The phase stability in part of the P2O5-bearing pseudoquaternary system CaO–SiO2–Al2O3–Fe2O3 has been studied by electron probe microanalysis, optical microscopy, and powder X-ray diffractometry. At 1973–1653 K, the α-Ca2SiO4 solid solution [α-C2S(ss)] and melt coexisted in equilibrium, both chemical variations of which were determined as a function of temperature. The three phases of melt, calcium aluminoferrite solid solution (ferrite), and C2S(ss) coexisted at 1673–1598 K. On the basis of the chemical compositions of these phases, a melt-differentiation mechanism has been, for the first time, suggested to account for the crystallization behavior of Ca3Al2O6 solid solution [C3A(ss)]. When the α-C2S(ss) and melt were cooled from high temperatures, the melt would be induced to differentiate by the crystallization of ferrite. Because the local equilibrium would be continually attained between the rims of the precipitating ferrite and coexisting melt during further cooling, the melt would progressively become enriched in Al2O3 with respect to Fe2O3. The resulting ferrite crystals would show the zonal structure, with the Al/(Al+Fe) value steadily increasing up to 0.7 from the cores toward the rims. The C3A(ss) would eventually crystallize out of the differentiated melt between the zoned ferrite crystals in contact with their rims. 相似文献
Summary: The effects of various additives: poly(D ‐lactic acid) (PDLA), talc, fullerene C60, montmorillonite, and various polysaccharides, on the non‐isothermal crystallization behavior of poly(L ‐lactic acid) (PLLA), during both the heating of melt‐quenched films from room temperature, and the cooling of as‐cast films from the melt, was investigated. When the melt‐quenched PLLA films were heated from room temperature, the overall PLLA crystallization was accelerated upon addition of PDLA or the stereocomplex crystallites formed between PDLA and PLLA, the mixtures containing PDLA, and the mixture of talc and montmorillonite. No significant effects on the overall PLLA crystallization were observed for talc, C60, montmorillonite, and the mixtures containing C60. Such rapid completion of the overall PLLA crystallization upon addition of the aforementioned additives can be ascribed to the increased density (number per unit volume or area) of PLLA spherulites. When the as‐cast PLLA films were cooled from the melt, the overall PLLA crystallization completed rapidly, upon addition of PDLA, talc, C60, montmorillonite, and their mixtures. Such rapid overall PLLA crystallization is attributable to the increased density of the PLLA spherulites and the higher nucleation temperature for PLLA crystallization. In contrast, the addition of various polysaccharides has no significant effect, or only a very small effect, on the overall PLLA crystallization during heating from room temperature or during cooling from the melt. This finding means that the polysaccharides can be utilized as low‐cost fillers for PLLA‐based materials, without disturbing the crystallization of the PLLA. The effect of additives in accelerating the overall PLLA crystallization during cooling from the melt, decreased in the following order: PDLA > talc > C60 > montmorillonite > polysaccharides.
Polarization optical photomicrographs of pure PLLA, and the PLLA‐F film, with the fullerene additive, during cooling from the melt (Process IIB). Both of the photomicrographs were taken at 120 °C. 相似文献
An inhibitor of lysosomal acid cholesteryl ester hydrolase (Acid CEH), (EC 3.1.1.13) was found in the cytosolic fraction of
rat liver and various other tissues. The extent of the inhibitory effect was dependent on the concentration of the cytosolic
protein. The Acid CEH inhibitor was heat-labile, nondialyzable, and its inhibitory activity significantly decreased by trypsin
or chymotrypsin digestion, but not by lipase digestion. The inhibitor had no effect on the activity of cathepsin D, β-glucuronidase
and acid phosphatase, which are other enzymes found in lysosomes. The present findings suggest that the inhibitor may be involved
in the regulation of the hydrolysis of cholesteryl esters in lipoproteins that have been transferred into the liver. 相似文献
The application of “active-layer-facing-draw-solution” (AL-DS) mode, which allows a considerably high water flux in forward osmosis (FO) processes, is hindered by severe fouling occurring within the porous support of the FO membranes. We designed a series of “three-dimensionally” antifouling FO membranes by an extremely convenient and scalable approach, by using in situ reduced aliphatic polyketone (PK) membranes (rPK) and the silver-nanoparticles-immobilized rPK-Ag membranes as the substrates for thin-film composite (TFC) FO membrane preparation. This modification imparted enhanced hydrophilicity compared with the original PK-TFC membrane, without affecting the morphology and transport properties. Benefiting from the three-dimensional antifouling structure, the modified TFC membranes (i.e., rPK-TFC and rPK-Ag-TFC membranes) demonstrated excellent and comprehensive fouling resistance towards a variety of organic foulants, as well as biofouling resistance towards Escherichia coli. These results provide useful insights into the fabrication of antifouling FO membranes for water purification purposes and pressure retarded osmosis (PRO) process. 相似文献
Porous γ-alumina (γ-Al2O3) is one of widely used ceramic materials. To maximize the application potentials attempt was made to prepare multifunctional γ-Al2O3 ceramic composite particles following magnetization and then seeded polymerization with epoxide functional glycidyl methacrylate (GMA). γ-Al2O3 particles were first prepared by a modified sol-gel approach and then doped with variable content Fe3O4 nanoparticles. At higher Fe3O4 content the magnetite nanoparticles were oriented into needle like hairy structure basically grown from the surface of γ-Al2O3 particles. Before the seeded polymerization the magnetic γ-Al2O3 particles were modified with SiO2 layer to improve the compatibility with the PGMA layer. The produced multifunctional ceramic particles were named as γ-Al2O3/Fe3O4/SiO2/PGMA nanocomposite because one of the phases constituting Fe3O4 was in nano-size range. The produced nanocomposite particles possessed superparamagnetic properties and could be isolated from the dispersion medium by external magnetic field. Fourier Transform IR (FTIR) and X-ray photoelectron spectroscopic (XPS) data revealed that final nanocomposite particles contained reactive epoxide groups on or near the surface. The produced multifunctional γ-Al2O3 ceramic nanocomposite particles can be useful in biotechnology, catalysis and adsorbents for pollutant removal. 相似文献
Stereo diblock polylactides (SDB‐PLAs) composed of relatively short poly(d ‐lactide) (PDLA) segments and relatively long poly(l ‐lactide) (PLLA) segments were synthesized to have a wide number‐average molecular weight (Mn) range of 2.5 × 104–2.0 × 105 g mol?1 and d ‐lactyl unit content of 0.9–38.6%. The effects of incorporated short PDLA segments (Mn = 2.0 × 103–7.7 × 103 g mol?1) on crystallization behavior of the SDB‐PLAs were first investigated during heating after complete melting and quenching or during slow cooling after complete melting. Stereocomplex (SC) crystallites can be formed at d ‐lactyl unit content as low as 4.3 and 5.8% for heating and slow cooling, respectively, and for Mn of PDLA segments as low as 2.0 × 103 and 3.5 × 103 g mol?1, respectively. With decreasing Mn and increasing d ‐lactyl unit content, the cold crystallization temperature during heating decreased and the crystallization temperature during slow cooling increased. With increasing d ‐lactyl unit content, the melting enthalpy (ΔHm) of SC crystallites during heating and the crystallinity (Xc) of SC crystallites after slow cooling increased, whereas ΔHm of PLLA homo‐crystallites during heating and Xc of PLLA homo‐crystallites after slow cooling decreased. The total ΔHm of SC crystallites and PLLA homo‐crystallites during heating and the total Xc after slow cooling became a minimum at d ‐lactyl unit content of 10–15% and gave a maximum at d ‐lactyl unit content of 0%. Despite the accelerated crystallization of some of SDB‐PLAs, the low values of total ΔHm and Xc at d ‐lactyl unit content of 10–15% are attributable to the formation of two crystalline species of SC crystallites and PLLA homo‐crystallites. 相似文献