Effect Of Matrix Structure Research Articles

Effects of Matrix Structure on Protein Digestibility and Antioxidant Property of Different Soybean Curds During In Vitro Digestion.

This study compared the three most common types of tofu (soybean curd), which were prepared by using magnesium chloride (MgCl2 tofu), calcium sulfate (CaSO4 tofu), and glucono-δ-lactone (GDL tofu) coagulants. The results showed that GDL tofu had a higher water holding capacity than MgCl2 tofu and CaSO4 tofu, which was attributed to its high surface hydrophobicity and disulfide bond content. GDL tofu possessed the lowest firmness, gumminess, and chewiness, along with a uniform network structure and a thin protein matrix. In contrast, MgCl2 tofu exhibited an inhomogeneous network structure with a thick protein matrix. Combining the results of protein hydrolysis degree, SDS-PAGE, and free amino acids during in vitro digestion, it was indicated that the degree of protein digestion in GDL tofu was the highest. After intestinal digestion, GDL tofu had the highest total phenolic content, ferric reducing antioxidant power, and DPPH value. These results demonstrated the superior protein digestibility and antioxidant property of GDL tofu during in vitro digestion due to its structural characteristics that facilitate enzyme diffusion in the matrix. The findings offer insight into the protein digestibility and antioxidant properties of different types of tofu during digestion from structural characteristic perspective and valuable reference information for consumer dietary nutrition.

Effect of matrix structure on mechanical properties and dry rolling–sliding wear performance of alloyed ductile iron

The influence of matrix structure on mechanical properties and dry rolling–sliding wear performance of alloyed ductile iron was examined. Four kinds of alloyed ductile irons with different matrix structures were produced through an adequate balance of alloying elements. Tensile tests and dry rolling–sliding wear tests were carried out at room temperature. The results show that yield strength and ultimate tensile strength increase, while elongation decreases until the matrix fully becomes pearlite. The lower matrix hardness results in more graphite emerging on the contact surface, which yields the decrease in friction coefficient. Besides, the wear rate decreases with the increase in matrix hardness among alloyed ductile irons except that with full pearlite matrix, the wear performance of which seems to be deteriorated due to poor fracture toughness. The main wear mechanism is delamination under an air-cooling condition. Based on the results of mechanical and wear tests, ductile iron with about 80% pearlite exhibits better wear performance as well as relatively reasonable mechanical properties.

Effects of Matrix Structure on Hydrogen Embrittlement in Ductile Iron

Effects of Matrix Structure on Hydrogen Embrittlement in Ductile Iron

Effects of Matrix Structure and Stress Ratio on Fatigue Limit of Spheroidal Graphite Cast Iron

Effects of Matrix Structure and Stress Ratio on Fatigue Limit of Spheroidal Graphite Cast Iron

Morphology of blends containing high concentrations of POSS nanoparticles in different polymer matrices

AbstractThis article reports an investigation into the miscibility and morphology of octaisobutyl‐substituted polyhedral oligomeric silsesquioxane (ibPOSS) nanocages over a wide concentration range (25–75 wt%) in polymer matrices, produced by solution blending. Three different, strategically chosen polymers were used: polystyrene (PS), poly(isobutyl methacrylate) (PIBMA), and poly(methyl methacrylate) (PMMA), to allow the effect of matrix structure and polarity on miscibility to be investigated. Differential scanning calorimetry, dynamic mechanical analysis, X‐ray diffraction, and scanning electron microscopy were used to characterize the composite systems. The Tg of PMMA and PIBMA were found to increase with introduction of ibPOSS, whereas PS did not show any significant change of Tg with increasing POSS content, indicating differing degrees of interaction. The phase separation has been found and a cubic POSS crystal structure has been observed in all blends with different size. The glass transition increased with concentration, even though all compositions were predominantly phase‐separated, and we suggest that this is due to the influence of the external face of the crystalline units on the polymer chains, and possibly some polymer contained within the crystalline POSS phase. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers

Optimization of a scanner imaging technique to accurately study oil migration kinetics

The aim of this study was to refine an image analysis technique that was developed in our laboratory in order to study oil migration in confectionery products (Marty, S., Baker, K., Dibildox-Alvarado, E., Neves Rodrigues, J., & Marangoni, A. G. (2005). Monitoring and quantifying of oil migration in cocoa butter using a flatbed scanner and fluorescence light microscopy. Food Research International). The migration of a nile red stained oily phase (soft fat) was monitored in tempered cocoa butter matrices kept at 18 °C for about 75 days. Oil migration kinetics was quantified using a common flatbed scanner followed by image processing and analysis. The most reliable parameter derived from this analysis is the position of the dye front (I10) where the intensity of the dye is 10% of maximum. The determination of the amount of dye migrated from pixel intensity measurements was found to be highly affected by cocoa butter structure at times greater than 28 days, but I10 was not. The determination of a model-independent oil migration rate (I10/tn) using this method was found to be highly reproducible and accurate. Due to the observed non-linearity of the oil migration process and the effects of matrix structure on the determination of pixel intensity (and thus mass of dye migrated), the quantification of oil migration using the simplified version of Fick’s second law is not recommended.

The effect of matrix structure on the diffusion of fluids in porous media

The effect of matrix structure on the transport properties of adsorbed fluids is studied using computer simulations and percolation theory. The model system consists of a fluid of hard spheres diffusing in a matrix of hard spheres fixed in space. Three different arrangements of the fixed spheres, random, templated, and polymeric, are investigated. For a given matrix volume fraction the diffusion coefficient of the fluid, D, is sensitive to the manner in which the matrix is constructed, with large differences between the three types of matrices. The matrix is mapped onto an effective lattice composed of vertices and bonds using a Voronoi tessellation method where the connectivity of bonds is determined using a geometric criterion, i.e., a bond is connected if a fluid particle can pass directly between the two pores the bond connects, and disconnected otherwise. The percolation threshold is then determined from the connectivity of the bonds. D displays universal scaling behavior in the reduced volume fraction, i.e., D approximately (1-phi(m)phi(c))(gamma), where phi(m) is the matrix volume fraction and phi(c) is the matrix volume fraction at the percolation threshold. We find that gamma approximately 2.2, independent of matrix type, which is different from the result gamma approximately 1.53 for diffusion in lattice models, but similar to that for conduction in Swiss cheese models. Lattice simulations with biased hopping probabilities are consistent with the continuous-space simulations, and this shows that the universal behavior of diffusion is sensitive to details of local dynamics.

The effect of matrix structure on the fatigue behavior of austempered ductile iron

The primary objective of this study has been to investigate the fatigue behavior of the austempered unalloyed ductile iron. Ductile iron specimens were austenized at 900 °C for 110 min and then one group specimens were austempered at 230, 330, 430 °C for 60 min, and another one group specimens were austempered at 330 °C for 30, 60, 120 min to obtain different microstructures. Rotating bending tests (10 million cycles) were conducted on the ductile iron and the austempered specimens selecting completely reversed cycle of stress ( R = minimum stress/maximum stress = −1). The highest fatigue strength was found in the bainitic structure (ausferritic). The presence of martensite or carbide phases in the structure of austempered ductile iron reduces the fatigue strength.

Effect of matrix structure on ultrasonic attenuation of ductile cast iron

The ultrasonic attenuation of ductile cast irons with different matrices was investigated by means of ultrasonic echo waves. In the ductile cast irons with ferritic and pearlitic matrix structures, both of the ultrasonic attenuation increased with frequency. For similar frequencies, the ultrasonic attenuation of the pearlitic matrix was larger than that of the ferritic matrix. Based on the theory of ultrasonic attenuation in the solid, the mechanisms of ultrasonic attenuation in the ductile cast irons with different matrices were analyzed. It indicated that in the ductile cast irons with transformation of matrix from the ferrite to the pearlite, the mechanism of ultrasonic attenuation varied in the range of present frequencies. In the ferritic matrix, the total ultrasonic attenuation was mainly attributed to the scattering loss which included the stochastic scattering and the Rayleigh scattering. On the contrary, the absorption loss predominated in the total ultrasonic attenuation of the ductile cast iron with pearlitic matrix.

Effect of matrix structure on the impact properties of an alloyed ductile iron

An investigation was performed to examine the influence of the matrix structure on the impact properties of a 1.03% Cu, 1.25% Ni and 0.18% Mo pearlitic ductile iron. Specimens were first homogenized at 925 °C for 7 h and a fully ferritic structure was obtained in all ductile iron samples. Then, various heat treatments were applied to the homogenized specimens in order to obtain pearlitic/ferritic, pearlitic, tempered martensitic, lower and upper ausferritic matrix structures. The unnotched charpy impact specimens were tested at temperatures between − 80 °C and + 100 °C; the tensile properties (ultimate tensile strength, 0.2% yield strength and elongation) and the hardnesses of the matrix structures were investigated at room temperature. The microstructures and the fracture surfaces of the impact specimens tested at room temperature were also investigated by optical and scanning electron microscope. The results showed that the best impact properties were obtained for the ferritic matrix structure that had the lowest hardness, yield and tensile strength. Ductile iron with a lower ausferritic matrix had the best combination of ultimate tensile strength, percent elongation and impact energies of all structures.

In silico study on the effects of matrix structure in controlled drug release

Abstract Purpose: To study the effects of drug concentration and spatial distribution of the medicament, in porous solid dosage forms, on the kinetics and total yield of drug release. Methods: Cubic networks are used as models of drug release systems. They were constructed by means of the dual site–bond model framework, which allows a substrate to have adequate geometrical and topological distribution of its pore elements. Drug particles can move inside the networks by following a random walk model with excluded volume interactions between the particles. The drug release time evolution for different drug concentration and different initial drug spatial distribution has been monitored. Results: The numerical results show that in all the studied cases, drug release presents an anomalous behavior, and the consequences of the matrix structural properties, i.e., drug spatial distribution and drug concentration, on the drug release profile have been quantified. Conclusions: The Weibull function provides a simple connection between the model parameters and the microstructure of the drug release device. A critical modeling of drug release from matrix-type delivery systems is important in order to understand the transport mechanisms that are implicated, and to predict the effect of the device design parameters on the release rate.

Effects of Matrix Structure on the Resonant Vibration Behavior of Spheroidal Graphite Cast Iron

This investigation examined the resonant vibration fracture behaviors of spheroidal graphite (SG) cast iron with various matrix structures. The results show that the vibration life is determined by a combined effect of the damping capacity and cracking resistance of the matrix. The structure surrounding graphite nodules also plays an important role since the stress concentrates in the vicinity of the nodules during vibration.

Evaluation of patch isolation metrics in mosaic landscapes for specialist vs. generalist dispersers

We examined the effects of matrix structure and movement responses of organisms on the relationships between 7 patch isolation metrics and patch immigration. Our analysis was based on simulating movement behaviour of two generic disperser types (specialist and generalist) across mosaic landscapes containing three landcover types: habitat, hospitable matrix and inhospitable matrix. Movement, mortality and boundary crossing probabilities of simulated individuals were linked to the landcover and boundary types in the landscapes. The results indicated that area-based isolation metrics generally predict patch immigration more reliably than distance-based isolation metrics. Relationships between patch isolation metrics and patch immigration varied between the two generic disperser types and were affected by matrix composition or matrix fragmentation. Patch immigration was always affected by matrix composition but not by matrix fragmentation. Our results do not encourage the generic use of patch isolation metrics as a substitute for patch immigration, in particular in metapopulation models where generic use may result in wrong projections of the survival probability of metapopulations. However, our examination of the factors affecting the predictive potential of patch isolation metrics should facilitate interpretation and comparison of existing patch isolation studies. Future patch isolation studies should include information about landscape structure and the dispersal distance and dispersal behaviour of the organism of interest.

Effects of Matrix Structure and Defect Size on Fatigue Limit of Heat-treated Spheroidal Graphite Cast Iron

Effects of Matrix Structure and Defect Size on Fatigue Limit of Heat-treated Spheroidal Graphite Cast Iron

Transition metal complexes bound to macroporous resins carrying nitrile groups. Effect of matrix structure on the activity of supported catalysts

Two groups of resins bearing nitrile (CN) groups based on macroporous copolymers of acrylonitrile and divinylbenzene (AN/DVB) and terpolymers of styrene, acrylonitrile and divinylbenzene (S/AN/DVB) have been used as polymer matrices for the immobilization of Rh(I), Pt(II) and Pd(II) complexes. A group of four S/DVB resins functionalized with the CN ligands have been prepared and used for comparison. The resins differ in their chemical and physical structure, local concentration of the CN groups and their availability. Characterization of the heterogeneous complexes by IR spectroscopy confirmed the coordination of the metal ions to the polymer-CN ligands. The catalytic behaviour of the immobilized complex catalysts was tested in the hydrosilylation of 1-hexene. The activity of the polymer-bound catalysts strongly depends on the structure of the support used. The largest effect of the chemical structure of the polymer was found for the catalysts immobilized on the AN/DVB resins, while the polymer morphology played the major role in the high activity of the catalysts attached to the S/N/DVB resins. Lower activity was found for the systems bound to the functionalized S/DVB resins. Both polymer-supported Pt and Rh systems appeared to be highly effective for the hydrosilylation of the CC double bonds, but the platinum catalysts proved to be considerably more active. The rhodium catalysts were found efficient in the hydrosilylation of ketones. The immobilized Pd(II) complex was reduced to the metallic Pd by hydrosilanes. The supported Pt catalyst remained active when recycled 5 times, while the activity of the rhodium systems gradually decreased. The results offer the possibility of choosing the most suitable polymer matrix for the immobilization of metal complex catalysts for use in hydrosilylation and other catalytic reactions.

Environmental stress corrosion behavior of polyamides and their composites with short glass fiber and glass swirl mat

Environmental stress corrosion cracking (ESC) behavior of different polyamides (PA) without and with short and glass fiber mat reinforcements was studied in air, water and diluted sulfuric acid and compared. Whereas the neat polymers and their short glass fiber reinforced versions failed by crack growth, the breakdown of the glass mat reinforced polyamide block copolymer (NBC) depended on the corrosion loading history, i.e. on the immersing time. The ESC response of the systems studied was analysed and summarized schematically indicating the effects of matrix structure, type and amount of the reinforcement and environment. Characteristic failure events were also revealed and included in related models. Guide-lines for further material improvements were deduced.

Effects of matrix structure on mechanical properties of carbon/carbon composites

Mechanical properties of carbon/carbon composites prepared by thermal-gradient CVD technique were investigated by three-point flexural tests. The mechanical properties are strongly influenced by the matrix structure, which in turn depends on the deposition conditions employed. The lower fracture stress and elastic modulus of isotropic structure and columnar structure are due to the low matrix density and to the presence of matrix cracks, respectively. The transition structure shows relatively high modulus and stress. The fracture strain remains almost constant over the whole ranges investigated. The role of the matrix crack during the fracture is discussed.

Zn-Al合金の腐食挙動に及ぼす組織の影響

Zn-Al合金の腐食挙動に及ぼす組織の影響

Influence of matrix structure on fatigue strength of nodular iron with high tensile strength.

The rotating fatigue tests were carried out on nodular irons with 7 types of matrix structures prepared by heat treatments, and effects of matrix structure on the fatigue limit σw were examined. In order to study the crack initiation and growth, the fracture surface was observed by SEM. The results obtained were as follows : (1) The effect of matrix structure on σw was remarkable. (2) Among irons with ferrite-pearlite duplex structures, the iron with the finest spheroidal graphite prepared by the metal mold had the highest fatigue limit. (3) Among irons with hardened matrix structure prepared by cooling of high rate, the iron with upper bainite had the highest fatigue limit. (4) The matrix structure influenced the metallurgical factor that initiated the crack, because increasing Hv of the matrix structure induced the high notch sensivity of micro-porosity. This fact caused the effect of matrix structure on σw.

Reactions of recoil chlorine-38 in crystalline p-dichlorobenzenes

The effects of matrix structure on the chemical reactions occurring as the results of /sup 37/Cl(n,..gamma..)/sup 38/Cl in solid samples of p-dichlorobenzene were studied. No significant variations in the yields of the products formed were observed in the three phases ..cap alpha..,..beta.., and ..gamma.. of p-dichlorobenzene. These and other results suggest that the /sup 38/Cl-labeled partent products are predominantly formed via hot /sup 38/Cl-for-Cl replacement reactions.