Application of GC–MSD and LC–MS/MS for the determination of priority pesticides in baby foods in Serbian market

Babies and small children are especially sensitive population to the exposure to environmental contaminants. Their small mass and developing systems, including brain development may show adverse health effects from even low levels of contamination on a chronic or single dose case. In this paper one extraction method and two chromatographic techniques for the determination of pesticide residues in baby food were evaluated. A liquid chromatography–tandem mass spectrometry technique combined with electrospray ionization (ESI), (LC–MS/MS) and gas chromatography–mass spectrometry detection (GC–MSD) technique were applied in the detection of 50 pesticides in baby food. So-called QuEChERS (quick, easy, cheap, effective, rugged and safe) method was used as a sample preparation procedure. The recoveries were investigated at three levels (5, 10 and 50 μg/kg) and the results obtained showed compliance with the contemporary EU requirements with a few exceptions. LOQs for most of the tested pesticides were below the EU MRLs (10 μg/kg), except deltamethrin, cypermethrin, fenvalerate, phosalone and beta-cyfluthrin (LOQs were 10 μg/kg). Both techniques were applied in the analysis of 50 samples of baby food manufactured in Serbia.     

Data clustering based on quantum synchronization

Natural Computing - There exists a specific class of methods for data clustering problem inspired by synchronization of coupled oscillators. This approach requires an extension of the classical...     

A shift of the perceptual attributes of color due to the manifestation of the simultaneous contrast effect on a display

This research shows the effect of simultaneous contrast on a design solution that generates it, and it also shows how its manifestation affects the shift of perception attributes of the observer's color. In the conducted research, 55 subjects had to harmonize the primary stimuli from the reproduction obtained with the help of digital printing technology, with the primary stimuli presented on two computer screens. As a visual harmonization technique, simultaneous binocular harmonization was used. The primary stimuli were made achromatic, with a 50% Raster Tone value (RTV), and are surrounded by achromatic secondary stimuli whose values increase in steps from 10% RTV up to 100% RTV. A shift in the perceptual attributes of color has been shown with the help of the CIEDE2000 system. Using ANOVA with repeated-measures and Fisher's post hoc analysis, statistically significant differences were found between the perceived means of shift in the ΔC₀₀ chroma and ΔL₀₀ lightness on defined samples on both computer screens, while in the case of the ΔH₀₀ hue, no statistically significant differences were observed. The research also determined colorimetric differences in the ΔE₀₀ color difference. Moreover, the student's t test was used to determine that the effect is stronger when manifested on the Lenovo computer than on the Asus computer screen (P < .05).     

Large-scale parallel arrays of silicon nanowires via block copolymer directed self-assembly

Extending the resolution and spatial proximity of lithographic patterning below critical dimensions of 20 nm remains a key challenge with very-large-scale integration, especially if the persistent scaling of silicon electronic devices is sustained. One approach, which relies upon the directed self-assembly of block copolymers by chemical-epitaxy, is capable of achieving high density 1?:?1 patterning with critical dimensions approaching 5 nm. Herein, we outline an integration-favourable strategy for fabricating high areal density arrays of aligned silicon nanowires by directed self-assembly of a PS-b-PMMA block copolymer nanopatterns with a L(0) (pitch) of 42 nm, on chemically pre-patterned surfaces. Parallel arrays (5 × 10(6) wires per cm) of uni-directional and isolated silicon nanowires on insulator substrates with critical dimension ranging from 15 to 19 nm were fabricated by using precision plasma etch processes; with each stage monitored by electron microscopy. This step-by-step approach provides detailed information on interfacial oxide formation at the device silicon layer, the polystyrene profile during plasma etching, final critical dimension uniformity and line edge roughness variation nanowire during processing. The resulting silicon-nanowire array devices exhibit Schottky-type behaviour and a clear field-effect. The measured values for resistivity and specific contact resistance were ((2.6 ± 1.2) × 10(5)Ωcm) and ((240 ± 80) Ωcm(2)) respectively. These values are typical for intrinsic (un-doped) silicon when contacted by high work function metal albeit counterintuitive as the resistivity of the starting wafer (～10 Ωcm) is 4 orders of magnitude lower. In essence, the nanowires are so small and consist of so few atoms, that statistically, at the original doping level each nanowire contains less than a single dopant atom and consequently exhibits the electrical behaviour of the un-doped host material. Moreover this indicates that the processing successfully avoided unintentional doping. Therefore our approach permits tuning of the device steps to contact the nanowires functionality through careful selection of the initial bulk starting material and/or by means of post processing steps e.g. thermal annealing of metal contacts to produce high performance devices. We envision that such a controllable process, combined with the precision patterning of the aligned block copolymer nanopatterns, could prolong the scaling of nanoelectronics and potentially enable the fabrication of dense, parallel arrays of multi-gate field effect transistors.     

Potential of proton-enhanced 13C n.m.r. for the classification of kerogens

High resolution n.m.r. spectroscopy, involving the technique of cross-polarization, along with magicangle spinning, was used in the structural characterization of eight kerogens of different origins, selected to represent the three types of kerogens (types I–III evolution paths). The influence of cross-polarization dynamics on the sensitivity of the method and the ratio of individual fractions in the spectrum was studied in more detail. It is suggested that an analysis of the influence of the mixing time is necessary prior to definitive characterization of any sample. Good separation of signals in aliphatic, aromatic, and carboxylic regions was achieved. The general correlation between the ¹³C n.m.r. structural characteristics and the classification based on ultimate analysis of the kerogens (types I–III, van Krevelen atomic H/C vs. O/C diagrams) was found to be satisfactory. The structural features of kerogens derived from ¹³C n.m.r. analysis agreed quite well with characteristics constituting the above mentioned classification. The ¹³C n.m.r. method used in this paper may be considered promising in the classification of kerogens.     

Proteome Based Approach Defines Candidates for Designing a Multitope Vaccine against the Nipah Virus

Nipah virus is one of the most harmful emerging viruses with deadly effects on both humans and animals. Because of the severe outbreaks, in 2018, the World Health Organization focused on the urgent need for the development of effective solutions against the virus. However, up to date, there is no effective vaccine against the Nipah virus in the market. In the current study, the complete proteome of the Nipah virus (nine proteins) was analyzed for the antigenicity score and the virulence role of each protein, where we came up with fusion glycoprotein (F), glycoprotein (G), protein (V), and protein (W) as the candidates for epitope prediction. Following that, the multitope vaccine was designed based on top-ranking CTL, HTL, and BCL epitopes from the selected proteins. We used suitable linkers, adjuvant, and PADRE peptides to finalize the constructed vaccine, which was analyzed for its physicochemical features, antigenicity, toxicity, allergenicity, and solubility. The designed vaccine passed these assessments through computational analysis and, as a final step, we ran a docking analysis between the designed vaccine and TLR-³ and validated the docked complex through molecular dynamics simulation, which estimated a strong binding and supported the nomination of the designed vaccine as a putative solution for Nipah virus. Here, we describe the computational approach for design and analysis of this vaccine.     

POLYCYCLIC AROMATIC HYDROCARBONS IN PRODUCTS OF A BEET SUGAR FACTORY IN VOJVODINA: LEVELS AND INTAKES

The levels of 16 EPA polycyclic aromatic hydrocarbons (PAHs) were investigated in samples of sugar beets and their products representative for a beet sugar factory located in the central part of Vojvodina, the main agricultural region in Serbia. The sum of the detected PAHs ranged from 51 pg g ^?1 ww for molasses to 391 pg g ^?1 ww for dried sugar beet pulp. The concentration of benzo(a)pyrene (BaP) for all sample types was about or less than 100 pg g ^?1 ww, which is far less than the existing Serbian and EU tolerances set for some foodstuffs. The Serbian intake of BaP via total sugar consumption that ranged from 70–85 g per capita day ^?1 , was assessed to be from 0.029 to 0.035 ng kg ^?1 b.w. day ^?1 . Furthermore, the toxic equivalency factor (TEF) approach was used to estimate the carcinogenicity of PAH mixture found in analyzed samples.     

Single-step preparation of rutile-type CrNbO4 and CrTaO4 oxides from oxalate precursors–characterization and properties

Chromium niobate and tantalate (CrNbO₄ and CrTaO₄) were synthesized by pyrolysis of the oxalate-based heterometallic complexes [Cr₂(bpy)₄(μ-O)₄Nb₂(C₂O₄)₄]·3H₂O (Cr-Nb) and [Cr(bpy)₂(H₂O)(μ-O)Ta(C₂O₄)₃]₂·3.5H₂O (Cr-Ta) (bpy = 2,2'-bipyridine). Compared to conventional solid-state synthesis, herein studied oxides are prepared at lower temperatures, in one step without repeating grinding procedures. The structure, morphology, and optical properties of the as-synthesized oxides were characterized using powder X-ray diffraction (PXRD), field emission scanning electron microscopy (SEM), the thermogravimetric and differential thermal analysis (TG/DTA) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The determined band gap energies of CrNbO₄ and CrTaO₄ are 2.39 and 2.82 eV, respectively, which prompted us to investigate photocatalytic activity of these oxides in degradation of dyes. Microscopy studies show that the particles of both oxides began to aggregate into bigger particles, leading to an increase in grain size. Additionally, magnetization measurements on both oxides revealed spin-glass behavior at low temperatures.