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This work probes the effect of ultrasonic melt treatment (UST) on primary intermetallic particles and α-Al using pure Al and Al–Zr alloys (Al–0.3Zr–0.1Ti, Al–0.5Zr, Al–0.5Zr–0.5Mg–0.9Si) solidified at various cooling rates of 0.2–70 K s−1. The application of UST is shown to decrease the size and increase the number density and volume fraction of D023-structured primary Al3Zr and Al3(Zr,Ti) particles with a high nucleation potency for α-Al formation. High-resolution transmission electron microscopy analysis reveals that the cavitation-induced wetting and dispersion of γ-Al2O3 inoculant particles contribute to the refinement of primary intermetallic particles. The grain size of Al–Zr alloys increases with increasing cooling rate because of the concomitantly reduced formation of primary intermetallic inoculant particles. The UST-induced refinement of primary Al3Zr particles and the increased number density lead to grain refinement in Ti-free Al–Zr alloys. For the Ti-containing Al–Zr alloy, UST-induced grain refinement is achieved only at a very low cooling rate of 0.2 K s−1, possibly because of the side effects of UST on the growth-restricting influence of Ti. The fast cooling–induced solidification enables significant age-hardening by L12-Al3Zr nanoprecipitation (~5 nm) and is not affected by UST. Thus, this study shows that UST can be used to reduce the degree of grain coarsening of age-hardenable Al–Zr alloys at high cooling rates.

Interfacial and emulsifying properties of fractionated cricket powder were assessed to identify whether emulsification properties originate from protein or chitin particles. Fractions extracted in alkaline water, containing high protein and mineral contents, increased the surface pressure of heptane-water interfaces with near-saturation equilibrium surface pressure of 31 mN/m. Dynamic surface pressure profiles indicated adsorption of protein clusters to the interface. Emulsification capacity of protein fraction was 50% greater than that of the source cricket flour, although oil-in-water emulsions prepared with 1–2% (w/w) protein fraction formed a cream layer within one day of storage. Emulsified layers persisted for up to 20 days, and light scattering measurements described a stable population with surface-volume-mean diameter of approximately 3 μm. Chitin-rich fractions milled to a particle size of 0.5–200 μm contributed negligible surface pressure, and its emulsification capacity was 5% of the value for the source cricket flour. Emulsions prepared with chitin-rich fractions coexisted with an unstable precipitate layer comprising 60% of the added solid, which was attributed to larger particles with poor emulsifying capability. Stable chitin-stabilized emulsion phases were resistant to creaming, yet volume-mean droplet diameter surpassed 50 μm within 24 h of storage. Both protein and chitin fractions have emulsifying capabilities but would require further processing or secondary additives to achieve desirable storage stability., Graphical abstract Image 1, Highlights • Alkali-extracted proteins and chitin particles were obtained from ground cricket. • Protein fractions demonstrated strong surface activity. • Protein-stabilized emulsions creamed quickly but droplets grew slowly. • Only smallest of micrometer-scale chitin particles participated in emulsification. • Chitin-particle emulsions were prone to rapid droplet growth.

Aluminum alloys have been widely used in various industries, and continuous improvement in the properties of these alloys is required to meet consumer demand for high-performance devices. This review introduces five recent case studies where the CALPHAD method was applied in the development of high-performance Al alloys. CALPHAD calculations can reasonably predict the solidification microstructure of the Al-7Si-2Cu-1Mg alloy and 4343/3527/4343 brazing sheets, although, some deviations are caused by solid-state diffusion occurring during the actual solidification process. CALPHAD is useful for predicting the complex solidification behavior of Al-(12-18)Si piston alloys and Al-6Mg-9Si-10Cu-10Zn-3Ni natural composites, and the precipitation behavior of the Al matrix. The application of CALPHAD can also provide valuable information on the properties of Al alloys, such as that on the erosion of brazing sheets, fluidity of alloy melts, and refinement of secondary phases by melt treatment.

A mechanism describing the synergistic effect of ultrasonic melt treatment (UST) and subsequent fast cooling on the refinement of primary Si particles in a hypereutectic Al−Si alloy was investigated by examining inoculant particles via high-resolution transmission electron microscopy, serial sectioning, and melt filtration. The application of UST activated non-wetting MgAl2O4 particles with diameters of ∼0.5 μm to nucleate the primary Si phase. The cavitation-enhanced wetting of MgAl2O4 particles caused the formation of the AlP phase at the MgAl2O4 interface, further improving the nucleation potential. The cavitation-enhanced wetting and dispersion of inclusions (such as MgAl2O4) also resulted in the refinement and de-agglomeration of AlP particles. The UST-induced changes to the inoculant particles ultimately increased their number density, and the observed effects became more pronounced after increasing the degree of undercooling up to 20 K, leading to enhanced refinement of primary Si particles at higher cooling rates (up to 102 K s−1).

This paper shows that the addition of transition elements significantly influences the microstructure and tensile properties of Al–12Si alloy cast under ultrasonic melt treatment (UST). The alloys contained primary Si, eutectic Si and a variety of intermetallic compounds (IMCs); the addition of Mn and Ni changed the solidification sequence by forming primary α-Al15(Fe,Mn)4Si2 and e-Al3Ni prior to primary Si formation. The primary Si and primary IMCs competitively consumed the nucleation sites introduced by UST, thereby influencing their refining efficiencies; the efficiency of primary Si refinement by UST increased with increasing the fraction of primary Si formed prior to IMC formation, whereas it deteriorated with increasing primary IMC fraction. The refining efficiency of eutectic Si and eutectic IMCs was not affected by the type and fraction of the primary phase. Using a Ti sonotrode for UST caused Ti contamination, resulting in grain refinement by forming Ti(Al,Si)3 particles and increasing the amount of Ti solutes. Regardless of transition elements content, the application of UST improved the tensile strength at 25 °C and 350 °C. The refinement of IMCs caused by UST allowed the alloy to contain more IMCs without deterioration of room-temperature tensile strength. This enhanced the increment of high-temperature tensile strength by IMCs. Ductility of heavily alloyed systems was also improved by UST.

The effects of ultrasonic melt treatment (UST) on the microstructure and tensile properties of three multicomponent Al Si alloys with different Si contents (12, 15, and 18 wt%Si) and solution treatments were systematically investigated at room and elevated (350 °C) temperatures. The microstructures of these alloys consisted of primary Si, eutectic Si, Mg2Si, and various types of aluminides, but the average size and area fraction of the primary Si increased with Si content. The application of UST caused a transformation from dendritic to equiaxed cells and a reduction in grain size, with a significant reduction in the size of all secondary phases (i.e., Si, Mg2Si and aluminides). Both the strength and ductility at room and elevated temperatures were greatly improved by UST, mainly due to microstructure refinement. Improvements in the high-temperature tensile strength as a result of UST increased with increasing Si contents, due to the enhanced refinement of primary Si by UST with increasing Si contents. The spherodization of rigid phases induced by solution treatment can improve the strength and ductility at room temperature, but can also cause a loss of strength at elevated temperatures due to the relaxation of the interconnected network structure of rigid phases caused by their spherodization.

The combined effects of ultrasonic melt treatment (UST) with the cooling rate on the microstructural evolution in a multicomponent Al-14Si-CuNiMg casting alloy was investigated. UST was applied to a melt at 800°C, followed by casting into a steel step mold at cooling rates in the range of 4-32 K/s. UST in the fully liquid state significantly reduced the sizes of the primary phases (the phases formed before Al) crystallized in the initial stage of solidification, and the structural refinement by UST became more pronounced for a faster cooling. With trace additions of Ti, V and Zr, the primary phase is most likely (Al,Si)3(Zr,Ni,Fe), and primary Si and then Al3Ni are sequentially formed upon solidification. AlP particles, well-known nucleants for primary Si, were also found to exist inside the (Al,Si)3(Zr,Ni,Fe) and Al3Ni which exhibited a very low lattice misfit with AlP (~0.7 and 4.7%, respectively). This importantly suggests that AlP can nucleate all the primary phases while it has the highest efficiency of structural refinement by UST for (Al,Si)3(Zr,Ni,Fe) phase that first nucleated in the molten metal. The nucleation of the primary phases was quantified using an analytical model based on exponential statistics. The hierarchical refinement operated by UST is further discussed.

The effects of ultrasonic melt treatment (UST) on the microstructure and mechanical properties of Al-12.2Si-3.3Cu-2.4Ni-0.8Mg-0.1Fe (wt%) piston alloy were systematically investigated. Rigid colonies consisting of primary Si, eutectic Si, Mg 2 Si and various aluminides (e-Al 3 Ni, δ-Al 3 CuNi, π-Al 8 FeMg 3 Si 6 , γ-Al 7 Cu 4 Ni, Q-Al 5 Cu 2 Mg 8 Si 6 and θ-Al 2 Cu) were observed in the as-cast alloys. The sizes of the secondary phases, eutectic cell and grain were significantly decreased by UST because of the enhanced nucleation of each phase under ultrasonic irradiation. The yield strength, tensile strength and elongation at 25 °C were significantly improved by UST mainly because of the refinement of the microstructures. Both tensile strength and elongation at 350 °C were also improved by UST despite the unchanged yield strength.

A trace addition of Zr to a multicomponent Al-14Si-3Cu-4.5Ni casting alloy has often been found to form a coarse plate-like Zr-rich intermetallic compound with a size of a few tens of μm at the beginning of solidification. Evaluation of the phase composition has confirmed that the Zr-rich intermetallic phase consists of multicomponent constituent elements, mainly Al, Si, Ni and Fe, and is present in a form of (Al,Si)3(Zr,Ni,Fe). The existence of such a complex (Al,Si)3(Zr,Ni,Fe) phase has not yet been predicted by phase equilibria calculation of the multicomponent Al-14Si-CuNiMg systems. In this paper, transmission electron microscopy studies combined with electron backscattered diffraction pattern analysis reveals the crystallography information of the (Al,Si)3(Zr,Ni,Fe) phase for the first time and identifies it as a modified Al3Zr-D023 crystal (tetragonal, I4/mmm(139)) with slightly changed lattice parameters of a = b = 3.275 A and c = 15.475 A. The primary (Al,Si)3(Zr,Ni,Fe) phase is found to nucleate directly onto AlP particles. The mechanical properties of the Zr-rich intermetallics were also investigated using nanoindentation at both room and elevated temperatures and were compared to those of the Si phase.

A melt-assisted solid flame synthesis approach was applied to synthesize boron nanoparticles in argon gas and air atmospheres. For this purpose, we investigated the characteristics of a thermally induced combustion wave in B 2 O 3 + α Mg mixtures ( α = 1.0–1.5 mol) in argon and air atmospheres. Utilizing stoichiometrically insufficient amounts of magnesium ensured that a large portion of molten B 2 O 3 remained in the sample, which reduced the combustion parameters and favored the formation of boron nanoparticles. Under these conditions the combustion temperature and burning velocity were controlled in the range of 1300–1580 °C and 0.065–0.18 cm/s, respectively, and boron nanoparticles in a ∼20–200 nm size range were obtained. The characteristics of boron nanoparticles (morphology, purity, specific surface area, oxidation activity, etc.) were analyzed and a reaction pathway leading to boron nanoparticles synthesis was proposed.

The effect of the Ti/B4C mole ratio on the fabrication behavior of Al composites is investigated using Al–Ti–B4C powder mixtures as reactants. The quick spontaneous infiltration (QSI) process combined with the combustion reaction and DTA analysis were used. According to the thermodynamic predictions, which are verified in the experimental results, TiB2 is formed in all the samples whereas TiC is only formed in reactants with a Ti/B4C mole ratio of more than two. The C atoms from the reacted B4C do not move into TiC but instead they move into Al3BC or Al4C3 when the Ti/B4C mole ratio is less than two. In addition, the reaction mechanism with a Ti/B4C mole ratio of 0.75 is investigated extensively.

The link between language and false belief (FB) understanding has been the focus of considerable debate regarding which language component (semantics, general language, or complementation) is necessary for FB development. We examined the relative roles of complementation and receptive vocabulary in FB development in Korean-speaking and English-speaking children. FB understanding, memory for complements involving the verbs think , say and want , and receptive vocabulary were measured at three time points in 59 Korean-speaking children and 72 English-speaking children. A multi-level growth model indicated that the development of receptive vocabulary and separately the development of think understanding uniquely predicted the development of FB understanding. Neither say nor want was associated with FB understanding. The same pattern was found for Korean- and English-speaking children. The results provide evidence for the role of general language in FB understanding and against the unique role of sentential complementation.

A novel, quick, spontaneous infiltration process that combines with a combustion reaction from a powder mixture of Al–Ti–B4C–CuO is presented. The process is realized in a simple and economical way, with the whole process being performed in air in a few minutes. The microstructures of the composites exhibit quasi-continuous three-dimensional network structures composed of infiltrated aluminum and B4C particles surrounded by the aggregates of the reaction products. The composites exhibit a high elastic modulus with a low coefficient of thermal expansion.

Microstructures and wear properties of a newly developed Al–Mg–Si–CoNi alloy by the addition of ball-milled CoNi powders have been investigated. The ball-milled CoNi powder reacted with aluminum to form a ternary Al4(Ni,Co)3 phase in the microstructure and the phase retained its crystal structure until T6 treatment. The wear properties of the Al–Mg–Si–CoNi alloy have been compared to a commercial A6061 (Al–Mg–Si) alloy under dry sliding conditions. The wear test was conducted under a frequency of 4 Hz and a load range of 50–300 N. The Al–Mg–Si–CoNi alloy exhibited better wear properties than the A6061 alloy for all test conditions in this investigation. On the basis of the observation and analysis of the worn surface, worn subsurface and wear debris, the wear mechanism acting on each load has been evaluated for an Al–Mg–Si–CoNi alloy and an A6061 alloy.

A simple casting process has been applied to produce binary Mg–X (X = Ni, Cu or Al) in situ composites for hydrogen storage. Besides a major single phase of primary Mg, nanostructured eutectic networks of Mg–Mg2Ni, Mg–Mg2Cu and Mg–Mg17Al15 were formed during solidification of Mg–Ni, Mg–Cu and Mg–Al alloys, respectively. Each intermetallic phase has different effects on the hydrogen sorption kinetics of the Mg alloys due to their different reactivities with hydrogen. In this study, the relationship between hydrogen migration and microstructure of the cast Mg alloys is investigated. The influence of hydrogenation/dehydrogenation cycling on the formation of porous structures is further discussed.

In this work, a systematic study on the fabrication of Mg–Ni hydrogen storage materials is presented. Mg–6 wt% Ni base alloys were fabricated by a melting and casting process, and then ball milled by planetary ball milling. As a comparison, a sample of Mg + 6 wt% Ni was also prepared by ball milling pure elemental powders. X-ray diffraction patterns of the cast and ball-milled (BM)-cast samples show the existence of both Mg and Mg2Ni phases, while in the BM-powder sample there are some peaks corresponding to Ni particles. Hydrogen sorption properties of the samples were measured at 200 °C and 250 °C. The thermodynamic behaviour of hydrogenated samples was also investigated by differential scanning calorimetry. The ball-milled samples show enhanced hydrogen sorption properties in comparison with the cast samples, and ball-milling after casting results in superior hydrogen absorption/desorption properties in comparison with the ball-milled powder. Our discussion demonstrates that by ball-milling after casting, the Ni particles can penetrate into the deeper layers of magnesium particles and show a combination of the catalytic roles in terms of both hydrogen dissociation and hydrogen pumping to the interface between the catalyst and the Mg.

The inexpensive fabrication technique of casting is applied to develop new Mg–Ni based hydrogen storage alloys with improved hydrogen sorption properties. A nanostructured eutectic Mg–Mg2Ni is formed upon solidification which introduces a large area of interfaces along which hydrogen diffusion can occur with high diffusivity. After a few cycles of hydrogenation and dehydrogenation, an ultrafine porous structure formed in the eutectic Mg–Mg2Ni and some cracks developed along the interface between the eutectic and the α-Mg matrix. This indicates that hydrogen atoms introduced into the alloys preferentially migrate along the interfaces in the nanostructured eutectic which enables effective short-range diffusion of hydrogen. Furthermore, transition metals (TMs) such as Nb, Ti and V in the range 240–560 ppm are added directly to molten Mg-10 wt% Ni alloys and are found to form intermetallic compounds with Ni during solidification. The alloys can store 5.6–6.3 wt% hydrogen at 350 °C and 2 MPa. TM-rich intermetallics distributed homogeneously in the cast alloys appear to play a key role in accelerating the nucleation of Mg from MgH2 upon dehydrogenation. This leads to a significant improvement in the hydrogen desorption kinetics.

Mg-10 wt% Ni alloys containing up to 1 wt% Nb were fabricated by a casting technique, followed by ball-milling with 5 wt% multi-walled carbon nanotubes. Further mechanical alloying with 1.5, 3, and 5 at % Nb was applied to a cast Mg-10 wt% Ni-370 ppm Nb alloy to investigate the catalytic role of Nb in hydrogen dissociation. The microstructure and distribution of Nb and Mg2Ni in the alloys were characterised by SEM. The absorption and desorption kinetics of the samples were measured by Sieverts’ apparatus at various temperatures. The results show that addition of Nb during casting accelerates the hydrogen diffusion compared to the cast binary Mg-10 wt% Ni alloy. Moreover, ball-milling of the alloy with metallic niobium leads to the formation of BCC phase of Mg–Nb solid solution, which significantly improves the hydrogenation properties of the alloy. DSC results show that mechanical alloying of Mg-10 wt%Ni-370 ppm Nb with Nb in excess of 1.5 wt% decreases the desorption temperature by approximately 100 °C compared to the ball-milled cast alloy.

The current study investigated the effects of alcohol and gender on the intentions of engaging in sexual risk-taking. Young adults (101 men, 99 women) were randomly assigned to the alcohol, placebo, or no-alcohol conditions. Participants listened to an audiotaped scenario that presented a romantic situation between a man and a woman who had just met. Participants were asked to imagine that they were one of the individuals in the scenario and then judged their intentions to engage in sexual risk-taking. Similar previous studies (e.g., Abbey, Saenz, & Buck, 2005) employing a vignette in which the couple had known each other prior to the romantic encounter found that intoxicated individuals reported a greater willingness to engage in sexual activity than those in the placebo and control groups. In contrast, the current study's results showed that intoxicated and placebo-treated women reported a greater intention of engaging in sex than sober women (b=4.92, t=2.42, p

An Mg–6 wt% Ni alloy was fabricated by a casting technique and the drilled chips ball-milled by high energy ball milling to be examined for their hydrogenation modified with multi-walled carbon nanotubes (MWCNTs). The activation characteristics of ball-milled alloy are compared with those of the materials obtained by ball milling with 5 wt% MWCNTs for 0.5, 1, 2, 5 and 10 h. MWCNTs enhanced the absorption kinetics considerably in all cases. The hydrogen content of the modified powder with MWCNTs reached maximum hydrogen capacity within 2 min of exposure to hydrogen at 370 °C and 2 MPa pressure. X-ray diffraction analysis provided evidence that no carbon-containing phase was formed during milling. However, milling with MWCNTs reduced the crystallite size, even if the milling was carried out for only an hour. The rate-controlling steps of the hydriding reactions at different milling times were determined by fitting the respective kinetic equations. Evidence is provided that nucleation and growth of hydrides are accelerated drastically by a homogenous distribution of MWCNTs on the surface of the ball-milled powders. We show that MWCNTs are very effective at promoting the hydriding/dehydriding kinetics, as well as in increasing the hydrogen capacity of the magnesium alloy.

The impact of freezing–thawing and freeze–drying on the physical stability of oil-in-water (O/W) emulsions containing protein-coated and protein/polysaccharide-coated droplets has been studied. O/W emulsions (2 wt% corn oil, 0.12 wt% β-lactoglobulin, pH 3.5) were prepared that contained either 0 or 0.2 wt% pectin or ι -carrageenan, and 0–8 wt% maltodextrin. The emulsions were then subjected to either freeze–thaw cycling (−20 °C, 22 h; +30 °C, 2 h; ×2) or freeze–drying and reconstitution (pH 3.5). The stability of the emulsions to freeze–thaw or freeze–dry processing was then analyzed using particle size, microstructure, and creaming stability measurements. All emulsions were unstable to these processes in the absence of maltodextrin, which was attributed to extensive droplet aggregation during freezing and/or dehydration. In the presence of maltodextrin, the emulsions containing polysaccharide coatings had better stability to droplet aggregation after freeze–thaw cycling and freeze–drying than emulsions containing no polysaccharides. Specifically, considerably less maltodextrin was required to form stable emulsions when the polysaccharide coatings were present. We propose that the anionic polysaccharides formed a protective layer around the lipid droplets that improved their stability to freeze–thaw cycling and freeze–drying.

Past studies have shown inconsistent conclusions on the empirical validity of the duplex decomposition assumption that Luce proposed (1997) . The duplex decomposition assumption states that a person would feel indifferent between playing a mixed (gain and loss outcomes) lottery and playing two lotteries simultaneously or successively where one lottery is the gain part and the other lottery is the loss part of the original mixed lottery. The current study tested this assumption by investigating the equality between the certainty equivalent of a binary lottery, CE (BL), and the certainty equivalent of the duplex decomposed lottery, CE (DDL), while controlling for the response variability in the estimated CEs. The results from two experiments showed that for 69% of responses, the difference between the CE (BL) and CE (DDL) was smaller than or equal to the response variability in estimating CEs, implying that duplex decomposition cannot be rejected for a majority of responses. The size of response variability in estimated CEs was discussed.

We investigate the empirical validity of two hypotheses, duplex decomposition (DD) and general segregation (GS), regarding decomposition of a binary gamble of a gain and a loss into two unitary gambles in which one consequence of each gamble is no change from the status quo. Four binary lotteries (money gambles with specified probabilities) and four decomposed lotteries designed to test GS and four decomposed lotteries to test DD were constructed, and certainty equivalents (CEs) were estimated for each lottery. Respondents’ indifference between a binary lottery and a decomposed lottery was determined by evaluating the equality between the CE of a mixed binary lottery and the CE of the corresponding decomposed lottery. Given the variability of estimates of CEs and the lack of a clear statistical definition for the equality between two CEs, we applied several criteria: we counted responses where the difference between two CEs was either ±2% (the strictest criterion), ±4%, ±6%, or ±8% (the most lenient criterion) of the range of lottery outcomes. The results showed that under the strictest criterion, GS held for 25% of the responses and DD for 22%. Under the most lenient criterion, GS held for 56% of the responses and DD for 52%. Depending upon the criterion used, between 39 and 75% of the responses were consistent with at least one of the hypotheses. Several methodological problems in determining the indifference between two lotteries are discussed.

The effects of prepolymer molecular structure were studied in terms of reflection efficiency, polymer grating shrinkage and electro-optic property. Especially, efforts have been made to quantify holographic grating shrinkage during fabrication by modifying the chemical structure of segmented polyurethane acrylates.

This paper critically examines how risk-taking behaviors can be modeled from a decision-making perspective. We first review several applications of a decision perspective to the study of risk-taking behaviors, including studies that investigate consequence generation and the components of the overall utility (i.e., consequence, desirability, and likelihood) of risk-taking and studies that investigate the validity of two decision-oriented models (subjective expected utility and the theory of reasoned action) in predicting risk-taking behaviors. We then discuss challenges in modeling risk-taking behaviors from a decision-making perspective. These challenges include (i) finding the factors that are necessary to improve the predictability of models, (ii) difficulties in eliciting the individual components of overall utility, and (iii) incorporating overall utility changes over time. Copyright 1999 Academic Press.

The present experiment was designed to test whether choice-induced certainty equivalents (CEs) and joint receipt (JR) of gambles exhibit certain properties such as the equality of JR and convolution, monotonicity of convolution, monotonicity of JR over gambles, additivity of JR over gambles and money, segregation of a common consequence, additive segregation when JR is replaced by +, and several other derivative properties. Subjects were partitioned into "gamblers" and "nongamblers" by their performance on screening gambles. Assuming that CE is order preserving, monotonicity of JR and additivity of JR over gambles were both rejected whereas additivity of JR over money, segregation, and additive segregation were all sustained for gamblers and nongamblers. For gamblers, convolution is not monotonic but is equivalent to JR and segregation and additive segregation are not equivalent. For nongamblers, convolution is monotonic but is not equivalent to JR and segregation and additive segregation are probably equivalent.

The electrical conductivity measurements on single crystals of K 2 SO 4 have been carried out in the temperature range from 300 to 800°C. The bulk ionic conductivity along the three principal crystallographic axes has been determined by means of complex impedance formalism. The ionic conductivity in the low-temperature β phase follows closely the classical Arrhenius law up to around 540°C, which is some 50°C below the β → α transition temperature ( T c ). From 540°C, the slope of the conductivity curve increases up to T c and is attributed to the existence of a pretransitional region, in which significant rotational disorder of sulfate ions is present. The thermal hysteresis of theα ↔ β transition and the conductivity anisotropies are discussed. The dielectric properties and the conductivity relaxation studies by means of electric modulus formalism are also discussed.

α-Chymotrypsin (ChT) is covalently linked to various poly(ethylenimine) (PEI) derivatives by using a carbodiimide as a coupling reagent. The PEI derivatives contain cationic or anionic microenvironments. In addition, hydrophobic microdomains are created on the PEI backbones in conjunction with the ionic environments. Stabilization of the tertiary structure of ChT by the cross-linking PEI derivatives is reflected by much greater resistance of the PEI-bound ChTs to thermoinactivation. Depending on the structural elements incorporated into the PEI derivatives, the activity of ChTs linked to PEI derivatives in either/both acidic or/and basic pH ranges is much greater than that of native ChT. The nature of microdomains introduced to the globular backbone of PEI affects the p K a values of the active-site groups of ChT sensitively. Cationic microenvironments created on the PEI backbone retards protonation of His-57 more than that of Ile-16. Anionic microenvironments of the PEI backbone stabilize the ammonium ion of Ile-16 more than the imidazolium ion of His-57. Moreover, substrate binding by the active site appears to render His-57 more sensitive to the change in the microenvironments.