Dilatometric studies of phase transition in NaNH4SeO4·2H2O single crystal

Thermal expansion of NaNH₄SeO₄SeO₄2H₂O crystal was measured by means of dilatometric method along three crystallographic axes in the temperature range of 300-140 K. Anomalies of relative expansion and thermal expansion coefficients related to ferroelectric phase transition were observed and confirmed its continuous character.     

Microstructural changes upon annealing in ODS-strengthened ultrafine grained ferritic steel

In this study, the stability of grain size and oxide nanoparticles in the ODS steel upon annealing at high temperature (650–1350 °C) has been evaluated. The ODS Fe–Cr–W–Ti–Y₂O₃ steel has been manufactured by powder metallurgy, consolidated by hot isostatic pressing and processed by hydrostatic extrusion. Such a processing brings about ultrafine grain structure reinforced with oxide nanoparticles (few nm in diameter) and results in superior mechanical properties. The stability of nano-oxides has been analyzed by small angle X-ray scattering together with transmission electron microscopy. The results obtained revealed excellent thermal stability of ultrafine grained ODS ferritic steel, which was attributed to the resistance of oxides against coarsening.     

Characterization of Extruded and Toasted Milk Protein Concentrates

Important functional properties of milk protein concentrate with 80% protein (MPC80), modified with low‐ and high‐shear extrusion, or low‐temperature toasting were compared. The effect of high‐ and low‐shear profile screws in a corotating twin‐screw extruder, and 4 different ramped temperature profiles with die temperatures of 65, 75, 90, and 120 °C were compared. Extrudates were pelletized, dried, and ground to a fine powder. Toasting was done at 75 and 110 °C for 4 h for milk protein modification. Extruded and toasted MPC80 had reduced protein solubility and surface hydrophobicity. Extrusion decreased water‐holding capacity (WHC). Toasted MPC80 had increased WHC when treated at 75 °C, but WHC decreased when heated at 110 °C. The treatments had no strong influence on gel strength. Reduced and nonreduced sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed peptide structural changes that occurred due to processing, especially for whey proteins. Results are discussed in terms of potential for application of extruded or toasted MPC80 in high‐protein nutrition bar applications.     

Influence of intercalated organoclay on the phase structure and physical properties of PTT–PTMO block copolymers

Poly(trimethylene terephthalate-block-tetramethylene oxide) (PTT–PTMO) copolymer/organoclay nanocomposites were prepared by in situ polymerization. They showed an intercalated silicate structure, as determined by X-ray diffraction and transmission electron microscopy. The influence of intercalated organoclay on the two-phase structure and mechanical properties of PTT–PTMO block copolymer was examined by using DSC and tensile tests. The DSC results imply that the silicate layers (Nanofil 32) in PTT–PTMO act as nucleation agents and accelerate the crystallization of PTT hard phase during the cooling down process from the melt. The introduction of silicate layers does not have great effect on the glass transition temperature of PTMO-rich soft phase, melting temperature of PTT hard phase, and degree of crystallinity of the nanocomposites. As the organoclay loading in the nanocomposites increase, the enhanced tensile modulus and yield stress was observed. The cyclic tensile tests showed that obtained nanocomposites have values of permanent set comparable to the neat PTT–PMO copolymer.     

Modulated On-axis Circular Zone Plates for a Generation of Three-dimensional Focal Curves

Abstract

This paper presents a new kind of computer-generated zone plate, which we call a modulated circular zone plate. These plates reconstruct a special class of focal curves. The curves are three-dimensional and lie on the lateral surface of a cylinder. As a particular case, we propose zone plates which are able to focus light on to a line segment along the optical axis. The experimental results illustrate the focusing properties of the zone plates.     

EXISTENCE OF A GENERALIZED SOLUTION IN THERMOELASTICITY WITH ONE RELAXATION TIME

The existence of a generalized solution to a natural stress-flux initial boundary-value problem of thermoelasticity with one relaxation time is established. It is shown that the solution is the limit of a sequence of classical solutions belonging to a functional space of the Sobolev type.     

Shape understanding system: Visual intelligence tests

Understanding is based on a large number of highly varied abilities called intelligence that can be measured. In this paper understanding abilities of the shape understanding system (SUS) are tested based on the methods used in intelligence tests. These tests are formulated as tasks given to the system and performance is compared with the human performance of these tasks. The main novelty of the presented method is that the process of understanding is related to the visual concept represented as a symbolic name of the possible class of shapes. The visual concept is one of the ingredients of the concept of the visual object (the phantom concept) that makes it possible to perform different tasks that are characteristic for visual understanding. The presented results are part of the research aimed at developing the shape understanding method that would be able to perform complex visual tasks connected with visual thinking. The shape understanding method is implemented as the shape understanding system. © 2005 Wiley Periodicals, Inc. Int J Int Syst 20: 799–826, 2005.     

Particle monolayers formed under irreversible conditions: jamming coverages and structure

The random sequential adsorption (RSA) approach was used for modelling irreversible adsorption phenomena of polyatomic particles at homogeneous interfaces. Particles of spherical and spheroidal shape, characterised by various axis ratio parameter A, were considered. In the latter case, the flat (side-on) and unoriented adsorption was discussed. The sticking probability (available surface function) was determined for various particle shapes together with “jamming” coverages for clean and precovered surfaces. The structure of adsorbed particle monolayers (under transient and jammed states) was analysed quantitatively in terms of the pair correlation functions. Methods of extrapolation of these results to interacting (soft) particle systems were also discussed. The theoretical predictions were confronted with existing experimental results derived for monodisperse spherical particles. A good agreement with theory was found both in respect of jamming coverages and the monolayer structure. These theoretical and experimental studies demonstrated that minor amounts of small particles (nanometer size range) exert decisive influence on adsorption of larger particles. This phenomenon can be treated as analogous to the surface poisoning effect occurring in heterogeneous catalytic systems. This revised version was published online in August 2006 with corrections to the Cover Date.     

Influence of Alkyl Chain Length on Thermal Properties,Structure, and Self-Diffusion Coefficients of Alkyltriethylammonium-Based Ionic Liquids

The application of ionic liquids (ILs) has grown enormously, from their use as simple solvents, catalysts, media in separation science, or electrolytes to that as task-specific, tunable molecular machines with appropriate properties. A thorough understanding of these properties and structure–property relationships is needed to fully exploit their potential, open new directions in IL-based research and, finally, properly implement the appropriate applications. In this work, we investigated the structure–properties relationships of a series of alkyltriethylammonium bis(trifluoromethanesulfonyl)imide [TEA-R][TFSI] ionic liquids in relation to their thermal behavior, structure organization, and self-diffusion coefficients in the bulk state using DSC, FT-IR, SAXS, and NMR diffusometry techniques. The phase transition temperatures were determined, indicating alkyl chain dependency. Fourier-transformed infrared spectroscopy studies revealed the structuration of the ionic liquids along with alkyl chain elongation. SAXS experiments clearly demonstrated the existence of polar/non-polar domains. The alkyl chain length influenced the expansion of the non-polar domains, leading to the expansion between cation heads in polar regions of the structured IL. ¹H NMR self-diffusion coefficients indicated that alkyl chain elongation generally caused the lowering of the self-diffusion coefficients. Moreover, we show that the diffusion of anions and cations of ILs is similar, even though they vary in their size.     

Analysis of a cross wedge rolling process for producing drive shafts

The paper discusses the problems of forming parts such as stepped shafts by cross wedge rolling (CWR). In industrial practice, this rolling process is performed at stages, i.e., in several passes, when large cross-sectional reductions are involved. The same can also be done using a different design of this forming process, namely, multi-wedge cross rolling (MWCR), in which the workpiece is simultaneously formed by several pairs of tools (wedges). This paper compares the above two methods with respect to forming a drive shaft. Wedge tools used in both forming processes are described, and the numerical results of the simulations performed to verify the adopted solutions are reported. The results demonstrate that the MWCR method offers more advantages than the classical CWR technique. Consequently, MWCR is then verified in experimental tests. The experimental results confirm that parts such as stepped shafts can be formed by the MWCR method.