•Three tautomers of 5-methylbenzotriazole (5MeBTA) have similar stability.•Vibrational spectra show the presence of 1H- and 3H-5MeBTA tautomers in the solid state.•Formation of NH···N hydrogen bonds ...between the 1H- and 3H-5MeBTA tautomers is confirmed.•5MeBTA is a strong agent against A. niger, C. albicans and L. monocytogenes.
Three tautomeric forms (1H-, 2H-, 3H-) of 5-methylbenzotriazole (5MeBTA) and the tetramer, which includes the 1H-5MeBTA and 3H-5MeBTA tautomers connected by N3−H⋅⋅⋅N3 and N1−H⋅⋅⋅N2 intermolecular hydrogen bonds, have been studied by density functional theory (DFT) using B3LYP, B3LYP-D3 and ωB97XD methods combined with the 6–31++G(d,p) basis set. Calculations for the tetramer have revealed that intermolecular N3⋅⋅⋅N3 distances range from 2.881 to 2.851 Å, while the N1⋅⋅⋅N2 distances vary between 2.965 and 2.915 Å. These distances are very similar to those reported for the crystal of 5MeBTA (R. K. Belter, F. R. Fronczek, CCDC 1971683, 2019). The theoretical Raman and infrared spectra of the tetramer are in a very good agreement with the FT-Raman and FT-IR spectra of 5MeBTA in the solid state, measured in this work. A detailed interpretation of the experimental vibrational spectra has been made on the basis of the calculated potential energy distribution (PED). Microbiological studies in vitro were conducted for 5MeBTA and benzotriazole (BTA) against six bacterial strains (E. coli, K. pneumoniae, P. aeruginosa, B. subtilis, L. monocytogenes and S. aureus) and two fungal strains (A. niger and C. albicans). The results have shown that the substitution by the methyl group at the C-5 atom of BTA leads to an increase in activity against tested strains, in comparison to BTA. For 5MeBTA, the inhibition zones for bacteria and fungi range from 12 mm to 20 mm, and from 13 mm to 24 mm, respectively. The title compound has revealed particularly strong activity against A. niger, C. albicans and L. monocytogenes (with inhibition zones ≥ 20 mm).
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In this study, aerobic granular sludge (AGS) was used instead of activated sludge to assess the feasibility of AGS treatment of refractory textile-dyeing wastewater. SVI30 and average sludge size of ...31 mL/g and 400 μm in the stable stage, which significantly improved sludge settleability. The experiment was designed with five operation stages, and the removal efficiency of COD and TN achieved 77.2 ± 2.5 % and 64.7 ± 1.7 % in stable stage V. AGS can fully remove pollutants to achieve the highest removal efficiency, and shortens the hydraulic retention time and air flow rate, thus saves energy and maintains stability. The specific oxygen uptake rate, nitrification rate, and denitrification rate of sludge in the system had the same change trend and peaked in the AGS maturity stage, which was 39.8 ± 0.6 mg O2/g vss·h, 4.4 ± 0.2 mg NH4+–N/g vss·h, 9.0 ± 0.5 mg NO3−–N/g vss·h, respectively. The genera Candidatus_Competibacter (12.1–18.9 %) and unclassified_f__Comamonadaceae (15.5–22.4 %) were the most abundant denitrifying bacteria after granulation. The toxic tolerant bacteria norank_o__SBR1031, norank_f__A4b, Immundisolibacter, norank_o__Ardenticatenales, and norank_f__Caulobacteraceae were enriched in granules, which enhanced the sludge resistance. This work provides insights for AGS in the face of refractory textile-dyeing wastewater, which helps to enhance the removal efficiency of nutrients and sludge resistance.
•Aerobic granular sludge (AGS) can adapt to refractory wastewater for a long-term.•The microbial activity of AGS was higher than activated sludge (AS).•AGS has advantages over AS for nutrient removal in textile-dyeing wastewater.•The enrichment of toxic tolerant bacteria enhanced the resistance of AGS.
Oral diseases as gingivitis, periodontitis, aphthous ulcers and dental caries are widespread in infants and children especially in developing countries. In this study, different Cetylpyridinium ...chloride (CPC) mucoadhesive buccal films based on chitosan (CS) blended with hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), hydroxyethyl cellulose (HEC) and polyvinyl alcohol (PVA) were developed and thoroughly characterized to improve the conventional treatment of oral diseases. Physicochemical characterization, surface pH, mechanical properties, mucoadhesion, swelling, in vitro release and microbiological activity were assessed. All films showed homogeneous content, thickness and acceptable pH for buccal mucosa. Films formulated from CS only showed the highest swelling index while blended CS films formulated using PVA and HEC showed the highest mucoadhesion however PVA based films showed higher tensile strength. The developed blended CS film with PVA (F11) displayed good antimicrobial activity and good kill-time against Streptococus mutans indicating that films based on CS-PVA could be a promising substitute for the treatment of oral diseases.
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•Chloramphenicol:β-cyclodextrin:N-acetylcysteine complex was prepared and characterized.•The water solubility of chloramphenicol was improved.•Toxicity of chloramphenicol in ...leukocytes was decreased.•Antibiofilm activity of chloramphenicol against Staphylococcus was enhanced.•The complexes maintained good antibacterial activities in vitro.
The purpose of this study was to improve the physicochemical and biological properties of chloramphenicol (CP) by multicomponent complexation with β-cyclodextrin (β-CD) and N-acetylcysteine (NAC). The present work describes the ability of solid multicomponent complex (MC) to decrease biomass and cellular activity of Staphylococcus by crystal violet and XTT assay, and leukocyte toxicity, measuring the increase of reactive oxygen species by chemiluminescence, and using 123-dihydrorhodamine. In addition, MC was prepared by the freeze-drying or physical mixture methods, and then characterized by scanning electron microscopy and powder X-ray diffraction. Nuclear magnetic resonance and phase solubility studies provided information at the molecular level on the structure of the MC and its association binding constants, respectively. The results obtained allowed us to conclude that MC formation is an effective pharmaceutical strategy that can reduce CP toxicity against leukocytes, while enhancing its solubility and antibiofilm activity.
•Clarithromycin solid forms were studied.•Exhaustive characterization in solid state was realized.•The physical stability was evaluated.
Some polymorphic drugs may undergo solid-state transformations ...as a result of storage and manufacturing processes, which could have a significant impact on the performance characteristics of the drug. The present study was conducted as a strategy to provide information on clarithromycin polymorphs. The exhaustive characterization of solid form 0, an ethanol solvate, was performed starting with the development of a new synthesis route. The structural characterization was carried on by comparing the form 0 with the form II, the one currently used on the market. A variety of techniques, such as solid state nuclear magnetic resonance, X-ray powder diffraction, infrared spectroscopy, thermoanalytical methods and confocal microscopy, were used to identify the form 0. These studies revealed important intermolecular interactions, as well as certain spatial and morphological particularities. The biopharmaceutical properties including solubility in water and simulated gastric fluid, and microbiological performance were investigated. The physical stability under normal storage conditions during 15 months was examined, revealing a desolvation process and a subtle polymorphic transformation. The studies performed on the ethanol solvate of clarithromycin could prove to be a useful tool for assays used to ensure that the drug quality remains without changes in the final dosage product.
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The paper shows that seed and planting material treatment is the most economical and least dangerous way to use pesticides. The formula of ecotoxicity calculation for comparing the danger level of ...soil pollution by various substances was given. The analysis of influence of some seed disinfectants: Black Jack (active substances – humic acids (19-21%) and fulvic acid (3-5%); Kelpak (active substances – auxins (11 mg/l), cytoxins (0.03 mg/l); Dalila (imidacloprid 600 g/l); Impact K (flutriafol (117.5 g/l) and carbendazim 250 g/l) on various groups of plants, soils and microorganisms was carried out. It was proven that the use of drugs with fungicidal action causes a certain effect on some soil parameters, mostly due to the effect on the microbiological activity of the soil. The results obtained in the research show that each of the chemical compounds, which is the active substance of the studied pesticides, does not have a significant detrimental effect on the rhizosphere biota when used separately; however, regular use of chemical pesticides can lead to an irreversible disturbance of the natural microbial balance in the soil and a gradual loss of fertility. Much attention is paid to the study of soil organisms, in particular earthworms, which have become the main test species in the tests to assess the toxicity of new xenobiotics, as well as to calculate the risks of adverse effects of pollutants on the environment. It was shown that pesticides of different nature of action have varying effects on soil microbiota and earthworms. Studies have shown that pre-sowing treatment of seeds with pesticides has undeniable economic, organizational and technological advantages over other methods of applying chemical plant protection products. The calculation of the ecological danger of pesticides was carried out and it was concluded that pre-sowing seed treatment can be called an ecologically low-hazardous measure. The paper recommended the main ways to prevent the increase of the negative impact of pesticides (including seed disinfectants) on the environment.
The article considers the results of many years of field experiment (1968-2018) conducted in the Central part of the Non-Chernozem zone of Russia (Vladimir region). The research was carried out ...during eleven rotations of the four-field grain crop rotation. The study shows the effect of use of organic and mineral fertilizers applied in various doses and combinations on crop rotation yield, fertility of sod-podzolic sandy loam soil. It was found that the organomineral fertilizer system (manure 10 t/ha + N
50
P
25
K
60
) provided stable crop rotation productivity (on average for eleven rotations) at the level of 39.9 c. e./ha, or 79.7 % higher than the control without fertilizers. The mineral fertilizer system at medium doses of fertilizers (N
50
P
25
K
60
) was at the level of the organomineral system. The organic system was inferior in efficiency to the mineral system, both at medium doses (manure 10 t/ha) and at elevated doses (manure 20 t/ha). At the same time, the long-term use of organic fertilizers provided an increase in the humus content, depending on the dose of litter manure, by 16-36 % compared to the initial values. The use of organic fertilizers led to the stabilization of the content of available forms of potassium in the soil at an average and elevated level, respectively. Stabilization of the content of mobile phosphorus in the soil at the level of average supply was noted in mineral, organomineral and organic fertilizer systems, respectively, with low and medium doses. When using increased doses of fertilizers, there is a further increase in the content of nutrients in the soil. Growing crops in crop rotation without the use of organic and mineral fertilizers gradually led to a decrease in yield. The use of fertilizers provided greater stability of crop yields over the years of the study compared to the variant without fertilizers. The soil in the variants with organic (manure 20 t/ha) and organomineral (manure 10 t/ha + N
50
P
25
K
60
) fertilizer systems was characterized by high values of the main physiological groups of microorganisms. The ratio of the number of amylolytic and proteolytic microorganisms was 1.1-1.2, that indicated a balance in the processes of mineralization of organic matter in the soil and its humification.
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•Zn(I3AAH)2)n (1), a 2D polymer of plant hormone (I3AAH2) was synthesized.•The structure of 1 was confirmed by XRD, FT-IR, FT-Raman, 1H and 13C NMR studies.•Zn(II) is bound by four ...oxygen atoms of four O-deprotonated I3AAH− ligands.•For 1, the inhibition zones for bacteria were from 11 mm to 14 mm.
A new 2D coordination polymer of indole‑3‑acetic acid (I3AAH2) with Zn(II), Zn(I3AAH)2n (1) has been synthesized and fully characterized using single-crystal X-ray diffraction, infrared, Raman, 1H and 13C NMR spectroscopy, DFT calculations and microbiological activity tests. The crystal structure is monoclinic, space group P21/n, with a = 6.1948(2), b = 7.4954(3), c = 36.2877(12) Å, β = 94.006(3)°, V = 1680.81(9) Å3 and Z = 4. The Zn atom is bound to four oxygen atoms of four O-deprotonated I3AAH− ligands, in a slightly distorted tetrahedral environment. The carboxylate groups adopt the μ-O,O′ bidentate bridging mode. Non-classical CH⋯O intra- and intermolecular interactions provide ancillary structural stabilization of 1. A theoretical study was carried out at the B3LYP/6–31++G(d,p) level. Detailed vibrational assignment for 1 was based on the calculated PED. The in vitro antibacterial activity against Gram-negative (E. coli, P. aeruginosa) and Gram-positive (B. subtilis, L. monocytogenes and S. aureus) bacteria and in vitro antifungal activity against A. niger and C. albicans of 1 were investigated. For comparison, similar microbiological tests were performed for four other Zn(II) complexes (2–5) with indolecarboxylic acids reported earlier. For 1, the inhibition zones for bacteria were from 11 mm to 14 mm, but for fungi, no inhibition zones were observed. Promising results were obtained for 3, against B. subtilis, L. monocytogenes and A. niger and for 4 against B. subtilis (with inhibition zones >20 mm).
Biochar applied to the soil has contributed to the improvement of soil quality, the availability of nutrients for plants, and carbon retention. Besides, the presence of biochar can affect microbial ...activity. However, information about the action of biochar in the microbial community is scarce. Thus, we hypothesize that biochar, with or without previous addition of NPK fertilizer may alter the activity of some enzymes and total microbial quality of soil. The objective of this study was to evaluate the enzymatic activities and the total microbiological activity of soil amendments with different doses of biochar and grown with sugarcane over time. For two consecutive years, soil samples were collected in the sugarcane planted line amendment with biochar. Sugarcane was planted in 2017, in a randomized block design, a 5 × 2 factorial scheme, with four replications: five doses of biochar (0, 10, 20, 30 and 40 Mg ha−1 (megagram per hectare)), with and without correction of soil fertility. The activities of the enzymes β-glucosidase, acid phosphatase, arylsulfatase, urease, and total microbial quality of the soil were evaluated (fluorescein diacetate method). The application of biochar from eucalyptus residues up to the dose of 30 Mg ha−1 increased the activity of the enzymes β-glucosidase, acid phosphatase, arylsulfatase, urease and the total microbial quality of the soil; however, higher doses reduced the activity of these enzymes and the total microbial quality of the soil over time. The application of mineral fertilizers, in combination with biochar, increased the enzymatic activity of β-glucosidase, arylsulfatase and urease and the total microbial quality of the soil in the soil over time. On the other hand, the addition of NPK fertilizer reduced the activities of the acid phosphatase.
•The 30 Mg ha−1 biochar dose in soil resulted in the highest microbiological activity.•Biochar plus NPK increases B-glucosidase and urease activity over time.•Biochar plus NPK in soil increases B-glucosidase, arylsulfatase, and urease activity.•Biochar plus NPK in soil reduces acid phosphatase activity.
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