scholarly journals Application of X-ray tomography to evaluate liming impact on earthworm burrowing activity in an acidic forest soil under laboratory conditions

Geoderma ◽  
2013 ◽  
Vol 202-203 ◽  
pp. 45-50 ◽  
Author(s):  
A. Auclerc ◽  
Y. Capowiez ◽  
F. Guérold ◽  
J. Nahmani
Keyword(s):  
Forest Soil ◽  
X Ray ◽  
Laboratory Conditions ◽  
Burrowing Activity

14C Translocation patterns in peach and apricot shoots

1968 ◽  
Vol 19 (5) ◽  
pp. 775 ◽  
Author(s):  
PE Kriedemann
Keyword(s):  
Main Stem ◽  
Advanced Stage ◽  
Fruit Removal ◽  
X Ray ◽  
Laboratory Conditions ◽  
Fruit Maturity

14CO2 was supplied under laboratory conditions to the terminal leaves of peach and apricot shoots taken from orchard trees over the period from flowering to fruit maturity. The distribution of 14C assimilates along the shoot, and the patterns of deposition within the developing fruit were recorded on X-ray film. In both peach and apricot shoots, the terminal leaves, soon after emergence, exported assimilates to adjacent fruit which competed successfully with nearby expanding leaves, although isolated leaves (in peach) were capable of importing. At a more advanced stage only the fruits imported assimilates from the terminal leaves, and the labelled substrates were deposited in both flesh and inner seed structures despite the hardened stone. The fruit continued to accumulate 14C photosynthate even when completely ripe. Following fruit removal, export from the terminal leaves on the peach shoot was minimal, and labelled photosynthate was detected only in the main stem; whereas in apricot shoots, mature lower leaves showed extensive import of current assimilates.

Controlling Laboratoey Conditions: Preventing the Problem, The Health Physicist's Viewpoint

1986 ◽  
Vol 30 ◽  
pp. 575-582
Author(s):  
Ted de Castro
Keyword(s):  
X Rays ◽  
X Ray ◽  
Laboratory Conditions

After having heard about the magnitude of the problem of safety in the use of analytical x-ray equipment and then learned of the consequences of exposure to these x-rays, it is hard not to be convinced that a problem exists. Also being aware of the degree of responsibility in the event of an accident, it is clear that steps must be taken to prevent such occurrences. Controlling laboratory conditions is the key to prevention and, therefore, the solution to the problem.Controls may be imposed administratively or with hardware. Administrative controls are easy and inexpensive to impose. Enforcement, however, is time consuming and difficult, since such controls need only be ignored to be compromised. Hardware controls are more positive and difficult to ignore. The bypassing of hardware controls is usually invasive on the equipment and leaves evidence.When imposing controls it is necessary not to lose sight of the operational needs which brought the x-ray unit into your organization to begin with. Analytical x-ray machines are safest during massive power failures—but not very useful. Administrative and hardware controls which hobble the use of the equipment will be violated. Cooperation between the health physicist and the x-ray users can bring together the requirements of safety and Utility to create controls which will work.

Some soil morphological effects of earthworm activity; field data and X-ray radiography.

1978 ◽  
Vol 26 (2) ◽  
pp. 145-160 ◽  
Author(s):  
H. Rogaar ◽  
J.A. Boswinkel
Keyword(s):  
Lumbricus Terrestris ◽  
Apple Orchard ◽  
Channel Structure ◽  
Grass Cover ◽  
X Ray ◽  
Yield Increase ◽  
Permanent Pasture ◽  
Burrowing Activity ◽  
Time Since Introduction ◽  
Earthworm Activity

The effects of the burrowing activity of earthworms on recently reclaimed polder soils were studied in the field and by binocular microscopy and X-ray stereo-radiography. Most observations are from a plot in a grassed apple orchard, some from a permanent pasture. Species involved comprise Lumbricus terrestris, Allolobophora caliginosa, A. rosea, A. chlorotica and L. rubellus. Under grass cover, an A1 horizon is formed, increasing in thickness with time since introduction of the worm population. Under clean cultivated conditions and in strongly compressed wheel tracks, however, development of an A1 horizon is inhibited. The A1 horizon mainly consists of earthworm excreta, which fill most of the burrows. The pre-existing channel structure produced by roots is disrupted by the earthworms. The earthworm activity leads to a marked increase in air permeability of the surface horizon. This may not be sufficient explanation for the previously-reported yield increase of the orchard or the divergence in composition of the grass cover. Several kinds of burrows are distinguished by their shapes and contents, and ascribed to different species or genera. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Occurrence of a ferrous, trioctahedral smectite in Recent sediments of Atlantis II Deep, Red Sea

Clay Minerals ◽  
1985 ◽  
Vol 20 (3) ◽  
pp. 389-404 ◽  
Author(s):  
D. Badaut ◽  
G. Besson ◽  
A. Decarreau ◽  
R. Rautureau
Keyword(s):  
Diffraction Study ◽  
Red Sea ◽  
Optical Investigation ◽  
Octahedral Sheet ◽  
X Ray ◽  
Laboratory Conditions ◽  
Atlantis Ii Deep ◽  
Hydrothermal Spring ◽  
Recent Sediments ◽  
Trioctahedral Smectite

AbstractA trioctahedral, ferrous smectite has been located in the uppermost deposits of Atlantis II Deep, SW basin, Red Sea. This clay is very unstable when removed from its environment of formation and, for example, oxidizes during desiccation under laboratory conditions. Only X-ray transmission diffraction study of the mud itself demonstrates the trioctahedral character of the clay. Electron-optical investigation shows that oxidation within the octahedral sheet creates a juxtaposition of dioctahedral and trioctahedral sub-lattices in the same particle. Ferrous smectite authigenesis is located near the hydrothermal spring outlets of the Atlantis II Deep.

scholarly journals Correcting field determination of elemental contents in soils via portable X-ray fluorescence spectrometry

2020 ◽  
Vol 44 ◽  
Author(s):  
Thaís Santos Branco Dijair ◽  
Fernanda Magno Silva ◽  
Anita Fernanda dos Santos Teixeira ◽  
Sérgio Henrique Godinho Silva ◽  
Luiz Roberto Guimarães Guilherme ◽  
...  
Keyword(s):  
Linear Regression ◽  
Regression Models ◽  
Prediction Models ◽  
Elemental Content ◽  
Auxiliary Variables ◽  
Linear Regression Models ◽  
X Ray ◽  
Laboratory Conditions ◽  
Elemental Contents ◽  
Field And Laboratory Conditions

ABSTRACT Portable X-ray fluorescence (pXRF) spectrometry has been useful worldwide for determining soil elemental content under both field and laboratory conditions. However, the field results are influenced by several factors, including soil moisture (M), soil texture (T) and soil organic matter (SOM). Thus, the objective of this work was to create linear mathematical models for conversion of Al2O3, CaO, Fe, K2O, SiO2, V, Ti and Zr contents obtained by pXRF directly in field to those obtained under laboratory conditions, i.e., in air-dried fine earth (ADFE), using M, T and SOM as auxiliary variables, since they influence pXRF results. pXRF analyses in field were performed on 12 soil profiles with different parent materials. From them, 59 samples were collected and also analyzed in the laboratory in ADFE. pXRF field data were used alone or combined to M, T and SOM data as auxiliary variables to create linear regression models to predict pXRF ADFE results. The models accuracy was assessed by the leave-one-out cross-validation method. Except for light-weight elements, field results underestimated the total elemental contents compared with ADFE. Prediction models including T presented higher accuracy to predict Al2O3, SiO2, V, Ti and Zr, while the prediction of Fe and K2O contents was insensitive to the addition of the auxiliary variables. The relative improvement (RI) in the prediction models were greater in predictions of SiO2 (T+SOM: RI=22.29%), V (M+T: RI=18.90%) and Ti (T+SOM: RI=11.18%). This study demonstrates it is possible to correct field pXRF data through linear regression models.

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

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