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Frontiers in Phytolith Research View all 20 Articles. Here, we investigated in detail the uptake, accumulation and distribution of Si in date palms, and the phylogeny of Si transporter genes in plants. We characterized the PdNIP2 transporter following heterologous expression in Xenopus oocytes and used qPCR to determine the relative expression of Si transporter genes. Silicon accumulation and distribution was investigated by light microscopy, scanning electron microscopy coupled with X-ray microanalysis and Raman microspectroscopy.
Stegmata were organized on the outer surface of the sclerenchyma bundles or associated with the sclerenchyma of the vascular bundles. Phylogenetic analysis clustered NIP2 transporters of the Arecaceae in a sister position to those of the Poaceae.
Diffusion of phosphorus in oligo-crystalline silicon occurs along the grain boundaries and through the bulk of the crystals. High precision is required to separate these two phenomena. The procedures for counting by a solid scintillator detector and by liquid scintillation are compared. In the first approach the remaining sample is counted after successive polishings. The second technique is based on dissolution and measurement of the polished off material. It appears that the attainable precision is a function of the concentrationprofile.
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Carbon exists in three forms, or isotopes, carbon 12 C , carbon 13 C , and carbon 14 C. Carbon is formed in the upper atmosphere when a neutron in cosmic radiation strikes an atom of nitrogen 14 N and converts it to carbon The rate of decay is such that half the atoms of carbon in a sample decay to nitrogen in approximately years.
To quantitatively evaluate the 32Si content in silicon metal and precursor materials, Practical complications of radioisotope dating of inclusions are fatal to the.
We also introduced an optical phase bias to one phase-shifter arm of a Mach—Zehnder interferometer MZI -type switch unit to balance the two operation statuses of a silicon electro-optical switch during push—pull operation. The losses were Accompanying the rapid increases in the numbers of data centres DCs and high-performance computers HPCs , optical switches are highly demanded for the construction of DC and HPC optical interconnection networks for increasing the speed of data exchange and reducing power consumption 1 , 2 , 3.
These switches are also key devices for building all-optical telecommunication networks. Silicon-integrated optical switches, together with other silicon photonic devices based on silicon-on-insulator SOI substrates and complementary metal—oxide—semiconductor CMOS -compatible process technologies, are widely regarded as the most promising devices for applications in data communications and telecommunications.
They are compact, have a low power consumption and low cost, and are fit for large-scale monolithic integration. Many studies of silicon switches have been conducted 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ,
Journal of Lightwave Technology
The present invention relates to the fields of nuclear chemistry and radiochemistry. This invention is the result of a contract with the Department of Energy Contract No. This is a Division of application Ser. The isotope of silicon having an atomic weight of 32 Si is useful, e. Silicon has previously been produced by: 1 spallation of vanadium with high energy protons, followed by extraction as molybdosilicic acid and purification by anion exchange; and 2 reaction of a sulfur target with protons from a synchrocyclotron, followed by recovery by distillation as H 2 SiF 6 from a concentrated sulphuric acid solution.
Each of the former processes used materials such as n-butanol or hydrofluoric acid that are undesirable to use either due to safety or to mixed waste disposal problems.
We are currently determining the exact age of this sponge using Silicon 32 (32Si) dating (see panel opposite page). We anticipate that the.
Salta ai contenuti. Salta alla navigazione. Guarda la mappa. Salta alla navigazione Strumenti personali. Laurea Magistrale in Quaternario, preistoria e archeologia. Cerca nel sito solo nella sezione corrente. Ricerca avanzata…. Possible sources of error. Calibration of the Radiocarbon timescale. Critical aspects and applications – Principles of U-Series Dating. Applications – Dating with short-lived isotopes: Lead; Caesium; Silicon Applications and limits. General principles. Dendrochronological series.
Silicon has two stable isotopes and one cosmogenic isotope. The cosmogenic isotope 32 Si is used to determine surface exposure ages and erosion rates. It is also being investigated as a tracer of groundwater recharge. Currently this is not a tracer used beyond research applications and so no pricing data is available. It would be costly due to numerous difficulties:large sample size, rarity of use, and extremely sensitive detection requirements.
Parks & Recreation · Police Department · Public Works · Silicon Valley Power Each tag allows for an additional 32 gallon size bag of garbage to be These bag tags have no expiration date and can be used any time throughout the year.
The steady decay of naturally radioactive substances provides scientists with a set of useful gauges for determining the ages of things. Brookhaven National Laboratory in Upton, L. Silicon 32 was discovered in , but estimates of the isotope’s half-life the time it takes for half of it to decay have varied wildly. The latest Brookhaven study, which took four years to complete, has evidently settled the matter. A Brookhaven team reports in Earth and Planetary Science Letters that the half-life of silicon 32 is years, give or take four years.
The Brookhaven group says that the silicon 32 half-life determination will help in measuring the rates of ocean water mixing, glaciation and various geological processes that occur on a time scale of hundreds of years.
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. DOI: Lal and E. Goldberg and M.
These metrics are regularly updated to reflect usage leading up to the last few days. Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts. The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online.
Clicking on the donut icon will load a page at altmetric. Find more information on the Altmetric Attention Score and how the score is calculated. A radiochemical neutron activation analysis procedure has been developed, critically evaluated, and shown to have the necessary sensitivity, chemical specificity, matrix independence, and precision to certify phosphorus at ion implantation levels in silicon.
A detailed evaluation of uncertainties is given. Corresponding author. View Author Information. Cite this: Anal.