Volume 69, Issue 8

The development of a sensor based on the functionalization of common filter paper with deferoxamine (DFO) is proposed with the prospect to produce a solid phase for iron(III) and vanadium(V) sensing. The main features of this sensor are the simplicity of operation, good sensitivity and feasible applicability to real samples without the need of pre-treatment procedures. DFO was selected not only for it is easily anchored to the solid support, but also because it forms colored complexes with iron(III) and vanadium(V); hence, the developing of a simple colorimetric sensor can be considered. In particular, an innovative and economic way to perform colorimetric measurements using a desktop scanner is described. A complete characterization of the functionalized material is also reported.

A multi-analytical approach was used to investigate Roman lead-glazed ceramic artefacts from archaeological excavations at Pompeii and Herculaneum (Italy) aiming at defining the production technology of both glaze and ceramic body, by way of integrated investigations. The chemical, structural, and micro-morphological characterisations were performed using a combination of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), optical microscopy (OM), scanning electron microscopy (SEM), and micro-Raman spectroscopy. Fragments of artefacts (skyphoi, oil lamps, bowls, askoi, amphorae, krateres) of great historical and archaeological interest were sampled. LA-ICP-MS was used to determine the elemental composition by virtue of its effective lateral resolution, its ability to detect most elements and also to analyse comparably small samples. All the archaeological objects were coated with a lead-based glaze produced using a lead oxide-plus-quartz mixture, with sodium/potassium feldspars added as a flux and two different metals used: copper and iron. Two types of ceramic pastes have been identified, but chemometric techniques support the hypothesis of a Campanian provenance for the raw materials. Degradation phenomena such as the partial devitrification of the glaze, i.e. the slow structural reorganisation towards stable crystalline phases, and the leaching by mineral dissolution in the soil, were determined.

Two cholinesterases: acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), are known. The enzymes are important in the body and alteration of their activity has significant use in the diagnosis of poisoning, liver function, etc. Currently available methods for the determination of cholinesterases have some major drawbacks including various interferences and the inability to be used for decreasing the enzyme activity in the presence of reversible inhibitors due to sample dilution; hence, a method for dilution free assay of cholinesterases is desired. Here, microplates were modified with indoxylacetate (100 μL of 10 mmol L −1 solution) and used for cholinesterases assay after drying at 37◦C. The fact that indoxylacetate remains stable in dry state and serves simultaneously as a chromogen and substrate provide good prerequisites for the method. The limit of detection for BChE was 0.71 U while that for AChE was 2.8 U per a 100 μL sample (solution of enzyme or plasma sample). The limit of detection is low enough to allow standard examination of cholinesterasemia. The two cholinesterases can be distinguished from each other using selective inhibitors such as donepezil and iso-OMPA. The new method was also successfully validated for the standard Ellman’s assay using plasma samples with BChE activity adjusted by carbofuran. The new method based on indoxylacetate seems promising for routine tests.

Properties of beta-glucosidase produced by Aspergillus niger URM 6642 recently isolated from the Atlantic rainforest biome and its potential tolerance to saccharification of lignocellulosic biomass products and fermentation inhibitors was evaluated. The fungus was cultivated under solid state culture conditions at 37°C with different agro-industrial wastes. High levels of beta-glucosidase (3778.9 U g −1 ) from A. niger were obtained with rice meal as substrate under solid state culture conditions after ten days. Optimum pH for this particular beta-glucosidase activity was 4.0 although it was stable in the range of 4.0 to 7.0. The half-life (T 1/2 ) of beta-glucosidase at 55°C is 3 h. However, at the optimum temperature of the enzyme, 65°C, T 1/2 is 20 min. The enzyme showed tolerance to various compounds such as glucose, xylose, 5-hydroxymethyl furfural, furfural, coumarin, ethanol and acetic acid. Therefore, beta-glucosidase from the novel A. niger species may be of potential use in the saccharification of lignocellulosic biomass, as well as an additional enzyme supplement in cellulase cocktails used to increase the yield of fermentable sugars.

Tyrosinase from Agaricus bisporus was immobilised covalently on mesostructured siliceous foam (MCF) and three mesoporous silicas of SBA-15 type of different pore sizes, regarded as the reference, to reveal that MCF was the superior enzyme support. All the carriers were functionalised using 3-aminopropyltrimethoxysilane and the enzyme was attached covalently via glutaraldehyde or by simple adsorption and it was also cross-linked with glutaraldehyde in selected samples. The experiments indicated that only tyrosinase attached covalently was highly active and that postimmobilisation cross-linking slightly reduced its activity with no improvement in stability. MCFbound tyrosinase was the best biocatalyst with monophenolase and diphenolase activities of 3627 U mL −1 and 53040 U mL −1 of carrier sediment, respectively. Inactivation studies at 55°C showed that MCF-bound tyrosinase was 20 times more stable than the native enzyme, whereas for typical SBA-15 it was only 12 times. A comparative study with other, non-siliceous enzyme supports indicated that aminated MCF appeared to be the carrier of choice for the covalent attachment of tyrosinase.

The paper deals with the displacement washing of unbleached pulp cooked from rapeseed straw by soda pulping under laboratory conditions. Pulp fibres were characterised by their average length, as well as by effective specific volume and surface. Using the step function input change method, the washing breakthrough curves measured for alkali lignin as a tracer were described by the dispersed plug flow model containing a dimensionless criterion, the Péclet number. Besides the wash yield, the dispersion coefficient as well as the mean residence time and space time were evaluated. Preliminary results obtained for soda rapeseed pulp were compared with those for kraft hardwood (beech) and softwood (spruce, pine) pulps published earlier. The wash yield measured for soda pulp was found to be lower than that for hardwood and softwood pulps which manifested lower hydraulic resistance. The presence of silique valves in rapeseed straw resulted in lower mean residence time of lignin removed from the pulp bed in comparison with pulp manufactured from stalks only.

Demand for high-value petroleum products is increasing and crude oils and their distillation products are becoming heavier. The thermal cracking of a vacuum residue (VR) from REB (Russian Export Blend) crude oil was carried out in an autoclave. LCO (light cycle oil), naphtha, and brown coal (BC) were added with the aim of studying their effect on the final products composition. The elemental analysis (%C, %N, %H, %S) was performed and dynamic viscosity, density, GC of gases (“Refinery Gas Analysis”), solubility in hexane and toluene, and simulated distillation were examined in raw materials, gaseous, and liquid products. As anticipated, due to its high aromatics content, the addition of LCO proved the best option, obtaining the highest yield of lighter liquids. The naphtha addition resulted in a slight increment of heavier products in the gaseous phase and higher yields to solids. The literature does not contain any extensive studies of the addition of BC to VR in the hydrovisbreaking process. The addition of BC resulted in an increment in the yield of the gaseous product and assumed the highest relative total consumption of hydrogen during the reaction.

The antimicrobial properties of fifteen essential oils (EOs) tested on seventeen microorganisms were determined using the vapour-agar contact method. The most effective EOs (i.e. Lavandula angustifolia, Cymbopogon nardus, Citrus aurantifolia, Juniperus communis, Myrtus communis and Cinnamomum zeylanicum), whose volatile components afforded the best antimicrobial properties, were selected for a detailed study of chemical composition. All these six EOs contained one to three main components that presented 67-91 mass % of total mass of a corresponding essential oil. The amount of other components was much lower (less than 5 mass %). The volatile components of Lavandula angustifolia exhibited the most effective antimicrobial properties because they completely inhibited the tested bacteria and fungi within 3 days and 1 week, respectively. The components of Lavandula angustifolia with the highest concentration in the gaseous phase were linalool (99.0 ppmv), eucalyptol (44.9 ppmv), linalyl acetate (25.9 ppmv), myrcene (22.2 ppmv), β-trans-ocimene (19.7 ppmv), camphor (16.7 ppmv) and limonene (14.9 ppmv).

New salts containing cations of selected pyridine derivatives of the composition [pyH]NO 3 , where py is 2-pyridylmethanol (2-(hydroxymethyl)pyridine, 2pm), 3-pyridylmethanol (3-(hydroxymethyl) pyridine, 3pm), isonicotinamide (4-(aminocarbonyl)-pyridine, inia) and thionicotinamide (4- (aminothiocarbonyl)pyridine, tnia) were synthesised using two methods. By the first method, the above salts were obtained from reaction mixtures prepared from Fe(NO 3 ) 3 ·9H 2 O and the appropriate pyridine derivative py in ethanol without the addition of acids. The protons required for protonation of the given pyridine derivatives are formed by the protolytic reaction of [Fe(H 2 O) 6 ] 3+ , which acts as a cationic Brønstedt acid. These cations are present in the solid state of Fe(NO 3 ) 3 · 9H 2 O as well as in its solutions. Under the second procedure, the salts were prepared by a direct reaction of the selected pyridine derivative py with a diluted solution of HNO 3 . The first method affords crystals with lower yields but the second method produces microcrystals with higher yields. All the compounds were characterised by elemental analysis, infrared and NMR spectroscopic analyses and [3pmH]NO 3 and [2pmH]NO 3 by X-ray structure analysis also. [3pmH]NO 3 crystallises in the monoclinic and [2pmH]NO3 in the triclinic system.

The density of the LiF-Li 2 CO 3 melts system was measured using the Archimedean method. Using the quadratic regression orthogonal design with two factors, a regression equation for the density of LiF-Li 2 CO 3 melts was obtained in which the concentration of LiF and temperature were considered. The results indicated that the density of the LiF-Li 2 CO 3 melts decreased with either increasing the concentration of LiF or increasing temperature; a linear relation was observed between density and temperature. In addition, the influences of NaF, KF, NaCl, and KCl additives on the densities of the given systems were studied. The addition of NaF and KF increased the density of the melts, whereas NaCl and KCl resulted in an initial increase and subsequent decrease with an increasing additive concentration. The density attained a maximum at NaCl and KCl mass fraction of approximately 15 %.

Progression of drug resistance among bacterial and fungal pathogens justifies the development of novel antimicrobial agents. Thus, a series of novel sulphamethoxazole-based ureas and imidazolidine- 2,4,5-triones have been designed and synthesised. The urea derivatives were obtained by the reaction of sulphamethoxazole and isocyanates, and their cyclisation to imidazolidine-2,4,5-triones was performed via oxalyl chloride. All synthesised derivatives were evaluated in vitro to determine their activity against gram-positive and gram-negative bacteria, fungi, Mycobacterium tuberculosis, and atypical mycobacteria and their cytotoxicity. The growth of mycobacteria was inhibited within the range of 4-1000 μM and M. tuberculosis was the least-susceptible strain. 4-(3-Heptylureido)- N-(5-methylisoxazol-3-yl)benzenesulphonamide was identified as the most promising compound because it exhibited the highest activity against atypical mycobacteria at minimum inhibitory concentrations, from 4 μM, and with acceptable toxicity (selectivity indices for M. avium and M. kansasii higher than 16 and 62.5, respectively). Gram-positive bacteria, including methicillinresistant Staphylococcus aureus, were inhibited at concentrations starting from 125 μM, whereas the investigated derivatives exhibited almost no antifungal potency and activity against gram-negative species.

In the present study, a series of chalcone derivatives including 17 new compounds were synthesised; their antibacterial activities against eleven bacteria, and their free radical-scavenging activities using DPPH were evaluated. All compounds showed significant antibacterial activities against both Grampositive and Gram-negative bacteria. In particular, compound IIIf strongly inhibited Staphylococcus aureus (JMC 2151) and Enterococcus faecalis (CARS 2011-012) with MIC values of 6.25 μg mL −1 and 12.5 μg mL −1 , respectively, which are comparable to that of the standard antibiotic, nalidixic acid. Compound IIIg also inhibited S. aureus with a MIC value similar to that of nalidixic acid (6.25 μg mL −1 ). Furthermore, like nalidixic acid (MIC value of 25 μg mL −1 ), compounds IIIa, IIIc and IIId inhibited Listeria monocytogenes (ATCC 43256) with MIC values of 25 μg mL −1 , 12.5 μg mL −1 and 25 μg mL −1 , respectively. Quantitative structure-activity relationship (Q-SAR) studies using physicochemical calculations indicated that the antibacterial activities of chalcone derivatives correlated well with predicted physicochemical parameters (logP and PSA). Docking simulation by positioning the most active compound IIIf in the active site of the penicillin-binding protein (PBP-1b) of S. aureus was performed to explore the feasible binding mode. Furthermore, most of the compounds synthesised exhibited significant DPPH radical-scavenging activity, although compounds IIc and IIIc exhibited the greatest antioxidant activity with IC50 values of 1.68 μM and 1.44 μM, respectively, comparable to that of the standard antioxidant, ascorbic acid (1.03 μM).

Polypyrrole nanowires (PPyNWs) were fabricated and examined as a structural component of amperometric biosensor matrix. An enzyme, tyrosinase (TYR), was immobilized onto PPyNWs using glutaraldehyde (GA). Matrix composite morphology was investigated using scanning electron microscopy. Electrochemical behavior of the prepared PPyNWs/GA/TYR biosensor towards catechol was studied and the assessment of its analytical characteristics was carried out taking into account linear range, sensitivity, repeatability, reproducibility and operational stability.

In order to promote attachment of the ristocetin aglycone molecule to the surface of the influenza virus, the aglycone was derivatized with a hemagglutinin ligand sialic acid moiety using a click reaction. The sialoristocetin derivative exhibited somewhat lower anti-influenza virus activity than ristocetin and aglycoristocetin.