Meshless methods for the inverse problem related to the determination of elastoplastic properties from the torsional experiment

The problem of determining the elastoplastic properties of a prismatic bar from the given experimental relation between the torsional moment M and the angle of twist per unit length of the rod’s length θ is investigated as an inverse problem. The proposed method to solve the inverse problem is based on the solution of some sequences of the direct problem by applying the Levenberg-Marquardt iteration method. In the direct problem, these properties are known, and the torsional moment is calculated as a function of the angle of twist from the solution of a non-linear boundary value problem. This non-linear problem results from the Saint-Venant displacement assumption, the Ramberg–Osgood constitutive equation, and the deformation theory of plasticity for the stress–strain relation. To solve the direct problem in each iteration step, the Kansa method is used for the circular cross section of the rod, or the method of fundamental solutions (MFS) and the method of particular solutions (MPS) are used for the prismatic cross section of the rod. The non-linear torsion problem in the plastic region is solved using the Picard iteration.     

Cross-coupling of vinyldisilacyclobutane with olefins catalyzed by [RuH(Cl)(CO)(PCy3)2]

Cross-coupling of vinyldisilacyclobutane with a variety of olefins in the presence of [RuH(Cl)(CO)(PCy₃)₂] leads to stereoselective formation of functionalized vinyldisilacyclobutanes. Analogous homo-coupling of vinyldisilacyclobutane leads to the formation of E- and gem-bis(silyl)ethenes. The reaction offers a new route for synthesis of attractive monomers for ring opening polymerization (ROP).     

Determination of Calcium and Iron and Measurements of Ash Content in the Brown Coal

Applying the XRF technique and the low-energy X-ray backscattering method an attempt of calcium and iron determination, as well as measurement of the ash content in the brown coal was made. A ²³⁸Pu source, an argon filled propotional counter and a three channel pulse height analyser were used. A simple theoretical model is proposed and obtained results are discussed.     

Electrostatic docking of a supramolecular host-guest assembly to cytochrome c probed by bidirectional photoinduced electron transfer

A water-soluble octacarboxyhemicarcerand was used as a shuttle to transport redox-active substrates across the aqueous medium and deliver them to the target protein. The results show that weak multivalent interactions and conformational flexibility can be exploited to reversibly bind complex supramolecular assemblies to biological molecules. Hydrophobic electron donors and acceptors were encapsulated within the hemicarcerand, and photoinduced electron transfer (ET) between the Zn-substituted cytochrome c (MW = 12.3 kD) and the host-guest complexes (MW = 2.2 kD) was used to probe the association between the negatively charged hemicarceplex and the positively charged protein. The behavior of the resulting ternary protein-hemicarcerand-guest assembly was investigated in two binding limits: (1) when K(encaps) ? K(assoc), the hemicarcerand transports the ligand to the protein while protecting it from the aqueous medium; and (2) when K(assoc) > K(encaps), the hemicarcerand-protein complex is formed first, and the hemicarcerand acts as an artificial receptor site that intercepts ligands from solution and positions them close to the active site of the metalloenzyme. In both cases, ET mediated by the protein-bound hemicarcerand is much faster than that due to diffusional encounters with the respective free donor or acceptor in solution. The measured ET rates suggest that the dominant binding region of the host-guest complex on the surface of the protein is consistent with the docking area of the native redox partner of cytochrome c. The strong association with the protein is attributed to the flexible conformation and adaptable charge distribution of the hemicarcerand, which allow for surface-matching with the cytochrome.     

Workplace air measurements and likelihood of exposure to manufactured nano-objects,agglomerates, and aggregates

Workplace exposure to nanoparticles from gas metal arc welding (GMAW) process in an automobile manufacturing factory was investigated using a combination of multiple metrics and a comparison with background particles. The number concentration (NC), lung-deposited surface area concentration (SAC), estimated SAC and mass concentration (MC) of nanoparticles produced from the GMAW process were significantly higher than those of background particles before welding (P < 0.01). A bimodal size distribution by mass for welding particles with two peak values (i.e., 10,000–18,000 and 560–320 nm) and a unimodal size distribution by number with 190.7-nm mode size or 154.9-nm geometric size were observed. Nanoparticles by number comprised 60.7 % of particles, whereas nanoparticles by mass only accounted for 18.2 % of the total particles. The morphology of welding particles was dominated by the formation of chain-like agglomerates of primary particles. The metal composition of these welding particles consisted primarily of Fe, Mn, and Zn. The size distribution, morphology, and elemental compositions of welding particles were significantly different from background particles. Working activities, sampling distances from the source, air velocity, engineering control measures, and background particles in working places had significant influences on concentrations of airborne nanoparticle. In addition, SAC showed a high correlation with NC and a relatively low correlation with MC. These findings indicate that the GMAW process is able to generate significant levels of nanoparticles. It is recommended that a combination of multiple metrics is measured as part of a well-designed sampling strategy for airborne nanoparticles. Key exposure factors, such as particle agglomeration/aggregation, background particles, working activities, temporal and spatial distributions of the particles, air velocity, engineering control measures, should be investigated when measuring workplace exposure to nanoparticles.     

Effect of high pressure on mesophilic starters for cheesemaking

In the experiment, the effect of pressurization on the survival as well as acidifying and proteolytic activity of mesophilic commercial starters used for cheesemaking was studied. The samples were exposed to a single and a double (after 24 h) pressurization in the range of 200-800 MPa, for 15 minutes, at 20 °C. Analyses were performed immediately after the processing as well as after 1, 2, and 3 weeks of storage at 4 °C. A double processing at 600 and 800 MPa caused an irreversible reduction in the number of microorganisms, inhibited the process of milk acidification but preserved approximately 20% of the initial proteolytic activity of the bacterial enzymes.     

Influence of high pressure on some biochemical properties of kefir microflora (effect of HPP on kefir microflora)

The effect of high pressure on some biochemical properties of lactic acid bacteria present in kefir was investigated. Three strains of lactococci and three strains of lactobacilli, isolated from lyophilised kefir culture, were activated in milk and subjected, at room temperature, to pressurisation at 500 MPa, for 15 minutes. Both in the unpressurised and pressurised culture the following factors were determined: survivability of microorganisms, aroma-producing activity, acidity, ability to ferment lactose and antibacterial activity. As a result of pressurisation, the initial number of bacteria decreased by ca. 2-4 order of magnitude in the case of lactococci and by ca. 5-6 order of magnitude in case of lactobacilli. After pressurisation, decrease in ability of bacteria to produce aroma was observed. Following pressurisation, an increase of acidity (pH) and slight decrease of titratable acidity (°SH) in the cultures was observed. As compared to lactococci, acidity of lactobacilli culture was reduced to a bigger extent. Pressurisation did not effect the capability of lactococci to utilise lactose. In case of lactobacilli it was partly inhibited for the first 24 hours after processing. As a consequence of pressurisation, the studied microorganisms lost their antibacterial activity.     

One‐day pulsed‐field gel electrophoresis protocol for rapid determination of emetic Bacillus cereus isolates

Bacillus cereus, the Gram‐positive and spore‐forming ubiquitous bacterium, may cause emesis as the result of food intoxication with cereulide, a heat‐stable emetic toxin. Rapid determination of cereulide‐positive B. cereus isolates is of highest importance due to consequences of this intoxication for human health and life. Here we present a 1‐day pulsed‐field gel electrophoresis for emetic B. cereus isolates, which allows rapid and efficient determination of their genomic relatedness and helps determining the source of intoxication in case of outbreaks caused by these bacilli.     

Extraction properties of octaethyltetraamidopyrophosphate (OETAPP)

The extraction of thorium and hafnium was studied in the system of 0.1M OETAPP in CHCl₃/HCl or HNO₃ at acid concentrations of 1–10 M. It has been found by the dilution method that under the experimental conditions mono- and disolvates of thorium nitrate or hafnium chloride, the disolvate of thorium chloride or the monosolvate of hafnium nitrate are formed. The solvation and hydration energies of thorium chloride in the system of 1M ThCl₄ in 1M HCl−1M OETAPP in CHCl₃ as well as their difference were calculated.