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In this study, caffeine was adsorbed onto montmorillonite and the surface of the montmorillonite was observed before and after the adsorption. Observations were performed by X-ray diffractometry (X...

In this work, rice husk ash was used as silica source to synthesize NaX zeolite potentially suitable for CO2 adsorption. The produced material, denoted NaX-RHA, was characterized employing X-ray diffraction, scanning electron microscopy and gas adsorption porosimetry, in order to verify the occurred production of well-crystallized NaX zeolite with a significant degree of purity. CO2 adsorption isotherms on NaX-RHA were volumetrically evaluated in the 298–348 K temperature range up to standard pressure, revealing performances that are higher than those reported for commercial similar substrates. The experimental data regarding CO2 adsorption on NaX-RHA were very satisfyingly fitted by the semiempirical Sips model. Analyzing the best fitting values of model parameters allowed to conclude that the synthesized adsorbent could be quite suitable for applications like CO2 capture from flue gas.

For composites, it is of great importance to fabricate well-dispersed green compacts, in order to improve their mechanical properties and reliability. In the present study, the slip-casting technique was applied to the fabrication of ZrO2-WC-Al2O3 composites. The specific gravity of each composition in this material was very different, that is, 6.07 for ZrO2, 15.6 for WC and 3.94 for Al2O3. The compositions in the green compacts were afraid to separate from each other owing to the difference in their specific gravities, leading to heterogeneity in the microstructure. The relative density of the obtained compacts was approximately 60%. WC and Al2O3 were well-dispersed in the ZrO2 matrix. The separation and/or heterogeneity due to difference could not be recognized by energy-dispersive X-ray analysis. The slip-casting technique was found to be applicable to the fabrication of ceramic composites consisting of raw powders with different specific gravities.

Introduction of an alkyl (aralkyl) substituent at the 7-position of 7-ethoxycarbonyl-3,4-dimethoxynorcaradiene (7a) gives fairly stable norcaradienes (NCD) (7b-f). The reduction products (8b-f) of NCD (7b-f) exist mainly as NCD form especially at low temperature, although 8b-f possess no longer any π-acceptor at the 7-position. The present results clarify that two methoxyl groups as the π-donors at the 3,4-positson stabilize the NCD structure.

Copolymerization of ethylene with 1-hexene was carried out using two ansa-fluorenyl titanium derivative complexes. The substituent effect on the catalytic activity, monomer reactivity ratio and polymer property was investigated. It was found that the presence of t-Bu groups on fluorenyl ring exhibited remarkable catalytic activity and produced polymer with high molecular weight. However, these catalysts produce polymer with narrow molecular weight distribution, indicating the characteristic of single-site metallocene catalyst. Based on 13C NMR, we can observe that monomer reactivity ratio was affected by catalyst structure. The rH values of complex 2 were lower than that of complex 1 which might be result from the higher steric hindrance leading to a reduction of 1- hexene insertion step., {"references":["C. Piel, P. Starck, J.V. Sepp├ñl├ñ, and W. Kaminsky, \"Thermal and\nmechanical analysis of metallocene-catalyzed ethene-╬▒-olefin\ncopolymers: The influence of the length and number of the crystallizing\nside chains,\" J. Polym. Sci, Part A: Polym. Chem., vol. 44, no. 5, pp.\n1600-1612, Mar. 2006.","M. Smit, X. Zheng, R. Br├╝ll, J. Loos, J.C. Chadwick, and C.E. Koning,\n\"Effect of 1-hexene comonomer on polyethylene particle growth and\ncopolymer chemical composition distribution,\" J. Polym. Sci, Part A:\nPolym. Chem., vol. 44, no. 9, pp. 2883-2890, May. 2006.","Z.-g. Cai, Y. Nakayama, and T. Shiono, \"Substituent effects of tertbutyl\ngroups on fluorenyl ligand of [tBuNSiMe2Flu]ZrMe2,\" Chin. J.\nPolym. Sci., vol. 26, no. 5, pp. 575-578, 2008.","K. Nishii, H. Hagihara, T. Ikeda, M. Akita, and T. Shiono,\n\"Stereospecific Polymerization of Propylene with Group 4 ansa-\nFluorenylamidodimethyl Complexes,\" J. Organomet. Chem., vol. 691,\nno.1-2, pp. 2883-2890, Jan. 2006.","L.J. Irwin, J.H. Reibenspies, and S.A. Miller, \"A sterically expanded\n\"constrained geometry catalyst\" for highly active olefin polymerization\nand copolymerization: an unyielding comonomer effect,\" J. Am. Chem.\nSoc., vol. 126, no.51, pp. 16716-16717, Dec. 2004.","H. Li, and Y. Niu, \"Ethylene/╬▒-olefin copolymerization by\nnonbridged(cyclopentadienyl)(aryloxy)titanium(IV)\ndichloride/AliBu3/Ph3CB(C6F5)4 catalyst systems,\" J. Appl. Polym. Sci.,\nvol. 121, no.5, pp. 3085-3092, Sep. 2011.","C.J. Price, P.D. Zeits, J.H. Reibenspies, and S.A. Miller,\n\"Octamethyloctahydrodibenzofluorenyl: Electronic Comparisons\nBetween a Sterically Expanded Ligand and its Cyclopentadienyl\nAnalogues,\" Organometallics, vol. 27, no.15, pp. 3722-3727, Jul. 2008.","H. Hong, Z. Zhang, T. C. M. Chung, and R.W. Lee, \"Synthesis of new\n1-decene-based LLDPE resins and comparison with the corresponding\n1-octene- and 1-hexene-based LLDPE resins,\" J. Polym Sci, Part A:\nPolym. Chem., vol. 45, no.4, pp. 639-649, Feb. 2007.","T. Uozumi, and K. Soga, \"Copolymerization of olefins with Kaminsky-\nSinn-type catalysts,\" Makromol. Chem., vol. 193, no.4, pp. 823-831,\nApr. 1992.\n[10] M. Fineman, and S. D. Ross, \"Linear method for determining monomer\nreactivity ratios in copolymerization,\" J. Polym. Sci., vol. 5, no.2, pp.\n259-262, Apr. 1950.\n[11] T. Kelen, F. J. T├╝dös, \"Linear method for determining monomer\nreactivity ratios in copolymerization,\" J. Macromol. Sci. Chem., A9, pp.\n1-27, Apr. 1975."]}

The annealing behavior of α-SiC(0001) single crystals is studied using high energy ion implantations and thermal annealings. 1.0 MeV Ni+ ion implantations at RT were carried out on samples with fluence of 1 × 1015 and 1 × 10 17 cm 2 . Post-implantation annealings were performed in 1 atm Ar gas flow at 500, 1000 and 1500°C for 2 h. Samples were analyzed by Rutherford backscattering spectroscopy with channeling and scanning electron microscopy. During the 500°C annealing, the thickness of the introduced amorphous layer, TA, did not change for both samples. During the 1000°C annealing, TA decreased for the 1 × 10 15 Ni + cm 2 sample, but not for the 1 × 10 17 Ni + cm 2 . The initiation temperature of the recrystallization increases with the fluence. During the 1500°C annealing, an explosive recrystallization occurred for both samples. Moreover, in the recrystallized region of the 1 × 10 17 Ni + cm 2 sample, a layer with a high defect concentration was found in the depth range from 0.5 μm to 0.7 μm, but not for the 1 × 10 15 Ni + cm 2 . The recrystallization at 1500°C was accompanied by an extensive Ni diffusion. Then, the Ni profile changed from a Gaussian-like distribution to a trapezoid which extends from the surface to a depth 0.5 μm. The new Ni distribution is faced with the layer with a high defect concentration at a depth of 0.5 μm.

Introduction of an alkyl (aralkyl) substituent at the 7-position of 7-ethoxycarbonyl-3,4-dimethoxynorcaradiene (7a) gives fairly stable norcaradienes (NCD) (7b-f). The reduction products (8b-f) of NCD (7b-f) exist mainly as NCD form especially at low temperature, although 8b-f possess no longer any π-acceptor at the 7-position. The present results clarify that two methoxyl groups as the π-donors at the 3,4-positson stabilize the NCD structure.

In this paper, in order to develop the diagnostic technique, we deteriorated the low-voltage cables acceleratively under some thermal conditions and investigated the correlations related to elongation which could be considered as a value of degradation degree. As the experimental results, we found that the diagnostic technique of the equotip hardness method has its merits of nondestruction, small error and simplicity. Moreover we investigated the correlation between the equotip hardness and the elongation at break of PVC sheaths of several low-voltage cables, and obtained the master curve between equotip hardness and elongation. And then we developed the diagnostic apparatus based on the equotip hardness method.