Thermochemical characterization of chicken litter and peat as a source for energy recovery

The shortage of raw materials and the environmental problems due to pollution require development of new green technologies utilizing some wastes and transforming them to secondary raw materials. The aim of this work is to study the properties of poultry waste to propose possibilities to minimizing the released emissions and avoiding the risk for human health and the environment. At the same time, two types of low grade peats with different origin are studied as components for the production of soil conditioners. During the studies, we applied the inductively coupled plasma (ICP) and chemical analysis, powder X-ray diffraction, thermal analysis, IR spectroscopy, and scanning electron microscopy for determining the composition, crystal phase, the shape and size of particles, and thermal stability of the investigated samples. The chemical and the phase compositions of the studied samples confirmed that the content of nutrient compounds and of the carbon substances is suitable as an effective secondary raw material for soil conditioners. It is found that the poultry wastes and peat samples have a similar phase and chemical composition and contain an organic mass in the form of carbon components with amorphous, fibrous, and skeleton-like structure, suitable to be combined with other nutrient-containing compounds. During the thermal treatment, the carbon compounds are oxidized releasing heat. Based on that the materials under study are considered as environmentally friendly fuels, releasing relatively low emissions.     

Thermodynamics of oxygen in CaMnO3 − δ

The experimental data for equilibrium oxygen content were used in order to extract increments of partial molar thermodynamic functions of oxygen with changes of oxygen stoichiometry in calcium manganite CaMnO_3???δ . It is shown that along with the oxygen exchange reaction, thermal excitation of Mn⁴⁺ cations plays an important role in equilibration of charged manganese species that appear in response to the loss of oxygen at heating. The interrelation of partial molar enthalpy and entropy of oxygen with electron and ion defect formation parameters is obtained in approximation of the point defect model. The nearly linear changes of oxygen partial molar enthalpy are shown to directly reflect thermally driven changes in concentration of Mn³⁺ cations.     

Electron transport in CaMnO3 − δ at elevated temperatures: a mobility analysis

The drift mobility of electron charge carriers in oxygen non-stoichiometric manganite CaMnO_3???δ was calculated by combining the total electrical conductivity and oxygen non-stoichiometry data at 700–950 °С and oxygen partial pressure varying between 10^?6 and 1 atm. The carrier concentration changes with pressure and temperature were obtained with the help of the earlier-developed defect model involving reactions of oxygen exchange and thermal excitation of manganese sites. The activation energy for mobility is found to increase with oxygen non-stoichiometry. High-temperature electron transport properties of the manganite CaMnO_3???δ can be explained in terms of activated jumps of n-type small polarons in adiabatic regime. The relatively small mobility of charge carriers is explained by strong localization of polarons on manganese sites.     

Studies on the Structure and Properties of Membrane Phospholipase A1 Inclusion Bodies Formed at Low Growth Temperatures Using GFP Fusion Strategy

The effect of cultivation temperatures (37, 26, and 18 °C) on the conformational quality of Yersinia pseudotuberculosis phospholipase A₁ (PldA) in inclusion bodies (IBs) was studied using green fluorescent protein (GFP) as a folding reporter. GFP was fused to the C-terminus of PldA to form the PldA-GFP chimeric protein. It was found that the maximum level of fluorescence and expression of the chimeric protein is observed in cells grown at 18 °C, while at 37 °C no formation of fluorescently active forms of PldA-GFP occurs. The size, stability in denaturant solutions, and enzymatic and biological activity of PldA-GFP IBs expressed at 18 °C, as well as the secondary structure and arrangement of protein molecules inside the IBs, were studied. Solubilization of the chimeric protein from IBs in urea and SDS is accompanied by its denaturation. The obtained data show the structural heterogeneity of PldA-GFP IBs. It can be assumed that compactly packed, properly folded, proteolytic resistant, and structurally less organized, susceptible to proteolysis polypeptides can coexist in PldA-GFP IBs. The use of GFP as a fusion partner improves the conformational quality of PldA, but negatively affects its enzymatic activity. The PldA-GFP IBs are not toxic to eukaryotic cells and have the property to penetrate neuroblastoma cells. Data presented in the work show that the GFP-marker can be useful not only as target protein folding indicator, but also as a tool for studying the molecular organization of IBs, their morphology, and localization in E. coli, as well as for visualization of IBs interactions with eukaryotic cells.     

Dramatic Effect of A Ring Size of Alicyclic α-Dioximate Ligand Synthons on Kinetics of the Template Synthesis and of the Acidic Decomposition of the Methylboron-Capped Iron(II) Clathrochelates

Kinetics and thermodynamics of the template synthesis and of the acidic decomposition of the methylboron-capped iron(II) tris-1,2-dioximates—the clathrochelate derivatives of six (nioxime)- and eight (octoxime)-membered alicyclic ligand synthons—were compared. In the case of a macrobicyclic iron(II) tris-nioximate, the plausible pathway of its formation contains a rate-determining stage and includes a reversible formation of an almost trigonal-antiprismatic (TAP) protonated tris-complex, followed by its monodeprotonation and addition of CH₃B(OH)₂. Thus, the formed TAP intermediate undergoes a multistep rate-determining stage of double cyclization with the elimination of two water molecules accompanied by a structural rearrangement, thus giving an almost trigonal-prismatic (TP) iron(FII) semiclathrochelate. It easily undergoes a cross-linking with CH₃B(OH)₂, resulting in the elimination of H⁺ ion and in the formation of a macrobicyclic structure. In contrast, the analogous scheme for its macrobicyclic tris-octoximate analog was found to contain up to three initial stages affecting the overall synthesis reaction rate. The rates of acidic decomposition of the above clathrochelates were found to be also affected by the nature of their ribbed substituents. Therefore, the single crystal XRD experiments were performed in order to explain these results. The difference in the kinetic schemes of a formation of the boron-capped iron(II) tris-nioximates and tris-octoximates is explained by necessity of the substantial changes in a geometry of the latter ligand synthon, caused by its coordination to the iron(II) ion, due to both the higher distortion of the FeN₆-coordination polyhedra, and the intramolecular sterical clashes in the molecules of the macrobicyclic iron(II) tris-octoximates.     

Chlorine dioxide oxidation of dihydronicotinamide adenine dinucleotide (NADH)

The oxidation of dihydronicotinamide adenine dinucleotide (NADH) by chlorine dioxide in phosphate buffered solutions (pH 6-8) is very rapid with a second-order rate constant of 3.9 x 10(6) M(-1) s(-1) at 24.6 degrees C. The overall reaction stoichiometry is 2ClO2(*) per NADH. In contrast to many oxidants where NADH reacts by hydride transfer, the proposed mechanism is a rate-limiting transfer of an electron from NADH to ClO2(*). Subsequent sequential fast reactions with H(+) transfer to H2O and transfer of an electron to a second ClO2(*) give 2ClO2(-), H3O(+), and NAD(+) as products. The electrode potential of 0.936 V for the ClO2(*)/ClO2(-) couple is so large that even 0.1 M of added ClO2(-) (a 10(3) excess over the initial ClO2(*) concentration) fails to suppress the reaction rate.     

Simultaneous separation of inorganic anions and metal-citrate complexes on a zwitterionic stationary phase with on-column complexation

The retention and separation selectivity of inorganic anions and on-column derivatised negatively charged citrate or oxalate metal complexes on reversed-phase stationary phases dynamically coated with N-(dodecyl-N,N-dimethylammonio)undecanoate (DDMAU) has been investigated. The retention mechanism for the metal-citrate complexes was predominantly anion exchange, although the amphoteric/zwitterionic nature of the stationary phase coating undoubtedly also contributed to the unusual separation selectivity shown. A mixture of 10 inorganic anions and metal cations was achieved using a 20 cm monolithic DDMAU modified column and a 1 mM citrate eluent, pH 4.0, flow rate equal to 0.8 mL/min. Selectivity was found to be strongly pH dependent, allowing additional scope for manipulation of solute retention, and thus application to complex samples. This is illustrated with the analysis of an acidic mine drainage sample with a range of inorganic anions and transition metal cations, varying significantly in their concentrations levels.     

Memristive Effect in Ti3C2Tx (MXene) Polyelectrolyte Multilayers

The emerging novel class of two-dimensional materials – MХenes – have attracted significant research attention. However, there are only few reports on using the most prominent member of the MXene family, Ti₃C₂T_x, as an active material for memristive devices within a polyelectrolyte matrix and its deposition on inert electrodes like ITO and Pt. In this study, we systematically investigate Ti₃C₂T_x MXenes synthesized with two classical delamination agents, such as lithium chloride and tetramethylammonium hydroxide, to identify the most suitable candidate for memristive device applications. The characteristics of memristors based on the hybrid structures consisting of MXene−polyelectrolyte multilayers, specifically polyethyleneimine (PEI) and poly(sodium 4-styrenesulfonate) (PSS) are explored. The PEI(MXene)/PSS memristor exhibits a voltage threshold (V_SET/RESET) range of 1.5–2.0 V, enabling the transition from a high-resistive state (HRS) to a low-resistive state (LRS), along with a significant current switching ratio of approximately two orders of magnitude. The observed V_SET/RESET difference of approximately 4 V is further supported by density functional theory (DFT) calculated redox potential. These findings underscore the potential of polyelectrolyte-based memristors, such as the in PEI−Ti₃C₂T_x−PSS system, in facilitating the development of highly functional, self-assembled memristive devices with diverse applications.     

Analysis of urinary aromatic acids by liquid chromatography tandem mass spectrometry

The separation and detection of 11 urinary aromatic acids was developed using HPLC-MS/MS. The method features a simple sample preparation involving a single-step dilution with internal standard and a rapid 8 min chromatographic separation. The accuracy was evaluated by the recovery of known spikes between 87 and 110%. Inter- and intra-assay precision (CV) was below 11% in all cases and the analytes were observed to be stable for up to 8 weeks when stored at -20 degrees C. The method was validated based upon linearity, accuracy, precision and stability and was used to establish reference intervals for children and adults.     

Effects of mixed conductivity of nanocomposite membranes MF-4SC/PANI

Changes in the conducting and hydrophilic properties of composites MF-4SC/polyaniline (PAni) under conditions of prolonged synthesis have been studied. A maximum of PAni content of about 0.20 by weight, which can be incorporated into the matrix of MF-4SC under these conditions of synthesis, is determined. Percolation behavior of electrical conductivity of the composites after drying was observed. The conductivity of PAni salt inside MF-4SC was estimated within the frames of the percolation model. Using the fibrous cluster model of the membrane and the conductivity data on individual PAni, theoretical assessment of the electrical conductivity of nanocomposite MF-4SC/PAni has been performed. Reasons for a significant reduction in the conductivity of PAni during its integration into the structure of the initial matrix were discussed. A scale of membrane conductivity, reflecting changes in the electrical conductivity of composites at various stages of synthesis, was drawn.