Volume 70, Issue 10

A rapid and selective GC-MS method was optimised for the simultaneous analysis of fatty acids, phosphoethanolamine, phosphoglycerol and phosphoserine, which comprise the polar headgroups of phospholipids. Enzymatic hydrolysis was used for sample preparation to selectively release fatty acids and prevent cleavage of the phosphoester bonds of the polar headgroups. A two-step consecutive derivatisation of the fatty acids and polar headgroups was applied to enable the simultaneous analysis of the selected analytes. The method was tested on samples of cell membrane phospholipids of Bacillus subtilis , a microbe with a broad spectrum of fatty acids. This approach can accelerate and simplify biotechnological research and quality control. The experimental conditions were optimised using a chemometric approach denoted as experimental design.

A new simple cloud point extraction/preconcentration method was developed for the HPLC-MS/MS determination of disulfiram in synthetic urine. Some parameters with an effect on the extraction, such as the concentration of Triton X-114, pH influence, incubation time, equilibration temperature and centrifuging parameters, were studied and optimised. The method proposed for the HPLC-MS/MS determination of disulfiram in synthetic urine with preliminary cloud point extraction was validated. The calibration curve was linear in the range of 0.025-15.4 ng mL –1 . The limits of detection (3 σ ) and quantification (10 σ ) were 0.008 ng mL –1 and 0.025 ng mL –1 , respectively. The matrix effect (96 %), recovery of the extraction procedure (95 %) and overall “process efficiency” (91 %) were also estimated. The results show that the sensitivity, metrological characteristics, ecological safety, simplicity and convenience of the suggested procedure exceed its analogues based on extraction using organic solvents.

Amaranth, a staple food source in ancient Aztec, Maya and Inca cultures, has been recognized as a 21st century crop. This superfood, known as Inca wheat, attracts the worldwide attention of researchers and farmers for its superior agronomical and technological properties but especially because of its exceptional nutritive value. A combination of two-dimensional electrophoresis (2-DE) with MS facilitating the effective differentiation of 13 classes of Amaranthus cruentus L. “Ficha” mature seed proteins was used in the current study. The best resolution results in the 2-DE were obtained using immobilised pH gradients strips with a pH range of 5–8. Out of the 461 spots detected, 249 were successfully identified by LC-MS/MS analysis, making this the most inclusive protein profile of mature amaranth seed. Unknown proteins represented the most abundant class of proteins (59), the second most abundant category was related to energy (46) and then to seed storage proteins (43). These results expand the knowledge of the amaranth seed proteome and it is expected that the data presented here will contribute to further in-depth characterisation of Amaranthus seeds.

Hydrolytic enzymes e.g., Saps and KEX2 are, due to their role in Candida virulence, considered important targets for new synthetic inhibitors. MIC TI and MIC PI values indicate that disruption of SAP1-3 significantly increases the resistance of Candida mutants to β -ketosulfone ( 1 ). Contrariwise, sap123∆ showed sensitive phenotype to halogenated methylphenyl sulfone ( 2 ). Anticandidal potency of 2 differed in the Candida cells of kex2∆ . Sulfone is the most effective agent against the Candida albicans kex2∆ double mutant (MIC TI of 0.5 μ g mL –1 ). Up-regulation of KEX2 mediated the resistance of sap4-6∆ towards 2 . Both sulfones tested reduced the adhesion of the wild type cells significantly (P < 0.05). Contrariwise, sap123∆ showed significantly enhanced adhesion capability when 1 was used ( P < 0.05). Both sulfones had weak fungicidal effect on mature C albicans biofilms. It was shown that the uptake of IP correlates with the membrane perturbations caused by 1 in the blastoconidial cells. Sulfones were found to disturb the basic developmental phases of biofilm growth: adhesion and morphogenesis. Altered KEX2 levels for 1 can be caused by the compensatory mechanism for the maintenance of cell wall integrity and morphogenesis. KEX2 decreases the antifungal activity of sulfones. Sulfones affecting the crucial virulence factors of Candida can even eliminate these fungal infections.

Yeast responses to stress conditions include an increase in lipid content and concomitant changes in content of saturated and unsaturated fatty acids. Some fatty acids are among the dietetically important fatty acids and new possibilities are sought for their biotechnological production in addition to those already exploited from marine organisms, nuts and other sources. The possibility of the production of palmitoleic and linoleic acids resulting from new approaches to traditional biotechnologically useful yeast species ( Kluyveromyces polysporus , Saccharomyces cerevisiae , Torulospora delbrueckii ) and species capable of high accumulation of lipids ( Rhodotorula glutinis , Trichosporon cutaneum , Candida sp., Yarrowia lipolytica ) was explored. The most promising was the combination of two stress factors: limitation of N-sources (C/N mass ratio of 70 : 1) and oxidative stress induced by zero- valent iron nanoparticles. These conditions were conducive to the production of palmitoleic acid commonly used in cosmetics and medicine and ω -6-linoleic acid, a precursor of thromboxanes, prostaglandins and leucotrienes. The yield of these two fatty acids in T . cutaneum was more than 500 mg g −1 (dry mass) and in Candida sp. more than 600 mg g −1 (dry mass).

Entomopathogenic fungi are referred to as potential candidates as insect pest control agents. The objective of the study was to identify fatty acids and amino acids from Conidiobolus coronatus cultured on two different media. Each medium was extracted with ethyl acetate and its mixtures with isopropanol, acetonitrile and methanol. Analyses of fatty acids and amino acids of entomopathogenic fungus C. coronatus were performed by means of gas chromatography coupled with mass spectrometry. The analysis showed that the fungus C. coronatus produces the following groups of compounds: fatty acids and amino acids; α- and β -glucopyranose were also identified. The identified fatty acids included 12-20, 22 and 24 carbon atoms per chain. The highest content of fatty acids was detected in a mycelium sample cultured in a liquid minimal medium extracted with ethyl acetate. The lowest content of these organic compounds was identified in mycelium cultured in a liquid nutrient-rich medium extracted with ethyl acetate-methanol mixture. Fatty acids were found to account for 62.0 mass % to 94.4 mass % of all organic compounds in the analyzed mycelia. C18:1 acids were detected in the highest amounts when ethyl acetate was used as the extracting agent. The identified amino acids accounted for 4 mass % to 21 mass % of all organic compounds. Upon extraction of C. coronatus mycelium samples with the ethyl acetate-methanol mixture, two anomeric forms of glucose were also identified. An analysis of the studied material confirmed, that the entomopathogenic fungus C. coronatus is a very rich source of organic compounds, which might encourage its further research so as to identify an even larger number of compounds being produced by this species.

A series of Co-modified Ce 0.5 Zr 0.5 O 2 catalysts with different concentrations of Co (mass %: 0, 2, 4, 6, 8, 10) was investigated for diesel soot combustion. Ce 0.5 Zr 0.5 O 2 was prepared using the co-precipitation method and Co was loaded onto the oxide using the incipient wetness impregnation method. The activities of the catalysts were evaluated by thermogravimetric (TG) analysis and temperature-programmed oxidation (TPO) experiments. The results showed the soot combustion activities of the catalysts to be effectively improved by the addition of Co, 6 % Co/Ce 0.5 Zr 0.5 O 2 and that the 8 % Co/Ce 0.5 Zr 0.5 O 2 catalysts exhibited the best catalytic performance in terms of lower soot ignition temperature ( T i at 349 °C) and maximal soot oxidation rate temperature ( T m at 358 °C). The reasons for the improved activity were investigated by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), H2 temperature-programmed reduction (H 2 -TPR), X-ray photo-electron spectroscopy (XPS) and transmission electron microscopy (TEM). These results revealed that the presence of Co could lower the reduction temperature due to the synergistic effect between Co and Ce, thereby improving the activity of the catalysts in soot combustion. The 6 % Co catalyst exhibited the best catalytic performance, which could be attributed to the greater amounts of Co 3+ and surface oxygen species on the catalyst.

As a novel process intensification technology, microwave-assisted continuous reaction distillation (MRD) was proposed for the esterification reaction and separation of ethyl acetate (EtOAc). The effects of reflux ratio, mole ratio of acetic acid (HOAc) to ethanol (EtOH), reboiler duty, microwave power on EtOH conversions, EtOAc purity and mass ratio of distillate to feed (D/F) were explored. In comparison with conventional heating, the experimental results revealed that the EtOAc purity in the distillate under microwave conditions (MC) was improved. Computer simulations for conventional and MRD systems were performed using the Aspen Plus non-equilibrium stage model to substantiate the experimental results. The model predictions are in good agreement with the experimental data, revealing the accuracy and reliability of the non-equilibrium model. This new MRD process can be an effective and productive method of ester production.

Walls can exert a retardation effect on particles settling in bounded fluid media. In this work, the parallel plate retardation effect was studied for particles falling in non-Newtonian fluids along the centreline of parallel plate ducts. The eccentric effect was also investigated for those particles which approached the wall. For spheres settling in sodium carboxymethylcellulose (CMC) solutions, the variation in wall factors against the size ratio of the sphere’s diameter to the parallel plate wall spacing shows a non-linear trend; the particle settling velocity is independent at small size ratio, and then decreases quickly with increase in size ratio. A new correlation was presented covering a wider range of size ratios (0.02 < λ < 0.83) in the flow region of 0.0011 < Re < 9.75. When particles settle in polyacrylamide solutions, the fluid elasticity reduces the wall-retardation effect and it can be deduced that the drag reduction mechanism of some polyacrylamide solutions may weaken the wall retardation effect. As the spheres settling in the CMC solutions approach the wall, the neighbouring wall exerts no retardation effect at small size ratios (≤ 0.8). Then the settling velocity reduces sharply, while the effect is negligible for polyacrylamide solutions. In comparison with cylinders, the actuating range of the neighbouring wall is smaller for parallel plates.

Decomposition of flue gas desulfurization (FGD) gypsum in the presence of (10 mass %) magnetite and different mass fractions of anthracite, as a reducer, has been investigated under microwave irradiation in air atmosphere. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the decomposition residues. Both experiment results and theoretical analysis indicated that the optimum amount of anthracite added to the FGD gypsum (10 mass %) magnetite mixture was 8 mass %. Under optimum conditions, the maximum desulfurization degree after microwave treatment for 60 min at 1000°C was 93.86 %. Due to microwave heating and calcium ferrite formation, the decomposition temperature of FGD gypsum decreased to around 800°C in air atmosphere. Based on the XRD patterns and SEM images, the reaction of CaSO 4 with the additives occurred from the centre to the surface where the liquid phase was generated under microwave heating. SEM images also showed a lower amount of the liquid phase in the outermost layer samples, which prevented the formation of a kiln ring under microwave heating.

Blends of biodegradable polymers polylactic acid/thermoplastic starch/polyhydroxybutyrate (PLA/TPS/PHB) were prepared using a twin-screw extruder. The TPS content was constant (50 %) and the PHB content in the blends was gradually changed from 0 mass % to 20 mass %. TPS was prepared by melting, where a mixture of native starch, water and glycerol was fed into the twin-screw extruder. Average temperature of extrusion was 180 °C and the concentration of glycerol was 40 mass %. Influence of the PHB concentration in the blend and that of the processing technology on the mechanical and rheological properties of the PLA/PHB composition containing TPS were studied. Mechanical properties were measured 24 h after the film and monofilament preparation and also after the specific storage time to study the effect of storage on the properties. The results indicate that differences in morphology strongly influence the mechanical properties of the studied materials with identical material composition.

An extended study on a group of four soluble diphenyl-amino-stilbene based diphenyl-diketopyrrolo-pyrrole molecules has been carried out. Using the materials in thin-film transistors it was shown that the above-mentioned compounds can be successfully used as donors in organic photovoltaic devices. Influence of the molecular symmetry and solubilizing chain on the morphology and solar cell performance are described. It was shown that a shorter and non-branched ethyl acetate chain leads to higher charge carrier mobility, short circuit current, and better fill factor. After the basic optimization, a power conversion efficiency of about 1.5 % was reached. This, to the best of our knowledge, is the highest reported efficiency of thiophene-free small-molecule diketo-pyrrolopyrroles.

The metallisation of surfaces would be technologically very simple if it were possible to use the properties of the substances that decompose upon UV irradiation and produce species with a strong redox potential. In this work, diazene sulphonates are presented as possible reducing agents for Ag + in aqueous solutions and in thin solid layers. The photo-formation of Agnm+${\rm{Ag}}_n^{m + }$ clusters in the presence of diazene sulphonates in solutions was investigated via UV-VIS spectroscopy. Significant differences were observed in the electrical properties of surfaces after photo reduction; these occurred without any additional reducing agent.