Silicon carbonitride layers deposited on titanium and polyurethane by PACVD method

This work reports the results concerning formation and tribological properties of SiC _x N _y (H) layers deposited on Ti Grade 2 and polyurethane foil. Depending on the substrate, two variants of PACVD were used. The SiC _x N _y (H) layers on titanium were deposited with application of MWCVD (2.45 GHz, 2 kW). The layers on polyurethane were deposited using RFCVD (13.56 MHz, 400 W). Good adhesion between the SiC _x N _y (H) layers and polymeric foil was achieved by formation of a transitional C:N:H layer and incorporating Si gradient into the structure of the SiC _x N _y (H) layer. The chemical composition of the layers was tailored by precise control of the gaseous precursors ratios: [SiH₄]/[NH₃], [SIH₄]/[NH₃]/[CH₄], [SiH₄]/[CH₄] or [SiH₄]/[N₂]/[CH₄]. The structure and chemical composition of the obtained layers were subjected to further studies (FTIR, SEM/EDS). The roughness, friction coefficient and wear resistance were also measured. The results show that SiC _x N _y (H) layers offer attractive tribological properties which make them good candidates for various applications, including biomedical devices.     

Comparative study of nanopores in activated carbons by HRTEM and adsorption methods

Detailed analysis of nanopores (IUPAC micropores at pore half-width x < 1 nm) of carbonised porous phenolformaldehyde resin microbeads used as a precursor of activated carbon (AC) and CO₂ activated carbon (at 50% burn-off) has been performed on the basis of high-resolution transmission electron microscopy (HRTEM) image analysis and nitrogen adsorption data analysed using several density functional theory (DFT) methods. The results of quenched solid DFT (QSDFT) and nonlocal (NLDFT) are in agreement with the pore size distributions of nanopores based on the HRTEM image analysis. Development of porosity with progressive activation degree in a series of ACs leads to enhancement of the deviation of the pore shape from the used pore models. The TG/DTA data and Raman spectra show nonlinear but weak changes in the AC characteristics with increasing burn-off degree.     

Identification of Photoproducts of Hexahydroquinoline Derivatives by GC-EI-MS and HPLC-ESI-MS

Photoproducts of hexahydroquinoline derivatives have been analyzed with gas chromatography electro ionization-mass spectrometry (GC-EI-MS) and high performance chromatography electrospray ionization-mass spectrometry (HPLC-ESI-MS). The study was performed on four HHQ derivatives: 2,6,6-trimethyl-3-carbomethoxy-5-oxo-4-(R-phenyl)-1,4,5,6,7,8-hexahydroquinoline; R=2′-Me, 3′-Me, 2′-MeO, and 3′-MeO. The photochemical degradation of each of the HHQ derivatives led to the appearance of one product. The photoproducts were identified as the corresponding tetrahydroquinoline analogues, which were formed by dehydrogenation of dihydropyridine moiety. In GC-mass spectra, the most frequent way of fragmentation was elimination of CH₃* or CH₃O* radical of the ester group. In the photoproducts substituted at 2′-position of the phenyl ring, elimination of isobutene (C₄H₈) was observed. In the photoproducts with 3′-position substituents, elimination of COOCH₃* radical was noted.     

The Effect of Seed Size and Microstructure on Their Mechanical Properties and Frictional Behavior

The seeds of grass pea were selected based on their size, hardness, and microstructure in order to examine their mechanical properties and friction coefficients versus mass. The size, shape, mass, and static friction coefficients of seeds were determined using adequate methods. Seed hardness was measured using compression methods, and it was described by typical and corrected fracture parameters. The microstructure of cotyledons and seed surfaces was viewed using scanning electron microscopy, and surface microimages were processed by digital image analysis. The length of the examined seeds ranged from 5.86 mm to 14.25 mm, their width ranged from 5.47 mm to 12.93 mm, thickness from 4.59 mm to 6.21 mm, mass from 0.110 g to 0.570 g, projected area from 28.55 mm² to 148.73 mm², and roundness from 1.060 to 1.126. The static friction coefficients for seeds of the examined accessions and varieties determined on steel, wood, rubber, and PVC surfaces were 23.4–33.3°, 24.4–37.2°, 29.6–50.4°, and 22.4–35.4°, respectively. For grass pea seeds of irregular size and shape, corrected fracture energy values (with regard to seed mass and volume) were proposed as a more robust parameter of seed hardness. The values of the static friction coefficient depend on both seed mass and the microstructural properties of seed surface digitalized with the involvement of image analysis techniques.     

Structural changes in the wheat dough and bread with the addition of alpha-amylases

The influence of fungal and bacterial -amylases on the texture and microstructure of dough and bread was investigated. Loaf specific volume, crumb porosity and texture properties were accepted as bread structure and texture characteristics. The microstructure analysis of dough and bread using light and scanning microscopy methods was performed.The changes in loaf specific volume, crumb porosity and texture properties showed different anti-staling activity of the enzymes used. The simultaneous action of enzyme addition and the fermentation process evoked significant changes in the microstructure of dough. The character of these changes depended on the kind of enzyme used. A substantial effect of both amylases on starch behaviour during bread baking and staling was also observed.     

The Effect of Polycyclic Aromatic Hydrocarbons on the Structure of Organotrophic Bacteria and Dehydrogenase Activity in Soil

The objective of this article was to determine the structure of microbial communities and the activity of dehydrogenases in soil samples contaminated with four polycyclic aromatic hydrocarbons (PAHs), i.e., naphthalene, phenanthrene, anthracene, and pyrene, in the amount of 0, 1000, 2000, and 4000 mg kg^?1soil DM. Organic substances—cellulose, sucrose, and compost—were added to the samples in the amount of 0 and 9 g kg^?1soil DM. The experiment was performed in a laboratory on samples of loamy sand. Indices of colony development (CD) and eco-physiological diversity (EP) of organotrophic bacteria, soil resistance (RS), and soil resilience (RL) were calculated. Soil contamination with PAHs differentiated the structure of organotrophic bacteria, and the lowest CD and EP values were noted in soil samples containing pyrene. PAHs inhibited the activity of dehydrogenases, and pyrene exerted the most inhibitory effect on enzyme activity. Dehydrogenase activity was determined mainly by the applied PAH dose, the date of analysis and the type of organic substance added to soil. Low RL values indicate that exposure to PAHs induces long-term changes in dehydrogenase activity.     

Effect of ground corn steeping on starch properties

Pasting and thermal properties, and microstructure of starch from ground corn (GS) steeped at 52 °C in sulphurous acid solution (0.20%) at different steep times (8, 16, 24, 32 and 40 h) were investigated. The isolated starch obtained by wet milling was characterised by determining pasting properties in Rapid Visco Analyser (RVA), retrogradation enthalpy in differential scanning calorimetry (DSC), and microstructure of granules in light (LM) and scanning electron microscopy (SEM). Milling before steeping and long steep time caused reduction in peak, hot paste, cool paste, breakdown and setback viscosities. Steep time provoked an increase in the retrogradation temperatures (onset and peak), whereas no significant differences were found in retrogradation enthalpy. Microstructure characteristics analysed by SEM showed many cracks and cavities on surface in samples steeped 8 h, whereas samples steeped 40 h showed a great alteration and disruption of their inner layer. LM with polarised light confirmed that starches retained birefringence with several differences depending on the steep time. The use of ground kernels allowed a better steep solution–endosperm interaction, which caused changes in rheological, thermal and microstructural starch characteristics.     

Effectiveness of Water Management in Europe in the 21st Century

Research on water scarcity and water management in Europe has accelerated significantly in the past two decades, mainly as a result of growing water demand for agricultural, industrial, and municipal uses. Most research studies in the field evaluate water use and management by means of static indicators that depict a one-time value for a given time period (e.g., one year). This paper suggests a dynamic indicator measuring product (here: water) generational dematerialization. The indicator presents a comprehensive approach for evaluating water resources and water management strategies, as it represents a function of both resource use changes and population changes occurring simultaneously and over time. To accentuate the benefits of this dynamic indicator over static indicators as well as its practical applicability for decision-making support, the paper evaluates water management in Europe based on the total water use between 2001 and 2013. The results show that water management estimated cumulatively for the analyzed European countries has been effective for the last 13 years, though significant regional variations have been found. The research and the dynamic water generational dematerialization indicator can be helpful with addressing regional and national water deficit problems and designing sustainable water management strategies in the mid- and long-run.