scholarly journals Effect of substrate grain size on the growth and morphology of the submersed macrophyte Vallisneria natans L.

Limnologica ◽  
2012 ◽  
Vol 42 (1) ◽  
pp. 81-85 ◽  
Author(s):  
Z.Q. Li ◽  
L.Y. Kong ◽  
L.F. Yang ◽  
M. Zhang ◽  
T. Cao ◽  
...  
Keyword(s):  
Grain Size ◽  
Vallisneria Natans ◽  
Submersed Macrophyte

The role of NH+4 toxicity in the decline of the submersed macrophyte Vallisneria natans in lakes of the Yangtze River basin, China

2007 ◽  
Vol 58 (6) ◽  
pp. 581 ◽  
Author(s):  
Te Cao ◽  
Ping Xie ◽  
Leyi Ni ◽  
Aiping Wu ◽  
Min Zhang ◽  
...  
Keyword(s):  
Water Column ◽  
River Basin ◽  
Yangtze River ◽  
Yangtze River Basin ◽  
The Yangtze River ◽  
Submersed Macrophytes ◽  
Vallisneria Natans ◽  
Submersed Macrophyte ◽  
N Concentration ◽  
The Yangtze River Basin

Experimental and field studies were conducted to evaluate the effects of NH4+ enrichment on growth and distribution of the submersed macrophyte, Vallisneria natans L, in lakes of the Yangtze River in China, based on the balance between free amino acids (FAA) and soluble carbohydrates (SC) in the plant tissue. Increase of NH4+ rather than NO3– concentrations in the water column caused FAA accumulation and SC depletion of the plant. The plant showed a unimodal pattern of biomass distribution along both FAA/SC ratios and external NH4+ concentrations, indicating that a moderate NH4-N concentration (<0.3 mg L–1) benefited the plant, whereas the high NH4-N concentration (>0.56 mg L–1) eliminated the plant completely. Therefore, 0.56 mg NH4-N mg L–1 in the water column was taken as the upper limit for V. natans in lakes of the Yangtze River basin. The mesocosm experiment showed that at a high external NH4-N (0.81 mg L–1), V. natans failed to propagate with a loss of half SC content (5 mg g–1 DW) in the rhizomes, indicating that the consumption of carbohydrates for detoxification of excess NH4+ into non-toxic FAA significantly diminished carbohydrate supply to the rhizomes. This might consequently inhibit the vegetative reproduction of the plant, and also might be an important cause for the decline and disappearance of the plant with eutrophication. The present study for the first time reports substantial ecophysiological evidences for NH4+ stress to submersed macrophytes, and indicates that NH4+ toxicity arising from eutrophication probably plays a key role in the deterioration of submersed macrophytes like V. natans.

Ammonium loading disturbed the microbial food webs in biofilms attached to submersed macrophyte Vallisneria natans

2019 ◽  
Vol 659 ◽  
pp. 691-698 ◽  
Author(s):  
Lingling Yan ◽  
Xiaoying Mu ◽  
Bing Han ◽  
Songhe Zhang ◽  
Changhao Qiu ◽  
...  
Keyword(s):  
Food Webs ◽  
Microbial Food Webs ◽  
Vallisneria Natans ◽  
Submersed Macrophyte

scholarly journals Remedial function of submersed macrophyte Vallisneria natans to PAHs-contaminated sediments

2018 ◽  
Vol 30 (4) ◽  
pp. 1012-1018 ◽  
Author(s):  
ZHANG Yu ◽  
◽  
YAN Zaisheng ◽  
WU Huifang ◽  
JIANG Helong ◽  
...  
Keyword(s):  
Contaminated Sediments ◽  
Vallisneria Natans ◽  
Submersed Macrophyte

Effect of Shock Loading on the Microstructure of Uniloy 326

1974 ◽  
Vol 32 ◽  
pp. 504-505
Author(s):  
K. P. Staudhammer ◽  
L. E. Murr
Keyword(s):  
Grain Size ◽  
Shock Loading ◽  
Current Investigation ◽  
Two Phase ◽  
05 C ◽  
Shock Deformation ◽  
Heat Treated

The effect of shock loading on a variety of steels has been reviewed recently by Leslie. It is generally observed that significant changes in microstructure and microhardness are produced by explosive shock deformation. While the effect of shock loading on austenitic, ferritic, martensitic, and pearlitic structures has been investigated, there have been no systematic studies of the shock-loading of microduplex structures.In the current investigation, the shock-loading response of millrolled and heat-treated Uniloy 326 (thickness 60 mil) having a residual grain size of 1 to 2μ before shock loading was studied. Uniloy 326 is a two phase (microduplex) alloy consisting of 30% austenite (γ) in a ferrite (α) matrix; with the composition.3% Ti, 1% Mn, .6% Si,.05% C, 6% Ni, 26% Cr, balance Fe.

Aspects of microanalysis in a transmission electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 510-511
Author(s):  
R. Sinclair ◽  
B.E. Jacobson
Keyword(s):  
Grain Size ◽  
Electron Beam ◽  
Electron Microscope ◽  
Chemical Analysis ◽  
Transmission Electron Microscope ◽  
Vapor Deposition ◽  
Critical Currents ◽  
X Ray ◽  
Fine Grain ◽  
Transmission Electron

INTRODUCTIONThe prospect of performing chemical analysis of thin specimens at any desired level of resolution is particularly appealing to the materials scientist. Commercial TEM-based systems are now available which virtually provide this capability. The purpose of this contribution is to illustrate its application to problems which would have been intractable until recently, pointing out some current limitations.X-RAY ANALYSISIn an attempt to fabricate superconducting materials with high critical currents and temperature, thin Nb3Sn films have been prepared by electron beam vapor deposition [1]. Fine-grain size material is desirable which may be achieved by codeposition with small amounts of Al2O3 . Figure 1 shows the STEM microstructure, with large (∽ 200 Å dia) voids present at the grain boundaries. Higher quality TEM micrographs (e.g. fig. 2) reveal the presence of small voids within the grains which are absent in pure Nb3Sn prepared under identical conditions. The X-ray spectrum from large (∽ lμ dia) or small (∽100 Ǻ dia) areas within the grains indicates only small amounts of A1 (fig.3).

Novel magneto-optical recording materials: Bi-substituted garnet films

1991 ◽  
Vol 49 ◽  
pp. 776-777
Author(s):  
Takao Suzuki ◽  
Hossein Nuri
Keyword(s):  
Grain Size ◽  
Amorphous Film ◽  
Nitrogen Atmosphere ◽  
Optical Recording ◽  
Garnet Film ◽  
Media Noise ◽  
Garnet Films ◽  
Order Of Magnitude ◽  
A New Technique ◽  
A Current

For future high density magneto-optical recording materials, a Bi-substituted garnet film ((BiDy)3(FeGa)5O12) is an attractive candidate since it has strong magneto-optic effect at short wavelengths less than 600 nm. The signal in read back performance at 500 nm using a garnet film can be an order of magnitude higher than a current rare earth-transition metal amorphous film. However, the granularity and surface roughness of such crystalline garnet films are the key to control for minimizing media noise.We have demonstrated a new technique to fabricate a garnet film which has much smaller grain size and smoother surfaces than those annealed in a conventional oven. This method employs a high ramp-up rate annealing (Γ = 50 ~ 100 C/s) in nitrogen atmosphere. Fig.1 shows a typical microstruture of a Bi-susbtituted garnet film deposited by r.f. sputtering and then subsequently crystallized by a rapid thermal annealing technique at Γ = 50 C/s at 650 °C for 2 min. The structure is a single phase of garnet, and a grain size is about 300A.

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