The technique uses excitation of neurons to produce gamma ray emission by the treated material. Neutron activation analysis has many applications; one of them is that it is used in forensic medicine to establish evidences in criminal cases.

Neutron Activation Analysis is very sensitive and is therefore used to analyse for minor elements, which are present in very low concentrations. The method is especially useful for trace element analysis, e.g. in high-purity substances, and is therefore important in semiconductor techniques.

There are two noteworthy drawbacks to the use of NAA; even though the technique is essentially non-destructive, the irradiated sample will remain radioactive for many years after the initial analysis, requiring handling and disposal protocols for low-level to medium-level radioactive material; also, the number of …

Principles Neutron activation analysis is a physical technique that is based on nuclear reactions. The sample becomes radioactive when neutrons react with the nuclei of the elements’ atoms. Radionuclides are formed and subsequently decay by emitting gamma rays that are unique in half-life and energy.

PGNAA is often used for elements with rapid decay rates, elements with weak gamma emission intensities, and elements that cannot easily be determined by delayed gamma neutron activation analysis (DGNAA) such as hydrogen, boron, and carbon. In DGNAA, the emitted gamma rays are measured after irradiation.

Curie in 1934, neutron activation analysis was first developed by G. Hevesy and H. Levi in 1936. They used a neutron source (226Ra + Be) and a radiation detector (ionization chamber) and promptly recognized that the element Dy (dysprosium) in the sample became highly radioactive after exposure to the neutron source.

Radiochemical neutron activation analysis (RNAA) is a method for trace‐element determination based on the measurement of an indicator radionuclide, chemically separated from a neutron‐activated sample.

Radiation Sources In a spallation neutron source, pulses of very energetic protons (up to 1 GeV), produced by an accelerator, strike a heavy metal target such as mercury or liquid bismuth. Such an energetic proton when it strikes a target nucleus “spalls” or knocks out neutrons.

A story about the “discovery” of neutron activation analysis. The discovery of artificial radioactivity was forecast by H.G. Wells (1914) to take place in 1933. Frederic and Irene Joliot-Curie almost obliged Wells: two weeks into1934 they produced radioactive 30P by bombarding aluminum with alpha particles.

1 : exposure to radiation (such as X-rays or alpha particles) 2 : the application of radiation (such as X-rays or gamma rays) for therapeutic purposes or for sterilization (as of food) also : partial or complete sterilization by irradiation.

In this context, an unstable atom is said to be “radioactive,” and the energy it releases is referred to as “radiation.” When the radiation has enough energy to ionize other atoms (i.e., remove negatively-charged particles called “electrons”) in its path, it is referred to as “ionizing radiation.” Types of ionizing …

NAA is a synthetic plant hormone in the auxin family and is an ingredient in many commercial plant rooting horticultural products; it is a rooting agent and used for the vegetative propagation of plants from stem and leaf cuttings. It is also used for plant tissue culture.

Indole-3-acetic acid (IAA), the main auxin in higher plants, has profound effects on plant growth and development. Both plants and some plant pathogens can produce IAA to modulate plant growth.

The full form of NAA is 1-Naphthalene Acetic Acid. 2-4-D is 2,4-Dichlorophenoxyacetic acid.

PCIB (p-Chlorophenoxy isobutyric acid) is a putative antiauxin competing with auxins for binding sites.

2, 4-D and 2, 4, 5-T are artificial auxins used as weedicides. Naphthalene acetic acid (NAA) is also an artificial auxin widely used in agriculture. Thus, the correct answer is option D.

Some of the commonly known synthetic auxins are for example, Indole-3-propionic acid, Indole-3-pyruvic acid, 2, 4 Dichloro phenoxy acetic acid (2, 4-D), Phenoxyacetic acid, 2-Methyl-4-ChIorophenoxy acetic acid (Methoxone), β-Naphthoxyacetic acid, α-Naphthalene acetic acid, β-Naphthalene acetic acid, Anthracene acetic …

The synthetic auxins include the following herbicide families: benzoic acids, phenoxycarboxylic acids, pyridine carboxylic acids, and quinoline carboxylic acids that act similar to that of endogenous plant auxin.

To realize this project we selected two substances acting as plant hormones: naturally-occurring, main plant auxin – indole-3-acetic acid (IAA) as well as the synthetic compound of similar properties and comparable chemical structure, i.e. 1-naphthaleneacetic acid (NAA).

Their main function is to help plants grow and auxin stimulates plant cells to elongate . The tips of the growing stems and roots (apical meristem) of a plant is one of the main places where auxin is produced. Auxins are one specific group of hormones that are used: as weed killers.

With their application in crop production, auxin herbicides started a new era of weed control in modern crop production due to their systemic mobility in the plant and to their selective action, preferentially against dicot weeds in cereal crops.

Summary. The hormone-like herbicides such as 2, 4-D, 2,4,5-T, dicamba, and picloram provide essential tools for modern farming for control of undesirable vegetation on grazing land, in crop, and non-crop lands.

Phenoxy herbicides mimic a naturally occurring plant chemical called indole acetic acid (IAA). They cause unregulated IAA production in the plant, which leads to uncontrolled growth, twisting, thickening, elongation and eventually death as the weed literally grows itself to death.

2,4-Dichlorophenoxyacetic acid

Cytokinins are mainly synthesized in plant roots from where they are transported to the shoots. They play a major role in shoot formation and organogenesis in tissue culture. A number of synthetic cytokinins were developed following the discovery that diphenylurea (DPU) has cytokinin-like activity.

Auxin herbicides are similar to the natural auxin indole-3-acetic acid (IAA), as most are organic acids containing an aromatic ring and a carboxyl group and characterized by their low molecular weight (George, 1963. 1963.

10 Best Weed Killer Reviews of 2020

• Doctor Kirchner – Best Choice.
• Espoma Organic Weed Preventer – Safest for Kid and Pet-friendly.
• Natural Armor.
• BioSafe Weed Control Concentrate.
• Natria Grass and Weed Control.
• Compare-N-Save Concentrate Grass & Weed Killer.
• Southern Ag 2,4-D Amine Weed Killer.

Want The Strongest, Toughest Weed Killer?

• Glyphosate: The worlds most popular weed killer.
• Vinegar: A very popular “homemade” herbicide.
• Salt: The oldest weed killer.
• Sodium Chlorate. Was a popular weed killer in the UK that was long lasting and worked very well.
• Triclopyr.

Roundup is a “non-selective” weed killer: It deals death to any green plant. One alternative is herbicidal soap. Ammonium nonanoate is the active organic ingredient in Ortho Groundclear Grass and Weed Killer. Another choice is herbicidal vinegar.