Reactivity of Pt/Al2O3 and Pt/CeO2/Al2O3 catalysts for partial oxidation of methane to syngas

The ceria modified Pt/CeO2/Al2O3 and Pt/Al2O3 catalysts were studied in the partial oxidation of methane to syngas. The SEM, XRD, TPR and TPD techniques were used for the catalyst characterization. The addition of ceria could enhance the Pt dispersion and decrease the Pt crystallise size; the activity and selectivity of catalyst for partial oxidation were improved significantly, and the methane total oxidation was suppressed sharply. The ceria effect was also discussed in a detailed way.

Partial oxidation of methane to syngas over Pt-Ni/Al2O3 Catalyst

The catalytic partial oxidation of methane to syngas over Ni/Al2O3, Pt/Al2O3 and a series of Pt - Ni/Al2O3 catalysts was investigated. It was found that Pt - Ni/Al2O3 catalysts exhibit higher activity and stability than Ni/Al2O3 and Pt/Al2O3. TPR and TPD methods were used to characterize Pt - Ni bimetallic interactions in the catalysts. A series of Pt - Ni/Al2O3 catalysts and unsupported Pt - Ni samples were studied by XRD and XPS. It was found the formation of Pt - Ni alloy in the Pt - Ni/Al2O3 catalysts and the enrichment of platinum on the surface of the catalysts. It is concluded that the higher activity and stability of Pt - Ni/Al2O3 catalysts were caused by Pt - Ni bimetallic interactions.

Partial oxidation of methane to syngas over Pt/A(2)O(3) and Pt/CeO2/Al2O3

The catalytic oxidation of methane to syngas has been carried out over Pt/Al2O3 and Pt/CeO2/Al2O3. It was found that the catalysts with ceria exhibit a higher activity and selectivity than those without ceria. The catalysts were characterized by means of TPR, TPD, SEM-EDX and XRD. There is a strong interaction between ceria and platinum under the reaction condition, which increase the dispersion of platinum over catalysts, preventing the sinter of the Pt particles. As a result of the synergistic;effect between Pt and ceria, the activity of Pt/Al2O3 for combustion reaction was suppressed, the activity and selectivity :For partial oxidation were improved greatly. Another role of ceria in the catalyst is the enhancing of the WGSR, which leads to the increase of the selectivity of catalyst for hydrogen and accelerating the equilibrium of the reaction.

Partial oxidation of methane to synthesize gas over Ni/alpha-Al2O3 catalyst promoted by noble metals

The production of synthesis gas by partial oxidation bf methane in oxygen has been examined over Ni/alpha-Al2O3 catalyst promoted by noble metals(Rh, Ru, Pt and Pd), especially with Pt. The reactivity is considered in conjunction with the result of H-2-TPR, CO-TPD, SEM and XRD. It is found that small amount of Pt results in a great improvement of activity for the Ni/alpha-Al2O3 catalyst. The activity order is : Rh-Ni>Pt-Ni approximate to Ru-Ni>Pd-Ni, meantime the Pt improves the stability of Ni/alpha-Al2O3 catalyst except for Pd which is easy to he deactivated by carbon deposition. The results of TPD, SEM and XRD indicate that there is an interaction between Ni and Pt metals in the catalyst. The interaction increases the dispersions of Pt and Nit the presence of Pt suppresses the growth and the migration of Ni grains over the surface of the catalyst.

Cloning and sequence analysis of the partial sequence of the rbcL from Bryopsis hypnoides

The partial sequence of the rbcL from Bryopsis hypnoides, including the sequences of the upstream, extron and partial intron, was amplified by PCR and their sequences were determined. With Spinacia oleracea as the outgroup, neighbor-joining method and maximum parsimony method were used respectively to build phylogenetic trees according to the rbcL exon sequence among 13 species that were the typical species of six phyla. Two kinds of trees showed clearly that there were two groups among those species, the green lineage and the non-green lineage. And the relationships of algae in the green lineage were similar in the two trees but those in the non-green lineage were not consistent. Analysis of codon preference indicated that the codon preference of the rbcL exon of Bryopsis hypnoides distinctly differed from that of the relevant sequence of photosynthetic bacteria.

Purification and partial characterization of Mn superoxide dismutase from muscle tissue of the shrimp Macrobrachium nipponense

Superoxide dismutase (SOD; EC 1.15.1.1) is an enzyme that protects against oxidative stress from superoxide radicals in living cells. This enzyme had been isolated, purified and partially characterized from muscle tissue of the shrimp Macrobrachium nipponense. The purification was achieved by heat treatment, ammonium sulfate fractionated precipitation and column chromatograph on DEAE-cellulose 32. Some physiological and biochemical characterization of it was tested. The molecular weight of it was about 21.7 kDa, as judged by SDS-polyacrylamide gel electrophoresis. The purified enzyme had an absorption peak of 278 nm in ultraviolet region, and the enzyme remained stable at 25-45 degreesC within 90 min. However, it was rapidly inactivated at higher temperature. Treatment of the enzyme with 1 mM ZnCl2, SDS and 1 mM or 10 mM mercaptoethanol showed some increasing activity. However, the enzyme activity was obviously inhibited by 10 mM CaCl2, CuSO4, ZnCl2 and 1 mM CaCl2 and 10 mM K2Cr2O7. SOD activity did not show significantly variation after incubated with 1 mM CaCl2, EDTA and 10 MM SDS. The enzyme was insensitive to cyanide and contained 1.03 +/- 0.14 atoms of manganese per subunit shown in atomic absorption spectroscopy, which revealed that purified SOD was Mn superoxide dismutase. (C) 2004 Elsevier B.V. All rights reserved.

The complete amino acid sequence of growth hormone and partial amino acid sequence of prolactin and somatolactin from sea perch (Lateolabrax japonicus)

Growth hormone (GH), prolactin (PRL) and somatolactin (SL) were purified simultaneously under alkaline condition (pH 9.0) from pituitary glands of sea perch (Lateolabrax japonicas) by a two-step procedure involving gel filtration on Sephadex G-100 and reverse-phase high-performance liquid chromatography (rpHPLC). At each step of purification, fractions were monitored by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and by immunoblotting with chum salmon GH. PRL and SL antisera. The yields of sea perch GH, PRL and SL were 4.2, 1.0 and 0.28 mg/g wet tissue, respectively. The molecular weights of 19,200 and 20,370 Da were estimated by SDS-PAGE for sea perch GH and PRL, respectively. Two forms of sea perch SL were found: one (28,400 Da) is probably glycosylated, while the other one (23,200 Da) is believed to be deglycosylated. GH bioactivity was examined by an in vivo assay. Intraperitoneal injection of sea perch GH at a dose of 0.01 and 0.1 mug/g body weight at 7-day intervals resulted in a significant increase in body weight and length of juvenile rainbow trout. The complete sea-perch GH amino acid sequence of 187 residues was determined by sequencing fragments cleaved by chemicals and enzymes. Alignment of sea-perch GH with those of other fish GHs revealed that sea-perch GH is most similar to advanced marine fish, such as tuna, gilthead sea bream, yellowfin porgy, red sea bream, bonito and yellow tail with 98.4, 96.2%, 95.7%, 95.2%, 94.1% and 91% sequence identity, respectively. Sea-perch GH has low identity to Atlantic cod (76.5%), hardtail (73.3%), flounder (68.4%), chum salmon (66.3%), carp (54%) and blue shark (38%). Partial amino-acid sequences of 127 of sea-perch PRL and the N-terminal of 16 amino-acid sequence of sea-perch SL have been determined. The data show that sea-perch PRL has a slightly higher sequence identity with tilapia PRL( 73.2%) than with chum salmon PRL(70%) in this 127 amino-acid sequence. (C) 2001 Elsevier Science B.V. All rights reserved.

Geophysical signatures associated with fluid flow and gas hydrate occurrence in a tectonically quiescent sequence, Qiongdongnan Basin, South China Sea

Interpretation of high-resolution two-dimensional (2D) and three-dimensional (3D) seismic data collected in the Qiongdongnan Basin, South China Sea reveals the presence of polygonal faults, pockmarks, gas chimneys and slope failure in strata of Pliocene and younger age. The gas chimneys are characterized by low-amplitude reflections, acoustic turbidity and low P-wave velocity indicating fluid expulsion pathways. Coherence time slices show that the polygonal faults are restricted to sediments with moderate-amplitude, continuous reflections. Gas hydrates are identified in seismic data by the presence of bottom simulating reflectors (BSRs), which have high amplitude, reverse polarity and are subparallel to seafloor. Mud diapirism and mounded structures have variable geometry and a great diversity regarding the origin of the fluid and the parent beds. The gas chimneys, mud diapirism, polygonal faults and a seismic facies-change facilitate the upward migration of thermogenic fluids from underlying sediments. Fluids can be temporarily trapped below the gas hydrate stability zone, but fluid advection may cause gas hydrate dissociation and affect the thickness of gas hydrate zone. The fluid accumulation leads to the generation of excess pore fluids that release along faults, forming pockmarks and mud volcanoes on the seafloor. These features are indicators of fluid flow in a tectonically-quiescent sequence, Qiongdongnan Basin. Geofluids (2010) 10, 351-368.

Partial characterization of the hemolytic activity of the nematocyst venom from the jellyfish Cyanea nozakii Kishinouye

Using a recently developed technique to extract jellyfish venom from nematocysts, the present study investigated the hemolytic activity of Cyanea nozakii Kishinouye nematocyst venom on chicken erythrocytes. Venom extract caused a significant concentration-dependent hemolytic effect. The extract could retain its activity at -80 degrees C but was unstable when kept at 4 degrees C and -20 degrees C for 2 days. The hemolytic activity was inhibited by heating within the range of 37-100 degrees C. The extract was active over a pH range of 5.0-8.63 and the pH optima for the extract was 7.8. Incubation of the venom with sphingomyelin specially inhibited hemolytic activity by up to 70%. Cu2+ and Mn2+ greatly reduced the hemolytic activity while Mg2+, Sr2+ and Ba2+ produced a relatively low inhibiting effect on the hemolytic activity. Treatment with Ca2+ induced a concentration-dependent increase in the hemolytic activity. In the presence of 5 mM EDTA, all the hemolytic activity was lost, however, the venom containing 1.5 mM EDTA was stable in the long-term storage. PLA(2) activity was also found in the nematocyst venom of C. nozakii. These characteristics provide us a fundamental knowledge in the C. nozakii nematocyst venom which would benefit future research. (C) 2010 Published by Elsevier Ltd.

Phylogenetic analyses of some genera in Oedipodidae (Orthoptera : Acridoidea) based on 16S mitochondrial partial gene sequences

Based on the 16S mitochondrial partial gene sequences of 29 genera, containing 26 from Oedipodidae and one each from Tanaoceridae, Pyrgomorphidae and Tetrigidae (as outgroups), the homologus sequences were compared and phylogenetic analyses were performed. A phylogenetic tree was inferred by neighbor-joining (NJ). The results of sequences compared show that: (i) in a total of 574 bp of Oedipodidae, the number of substituted nucleotides was 265 bp and the average percentages of T, C, A and G were 38.3%, 11.4%, 31.8% and 18.5%, respectively, and the content of A+T (70.1%) was distinctly richer than that of C+G (29.9%); and (ii) the average nucleotide divergence of 16S rDNA sequences among genera of Oedipodidae were 9.0%, among families of Acridoidea were 17.0%, and between superfamilies (Tetrigoidea and Acridoidea) were 23.9%, respectively. The phylogenetic tree indicated: (i) the Oedipodidae was a monophyletic group, which suggested that the taxonomic status of this family was confirmed; (ii) the genus Heteropternis separated from the other Oedipodids first and had another unique sound-producing structure in morphology, which is the type-genus of subfamily Heteropterninae; and (iii) the relative intergeneric relationship within the same continent was closer than that of different continents, and between the Eurasian genera and the African genera, was closer than that between Eurasians and Americans.

北极Gakkel超慢速扩张脊大洋橄榄岩的地球化学特征及其意义

Gakkel Ridge in Arctic Ocean is the ulstraslow spreading ridge in the world with a full spreading rate decreasing from 14 mm/yr in the western end to 7mm/yr in the eastern end. To study the histories of partial melting and melt referilization occurred in the oceanic mantle beneath Gakkel Ridge, both extremely fresh and altered abyssal peridotites from two dredge hauls (PS66-238 and HLY0102-D70) have been selected in this research. Major and trace element data of the residual minerals suggest that all samples have been refertilized by late enriched melts after low to moderate degrees (3-12%) of partial melting in the stability field of spinel, whereas some samples also inherited signatures of partial melting in stability field of garnet. Os isotopic compositions of Gakkel samples have not been significantly affected by late processes, e.g., seawater alteration and melt refertilzaiton. Samples from both dredge hauls have similar range of 187Os/188Os, from strongly unradiogenic (~0.114) in the harzburgites to approximating the inferred values of PUM (primitive upper mantle) in some lherzolites (~0.129). Inherited ancient depletion events in the harzburgites with Re-depletion age up to 2 billion years are unrelevant to the recent genesis of MORB (mid-ocean ridge basalts) beneath Gakkel Ridge. Comparisons of highly siderophile elements (HSEs) between the fresh and altered samples suggested both Pd and Re were affected and thus are mobile during seawater alteration, whereas the other HSEs (i.e., Os, Ir, Ru an Pt) are stable. The fractionated HSEs patterns in the harzburgites suggest both PPGEs (Pt and Pd) and Re can be fractionated from IPGEs (Os, Ir and Ru) at low degree of partial melting, which might be due to physical dredging of sulfide melts by silicate melts rather than equilibrium partitioning between residues and silicate melts. Inferred HSEs budget of the PUM confirm the previous study that both Ru/Ir and Pd/Ir are suprachondritic in the PUM. Some modifications of late-veneer hypothesis are required in light of the unique PUM composition. HSEs and Os isotopic compositions of Gakkel abyssal peridotites indicate the oceanic mantle is highly heterogeneous within a scale of one dredge haul (<5 km). Both depleted and fertile mantle domains are likely to be mechanically juxtaposed in the asthenosphere in a state of ‘plum pudding’. Widely distribution of ancient depleted components in the asthenosphere suggests that DMM (depleted MORB mantle) should not be synonymous with the MORB source. The later is just the fertile part of the former, i.e., the depleted components in the DMM do not or contribute little to the genesis of MORB.

山东西部中生代碳酸岩和火山岩的地球化学特征及其成因研究

On account of some very peculiar features, such as extremely high Sr and Nd contents which can buffer their primary isotopic signatures against crustal contamination, deep-seated origin within mantle, and quick ascent in lithosphere, carbonatites are very suitable for deciphering the nature of sub-continental lithospheric mantle(SCLM) and receiving widespread attentions all around the world. The Mesozoic carbonatites located in western Shandong was comprehensively investigated in this dissertation. The extremely high REE concentrations, similar spider diagrams to most other carbonatites around the world and high Sr. low Mn contents of apatite from carbonatites confirm their igneous origin. The K depletion of carbonatites from this studies reflect the co-existing of carbonatite melts with pargasite+phlogopite lherzolite rather than phlogopite lherzolite. Geological characteristics and their occumng without associated silicate rocks argue against their origin of fractionation of or liquid immisibility with carbonated silicate melts. In contrast to the low S7Sr/86Sr and high l43Nd/l44Nd of other carbonatites in the world, carbonatites of this studies show EMU features with high S7Sr/86Sr and low l4jNd/144Nd ratios, which imply that this enriched nature was formed through metasomatism of enriched mantle preexisted beneath the Sino-korean craton by partial melts of subducted middle-lower crust of Yangtze craton. In addition to carbonatites, the coeval Mesozoic volcanic rocks from western Shandong were also studied in this dissertation. Mengyin and Pingyi volcanic rocks, which located in the south parts of western Shandong are shoshonite geochemically. while volcanic rocks cropped out in other places are high-K calc-alkaline series. All these volcanic rocks enriched in LREE and LILE. depleted in HFSE, and show TNT(strong negative anomalies in Ta, Nb. Ti) patterns in spider diagrams which are common phenomena in arc-related volcanic rocks. The Sr-Nd-Pb isotopic systematics reveal that the volcanic rocks decrease gradually in 87Sr/86Sr, 206Pb/204Pb, 20SPb/204Pb and increase in TDM from south to north, suggesting the distinction of SCLM beneath Shandong in Mesozoic is more explicit in south-north trending than in east-west trending. The variable features of SCLM can be attributed to the subduction of Yangtze craton beneath Sino-Korean craton, and subsequent metasomatism of SCLM by partial melts of Yangtze lower crust in different extent.

A study on the ignition process for the catalytic partial oxidation of methane to synthesis gas by MS-TPSR technique

The ignition processes for the catalytic partial oxidation of methane (POM) to synthesis gas over oxidic nickel catalyst (NiO/Al2O3), reduced nickel catalyst (Ni-0/Al2O3), and Pt-promoted oxidic nickel catalyst (Pt-NiO/Al2O3) were studied by the temperature-programmed surface reaction (TPSR) technique. The complete oxidation of methane usually took place on the NiO catalyst during the CH4/O-2 reaction, even with a pre-reduced nickel catalyst, and Ni-0 is inevitably first oxidized to NiO if the temperature is below the ignition temperature. It is above a certain temperature that Ni-0 is formed again, which leads to the start of the POM. The POM can be initiated at a much lower temperature on a Pt-NiO catalyst because of Pt promotion of the reduction of NiO. The POM in a fluidized bed can be easily initiated due to the addition of Pt.