Weibull modulus for diverse strength due to sample-specificity

By sample specificity it is meant that specimens with the same nominal material parameters and tested under the same environmental conditions may exhibit different behavior with diversified strength. Such an effect has been widely observed in the testing of material failure and is usually attributed to the heterogeneity of material at the mesoscopic level. The degree with which mesoscopic heterogeneity affects macroscopic failure is still not clear. Recently, the problem has been examined by making use of statistical ensemble evolution of dynamical system and the mesoscopic stress re-distribution model (SRD). Sample specificity was observed for non-global mean stress field models, such as the duster mean field model, stress concentration at tip of microdamage, etc. Certain heterogeneity of microdamage could be sensitive to particular SRD leading to domino type of coalescence. Such an effect could start from the microdamage heterogeneity and then be magnified to other scale levels. This trans-scale sensitivity is the origin of sample specificity. The sample specificity leads to a failure probability Phi (N) with a transitional region 0 < (N) < 1, so that globally stable and catastrophic modes could co-exist. It is found that the scatter in strength can fit the Weibull distribution very well. Hence, the Weibull modulus is indicative of sample specificity. Numerical results obtained from the SRD for different non-global mean stress fields show that Weibull modulus increases with increasing sample span and influence region of microdamage.

Evolutionary implications of multiple SINE insertions in an intronic region from diverse mammals

An analysis of the nuclear beta-fibrinogen intron 7 locus from 30 taxa representing 12 placental orders of mammals reveals the enriched occurrences of short interspersed clement (SINE) insertion events. Mammalian-wide interspersed repeats (MIRs) are present at orthologous sites of all examined species except those in the order Rodentia. The higher substitution rate in mouse and a rare MIR deletion from rat account for the absence of MIR in the rodents. A minimum of five lineage-specific SINE sequences are also found to have independently inserted into this intron in Carnivora, Artiodactyla and Lagomorpha. In the case of Carnivora, the unique amplification pattern of order-specific CAN SINE provides important evidence for the "pan-carnivore" hypothesis of this repeat element and reveals that the CAN SINE family may still be active today. Particularly interesting is the finding that all identified lineage-specific SINE elements show a strong tendency to insert within or in very close proximity to the preexisting MIRs for their efficient integrations, suggesting that the MIR clement is a hot spot for successive insertions of other SINEs. The unexpected MIR excision as a result of a random deletion in the rat intron locus and the non-random site targeting detected by this study indicate that SINEs actually have a greater insertional flexibility and regional specificity than had previously been recognized. Implications for SINE sequence evolution upon and following integration, as well as the fascinating interactions between retroposons and the host genomes are discussed.

Speciation and Phylogeography of Opsariichthys bidens (Pisces: Cypriniformes: Cyprinidae) in China: Analysis of the Cytochrome b Gene of mtDNA from Diverse Populations

Gao-Yan Li, Xu-Zhen Wang, Ya-Hui Zhao, Jie Zhang, Chun-Guang Zhang, and Shun-Ping He (2009) Speciation and phylogeography of Opsariichthys bidens (Pisces: Cypriniformes: Cyprinidae) in China: analysis of the cytochrome b gene of mtDNA from diverse populations. Zoological Studies 48(4): 569-583. The cyprinid fish Opsariichthys bidens Gunther is distributed in all major river systems of continental East Asia, and represents an attractive model for phylogeographic studies among cyprinid species or within a given species. In this study, we investigated the phylogeographic and demographic history of this species, using partial sequences of the cytochrome (cyt) b gene in mitochondrial (mt)DNA. Fish samples were collected from almost all major river systems where O. bidens is distributed in China. Sequence analysis showed remarkably high polymorphism, with 125 haplotypes in the 234 specimens examined, and with 89.8% of haplotypes occurring in only 1 specimen. A neutrality test indicated that some groups were not at mutation-drift equilibrium, suggesting a past population expansion. These results were supported by a mismatch distribution analysis. Based on our analysis, O. bidens consists of 4 groups belonging to 2 clades. The divergence time of the 2 clades was estimated to be 11.06-8.04 my. This value corresponds to the time of the 2nd uplift of the Qinghai-Tibet Plateau, the emergence of the East Asian monsoon, and the Epoch-6 Event. A two species scheme is proposed. http://zoolstud.sinica.edu.tw/Journals/48.4/569.pdf

The diverse Grania fauna (Clitellata : Enchytraeidae) of the Esperance area, Western Australia, with descriptions of two new species

Seven species of the marine enchytraeid genus Grania Southern, 1913 are described from sediments sampled during the 2003 International Workshop on the Marine Flora and Fauna of Esperance Bay and the Recherche Archipelago, on the southern coast of Western Australia. Two species are new to science, the euryhaline Tasmanian G. dolichura Rota and Erseus, 2000 represents a new record for the state, and the remaining four species were known from other parts of Western Australia. Grania quaerens sp. n. is recognized by having a high chaetal index (= 5 short chaetal foot), small coelomocytes, penial apparati with long whip-like terminal stylets, conspicuous spermathecae with ectally bulbous ducts, and ectally granulated ampullae housing sperm rings in their ental region. Grania sperantia sp. n. is readily distinguishable by the complete lack of lateral chaetae, a multiple-banded pattern of the clitellum, extremely long sperm funnels, and the intrasegmental location of the spermathecal pores. The latter new species and four others in the collection (G. bykane Coates, 1990, G. crassiducta Coates, 1990, G. dolichura, and G. ersei Coates, 1990) are remarkable in possessing the head organ, a sensory structure unique to Grania that was not noted previously in Western Australian species. When considering the whole genus, the geographic pattern of the head organ appears southern-centred: of the 17 species of Grania reported to possess it, as many as 13 inhabit the southern latitudes. The seventh species of the Esperance collection, G. vacivasa Coates and Stacey, 1993, is notable for the kind of items found in its gut and the unusual appearance of its pygidium.

Occurrence of Camallanus cotti in greatly diverse fish species from Danjiangkou Reservoir in central China

Two thousand four hundred fifty-eight fish comprised of 53 species were captured in the Danjiangkou Reservoir, in the northwestern part of Hubei Province, central China during 2004, to examine Camallanus cotti infections. We found that 19 cypriniform, 3 siluriforme, and 4 perciforme fishes were infected by the nematode. Our study revealed the species, Hemiculter bleekeri bleekeri, Culter oxycephaloide, Pseudolaubuca sinensis, Acanthobrama simony, Mylopharyngodon piceus, Ctenopharyngodon idella, Gnathopogon imberbis, G. argentatus, Saurogobio dabryi, S. dumerili, Gobiobotia ichangensis, Liobagrus marginatoides, and Ctenogobius shennongensis as new hosts of the worm. The number and range of fish host species found in this survey were much greater than any of the previous investigations. The mean prevalence, prevalence, mean abundance, and intensity of infection varied in different fish species, indicating a possible host preference. Moreover, we suggest that this nematode is a native parasite of cypriniform fishes in China, perhaps initially in the reaches of the Yangtze River.

A General Route to Construct Diverse Multifunctional Fe3O4/Metal Hybrid Nanostructures

We have developed a simple, efficient, economical, and general approach to construct diverse multifunctional Fe3O4/metal hybrid nanostructures displaying magnetization using 3-aminopropyltrimethoxysilane (APTMS) as a linker. High-density Au nanoparticles (NPs) could be supported on the surface of superparamagnetic Fe3O4 spheres and used as seeds to construct Au shell-coated magnetic spheres displaying near-infrared (NIR) absorption., which may make them promising in biosensor and biomedicine applications. High-density flower-like Au/Pt hybrid NPs could be supported on the surface of Fe3O4 spheres to construct multifunctional hybrid spheres with high catalytic activity towards the electron-transfer reaction between potassium ferricyanide and sodium thiosulfate. High-density Ag or Au/Ag core/shell NPs could also be supported on the surface of Fe3O4 spheres and exhibited pronounced surface-enhanced Raman scattering (SERS), which may possibly be used as an optical probe with magnetic function for application in high-sensitivity bioassays.

Carbon Nanotube/Silica Coaxial Nanocable as a Three-Dimensional Support for Loading Diverse Ultra-High-Density Metal Nanostructures: Facile Preparation and Use as Enhanced Materials for Electrochemical Devices and SERS

In this paper, we have reported a very simple strategy (combined sonication with sol-gel techniques) for synthesizing well-defined silica-coated carbon nanotube (CNT) coaxial nanocable without prior CNT functionalization. After functionalization with NH2 group, the CNT/silica coaxial nanocable has been employed as a three-dimensional support for loading ultra-high-density metal or hybrid nanoparticles (NPs) such as gold NPs, Au/Pt hybrid NPs, Pt hollow NPs, and Au/Ag core/shell NPs. Most importantly, it is found that the ultra-high-density Au/Pt NPs supported on coaxial nanocables (UASCN) could be used as enhanced materials for constructing electrochemical devices with high performance. Four model probe molecules (O-2, CH3OH, H2O2, and NH2NH2) have been investigated on UASCN-modified glassy carbon electrode (GCE). It was observed that the present UASCN exhibited high electrocatalytic activity toward diverse molecules and was a promising electrocatalyst for constructing electrochemical devices with high performance. For instance, the detection limit for H2O2 with a signal-to-noise ratio of 3 was found to be 0.3 mu M, which was lower than certain enzyme-based biosensors.

Diverse tetracycline resistant bacteria and resistance genes from coastal waters of Jiaozhou Bay

Environmental microbiology investigation was carried out in Jiaozhou Bay to determine the source and distribution of tetracycline-resistant bacteria and their resistance mechanisms. At least 25 species or the equivalent molecular phylogenetic taxa in 16 genera of resistant bacteria could be identified based on 16S ribosomal deoxyribonucleic acid sequence analysis. Enterobacteriaceae, Pseudomonadaceae, and Vibrionaceae constituted the majority of the typical resistant isolates. Indigenous estuarine and marine Halomonadaceae, Pseudoalteromonadaceae, Rhodobacteraceae, and Shewanellaceae bacteria also harbored tetracycline resistance. All the six resistance determinants screened, tet(A)-(E) and tet(G), could be detected, and the predominant genes were tet(A), tet(B), and tet(G). Both anthropogenic activity-related and indigenous estuarine or coastal bacteria might contribute to the tet gene reservoir, and resistant bacteria and their molecular determinants may serve as bioindicators of coastal environmental quality. Our work probably is the first identification of tet(E) in Proteus, tet(G) in Acinetobacter, tet(C) and tet(D) in Halomonas, tet(D) and tet(G) in Shewanella, and tet(B), tet(C), tet(E), and tet(G) in Roseobacter.

Diverse and Novel nifH and nifH-Like Gene Sequences in the Deep-Sea Methane Seep Sediments of the Okhotsk Sea

Diverse nifH and nifH-like gene sequences were obtained from the deep-sea surface sediments of the methane hydrate-bearing Okhotsk Sea. Some sequences formed novel families of the NifH or NifH-like proteins, of currently unresolved bacterial or archaeal origin. Comparison with other marine environments indicates environmental specificity of some of the sequences, either unique to the methane seep sediments of the Okhotsk Sea or to the general deep-sea methane seep sedimentary environments.

Incidence of diverse integrons and beta-lactamase genes in environmental Enterobacteriaceae isolates from Jiaozhou Bay, China

Environmental microbiology investigation was performed to determine the molecular diversity of beta-lactamase genes among ampicillin-resistant bacteria from Jiaozhou Bay. beta-lactamase genes were detected in 93.8% of the bacterial isolates identified as Enterobacteriaceae. The most frequently detected gene was bla(TEM), followed by bla(SHV), bla(OAX-1), bla(MOX) and bla(CMY). Most of the isolates (68.8%) were positive for the intI1 integrase gene, and two isolates were also found for the intI2 gene. The dfr and aadA gene cassettes were predominant. Anthropogenic contamination from onshore sewage processing plants might contribute predominantly to the beta-lactamase gene reservoir in the studied coastal waters. Environmental antibiotic-resistant bacteria and resistance genes may serve as bioindicators of coastal environmental quality or biotracers of the potential contamination sources. This is the first report of the prevalence and characterization of beta-lactamase genes and integrons in coastal Enterobacteriaceae from China.

Dibenzyl bromophenols with diverse dimerization patterns from the brown alga Leathesia nana

Six novel dibenzyl bromophenols (1-6) with different dimerization patterns and two propyl bromophenol derivatives (7 and 8), together with 11 known bromophenol derivatives, were isolated from the ethanolic extract of the brown alga Leathesia nana. On the basis of spectroscopic methods the structures of the new compounds were determined as 5,6'-diethyloxymethyl-3,4,2'-tribromo-2,3',4'-trihydroxydiphenyl ether (1), 2-(2,3-dibromo-4,5-dihydroxybenzyl)-3,5-dihydroxy-4-methoxybenzyl alcohol (2), 6-(2,3-dibromo-4,5dihydroxybenzyl)-2,3-dibromo-4,5-dihydroxy benzyl methyl ether (3), 9,10-dihydro-9,10-dimethoxy-3,4,7,8-tetrabromo-1,2,5,6-tetrahydroxyanthracene (4), (+)-3-(2,3-dibromo-4,5-dihydroxyphenyl)-4-bromo-5,6-dihydroxy-1,3-dihydroisobenzofuran (5), rel-(4aS*,10aR*)-(+/-)-6,7-dibromo-4a-hydroxy-3,8-dihydroxymethyl-10a-methoxy- 1,4,4a, 10a-tetrahydrodibenzo[b,e][1,4]dioxin-1-one (6), (E)-2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)propenal (7), and 2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)-1-propanol (8). Some compounds including 3 showed in vitro selective cytotoxicity against several human cancer cell lines. This is the first brown alga to be reported containing bromophenols.