Zinc tolerance and the binding of zinc as zinc phytate in Lemna minor. X-ray microanalytical evidence

1990 ◽  
Vol 137 (2) ◽  
pp. 140-146 ◽  
Author(s):  
R.F.M. Van Steveninck ◽  
M.E. Van Steveninck ◽  
A.J. Wells ◽  
D.R. Fernando
Keyword(s):  
Lemna Minor ◽  
Zinc Tolerance ◽  
X Ray

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

X-Ray Microanalytical Studies on Two Modes of Strontium Binding in Fronds of Lemna minor

1995 ◽  
Vol 22 (5) ◽  
pp. 817 ◽  
Author(s):  
RFMV Steveninck ◽  
DR Fernando
Keyword(s):  
Nutrient Solution ◽  
Microprobe Analysis ◽  
Lemna Minor ◽  
Mineral Elements ◽  
Cd Toxicity ◽  
X Ray ◽  
Oxalate Crystals

X-ray microprobe analysis of freeze-fractured Lemna fronds has shown that zinc (Zn) and cadmium (Cd) are not incorporated into oxalate crystals in idioblasts, whereas strontium (Sr) is readily incorporated as an alternative to calcium (Ca). Ca and Sr are uniformly distributed throughout the crystal bundle when both elements are present in the nutrient solution. However, in neighbouring, non-idioblast cells Sr (but not Ca) may also be incorporated into globular deposits of less than 1 �m diameter. These globules contain the mineral elements potassium and phosphorus and their composition appears to be identical to that of phytate globules which contain Zn or Cd under conditions of Zn or Cd toxicity.

The Uptake and Distribution of Potassium in Roots of Duckweed (Lemna Minor L) As Measured using Low Temperature X-Ray Microanalysis

1982 ◽  
Vol 40 ◽  
pp. 408-411
Author(s):  
Patrick Echlin ◽  
Clifford Lai ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Background Subtraction ◽  
Cell Walls ◽  
Lemna Minor ◽  
Beam Current ◽  
X Ray ◽  
Dark Regime ◽  
Low Temperature Microscopy

Lemna minor L. plants were grown in a 14 H light and 10 H dark regime at 298 K in a medium containing 2 mM [K+]. Roots, 20 mm long and photosynthetically active, were removed and prepared for low temperature microscopy using methods described elsewhere. Fracture faces were made using the AMRAY Biochamber and the analysis carried out using an AMRAY 1000A SEM fitted with an LaB6 gun and a Kevex Si (Li) x-ray detector at 15-17 kV and a beam current of 1-2 nA. A reduced raster (1.0 μm2) was placed at the centre of the cell being analysed, care being taken to avoid any contact with the cell walls. Samples were maintained at 100-110 K throughout analysis and an LN2 cooled anti-contamination device was inserted close to the specimen. The spectra were analysed using the peak/background (P/B) ratio technique following use of background subtraction and peak de-convolution routines. Between eight and twelve fracture faces were analysed for each of the ten sites along the length of the root and the data pooled and presented in Table I.

scholarly journals Biogenic ZnO Nanoparticles Synthesized Using a Novel Plant Extract: Application to Enhance Physiological and Biochemical Traits in Maize

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1270
Author(s):  
Daniele Del Buono ◽  
Alessandro Di Michele ◽  
Ferdinando Costantino ◽  
Marco Trevisan ◽  
Luigi Lucini
Keyword(s):  
Plant Extract ◽  
Lemna Minor ◽  
Metal Oxide Nanoparticles ◽  
Seed Priming ◽  
Crop Productivity ◽  
Oxide Nanoparticles ◽  
Zno Nps ◽  
X Ray ◽  
Beneficial Effects ◽  
Wide Range

The need to increase crop productivity and resistance directs interest in nanotechnology. Indeed, biogenic metal oxide nanoparticles can promote beneficial effects in plants, while their synthesis avoids the environmental impacts of conventional synthetic procedures. In this context, this research aimed to synthesize biogenic zinc oxide nanoparticles (ZnO-NPs) using, for the first time, an extract of a wild and spontaneous aquatic species, Lemna minor (duckweed). The effectiveness of this biogenic synthesis was evidenced for comparison with non-biogenic ZnO-NPs (obtained without using the plant extract), which have been synthesized in this research. XRD (X-ray diffraction), FE-SEM (field emission gun electron scanning microscopy), EDX (energy dispersive x-ray spectroscopy), TEM (transmission electron microscope) and UV-vis (ultraviolet-visible spectrophotometry) showed the biogenic approach effectiveness. The duckweed extract was subjected to UHPLC-ESI/QTOF-MS (ultra high-pressure liquid chromatography quadrupole time of flight mass spectrometry) phenolic profiling. This untargeted characterization highlighted a high and chemically diverse content in the duckweed extract of compounds potentially implicated in nanoparticulation. From an application standpoint, the effect of biogenic nanoparticles was investigated on some traits of maize subjected to seed priming with a wide range of biogenic ZnO-NPs concentrations. Inductive effects on the shoot and root biomass development were ascertained concerning the applied dosage. Furthermore, the biogenic ZnO-NPs stimulated the content of chlorophylls, carotenoids, and anthocyanin. Finally, the study of malondialdehyde content (MDA) as a marker of the oxidative status further highlighted the beneficial and positive action of the biogenic ZnO-NPs on maize.

A New Germacranolide and a New Ceramide from Salvia nubicola (Lamiaceae)

2007 ◽  
Vol 62 (10) ◽  
pp. 1333-1338 ◽  
Author(s):  
Muhammad S. Ali ◽  
Syed A. Ibrahima ◽  
Shakeel Ahmed ◽  
Emil Lobkovsky
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Growth Inhibition ◽  
Single Crystal ◽  
Diffraction Analysis ◽  
Lemna Minor ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
Strong Growth ◽  
X Ray ◽  
Soluble Part

The methanol-soluble part of Salvia nubicola has yielded a new germacranolide and a new ceramide named nubtrienolide and nubenamide, respectively. Structures of both the isolated constituents were elucidated with the aid of spectroscopic techniques; the nubtrienolide structure was further confirmed via single crystal X-ray diffraction analysis. Among both the metabolites, nubtrienolide showed strong growth inhibition against Pseudomonas aeruginosa while during phytotoxicity testing, the same compound promoted the growth of Lemna minor L. instead to inhibit it.

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.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx> 10 keV is likely due to fluorescence outside the He II ionization front.

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