Dynamics of air drawing in the melt blowing of nonwovens from isotactic polypropylene by computer modeling

The dynamics of stationary air drawing in the melt blowing of nonwovens were determined on the basis of a single‐filament model in a thin‐filament approximation that accounts for polymer viscoelasticity, heat of viscous friction in the polymer bulk, and surface energy. Predetermined distributions of the air velocity and temperature along the melt blowing axis were assumed. Axial profiles of the polymer velocity, temperature, elongation rate, filament diameter, tensile stress, and extrapressure were computed for the melt blowing of isotactic polypropylene. The effects of the air‐jet velocity, die‐to‐collector distance, and polymer molecular weight are discussed. We predicted that the filament attenuation and velocity at the collector located in the air‐drawing zone would increase with increasing die‐to‐collector distance. The air‐drawing zone was shorter for higher air velocities and lower molecular weights. No online crystallization was predicted before the achievement of the collector, and melt bonding of the filament in the web should have occurred during cooling on the collector, accompanied by spherulitic crystallization. Significant online extrapressure in the filament was predicted in the case of supersonic air jets as resulting from polymer viscoelasticity, which could have led to longitudinal splitting of the polymer into subfilaments. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of Inoculation with Probiotics and Ageing Time on Selected Functional Properties and Oxidation of Proteins in Dry-Cured Pork Loins

The effect of inoculation with a probiotic strain Lactobacillus casei ?OCK 0900 on changes in selected functional properties and protein oxidation of dry-cured pork loins during ageing was studied. The protein carbonyls content tended to increase significantly (p < 0.05) throughout ageing to reach a maximum level which was approximately two-fold the initial level in both samples. No statistically significant differences (p < 0.05) in carbonyl content were found between the control sample and sample inoculated with L. casei. The passage of ageing time was coupled with a statistically significant (p < 0.05) increase in the trichloroacetic acid soluble peptides concentration in examined loins. Inoculation with a probiotic strain did not have an influence on trichloroacetic acid soluble peptides concentration during the shortest ageing period. Results of measurements carried out for the control sample after 21 and 28 days of ageing were significantly lower (p < 0.05) than those obtained for the sample inoculated with L. casei ?OCK 0900. Free α-amino acids content in both samples increased continuously with increasing ageing time (p < 0.05). Inoculation of loins with a probiotic strain Lactobacillus casei ?OCK 0900 resulted in significantly higher peptides and free amino acids content. These differences might affect their organoleptic characteristics that need further investigations.     

Influence of flexible segment length on the phase structure and properties of poly(hexamethylene 2,5-furandicarboxylate)-block-biopolytetrahydrofuran copolymers

Two series of biobased poly(ether-ester)s comprised of poly(hexamethylene 2,5-furandicarboxylate) (PHF) as the rigid segments and biopolytetrahydrofuran (pTHF) with different molecular masses (1000 and 2000 g/mol) as the flexible segments were synthesized employing polycondensation in the molten state. The study mainly focuses on comparing these two series in terms of the length of the flexible segment. The content of pTHF segments in the copolymer chains varied from 25 to 75 wt.%. The molecular structure and composition, phase structure, and thermal and mechanical properties were characterized by nuclear magnetic resonance (¹H NMR) and Fourier-transformed infrared (FTIR) spectroscopies, differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and positron annihilation lifetime spectroscopy (PALS). In addition, mechanical performance and thermo-oxidative and thermal stability have been investigated. Moreover, cyclic tensile properties were studied to evaluate the elastic properties. ¹H NMR and FTIR spectroscopies demonstrate that the syntheses were correctly carried out, which made it possible to obtain the desired compositions of the block copolymers with high molecular masses. The decrease in T_m1, T_c1, and X_cPHF values was visible, along with the increase in the flexible segment content. Moreover, the characteristic properties measured by PALS and the values of temperatures designated from TGA (inert and oxidizing atmosphere) did not vary between copolymer series PHF-b-F-pTHF1000 and PHF-b-F-pTHF2000. In turn, along with an increase in flexible segment content and the length of the pTHF, the values of tensile modulus, stress at break, and hardness decrease, while the value of elongation at break increases.     

Effect of Modified Starches on Rheological Properties of Ketchup

The aim of this work was to study the effect of commercial modified starches of different origin on rheological properties of ketchup. The following starches were used to produce the ketchup samples: chemically modified potato (acetylated distarch adipate from potato starch), waxy maize (acetylated distarch adipate from waxy maize starch and hydroxypropyl distarch phosphate from waxy maize starch), and cassava (acetylated distarch adipate from cassava starch) starches and physically modified cassava and waxy maize starches (physically modified cassava starch and physically modified waxy maize starch). The SEM microphotographs revealed that swollen or disrupted starch granules were present in the ketchup samples. As was evaluated by particle size distribution analysis, two peaks characteristic for different starch granule sizes were observed, the first peak at about 100 μm for ketchup thickened with potato starch and the second one at about 50 μm for the rest of the samples. Ketchups showed non-Newtonian, shear-thinning flow with tendency to yield stress. Values of the rheological parameters describing the flow curves significantly correlated with Bostwick consistency. Ketchup samples exhibited different susceptibility for temperature changes, while values of flow activation energy were from 4.18 to 9.00 kJ/mol. On the basis of mechanical spectra, it is noted that values of G′ were higher than these of G″ showing that elastic properties dominated over the viscous ones. Ketchup samples exhibited properties of weak gels which were estimated from the values of G′ and G″ moduli and their relation and from values of tangent of phase angle (tan δ = 0.14???0.37). Principal component analysis revealed both similarities and differences in rheological behavior of the examined ketchup samples thickened with different modified starches.     

Hydrogen South Africa (HySA) Systems Competence Centre: Mission,objectives, technological achievements and breakthroughs

A long-term (15-year) Hydrogen and Fuel Cell Technologies (HFCT) Research, Development, and Innovation (RDI) strategy was officially launched in September 2008 by the Department of Science and Technology (DST) in South Africa. The Hydrogen South Africa (HySA) programme is based upon the beneficiation of the country's large Platinum Group Metal (PGM) resources. HySA comprises of three Centres of Competence: HySA Catalysis, HySA Infrastructure and HySA Systems. HySA Systems, a Systems Integration and Technology Validation Competence Centre on HFCT was established in 2007 at the South African Institute for Advanced Materials Chemistry (SAIAMC) at the University of the Western Cape (UWC). The main objective with HySA Systems is to (i) develop Hydrogen and Fuel Cell systems, demonstrators, prototypes and products, (ii) perform technology validation and system integration and (iii) focus on system oriented material R&D in two key HySA-programmes: (1) Combined Heat and Power (CHP) and (2) Hydrogen Fuelled Vehicles (HFV). HySA Systems is also responsible for the development, prototyping, testing and commissioning of the following key technologies: High Temperature (HT) Membrane Electrode Assemblies (MEAs), HT-Proton Exchange Membrane (PEM) fuel cells, metal hydrides for hydrogen storage and compression systems, hydrogen fuel cell/battery power modules, palladium membranes, and lithium-ion batteries. HySA Systems has successfully: a) implemented some pilot plant manufacturing facilities/capabilities for HFC components and systems in South Africa, b) been partnering with key international HFC and local industries, c) established a local Supply Chain of SMMEs, d) set up industrial/commercial agreements with national/international HFC players, e) been disseminating their findings/work in High Impact Factor Journals and National/International Conferences, and f) innovated and thus generated Intellectual Property in key HFC technologies.     

Development of Nitrogen-Hydrocarbon Atmospheric Carburizing and Process Control Methods

Atmospheric pressure carburizing and neutral carbon potential annealing in nitrogen containing small additions of hydrocarbon gases can offer cost and steel surface quality alternatives to the comparable, endothermic atmosphere, or vacuum operations. An experimental program was conducted for refining real-time process control methods in carburizing of AISI 8620 steel under N₂-CH₄, N₂-C₃H₈ blends containing <5 vol.% of hydrocarbon gas at 900 and 930 °C. Multiple types of gas analyzers were used to monitor residual concentrations of H₂, CO, CO₂, H₂O, O₂, CH₄, C₃H₈, and other hydrocarbons inside furnace. A modified shim stock technique was additionally evaluated for correlation with gas analysis and diffusional modeling using measured carbon mass flux values (g/cm²/s). Results of this evaluation work are presented.     

Analysis of the carbonization and formation of coal tar pitch mesophase under dynamic conditions

Thermokinetic analysis of three pitch samples was carried out: coal tar pitch obtained from light coke oven tar (P), mesophase pitch after 10.5 h (MP1), and mesophase pitch after 12 h (MP2) thermopreparation at 410 °C. The process was realized in a continuous system with a 10 kg mass being charged to the reactor. It was demonstrated using Kissinger’s law that the temperature criterion, the first-order thermokinetics and the calculated Arrhenius law parameters fulfill the isokinetic effect when the classical routes of thermokinetic analysis of the samples prepared under dynamic conditions (at three heating rates) are used, which makes the qualitative interpretation of differences between these samples difficult. An alternative solution was proposed using the relative rate of thermal decomposition. The temperature ranges of the chemical reactions leading to the formation of mesophase structures, as well as the temperature ranges of the coking processes of the Fixed Carbon phase, were determined.     

Tensor Product Decomposition,Entanglement, and Bogoliubov Transformations for Two Fermion System

We consider the two-fermion system whose states are subjected to the superselection rule forbidding the superposition of states with fermionic and bosonic statistics. This implies that separable states are described only by diagonal density matrices. Moreover, we find the explicit formula for the entanglement of formation, which in this case cannot be calculated properly using Wootters’s concurrence. We also discuss the problem of the choice of tensor product decompo-sition in a system of two fermions with the help of Bogoliubov transformations of creation and annihilation operators. Finally, we show that there exist states which are separable with respect to all tensor product decompositions of the underlying Hilbert space.Presented at the 36th Symposium on Mathematical Physics, “Open Systems & Quantum Information”, Toruń, Poland, June 9–12, 2004.     

Isoprenoid Alcohols are Susceptible to Oxidation with Singlet Oxygen and Hydroxyl Radicals

Isoprenoids, as common constituents of all living cells, are exposed to oxidative agents—reactive oxygen species, for example, singlet oxygen or hydroxyl radicals. Despite this fact, products of oxidation of polyisoprenoids have never been characterized. In this study, chemical oxidation of isoprenoid alcohols (Prenol‐2 and ‐10) was performed using singlet oxygen (generated in the presence of hydrogen peroxide/molybdate or upon photochemical reaction in the presence of porphyrin), oxygen (formed upon hydrogen peroxide dismutation) or hydroxyl radical (generated by the hydrogen peroxide/sonication, UV/titanium dioxide or UV/hydrogen peroxide) systems. The structure of the obtained products, hydroxy‐, peroxy‐ and heterocyclic derivatives, was studied with the aid of mass spectrometry (MS) and nuclear magnetic resonance (NMR) methods. Furthermore, mass spectrometry with electrospray ionization appeared to be a useful analytical tool to detect the products of oxidation of isoprenoids (ESI–MS analysis), as well as to establish their structure on the basis of the fragmentation spectra of selected ions (ESI–MS/MS analysis). Taken together, susceptibility of polyisoprenoid alcohols to various oxidizing agents was shown for the first time.