A modified drag coefficient model for calculating the terminal settling velocity and horizontal diffusion distance of irregular plume particles in deep-sea mining.

Deep-sea mining inevitably produces plumes, which will pose a serious threat to the marine environment with the continuous movement and diffusion of plumes along with ocean currents. The terminal settling velocity (wt) of irregular particles is one of the crucial factors for determining the plumes' diffusion range. It is generally calculated by drag coefficient (CD), while most existing CD models only consider single shape characteristic parameter or have a smaller range of Reynolds number (Re). In this study, a new shape factor (γ) of irregular particles is proposed by considering the thickness (one-dimension), the projected area (two-dimension), and the surface area (three-dimension) of irregular particles as well as their coupling effect to establish a modified CD model for calculating the wt. A modified Gaussian plume model is proposed to predict the horizontal diffusion distance of the plume particles by considering the settling velocity and diffusion effect of irregular particles. Research results show that the wt increases nearly linearly, with a gradually decreased slope and slightly then greatly with the increasing of γ, dp (diameter) and ρp (density), respectively. The modified CD model is verified to be more valid with a wider application range (Re < 3×105) than five existing CD models by the test results. The larger the ρp or dp, the larger the wt and thus the smaller the Sh. This study could provide a theoretical basis for calculating the plume diffusion range to further study the impact of deep-sea mining on the ocean environment.

A New Creep-Fatigue Interaction Model for Predicting Deformation of Coarse-Grained Soil.

Studying the creep-fatigue interaction of the coarse-grained soil (CGS) is very important for safety assessment and disaster prevention in subgrade engineering. Current research work is mainly focused on single creep or fatigue deformation. In this paper, a new creep-fatigue interaction model is established to predict the creep-fatigue interaction deformation of different gradation CGS based on the rheological mechanics and the interactive relationship between creep and fatigue complex compliance method. Triaxial creep-fatigue interaction tests of different gradations CGS under different average stresses and frequencies were conducted to verify the new creep-fatigue interaction model. Research results show that for the creep-fatigue and fatigue-creep interaction, the fatigue deformation is always larger than the creep deformation under the same stress level. For the creep-fatigue multi-interaction, the second creep and fatigue deformation are always smaller than the first creep and fatigue deformation. The results of the triaxial creep-fatigue interaction tests verify the validity of this new model.

A New Flattened Cylinder Specimen for Direct Tensile Test of Rock.

In recent decades, researchers have paid more attention to the indirect tensile test than to the direct tensile test (DTT) of rocks, mainly due to difficulties in the alignment and the stress concentration at the end of an intact cylindrical specimen. In this paper, a new flattened cylinder specimen and a clamp device were designed to obtain the true tensile strength of the rock in DTT. Stress distributions of the specimen with different lengths (l) and cutting thicknesses (t) were analyzed, and damage processes of the specimen were monitored by the Digital Image Correlation (DIC), the fractured sections were also scanned. Different mechanical parameters were also obtained by the DTT of the flattened cylinder specimens and the intact cylinder specimens, as well as the Brazilian disc. Research results show that the tensile strength obtained by DTT is smaller than the Brazilian disc and is slightly greater than the intact cylindrical specimen. The flattened cylinder specimen with 0.20 ≤ 2t/D < 0.68 and 0.10 ≤ l/D ≤ 0.20 is recommended to measure the true tensile strength of rock material in DTT. This new shape of the specimen is promising to be extended in the uniaxial or triaxial direct tension test.

Pseudomonas piscis sp. nov., isolated from the profound head ulcers of farmed Murray cod (Maccullochella peelii peelii).

A Gram-stain-negative, strictly aerobic, motile, rod-shaped bacterium with monopolar flagella, designated as MC042T, was isolated from the profound head ulcers of farmed Murray cod sampled from Zhejiang Province, China. Analysis of its 16S rRNA gene sequence and multilocus sequence analysis phylogeny showed that strain MC042T belonged to the genus Pseudomonas, showing the highest 16S rRNA gene sequence similarity to Pseudomonas juntendi BML3T (98.9 %), and less than 98.8 % similarity to other Pseudomonas species with validly published names. Whole-genome sequencing and phylogenetic reconstruction based on a core set of 1563 Pseudomonas genes further indicated that strain MC042T was most closely related to the clade formed by Pseudomonas protegens CHA0T and Pseudomonas saponiphila DSM 975T and distantly related to any of the validly published species of the genus Pseudomonas. Furthermore, strain MC042T could be distinguished from its closely related species of the genus Pseudomonas by its ability to assimilate maltose, d-xylose and melibiose, but not d-mannitol. The principal fatty acids were C16 : 0, summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1ω7c) and summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c). The respiratory quinone was Q-9. Polar lipids of strain MC042T comprised diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, unidentified glycolipids, an unidentified lipid, an unknown glycolipid and aminolipid. Based on its phenotypic, chemotaxonomic and phylogenetic features, strain MC042T is considered to represent a novel species, for which the name Pseudomonas piscis sp. nov. is proposed. The type strain is MC042T (=KCTC 72033T=MCCC 1K03575T).

Pseudomonas ovata sp. nov., Isolated from the Skin of the Tail of Farmed Murray cod (Maccullochella peelii peelii) with a Profound Ulceration.

A Gram-negative, strictly aerobic, motile, rod-shaped bacterium with monopolar flagellum, designated as F51T, was isolated from the skin ulcer of farmed Murray cod sampled from Zhejiang Province, China. Strain F51T grew at 4-37 °C (optimal temperature, 28 °C), pH 5.0-8.5 (optimal pH, 7.5) and NaCl concentration of 0-6.0% (w/v) (optimal concentration, 2.0%). Phylogenetic analysis based on average nucleotide identity (76.2-78.4%) and in silico DNA-DNA hybridization (22.3-23.2%) values revealed that strain F51T forms a distinct lineage in the clade of genus Pseudomonas with less than 98.9% 16S rRNA gene sequence similarity to type strains of the genus and represents a novel species related most closely to Pseudomonas floridensis LMG 30013T. Three housekeeping genes (rpoB, rpoD and gyrB) of strain F51T were analysed to further confirm that the isolate is distinctly delineated from related Pseudomonas species. Chemotaxonomic analysis indicated that the sole respiratory quinone of strain F51T is Q-9; its predominant cellular fatty acids are C16:0, summed feature 3 (iso-C15:0 2-OH and/or C16:1ω7c), summed feature 8 (C18:1ω7c and/or C18:1ω6c) and C10:0 3-OH; and its major polar lipids consist of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, two unidentified glycolipids, three unidentified phospholipids and an unidentified aminophosphoglycolipid. This composition is typical of the chemotaxonomic attributes of Pseudomonas. Based on its phenotypic, chemotaxonomic and phylogenetic features, strain F51T is considered to represent a novel species for which the name Pseudomonas ovata sp. nov. is proposed. The type strain is F51T (= KCTC 62133T = MCCC 1K03458T).

Chryseobacterium aurantiacum sp. nov., isolated from a freshwater pond used for Murray cod (Maccullochella peelii peelii) culture.

A yellow-pigmented, Gram-staining-negative, aerobic, non-motile and rod-shaped bacterium, designated strain F30T, was isolated from fresh water of a diseased farmed Murray cod with a profound ulceration pond in Zhejiang province, PR China. Growth was observed at NaCl concentrations of 0.5-3.5 % (w/v) (optimum, 1.5-2.0 %), temperatures of 10-35 °C (optimum, 28 °C) and pH 5.0-9.0 (optimum, 6.5). Phylogenetic analysis based on 16S rRNA gene sequences indicated that F30T represented a member of the genus Chryseobacterium, showing the highest similarity to Chryseobacterium jejuense DSM 19299T (99.0 %) and Chryseobacterium nakagawai NCTC 13529T (99.0 %), and less than 98.7 % similarity to other species of the genus Chryseobacterium with validly published names. The average nucleotide identity and in silico DNA-DNA hybridization values between F30T and the reference strains were 78.4-90.5 % and 2.6-42.5 %, respectively. The results of chemotaxonomic analysis indicated that the fatty acids, as well as the polar lipid profiles of F30T were similar to those of species of the genus Chryseobacterium, and the sole respiratory quinone was MK-6. On the basis of its phylogenetic, chemotaxonomic and phenotypic data, strain F30T represents a novel species, for which the name Chryseobacteriumaurantiacum sp. nov. is proposed. The type strain is F30T (=KCTC 62135T=MCCC 1K03457T).

Acinetobacter piscicola sp. nov., isolated from diseased farmed Murray cod (Maccullochella peelii peelii).

A taxonomic study was carried out on strain LW15T, which was isolated from the external lesions of diseased farmed Murray cod (Maccullochella peelii peelii) from an intensive culture pond. Cells of strain LW15T were Gram-negative, facultative-anaerobic, non-motile, and both coccobacillus- and bacillus-shaped. Growth was observed at NaCl concentrations of 0-2 % (w/v) (optimum, 0 %), 4-32 °C (optimum, 25-28 °C) and pH 5.0-9.0 (optimum, 7.0). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain LW15T was affiliated to the genus Acinetobacter, showing the highest similarity to Acinetobacter guillouiae CIP 63.46T (97.7 %) and other Acinetobacter species with validly published names (93.5-97.6 %). Whole-genome sequencing and phylogeny reconstruction based on a core set of 1061 Acinetobacter genes indicated that strain LW15T was most closely related to the clade formed by A. guillouiae CIP 63.46T and Acinetobacter bereziniae CIP 70.12T and distantly related to any of the described species of genus Acinetobacter. Furthermore, strain LW15T could be distinguished from all known Acinetobacter species by its ability to assimilate ß-alanine and l-arginine, but not d-glucose. The principal fatty acids were C18 : 1ω9c, C16 : 0 and C16 : 1ω7c/C16 : 1ω6c. The major respiratory quinone was Q-9. Polar lipids of strain LW15T comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, four phospholipids, aminolipid and two unknown lipids. Based on its phenotypic and genotypic data, strain LW15T represents a novel species of the genus Acinetobacter, for which the name Acinetobacterpiscicola sp. nov. is proposed. The type strain is LW15T (=MCCC 1K03337T=CICC 24241T=KCTC 62134T=JCM 32101T).

Effects of N precursor on the agglomeration and visible light photocatalytic activity of N-doped TiO2 nanocrystalline powder.

N-doped TiO2 nanocrystalline powders were prepared by the sol-gel method using various N precursors, including triethylamine, hydrazine hydrate, ethylenediamine, ammonium hydroxide, and urea. The samples were characterized by X-ray diffraction, N2 adsorption isotherms, transmission electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The photocatalytic activities of as-prepared samples under irradiation of visible light (lambda > 405 nm) were evaluated by photodecomposition of methyl orange. The alkalinity of N precursor was found to play a key role in the gel process. The N precursor with moderate alkalinity causes TiO2 nanoparticles to be sol-transformed into a loosely agglomerated gel. This transformation facilitates the preparation of an N-doped TiO2 powder with small nanocrystal size, large specific surface area, and high N doping level and results in high visible light photocatalytic activity. The N in TiO2 with N is binding energy at 399-400 eV may be assigned to the N-H species located in interstitial sites of TiO2 lattice which is the active N species responsible for the visible light photocatalytic activity. The N species of N 1s peak at 402 and 405 eV are ineffective to the visible light photocatalytic activity and may inhibit the photocatalytic activity. Moreover, a TiO2 nanoparticle powder with large specific area can be achieved by using urea as a template and then by using ammonium hydroxide to transform the sol into gel.