Low-temperature selective reduction of NO with propene over alkaline-exchanged mordenites

Partially protonated alkaline mordenites showed higher activity per acid amount below 573 K than acidic zeolites for the selective reduction of NO with C₃H₆ in the presence of O₂, which can be related to a high concentration of NO₃ ^- species in the zeolite channels. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of cell structure on oil absorption of highly oil absorptive polyurethane foam for on-site use

This article reports the effect of cell structure on oil absorption of highly oil-absorptive polyurethane foam (ON-PUR), which is suitable for on-site foaming. We have developed ON-PUR as an oil absorbing polyurethane foam using a very reactive recipe. ON-PUR was synthesized by mixing polyol, water, additives, and polymeric diphenylmethane diisocyanate (P-MDI) using a high-pressure foaming machine. Density, airflow, oil absorption of this foam, and cell structure by microscopy were measured. From these results, it was found that the airflow of this foam increased by crushing, and the oil absorption of this foam increased sharply in a narrow airflow range (from 0.1 to 0.8 scfm). This increase is estimated to be due to the decrease of closed cell structures by crushing treatment. Furthermore, we constituted on-site foaming system in bench scale, which was expected to be applicable to on-site preparation of ON-PUR. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 179–186, 1997     

Nucleation Effects of Nucleobases on the Crystallization Kinetics of Poly(L‐lactide)

The effects of nucleobases, especially uracil, on the nonisothermal and isothermal crystallization, melting behavior, spherulite morphology, and crystalline structure of bio‐based and biodegradable PLLA are studied. The melt‐ and cold‐crystallization rates of PLLA increase with increasing uracil loading. The melting behavior of nonisothermally melt‐ and cold‐crystallized PLLAs depends on the uracil content. The isothermal crystallization kinetics is analyzed based on an Avrami model. The incorporation of uracil changes the t_1/2/T_c profile of PLLA due to the more distinct heterogeneous nucleation effects at small supercooling. The crystalline structure of PLLA is not affected by uracil presence. The nucleation density increases and the spherulite size decreases by uracil incorporation.

     

Optical and adhesive properties of composite silica-impregnated Ca-α-SiAlON:Eu2+ phosphor films prepared on silica glass substrates

The compaction of a Eu-doped Ca-α-SiAlON phosphor powder was performed by electrophoretic deposition (EPD). The effect on the adhesion and optical properties of the silica precursor as both a binder of the powder and a filler of the air voids were evaluated. The adhesion of the silica impregnated composite film to the silica glass substrate was characterized by the tape test. The improvement of the external quantum efficiency was confirmed from the PL spectra measurement after the silica impregnation. The temperature dependence of the external quantum efficiency was also investigated in order to discuss the advantage of using the silica precursor as a binder for high-brightness LED applications.     

Improvement on sulfate resistance of blended cement with high alumina slag

This paper is focused on the effect of limestone and calcium sulfate content on sulfate resistance of ground granulated blast furnace slag (GGBS) blended cement. Sulfate resistance was evaluated using ASTM C 1012, and a variety of mechanisms of the sulfate resistance of GGBS blended cement were revealed by the analyses of hydration products and sulfate ion ingress. Although GGBS suppresses sulfate ion ingress, it is probable that alumina in GGBS tends to form ettringite with externally supplied sulfate ions. Addition of limestone and increase in calcium sulfate content allow both monocarboaluminate and ettringite to form prior to immersion in sulfate solution. These hydration products remain in the hardened cement matrix and act to suppress further formation of ettringite with external sulfate ions during immersion in sulfate solution. GGBS blended cement with a suitable amount of limestone powder and a controlled content of calcium sulfate exhibits markedly long term sulfate resistance.     

Synthesis of Red-Light-Responsive Pheophorbide-a Tryptamine Conjugated Photosensitizers for Photodynamic Therapy

Six methyl pheophorbide-a derivatives were prepared by linking a tryptamine side chain at the C-13 ¹ , C-15 ² and C-17 ³ positions of pheophorbide-a. P repared conjugates were characterized and evaluated for their photocytotoxicity against A549 cells. The conjugate 6 a with strong absorption at 413 nm (Soret band), 663–671 nm (Q bands) and comparable fluorescence quantum yield (0.26) was found to exhibit significant cytotoxicity (659 nM). Molecular integration of pheophorbide-a and tryptamines showed synergistic effects as the most potent conjugate 6 a was identified with enhanced photocytotoxicity when compared to methyl pheophorbide-a. T he conjugate 6 a was smoothly taken up by A549 cells and exhibited intracellular localization predominantly to lysosome in the cytoplasm. Upon photoirradiation 6 a generated singlet oxygen to show potent cytotoxicity toward A549 cells.     

Enhancing low-temperature energy harvesting by lead-free ferroelectric Ba(Zr0.1Ti0.9)O3

The energy-harvesting ability of the lead-free ferroelectric Ba(Zr,Ti)O₃ was investigated and greatly enhanced using the Kim novel electrothermodynamic cycle for low-temperature application. Ba(Zr,Ti)O₃ was synthesized with a Zr:Ti ratio of 10:90 (BZT10) by hot-press sintering, which exhibited a mix relaxor-ferroelectric behavior. For power generation using the Kim cycle with low and high temperatures of T_L = 25°C, T_H = 120°C, the most optimized temperature pattern occurred for a heating time of 12.5 s and a cooling time of 22.5 s. Under these conditions, the electric field increased during the novel isodisplacement process, and the displacement variation in the isoelectric step reached the highest value and maximized the BZT10 cycle loop area. Applying these conditions while lowering T_L to 20°C, an energy density N_D = 504 mJ/cm³ was achieved. This value is the highest obtained energy density in a practical test for lead-free ferroelectric bulk material in the BaTiO₃ family.     

The effects of Ni and Li doping on the performance of lithium manganese oxide material for lithium secondary batteries

Layered Li_0.7[M_1/6Mn_5/6]O₂ (M=Li, Ni) was synthesized using a sol-gel method. P2-Na_0.7[M_1/6Mn_5/6]O₂ precursor was first synthesized by a sol-gel method, and then O2-Li_0.7[M_1/6Mn_5/6]O₂ was prepared by an ion exchange of Li for Na in P2-Na_0.7[M_1/6Mn_5/6]O₂ precursor. From charge/discharge curves, it was seen that Li_0.7[Li_1/6Mn_5/6]O₂ has two plateaus similar to those observed from a spinel structure, but Li_0.7[Ni_1/6Mn_5/6]O₂ holds a single plateau as observed from a typical layered structure. It was considered that Li_0.7[Li_1/6Mn_5/6]O₂ undergoes a phase transformation from layered to spinel structure during the charge/discharge cycle, but Li_0.7[Ni_1/6Mn_5/6]O₂ maintains O2-layered structure after the cycles. Li_0.7[Ni_1/6Mn_5/6]O₂ was higher in discharge capacity and retention rate than Li_0.7[Li_1/6Mn_5/6]O₂.     

Shock-induced phase transition of oriented pyrolytic graphite to diamond at pressures up to 15 GPa

In studies of shock-induced phase transition of ordered pyrolytic graphite to a diamond-like phase, the lowest transition onset pressure was observed at 19.6 GPa. The phase transition in that case was considered to be martensitic. In the present study ordered pyrolytic graphite with voids between particles was loaded at pressures up to 15 GPa using a planar shock wave propagating along the basal plane of the graphitic crystal structure. As a result, both diamond-like carbon and diamond were observed in the postshock sample. The phase transition of graphite to diamond was assumed to occur by the release of distortional energy stored in the graphite particles, that is, diffusional-controlled reconstructive mechanism, on the basis of the data by high resolution electron microscopy together with electron energy loss spectroscopy.     

Effect of oxygen flow rate on the structural and electrochemical properties of lithium nickel oxides synthesized by the sol–gel method

The structural and electrochemical properties of LiNiO₂ powders were investigated as a function of the oxygen flow rate employed in the preparation of lithium nickel oxide. It was found that oxygen played an important role in the synthesis of highly crystallized LiNiO₂(R3¯m). In the crystallization process of LiNiO₂, a deficiency of oxygen in the calcination reactor induced the formation of impurities and cubic rock-salt structure (Fm3m) in LiNiO₂ powders. For LiNiO₂ prepared at higher oxygen flow rates, the electrode delivered high discharge capacities with relatively good retention rates. But very low electrode capacity was obtained from LiNiO₂ prepared at lower oxygen flow rates.