Preparation and properties of new polyurethane gels with a stress‐distributing function for medical applications

The purpose of this study is to prepare new polyurethane gels that can be used as stress‐ or pressure‐distributing materials, particularly by being combined with selective plasticizers for medical or clinical applications. Because low‐molecular‐weight plasticizer molecules in polymer gels intrinsically tend to migrate to the surface of the gels by the so‐called entropy effect in polymer miscibility, the stress‐distributing function may decrease gradually after a certain amount of time. Correspondingly, both the chemical nature of the plasticizer and polymer gels and the compatibility between the polymer segments and plasticizer should be deliberately considered as important factors in determining the thermophysical properties and stress‐distributing performance of polymer gels. New polyurethane gels comprising separated phases of soft and hard segments, the glass‐transition temperature of which was around the ambient temperature, were prepared, and selective plasticizers were combined to obtain an optimized formulation of gels for stress‐relieving properties. The glassy‐to‐rubbery transition of semicrystalline hard segments occurring around the ambient temperature caused the rearrangement of chain conformations, leading to the reduction of the pressure applied to the surface; this indicated that the pressure buildup or loss was somewhat related to the heat regulation by thermal absorption and release in the phase‐transition range. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2750–2758, 2006     

Synthesis and material properties of syndiotactic polystyrene/organophilic clay nanocomposites

Syndiotactic polystyrene (sPS)/organophilic clay nanocomposites were fabricated by direct‐melt intercalation method. To overcome the thermal instability of organophilic clay at high‐melt processing temperatures of sPS, an organophilic clay modified by alkyl phosphonium was adopted, which is known to be thermally stable. By using the newly synthesized clay, we could fabricate sPS intercalated nanocomposites. The microstructures of nanocomposites were confirmed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The crystallization rate of nanocomposites investigated by differential scanning calorimetry (DSC) does not increase despite the presence of clay, which may be due to the physical hindrance of organic modifiers in the clay dispersion. Nanocomposites exhibited enhanced mechanical properties such as strength and stiffness relative to the virgin polymer. In addition, thermal stability was confirmed to be improved by thermogravimetric analysis (TGA). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2144–2150, 2004     

Synthesis and characterization of poly(butylene terephthalate) nanocomposite fibers: Thermo‐mechanical properties and morphology

Nanocomposites of poly(butylene terephthalate) (PBT) with the organoclay C₁₂PPh‐MMT were prepared using in situ intercalation polymerization. Hybrids with various organoclay contents were processed for fiber spinning to examine their thermal behavior, tensile mechanical properties, and morphologies for various draw ratios (DRs). The thermal properties (T_g, T_m, and T_Dⁱ) of the hybrid fibers were found to be better than those of pure PBT fibers and were unchanged by variation of the organoclay loading up to 2 wt %. However, these thermal properties remained unchanged for DRs ranging from 1 to 18. Most clay layers were dispersed homogeneously in the matrix polymer, although some clusters were also detected. The tensile properties of the hybrid fibers increased gradually with increasing C₁₂PPh‐MMT content at DR = 1. However, the ultimate strengths and initial moduli of the hybrid fibers decreased markedly with increasing DR. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1247–1254, 2006     

Comparison of Sizes of Magnesia Crystals Calculated from X-ray Diffraction Line-Broadening and Transmission Electron Microscopy Observations

When MgO is formed by decomposition of MgCO₃ under vacuum, crystal sizes calculated from XRD line breadths are in reasonable agreement with direct TEM observations, 4.4 ± 0.6 nm compared with 3.2 ± 0.8 nm. For aligned MgO crystallites from Mg(OH)₂, the sizes calculated are discordant, 14.0 ± 3.0 nm and 2.6 ± 0.7 nm. The sizes calculated from XRD data are too large because the MgO crystallites form from Mg(OH)₂ in near-perfect alignment.     

Effects of data set features on the performances of classification algorithms

As the need to analyze big data sets grows dramatically, the role that classification algorithms play in data mining techniques also increases. Big data analysis requires more of the data sets’ characteristics to be included, such as data structure, variety of sources, and the rate of update frequency. In this paper, we evaluate scenarios that examine which data set characteristics most affect the classification algorithms’ performance. It is still a complex issue to determine which algorithm is how strong or how weak in relation to which data set. Thus, our research experimentally examines how data set characteristics affect algorithm performance, both in terms of accuracy and in elapsed time. To do so, we use a multiple regression method to evaluate the causality between data set characteristics as independent variables, and performance metrics as dependent variables. We also examine the role that classification algorithms play as moderator in this causality. All benchmark data sets in a UCI database are used that are fit to run the classification algorithm. Based on the results of the experiment, we discuss the requirements of legacy classification algorithms to address big data analysis in a new business intelligence era.     

Coke formation on the surface of α-Al2O3 in the catalytic pyrolysis of naphtha

The catalytic pyrolysis of naphtha has been carried out in a quartz reactor loaded with 5 mm α-A1₂0₃ spheres. The yields of ethylene and propylene exhibit about 10% and 5% higher values compared to the thermal pyrolysis in the absence of α-A1₂0₂ spheres at the same reaction conditions. The coke formation on α-A1₂0₃ spheres increased continuously along with the axial length of the reactor as well as with reaction time. Results suggest that the concentration of the coke precursors in the gas phase may increase along with the axial length of the reactor. Coke filled up completely the internal pore of the sphere near the exit of the reactor after reaction for 4 hr. The coke film on the external surface of the sphere grew continuously thicker. The coke formation was influenced strongly by the physical properties of the α-Al₂O₃ spheres. Coke deposition was the least on the α-A1₂0₃ sphere with the lowest surface area and pore volume among the tested α-A1₂0₃ spheres.     

Improvement of the water solubility and emulsifying capacity of rice proteins through the addition of isolated soy protein

The market for rice protein (RP) has been steadily growing, but applications of RPs as food ingredients and functional materials are limited due to poor solubility in water. Here, the complex of RP and isolated soy protein (ISP) was prepared, and the potential utility of RP–ISP complex as an emulsifier was evaluated. The solubility of the RP solution was 25.8% whereas it was greatly increased to 68.4% in the RP–ISP complex. The properties of RP and RP–ISP complex were assessed by scanning electron microscope, gel electrophoresis, circular dichroism, and surface hydrophobicity test. Next soybean oil emulsions were prepared using the RP and RP–ISP complex. The RP-stabilised emulsion was unstable to storage. In contrast, the RP–ISP complex-stabilised emulsions showed good stability, especially when more than 0.2% ISP was added. These data suggest that the preparation of soluble RPs by ISP could expand the applications of RP in the food industry.