Methodological approach to characterizing pollution of natural water bodies using satellite data with account of aggregation of finely dispersed mineral processing waste

The level of the environmental impact of the mining industry specifies the urgency of ecological management of the natural resources based on the satellite monitoring data. The high content of the suspended mineral particles in the industrial waters and the requirement to reduce their access to the natural water reservoirs determine the need to characterize the mininginduced pollution that can be carried out correctly with due account of the aggregate stability of dispersions. In spite of the theoretical concepts, prediction of the particles aggregation is limited by a lack of data on their interaction parameters. In order to parametrize the interactions in the mineral-water-mineral system it is proposed to use experimental data on aggregation of finely dispersed particles, obtained by the laser diffraction method in the equilibrium conditions. For this purpose the procedure of the experimental appraisal of the effective Hamaker constants has been elaborated using ores of developed deposits of the Kola mining complex as an example. The authors have studied the conditions of the surface layer of natural water reservoirs in the most industrially developed central part of the Murmansk region and defined characteristics of pollution with finely dispersed by-products of the mineral raw material treatment, according to the satellite observation data of the spatial distribution of the normalized difference turbidity index. The authors have established that the least propagation of the pollution into the natural water reservoirs is observed in the case of the apatite-nepheline ores processing by-products, which is explained by the effective aggregation of the finely dispersed nepheline particles. The proposed approach to apply data on mineral particles aggregation for interpretation of the satellite observations does not require carrying out in-situ observations and makes it possible to identify the mining-induced pollution of natural water reservoirs in industrial territories using suspended particles.

Influence of Carbon Dioxide and Humidity on the Stability of (La0.6Sr0.4)0.99Co1−xTixO3−δ Cathode

(La0.6Sr0.4)0.99CoO3−δ is a very promising cathode material due to its excellent electronic and ionic conductivity. However, when using non-artificial air from the ambient atmosphere, it contains impurities such as H2O and CO2. These chemicals cause degradation and performance loss of the cathode. Introduction of Ti into the B-site of (La0.6Sr0.4)0.99CoO3−δ improves the chemical stability of this material. (La0.6Sr0.4)0.99Co1−xTixO3−δ (0 ≤ x ≥ 0.1) electrodes prepared in this work were analyzed using X-ray diffraction method (XRD), X-ray photoelectron spectroscopy (XPS), and with electrochemical impedance spectroscopy (EIS). Studied (La0.6Sr0.4)0.99CoO3−δ materials with Ti in B-site showed reversible degradation under gas mixture with carbon dioxide addition. Under gas mixture with water addition, improved stability was observed for (La0.6Sr0.4)0.99Co1−xTixO3−δ materials with Ti in B-site compared to unmodified (La0.6Sr0.4)0.99CoO3−δ.

Mechanism and Structural Insights Into a Novel Esterase, E53, Isolated From Erythrobacter longus

Esterases are a class of enzymes that split esters into an acid and an alcohol in a chemical reaction with water, having high potential in pharmaceutical, food and biofuel industrial applications. To advance the understanding of esterases, we have identified and characterized E53, an alkalophilic esterase from a marine bacterium Erythrobacter longus. The crystal structures of wild type E53 and three variants were solved successfully using the X-ray diffraction method. Phylogenetic analysis classified E53 as a member of the family IV esterase. The enzyme showed highest activity against p-nitrophenyl butyrate substrate at pH 8.5–9.5 and 40°C. Based on the structural feature, the catalytic pocket was defined as R1 (catalytic center), R2 (pocket entrance), and R3 (end area of pocket) regions. Nine variants were generated spanning R1–R3 and thorough functional studies were performed. Detailed structural analysis and the results obtained from the mutagenesis study revealed that mutations in the R1 region could regulate the catalytic reaction in both positive and negative directions; expanding the bottleneck in R2 region has improved the enzymatic activity; and R3 region was associated with the determination of the pH pattern of E53. N166A in R3 region showed reduced activity only under alkaline conditions, and structural analysis indicated the role of N166 in stabilizing the loop by forming a hydrogen bond with L193 and G233. In summary, the systematic studies on E53 performed in this work provide structural and functional insights into alkaliphilic esterases and further our knowledge of these enzymes.

Newly Synthesized Micro-Nano Transition Metal Complexes of Hexadecanoic Acid as Anti-Microbial Agents: Synthesis, Characterization, and Biological Investigations

The synthesis of several metal complexes of d-block elements of hexadecanoic acid (palmitic acid) and its antimicrobial activity was reported in this study. UV-Vis and FT-IR spectroscopy studies were used to characterize and confirm the produced metal complexes by the shift in the absorbance and the formation of M-O linkage. The X-ray diffraction method was mainly used to examine the crystallographic faces of the complexes based on the transition metals. Thermal gravimetric investigation revealed that all metal palmitate complexes had high thermal stability in the range of 250-300°C. The metal complexes of hexadecanoic acid were examined for microbicidal activity against diverse bacterial strains and fungal pathogens using the agar well diffusion method. The copper palmitate complex presented excellent antibacterial activity among the other metal complexes. These outcomes suggest of using fatty acid metal complexes as a suitable candidate in several biomedical applications.

Amorphization and nanocrystal formation in a Pd–Ni–Cu–P alloy after cooling under different conditions

Structure formation during solidification of a Pd–Ni–Cu–P melt is studied. It is demonstrated that changes in the heat transfer conditions lead to a nonlinear change in the characteristics of the structure. The article presents the regimes of cooling the samples and the results of their structure and composition studies. It is found that a decrease in the cooling rate of the alloy leads to an increase in the size, proportion and composition of nanoinclusions in an amorphous matrix. X-ray diffraction method, electron probe microanalysis, transmission microscopy and scanning calorimetry are used for samples characterization. This article is part of the theme issue ‘Transport phenomena in complex systems (part 2)’.

Crystal structure and computational studies of N-((2-ethoxynaphthalen-1-yl)methylene)-4-fluoroaniline

The Schiff base compound, N-((2-ethoxynaphthalen-1-yl)methylene)-4-fluoroaniline, has been synthesized and characterized by X-ray diffraction method. The title compound, C19H16FNO, crystallizes in triclinic, space group P-1 (no. 2), a = 10.6343(9) Å, b = 11.4720(10) Å, c = 13.8297(13) Å, α = 102.466(7)°, β = 104.763(7)°, γ = 98.972(7)°, V = 1552.7(2) Å3, Z = 4, T = 293(2) K, μ(MoKα) = 0.086 mm-1, Dcalc = 1.255 g/cm3, 24355 reflections measured (3.16° ≤ 2Θ ≤ 51°), 5779 unique (Rint = 0.0794, Rsigma = 0.0696) which were used in all calculations. The final R1 was 0.0373 (I > 2σ(I)) and wR2 was 0.0763 (all data). The title compound contains two molecules with a similar structure in the asymmetric unit cell. The packing of the crystal structure is determined by weak C–H···F and C-H···N intermolecular hydrogen bonds. The contributions of these weak interactions in the crystal structure were calculated by the Hirshfeld surfaces and examined by the intermolecular interactions within the structure. The existence, nature and percentage contribution of different intermolecular interactions H···H, C···H, N···H, and F···H were determined using Hirshfeld surface analysis and fingerprint plots.

Benign Synthesis of Metal-Organic Framework (MIL-101-Cr) and Evaluation of Carbon-dioxide Adsorption Behaviour Employing Adsorption Isotherm Models

Background: In today’s world, rising temperature due to global warming is caused by higher concentration of carbon dioxide (CO2) emissions in the atmosphere. Metal-Organic Framework (MOF) materials have the potential to be used in carbon dioxide capture and utilization technology. Objective: The purpose of this work is to prepare metal-organic framework materials by a benign synthesis method using water as the solvent, followed by the characterization and property evaluation for CO2 adsorption study. Methods: MIL-101-Cr metal-organic framework and its derivatives with alkali ion dopants were prepared by benign hydrothermal synthesis route, which were characterized by powder X-ray diffraction method. The adsorption isotherms of CO2 for MIL-101-Cr and its derivatives were studied to comprehend the influence of alkali dopants on CO2 sorption behaviour. The equilibrium uptakes of CO2 were further evaluated by fitting the isotherms with Langmuir, Toth and Dubinin – Astakohv adsorption models to determine the adsorption parameters. Results: The crystalline structural integrity of MIL-101-Cr is not affected by doping with alkali ions. The isosteric heat of CO2 adsorption is diminished with an increase in alkali dopant size, while the induced surface structural heterogeneity increases with increasing alkali dopant size. Conclusion: The equilibrium and thermodynamic parameters calculated from this study are useful for applications in carbon dioxide capture and utilization technology.

Experimental Investigation on Aquatic Waste Water Hyacinth (Eichhorniacrassipes) Plant into Natural Fibre Polymer Composite – Biological Waste into Commercial Product

Present work dealt with evaluating the aquatic wastewater hyacinth plant long fibre reinforced withepoxy polymer composite mechanical strength, absorption, characterization, thermal degradation and stability, surface morphology studies. This research work water hyacinth long fibre is used as a reinforcement material and epoxy polymer matrix material is used as a matrix phase material. By utilizing the compression moulding hot press machine the different weight percentages (20, 25, 30, and 35%) of the hyacinth composite samples areproduced.Converting the biological waste into zero waste and useful product concept is achieved in this research. In this work hyacinth, long fibre is extracted with a new novel mechanical way (fabricated machine) of the extraction process. Hyacinth long fibre composite tensile strength (mechanical strength) is varied from 36.42 to 44.62MPa, flexural strength varied from 47.86 to 59.684MPa, and impact strength varied from 0.5 to 3.5J. After the 8th hour of monitoring the composite samples are attained constant values on both water and chemical absorption studies. By utilizing thermogravimetric analysis, x-ray diffraction method, Fourier transform infrared spectroscopy method the essential functional groups present in the hyacinth composites are identified. Based on the final experiment results the hyacinth fibre composite is highly recommended to the usage of profit oriented products.