) more expressed in necrotic areas of lungs infected by APP than in marginal zone, TBLN and in control lungs.