ANALYSIS OF WHOLE BLOOD AND PLACENTA—A CASE STUDY OF MOTHERS AND THEIR BABIES

In a previous report optimisation of ED-XRF and TXRF for whole blood analysis has been reported. In the present work the optimised technique has been applied to investigate possible influence on pregnancy outcome due to an environment characterised by high levels of pollutants. Two groups of maternal and neonate whole blood were analysed with TXRF and GFAAS. The material of the first group was taken from Zabrze (Upper Silesia, Poland), an industrial region with a high degree of pollution. The second group consisted of controls from the Goteborg region in Sweden, where the levels of toxic pollutants in the environment are not as high as those in Zabrze. The results show that as compared with…

Identification and Evaluation of Hazardous Pyrolysates in Bio-Based Rigid Polyurethane-Polyisocyanurate Foam Smoke

In this study, rigid polyurethane (PU) and polyisocyanurate (PIR) foam samples made from renewable material (tall oil fatty acid) based polyols were analyzed by pyrolysis gas chromatography mass spectrometry (Py-GC/MS) to obtain information about the full relative smoke content, with a focus on substance identification by their functional groups and hazardousness. The relative content of gaseous products produced during the thermal degradation was evaluated between the two samples, differenced by their assigned isocyanate (NCO) index value—150 and 300. The main thermal degradation components of the rigid PU-PIR foam were found to originate from the decomposition of isocyanate, primarily for…

Use of Wood Ash in the Forest and its Effect on the Concentration of Essential and Heavy Metallic Elements in Soil and Blueberries <i>(Vaccinium myrtillus L.)</i>

The aim of this research is to evaluate the influence of wood ash as an additive fertilizer to forest soil and growing blueberries (Vaccinium myrtillus L.) in terms of metallic element content. To evaluate the effect of wood ash on the forest ecosystem, was selected two forest areas which was fertilized with a certain amount of wood ash (bottom ash and fly ash). The selected forest areas were divided into two types of sampling plots (fertilized with ash and control). Obtained results showed that in the bottom ash dispersion area the concentration of Ca, K, Ni, Cu is almost twice higher in the fertilized plots than control plots. In the blueberries, metallic element content is similar and do…

Comparison of Different Classical and Instrumental Analysis Methods for Precise Quantification of Calcium and Phosphorous Ratio in Hydroxyapatite

The largest comparison of analytical techniques, useful for calcium phosphates, has been conducted, presenting recommendations for quality control and research of calcium phosphates. Results from three classical quantification methods (gravimetry, titramety, photometry) and three instrumental measurement methods (XRF, FAAS ICP-OES) are reported to determine the most accurate, fastest and cheapest analysis method. Remarks are given for increasing the accuracy for each method and corrections made for adsorbed water. For routine analysis, a recommendation is given to ICP-OES for a fast analysis, together with a less frequent use of gravimetry to validate the results and provide a periodic cros…

Lichens <i>(Xanthoria parietina)</i> - Bio-Indicators for Sulphur and Metallic Elements for Pollution Investigation in Riga City

The aim of the research was to investigate the pollution level of sulphur and metallic elements in Riga city (Freeport of Riga, Kundziņsala, Mežaparks) by using foliose lichens (Xanthoriaparietina) as a bio-indicators. Obtained results show that the Freeport of Riga is the most polluted area comparing with other neatest places in Riga city, Kundziņsala and Mežaparks. Evaluate a washing effect, obtained results shows that lichen thallus contains about 50 % of total amount of sulphur and investigated elements as dust particles on the surface of lichens.

On the way to ‘zero waste’ management: Recovery potential of elements, including rare earth elements, from fine fraction of waste

Abstract Existing schemes of solid waste handling have been improved implementing advanced systems for recovery and reuse of various materials. Nowadays, the ‘zero waste’ concept is becoming more topical through the reduction of disposed waste. Recovery of metals, nutrients and other materials that can be returned to the material cycles still remain as a challenge for future. Landfill mining (LFM) is one of the approaches that can deal with former dumpsites, and derived materials may become important for circular economy within the concept ‘beyond the zero waste’. Perspectives of material recovery can include recycling of critical industrial metals, including rare earth elements (REEs). The…

Ultra high performance liquid chromatography-time-of-flight high resolution mass spectrometry in the analysis of hexabromocyclododecane diastereomers: method development and comparative evaluation versus ultra high performance liquid chromatography coupled to Orbitrap high resolution mass spectrometry and triple quadrupole tandem mass spectrometry.

An efficient ultra high performance liquid chromatography (UHPLC)-time-of-flight high resolution mass spectrometry (TOF-HRMS) method was elaborated for the determination of hexabromocyclododecane (HBCD) diastereomers in fish samples and compared against UHPLC-Orbitrap-HRMS and UHPLC-triple quadrupole (QqQ) tandem MS (MS/MS) techniques. The TOF-HRMS analyzer was operated at high resolution (>10000 full width at half maximum (FWHM)) with scanning the m/z range from 600 to 700, to achieve picogram quantitation limits. The effects of various operational parameters on the instrumental response were systematically investigated. Evaluation of the influence of sample clean-up procedure steps on sig…

Investigation of mass graves in the Churchyard of St. Gertrude’s, Riga, Latvia

Analysis of Archaeological Bones for the Purpose of Reconstructing the Paleodiet of Medieval Inhabitants

Bone is one of the few materials that are consistently recovered from archaeological and paleontological sites; its chemical composition has the potential to provide valuable information about ancient human and faunal diet and health status. Diet is one aspect of the development of human culture; changes in dietary regimes occurred together with changes in the manner of food procurement. Gathering, hunting and, after domestication, cattle breeding, and finally agriculture, each stage of development of the dietary process also brought social stratification, which in turn led to a preferred diet for certain individuals (Smrcka 2005). The most frequently examined elements for the reconstructio…

Method development of levoglucosenone analysis by UHPLC-UV-MS in fast pyrolysis samples and aspects of its degradation in aqueous samples

Levoglucosenone ((1S,5R)-6,8-dioxabicyclo[3.2.1]oct-2-en-4-one or LGO; CAS number: 37112-31-5) is an extensively studied biomass based chemical and its potential applications in organic synthesis, as well as in the extraction of various natural substances, have been established; therefore developing dependable, yet fast and simple analytical methods for determining LGO in the products of thermochemical biomass processing is of great importance. In this work different UHPLC methods have been developed and compared for the determination of LGO in wood pyrolysis products. In addition to UV detection, LGO determination conditions by single quadrupole mass spectrometry have been adjusted with an…

Dataset of trace elements concentrations in snow samples collected in Jelgava City (Latvia) in December 2020

Abstract The data set provided in this article consist of two repeated data sets of chemical elements concentrations in snow samples. The snow samples were collected in Jelgava city at December 15th with 5 day exposition time. Snow samples were collected in 59 monitoring points in Jelgava city and in one sample in rural area monitoring point as control. The collected snow samples were melted, acidified with HNO3 and analysed with ICP-MS. The samples were analysed Aluminium (Al), Silicon (Si), Chrome (Cr), Manganese (Mn), Iron (Fe), Nickel (Ni), Copper (Cu), Zinc (Zn), Arsenic (As), Molybdenum (Mo), Cadmium (Cd), Barium (Ba), Tungsten (W), Lead (Pb). The collected data are with fundamental s…

THE EVALUATION OF STABLE ISOTOPIC RATIOS 13C AND 15N IN HUMIC ACIDS ALONG A FEN PEAT PROFILE

Mires are known as consistent environmental archives, but humic acids are the fraction of peat that is most recalcitrant and refractory to organic matter degradation, thus data on environmental changes during mire development can be recorded into them. This work was focused on the studies of stable isotopic ratios delta carbon-13 and delta nitrogen-15, and their distribution in humic acids within fen peat layers of different depths and peat composition. The variations in delta carbon-13 reflect isotopic variations in peat-forming plants over time and can be considered as a function of photosynthetic pathway that is being used to fix carbon dioxide. At the same time, variations in delta nitr…

Development and optimization of gas chromatography coupled to high resolution mass spectrometry based method for the sensitive determination of Dechlorane plus and related norbornene-based flame retardants in food of animal origin

An analytical method has been developed for the trace determination of 10 dechlorane-related compounds (DRCs) in food products by gas chromatography - high resolution mass spectrometry (GC-HRMS). The highest sensitivity of this instrumental analysis method was achieved by selection of the GC column type, optimization of the heated zones within the instrument, and adjusting the electron impact energy. The efficiency of solid phase extraction as clean-up procedure was also optimized. Two different types of cartridges - neutral silica gel and Florisil®, as well as seven organic solvents or their mixtures - n-hexane, cyclohexane, acetone, toluene, n-hexane/ethyl acetate, n-hexane/acetone, and n…

Deposition of Cu Nanoparticles on the Surface of Metallic Aluminum

Deposition of Cu particles by electrolysis at constant electrode potential and by internal electrolysis methods was investigated. The composition of deposited material was confirmed by optical and scanning electron microscope methods. Combination of electrolysis at constant electrode potential with internal electrolysis method was found most effective for fabrication of nanoparticle arrays. Single crystalline Cu particles are fabricated by internal electrolysis, while polycrystalline ones obtained by combined chronopotentiometric and internal electrolysis methods. The formation mechanism of Cu nanoparticles is described.

EDXRF and TXRF analysis of elemental size distributions and environmental mobility of airborne particles in the city of Riga, Latvia

Airborne particles were investigated in the central part of Riga during October 2000. Mass, black carbon and elemental concentrations of airborne particles were measured on Teflon filters from a dichotomous impactor, which samples fine (<2.5 µm) and coarse (2.5‐10 µm) fractions of particles. In order to obtain more detailed information on the size distributions of different elements, a seven-stage Batelle cascade impactor was used, in which quartz plates treated with silicone grease were utilized as backing for the different stages. Total reflection x-ray fluorescence (TXRF) and energy-dispersive x-ray fluorescence (EDXRF) spectrometry were used for elemental analysis on the quartz plates a…

Electrochemically etched sharp aluminium probes with nanoporous aluminium oxide coatings: demonstration of addressed DNA delivery

Electrochemical etching of metal wires is widely used to fabricate sharp probes for use in scanning tunnelling microscopy. In this work an electrochemical fabrication method for sharp aluminium probes coated with nanoporous anodised aluminium oxide (AAO) layer is described. The method presented here involves simultaneous anodisation and etching of aluminium wires. The probe apex radius as well as the nanopore length and diameter depend on the etching mode, which could be direct current (DC), alternating current (AC), or pulsed voltage mode (PVM). The probes, coated with a nanoporous AAO layer, were used to demonstrate addressed DNA delivery.

Enhanced Electrochemical Properties of Na0.67MnO2 Cathode for Na-Ion Batteries Prepared with Novel Tetrabutylammonium Alginate Binder

This research was funded by the State Education Development Agency, the Republic of Latvia, grant number 1.1.1.2/VIAA/1/16/166, "Advanced Materials for Sodium-Ion Batteries". Institute of Solid-State Physics, University of Latvia as the Centre of Excellence has received funding from the European Union's Horizon 2020 Framework Program H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.

Hydrothermal Processing for Increasing the Hydroxyl Ion Concentration in Hydroxyl Depleted Hydroxyapatite

Thermal spraying is commercially used to produce hydroxyapatite coatings, but the high temperature depletes hydroxyl ions in the structure. To return hydroxyapatite to its original state, it is necessary to restore the hydroxyl ion content in the structure. In this work, the effect of hydrothermal treatment on the hydroxyl ions was investigated in hydroxyapatite powder and thermally sprayed hydroxyapatite coatings. Samples were hydrothermally treated at 200 °C for 24 h and 48 h. Chemical phases were determined by X-ray diffraction, functional groups and hydroxyl ion concentration was examined by Fourier transform infra-red spectroscopy. Results showed that hydrothermal processing of hydroxy…

INTERFERENCE REMOVAL IN ICP-MS USING HE COLLISION CELL WITH TANDEM MS

Carbon and nitrogen stable isotope ratios of soils and grasses as indicators of soil characteristics and biological taxa

Abstract The use of stable isotope techniques can assist in understanding interactions of plants with various abiotic and biotic processes. In the research, we focused on carbon (C) and nitrogen (N) isotopes because they are the most important resources influencing plant function and the biogeochemical cycles. The 13C/12C and 15N/14N ratios in plants and in soils and the relationships between these ratios and biological and environmental factors of widely distributed native C3 plants (couch grass, plantain and yarrow) collected from two sites in St. Petersburg, Russia were studied. The soil characteristics of the sites were rather different. This had a significant effect on the isotope rati…

Characterization of softwood and hardwood lignoboost kraft lignins with emphasis on their antioxidant activity

Fractionation of softwood and hardwood LignoBoost kraft lignins, using sequential extraction with organic solvents of increasing hydrogen-bonding ability (dichloromethane, n-propanol, and methanol), was carried out. Using SEC, analytical pyrolysis, FTIR and UV/VIS spectroscopy, and chemical analytical methods, four fractions were obtained and characterized in terms of their yield, composition, functionality, lignin structural features, and antioxidant properties. In tests with free radicals (ABTS●+, DPPH●, O2●-) and the ORAC (oxygen radical absorbance capacity) assay, the high radical scavenging capacity of the lignin’s soluble fractions was demonstrated. The antioxidant activity of the fra…

Structural analysis of Borrelia burgdorferi periplasmic lipoprotein BB0365 involved in Lyme disease infection.

The periplasmic lipoprotein BB0365 of the Lyme disease agent Borrelia burgdorferi is expressed throughout mammalian infection and is essential for all phases of Lyme disease infection; its function, however, remains unknown. In the current study, our structural analysis of BB0365 revealed the same structural fold as that found in the NqrC and RnfG subunits of the NADH:quinone and ferredoxin:NAD+ sodium-translocating oxidoreductase complexes, which points to a potential role for BB0365 as a component of the sodium pump. Additionally, BB0365 coordinated Zn2+ by the His51, His55, His140 residues, and the Zn2+ -binding site indicates that BB0365 could act as a potential metalloenzyme; therefore…

Application of LA-ICP-MS as a rapid tool for analysis of elemental impurities in active pharmaceutical ingredients.

The control of inorganic contaminants in active pharmaceutical ingredients has a significant role in the quality control of drug products. The concentration limits for metal residues in drug products have been defined by various regulatory guidelines. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a powerful and fast analytical technique for multi-elemental analysis. A disadvantage in using LA-ICP-MS method is the lack of matrix reference materials for validation and calibration purposes. This article focuses on the handling strategy of laboratory-made matrix calibration standards for the quantification of elemental impurities in an active pharmaceutical ingredie…

Electrochemical Impedance Spectra of Particulate Matter and Smoke

Particularly aerosol particles of fine dimensions are recognized to have a strong impact on the climate change, on the atmospheric energy budget, on the environment and on human health. In this study coarse aerosol particles with different black carbon mass concentrations were investigated by electrochemical impedance spectroscopy. Present work describes preparation of particulate matter samples for impedance measurements, the principles of the structure of electrochemical cell and the relationship between parameters obtained from impedance spectra and black carbon mass concentration. Using complex electrode it is possible to obtain qualitative impedance spectra of particulate matter which …

Comparison of photodiode array, evaporative light scattering, and single-quadrupole mass spectrometric detection methods for the UPLC analysis of pyrolysis liquids

ABSTRACTIt is important to analyze pyrolysis liquids to evaluate the yield of valuable products as well as unfavorable by-products. This work focuses on choosing detectors for reversed-phase ultra high-performance liquid chromatography analysis of pyrolysis liquids. The linearity, sensitivity, precision, and recovery of photodiode array (PDA) detector, single-quadrupole mass spectrometer (MS), and evaporative light scattering (ELS) detector were compared for the quantitative determination of several typical compounds found in pyrolysis liquids. PDA and MS detectors were found to be suitable for the quantification of furans and phenol derivatives (furfural, vanillin, syringol), but sugars an…

Application of electrochemical impedance for characterising arrays of Bi2S3 nanowires

Abstract Electrochemical Impedance Spectroscopy (EIS) was used to characterise the electrical properties of bismuth sulphide (Bi2S3) nanowires (NWs) templated within anodic aluminium oxide (AAO) membranes. A specially engineered cell, with a nominal electrolyte volume of 0.1–0.2 ml, was used to hold and measure the electrochemical impedance of the fragile NW/AAO samples. An equivalent circuit model was developed to determine the filling density of nanowires within the porous templates. The EIS method can be utilised to probe the nanowire filling density in porous membranes over large sample areas, which is often unobtainable using electron microscopy and conductive atomic force microscopy t…

The application of headspace gas chromatography coupled to tandem quadrupole mass spectrometry for the analysis of furan in baby food samples.

Abstract Selective methodology employing a tandem quadrupole mass spectrometer coupled to a gas chromatograph with headspace autosampler (HS-GC–MS/MS) was elaborated in this study. Application of the elaborated procedure resulted in a limit of detection of 0.021 μg kg −1 and a limit of quantification of 0.071 μg kg −1 . The mean recoveries during in-house validation ranged from 89% to 109%, and coefficients of variation for repeatability ranged from 4% to 11%. The proposed analytical method was applied for monitoring the furan content of 30 commercial baby food samples available on the Latvian retail market. The level of furan found in these samples varied from 0.45 to 81.9 μg kg −1 , indic…

Impedance and admittance characteristics of Bi2S3 nanowire arrays

Current studies of the electrical impedance and admittance characteristics of the anodised aluminum oxide (AAO) nanoporous arrays and bismuth sulphide (Bi2S3) nanowire within AAO membranes are presented. The influence of potential and frequency scan rate effect produced on the real, imaginary and complex electrochemical impedance and double layer capacitance of the AAO nanopore and the Bi2S3 nanowire arrays were studied.

An impedance study of complex Al/Cu-Al2O3electrode

Electrochemical impedance spectroscopy (EIS) was used to investigate different Cu deposition regimes on Al surface obtained by internal electrolysis and to characterize properties of fabricated electrodes. EIS experimental data confirmed that Cu deposition by internal electrolysis is realized and the complex electrode system is obtained. The main difficulty in preparation of Al/Cu electrodes is to prevent aluminium oxidation before and during electrochemical deposition of Cu particles. In this work NaCl, CH3COONa, K2SO4, mono- and diammonium citrate electrolytes were examined to determine their suitability for impedance measurements. Al/Cu-Al2O3 electrode composition was approved by equival…

TG/DTA-FTIR as a method for analysis of tall oil based rigid polyurethane foam decomposition gaseous products in a low oxygen environment

Abstract This study is an investigation of the suitability of the thermogravimetry and differential thermal analysis method coupled with Fourier Transform Infrared spectrometry (TG/DTA-FTIR) for a thermal degradation gaseous product analysis of a rigid polyurethane-polyisocyanurate (PU-PIR) foam synthesised from high functionality tall oil fatty acids (TOFA) based polyols. The FTIR spectra of the TG-generated gaseous thermal degradation products of three PU-PIR formulations with varied high functionality TO based polyol content (45, 75 and 95 pbw) and a different tier of isocyanate (NCO) indexes (110, 150, 200, 300 and 400) for each formulation were compared to the spectra of a formulation …

Variations of some Metallic Elements in Different Parts of Lingonberries &lt;i&gt;(Vaccinium vitis-idaea L.)&lt;/i&gt;

The aim of the research was to evaluate the content of metallic elements in different parts of lingonberries (Vaccinium vitis-idaea L.) depending on their place of growth and evaluate the transfer factor values from between different parts of plants (fine roots, leaves, berries). Obtained results show that there are no significant differences between the content of Fe, Cu, Zn and K, and there are similar element transfer factors between different parts of lingonberries independent from which site the samples are taken.

Hydrothermally Synthesized Strontium Peroxyapatite

The current research focuses on peroxide ion incorporation in the structure of strontium hydroxyapatite (SrHAp) by exposure to H2O2 ina closed hydrothermal vessel under mild conditions at 130 to 170 °C. Peroxide enriched strontium apatite (SrPerAp) was characterized for structure by X-Ray diffraction, for peroxide content- by permanganometric titration and then viewed by SEM. This study continued from previous work that used 30%H2O2 and showed a higher included peroxide content after processing with 50% H2O2 at 130 °C 70% of the theoretical peroxide content in apatitic channels of strontium apatite. This is the highest peroxide content incorporated to date and employs a lower temperature th…

Crystal structure of human gamma-butyrobetaine hydroxylase.

Gamma-butyrobetaine hydroxylase (GBBH) is a 2-ketoglutarate-dependent dioxygenase that catalyzes the biosynthesis of l-carnitine by hydroxylation of gamma-butyrobetaine (GBB). l-carnitine is required for the transport of long-chain fatty acids into mitochondria for generating metabolic energy. The only known synthetic inhibitor of GBBH is mildronate (3-(2,2,2-trimethylhydrazinium) propionate dihydrate), which is a non-hydroxylatable analog of GBB. To aid in the discovery of novel GBBH inhibitors by rational drug design, we have solved the three-dimensional structure of recombinant human GBBH at 2.0A resolution. The GBBH monomer consists of a catalytic double-stranded beta-helix (DBSH) domai…

Efficacy of Ozonation Treatments of Smoked Fish for Reducing Its Benzo[a]pyrene Concentration and Toxicity

Ozone is widely used in food processing, for example, to decompose mycotoxins or pesticide residues, to extend the shelf life of products, and for sanitation. The objective of this study was to assess the possibility of expanding the application of ozone for oxidative degradation of polycyclic aromatic hydrocarbons (PAHs). The evaluation was conducted by ozonation of a benzo[a]pyrene (BaP) standard solution and smoked fish (sprats) contaminated with PAHs. The effect of ozonation was immediate in the BaP solution; 89% of this toxic compound was decomposed after only 1 min of treatment. However, the impact of ozonation on the smoked sprats was less pronounced, even after prolonged treatment. …

Method development for the simultaneous determination of polybrominated, polychlorinated, mixed polybrominated/chlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls and polybrominated diphenyl ethers in fish.

An analytical methodology was developed for simultaneous determination of five groups of persistent organic pollutants (POPs) including polybrominated, polychlorinated and mixed brominated-chlorinated dibenzo-p-dioxins and dibenzofurans (PBDD/DFs, PCDD/DFs and PXDD/DFs, respectively), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in fish samples. The presented analytical approach was based on well established and robust method for determination of PCDD/DFs and PCBs, which was augmented with gas chromatography coupled to high resolution mass spectrometry (GC-HRMS) to include PBDEs, as well as poorly investigated PBDD/DFs and PXDD/DFs at toxicologically significa…

Exploring Zinc Apatites through Different Synthesis Routes

nclusion of zinc in apatites is not completely understood due to complexes in solution preventing the incorporation or the inclusion of defects. Some work has shown zinc addition by alternative synthesis routes, but the level of incorporation has not been reassessed. This work uses a newly developed approach whereby zinc is included in an amorphous phase and subsequently crystallized. Different phosphate reactants (ammonium, sodium or potassium phosphates) were mixed together with calcium salts (calcium nitrate or calcium acetate) and the pH level adjusted (with ammonia or KOH) to investigate the ease of forming an amorphous phase and the inclusion of zinc. X-ray diffraction revealed that a…

Characterization of functional groups of airborne particulate matter

Particulate matter of organic combustibles burning consists of various hydrocarbons and radicals, which may cause harmful impact to human health. In this study solid particulate matter were collected on the filters from burning of various combustibles in a burning chamber and from atmosphere of city of Riga by dichotomous impactor. FTIR spectra were obtained before and after samples' treatment. Absorptions associated with aliphatic and aromatic hydrocarbons and alcohol functional groups were observed in the FTIR spectra. Free radicals of particulate matter were detected by electron paramagnetic resonance (EPR).

Multi-elemental EDXRF mapping of polluted soil from former horticultural land.

The distribution of major and trace elements was systematically investigated by use of energy dispersive X-ray fluorescence spectrometry (EDXRF) on a former horticultural soil. The purpose of the study was to combine mapping of soil element concentration levels with multivariate statistics for characterisation of soil metal pollution in relation to previous and present land use. A 1-ha study site was chosen from a former horticulture where a previous preliminary survey indicated increased concentration levels of toxic elements. The soil was sampled from the top 20 cm of the soil surface in a 10×10-m grid-like pattern covering the 1-ha study area. In addition, three soil profiles were studie…

Photoelectrochemical Bisphenol S Sensor Based on ZnO‐Nanoroads Modified by Molecularly Imprinted Polypyrrole

Molecularly imprinted polymers are important tools for the design of sensors and other molecular recognition based analytical systems. In this paper the development of a photoelectrochemical sensor for selective bisphenol determination is reported. The sensor is based on a glass/ZnO/MIP‐Ppy structure consisting of glass modified by a ZnO layer (glass/ZnO), which is functionalized by molecularly imprinted conducting polymer polypyrrole (MIP‐Ppy). The sensitivity of the sensor to bisphenol is in the range of 0.7&ndash;12.5 &micro;m. Selectivity tests to other bisphenolic compounds are performed. Some aspects of a photoinduced response mechanism in glass/ZnO/MIP‐Ppy nanostructures are predicte…

Synthesis of Peroxyapatite by Hydrothermal Processing

Peroxide ions in apatite provides an additional resource for imparting an antibacterial capability in apatite. A hydrothermal process has been developed for including peroxide ions into the apatite lattice. Three oxygen generation compounds, hydrogen peroxide, ammonium persulphate and paracetic acid were investigated for peroxyapatite generation. Hydrogen peroxide provides the highest peroxide containing apatite. Both the oxygen generation and the apatite lattice formation represented the two critical factors for producing peroxyapatite. Unlike with high temperature processing, the cooling rate did not influence the retained peroxide content. This new process provides a building block for i…

Content of polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls in fish from Latvian lakes

Seventeen polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDFs) of the highest priority as well as twelve dioxin-like polychlorinated biphenyls (dl-PCBs) were analyzed in the muscle tissues of the following freshwater fish species sampled from eleven Latvian freshwater lakes: perch (Perca flavescens), carp (Cyprinus carpio), eel (Anguilla rostrata), bream (Abramis brama), chub (Leuciscus cephalus), pike (Esox lucius), sheatfish (Silurus glanis) and roach (Rutilus). To analyze the selected persistent organic pollutants in fish matrices, an optimization of EPA-1613 and EPA-1668A clean-up procedures was carried out, followed by validation of the analytical procedure …

Humic Substances for Agricultural Applications: Properties and Challenges

Nowadays, humic substances, the main organic components of soils and many fossil sediments, are becoming a material of wide application in agriculture and many technologies. Elemental, functional and spectral (UV, fluorescence, FTIR, 13C NMR spectra) analysis of industrially produced, as well as reference humic substances demonstrate significant differences in properties of humic substances depending on their origin, and thus, their potential application in agriculture. For authentication of humic substances’ origin, their elemental composition, as well as stable isotope (δC, δN, δO) ratios can be used.

Bi2Se3 Nanostructured Thin Films as Perspective Anodes for Aqueous Rechargeable Lithium-Ion Batteries

This research was funded by the European Regional Development Fund Project (ERDF) No. 1.1.1.1/19/A/139. Y.R. acknowledges the support of post-doctoral ERDF project No. 1.1.1.2/VIAA/4/20/694. V.L. also acknowledges the support of “Strengthening of the capacity of doctoral studies at the University of Latvia within the framework of the new doctoral model”, identification No. 8.2.2.0/20/I/006. A.S. acknowledges the support from the Institute of Solid State Physics, University of Latvia, which, as the Center of Excellence, has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.