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1

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Acute toxicity of ammonia to the early stage-larvae and juveniles of Eriocheir sinensis H. Milne-Edwards, 1853 (Decapoda: Grapsidae) reared in the laboratory (1997)

Zhao, J-H ; Lam, T J ; Guo, J-Y

Oxford, UK : Blackwell Publishing Ltd

Aquaculture research 28 (1997), S. 0

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ISSN: 1365-2109

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Static-renewal bioassays were performed to evaluate the acute toxicity of ammonia to Eriocheir sinensis (H. Milne-Edwards) at three growing stages, namely zoea-I, zoea-II, and juvenile (0.06 g wet weight per crab). The 24 h LC50 values were 13.3, 20.2, and 109.3 mg (NH3+ NH4+) 1−1 (0.47, 0.71, and 3.10 mg NH3 I−1), the 48 h LC50 values being 6.8, 10.3, and 60.9 mg (NH3+ NH4+) 1−1 (0.24, 0.36, and 1.73 mg NH31−1), while the 72 h LC50 values were 5.7, 7.6, and 45.3 mg (NH3+ NH4+) 1−1 (0.20, 0.27, and 1.29 mg NH3 1−1) for zoea-I, zoea-II, and juveniles, respectively. The 96 h LC50 value for juveniles was 31.6 mg (NH3+ NH4+) 1−1(0.90 mg NH31−1). It was evident that the tolerance to ammonia increased during the same exposure time as the larvae developed to juveniles and decreased with prolonged exposure time. Compared with larvae, juveniles were more sensitive to the fluctuation of ambient ammonia concentrations in the certain range within which partial kills took place. The ‘safe level’ of ammonia based on the 96 h LC50 value and an application factor of 0.1 was 3.16 mg (NH3+NH4+)1−1 (0.09 mg NH3 1−1) for juveniles and those for zoea-I and zoea-II were 0.57 and 0.76 mg (NH3+ NH4+) 1−1 (0.02 and 0.03 mg NH3 1−1) based on 72 h LC50 values.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2109.1997.00888.x

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2

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Lethal doses of ammonia on the late-stage larvae of Chinese mitten-handed crab, Eriocheir sinensis (H. Milne-Edwards), (Decapoda: Grapsidae) reared in the laboratory (1998)

Zhao, J H ; Guo, J Y ; Lam, T J

Oxford, UK : Blackwell Publishing Ltd

Aquaculture research 29 (1998), S. 0

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ISSN: 1365-2109

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Four successive life stages (zoea-III, zoea-IV, zoea-V and megalopa) of the Chinese mitten-handed crab, Eriocheir sinensis (H. Milne-Edwards), were exposed to ammonia in a series of short-term bioassays with the static-renewal method at 22°C, pH 8.0 and 25%o salinity. The greatest sensitivity was observed in the zoea-III stage. The 24-h LC50 values for zoea-III, zoea-IV, zoea-V and megalopa were 32.8, 73.1, 84.0 and 90.1 mg L−1 for NH3+ NH4+, and 1.11, 2.36, 2.77 and 3.18 mg L−1 for NH3, respectively. The 72-h LC50 values for zoea-III, zoea-IV and zoea-V were 11.9, 23.6 and 38.2 mg L−1 for NH3+ NH4+, and 0.40, 0.76 and 1.26 mg L−1 for NH3, respectively. The 96-h LC50 values for megalopa were 37.3 mg L−1 for NH3+ NH4+ and 1.31 mg L−1 for NH3. It was found that ammonia tolerance increased with larval development from zoea-III to megalopa, especially from zoea-III to zoea-IV and from zoea-IV to zoea-V. A comparison of safe levels of ammonia among the different life stages indicated that all stages were significantly different with respect to safe levels of ammonia (P 〈 0.05) except zoea-V and megalopa, which had the highest safe levels. In general, both the larvae and juveniles of E. sinensis are less resistant to ammonia than those of other crustacean species studied so far.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2109.1998.00253.x

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3

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Protein digestibility and amino acid availability of several protein sources for juvenile Chinese hairy crab Eriocheir sinensis H. Milne-Edwards (Decapoda, Grapsidae) (2000)

Mu, Y Y ; Lam, T J ; Guo, J Y ; [et al.]

Oxford, UK : Blackwell Science Ltd

Aquaculture research 31 (2000), S. 0

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ISSN: 1365-2109

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Apparent and true values of protein digestibility (APD vs. TPD) and amino acid availability (AAAA vs. TAAA) of casein, gelatin, fish meal, shrimp meal, soybean meal and spirulina meal were determined for juvenile Chinese hairy crab Eriocheir sinensis H. Milne-Edwards. Assay diets were prepared by incorporation of 20% of a protein source into a reference diet. A protein-free diet (PFD) was used to estimate the metabolic faecal nitrogen (MFN) content and amino acid composition (MFAA). MFN content was 445.3 mg 100 g−1 PFD. MFAA ranged from 19.6 mg 100 g−1 PFD for tryptophan to 228.5 mg 100 g−1 PFD for glutamic acid. Casein and gelatin trended towards higher APD, while fish meal had the lower APD and TPD. Although there was reasonable agreement between protein digestibility and average amino acid availability, protein sources had significant effects on AAAA and TAAA. For total amino acids and most individual amino acids, casein and gelatin were relatively higher both in AAAA and in TAAA, soybean meal and spirulina meal intermediate, while fish meal was lower. Data of AAAA and TAAA suggest that soybean meal and spirulina meal could be used as substitutes for animal proteins. Individual AAAAs and TAAAs were variable within and among protein sources. Those results suggest that determination of amino acid availabilities is necessary for the more accurate and economical feed formulation.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2109.2000.00498.x

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4

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Dynamic light scattering of dilute PVA-borax aqueous solutions (1998)

Chen, C. Y. ; Guo, J. Y. ; Yu, T. L. ; [et al.]

Springer

Journal of polymer research 5 (1998), S. 67-76

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ISSN: 1572-8935

Keywords: Poly(vinyl alcohol) ; Borax ; Dynamic light scattering ; Dilute solutions

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: Abstract Poly(vinyl alcohol)-borate (PVA-borate) complexes in dilute aqueous solutions were investigated by dynamic light scattering (DLS). Two relaxation modes obtained, were scattering vector-q2 dependent and diffusive. The amplitude of slow mode was independent of borax concentration. In the very dilute PVA concentration regime ( [PVA] 〈 5 g/L), the PVA di-diol-borate complexation was dominated by intra-molecular reaction, and the fast mode correlation length ςf which corresponds to the polymer chain dimension increased rapidly with borax concentrations lower than 0.06 M, and reached an asymptote in the higher borax concentration regime. However, for a dilute PVA aqueous solution with higher PVA content (i.e., [PVA] = 9 g/L), both intra-and inter-molecular PVA di-diol-borate complexations might happen. The chain expansion and shrinkage of PVA-borate complex with increasing borax concentration was observed due to the balance between the electrostatic repulsion of the charged diol-borate complexes and the intra-molecular crosslink induced by the intra-molecular di-diol-borate complexation.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s10965-006-0042-y

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5

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Induction plasma synthesis of ultrafine SiC powders from silicon and CH4 (1995)

Guo, J. Y. ; Gitzhofer, F. ; Boulos, M. I.

Springer

Journal of materials science 30 (1995), S. 5589-5599

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ISSN: 1573-4803

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract Ultrafine SiC powders have been synthesized from elemental silicon and methane using induction plasma technology. The powder products were characterized by X-ray diffraction, thermogravimetric analysis, scanning and transmission electron microscopy, electron probe microanalysis, infrared spectroscopy, and surface area measurement. The powders collected from various sections of the reactor system showed different features reflecting different compositions and powder morphologies. The purest SiC powder was collected in the metallic filter. It was composed of both α-and β-phase of SiC with small levels of free silicon and carbon. The reaction route used is based on the evaporation of the injected pure silicon starting powder, followed by carburization of the silicon vapour using methane. The silicon evaporation rate was found to depend strongly on the particle size of the silicon powder. Using silicon powder with a mean particle diameter of 100 μm, at a plasma power level of P=43.2 kW, the conversion of silicon to SiC and the overall SiC content in the product powder was 44.2% and 50.8 wt%, respectively. The injection probe position was Z=9.3 cm, the silicon feed rate was 4 g min−1, and the C/Si molar ratio was 0.7. Using silicon particles with a mean diameter of 45 μm, the conversion and overall content of SiC increased to 70.4% and 73.9 wt%, respectively, under the same plasma operating conditions and powder feed rates. By appropriate selection of experimental conditions, ultrafine SiC powder of high quality was achieved.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00356691

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6

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Regeneration of cassava plants via shoot organogenesis (1998)

Li, H.-Q. ; Guo, J.-Y. ; Huang, Y.-W. ; [et al.]

Springer

Plant cell reports 17 (1998), S. 410-414

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ISSN: 1432-203X

Keywords: Key words Cassava ; Manihot esculenta Crantz ; Shoot regeneration ; Organogenesis

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract A novel regeneration system based on direct shoot organogenesis is described for cassava. Plants could be regenerated at high frequency by inducing shoot primordia on explants derived from cotyledons of cassava somatic embryos. After a passage on elongation medium, the regenerated shoots were easily rooted in hormone-free medium and could be successfully transplanted to soil. Using the shoot-organogenesis-based regeneration method, up to eight transplantable plantlets per explant could be regenerated. The system was optimised first for one cassava cultivar, and then its transferability to three other cultivars was demonstrated. This method widens the scope of in vitro regeneration modes of cassava, and is also compatible with Agrobacterium-mediated transformation. To develop an efficient system for production of somatic embryos for regeneration experiments, conditions for inducing primary and cycling somatic embryos were also studied, and highly efficient plant regeneration via germination of somatic embryos was achieved using maltose instead of sucrose in the culture medium, and combining paclobutrazol with 2,4-dichlorophenoxyacetic acid in the embryo induction medium.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002990050416

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7

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Study of the sintering properties of plasma synthesized ultrafine SiC powders (1997)

GUO, J. Y ; GITZHOFER, F ; BOULOS, M. I ; [et al.]

Springer

Journal of materials science 32 (1997), S. 5257-5269

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ISSN: 1573-4803

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract A study on the sintering of ultrafine SiC powders synthesized from elemental Si and CH4 using radio frequency (r.f.) induction plasma technology is reported. The powder had a particle size in the range of 40 to 80 nm and was composed of a mixture of α and β-SiC. It was subjected to pressureless sintering in an induction furnace in the presence of different sintering aids. With the addition of B4C (2.0 wt% B) by mechanical mixing, the powders could only be partially densified, with the highest value of 84.5% of theoretical density being achieved at 2170°C for 30 min. Through the use of “in-flight” boron doping of the powder during the plasma synthesis step (1.65 wt% B), the ultrafine powder obtained could be densified to above 90% of its theoretical density at 2050°C for 30 min. The addition of oxide sintering aids (7.0 wt% Al2O3+3.0 wt% Y2O3) by mehanical mixing produced sintered pellets of 95% of theoretical density at 2000°C for 75 min. The Vicker’s microhardness of the sintered pellets in this case was as high as 31.2 GPa. In order to improve our understanding of the basic phenomena involved, extensive microstructural (scanning electron energy microscopy: SEM), physical (shrinkage, weight loss, porosity, hardness) as well as chemical analysis (prompt gamma neutron activation analysis (PGNAA), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA)) was carried out. This helped establish a relationship between the properties of the as-synthesized powder and their sintering properties. The influences of sintering temperature, sintering time, additive concentration, and powder purity on the densification behaviour of the plasma-synthesized powders was investigated. The results were compared with data obtained using commercial powder.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1018602508405

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