Search results for "yield"
showing 10 items of 1338 documents
Fission studies at IGISOL/JYFLTRAP: Simulations of the ion guide for neutron-induced fission and comparison with experimental data
2020
For the production of exotic nuclei at the IGISOL facility, an ion guide for neutron-induced fission has been developed and tested in experiments. Fission fragments are produced inside the ion guide and collected using a helium buffer gas. Meanwhile, a GEANT4 model has been developed to simulate the transportation and stopping of the charged fission products. In a recent measurement of neutron-induced fission yields, implantation foils were located at different positions in the ion guide. The gamma spectra from these foils and the fission targets are compared to the results from the GEANT4 simulation. In order to allow fission yield measurements in the low yield regions, towards the tails a…
Odd-Even Effects in the Reaction 241Am(2n,f)
1992
Fission yields of the light fission products in the reaction 241Am(2n,f) have been measured. The results indicate an odd-even proton effect in the yield distribution of this odd nucleus with Z=95.
Status of independent yield measurements
1996
Recent progress in the measurement of independent yields in low energy nuclear fission is presented. Different experimental approaches are discussed and a survey of the most important experimental results obtained is given. Physical consequences for the understanding of the fission process are briefly referred.
High Yield Ultrafast Intramolecular Singlet Exciton Fission in a Quinoidal Bithiophene
2015
We report the process of singlet exciton fission with high-yield upon photoexcitation of a quinoidal thiophene molecule. Efficient ultrafast triplet photogeneration and its yield are determined by photoinduced triplet-triplet absorption, flash photolysis triplet lifetime measurements, as well as by femtosecond time-resolved transient absorption and fluorescence methods. These experiments show that optically excited quinoidal bithiophene molecule undergoes ultrafast formation of the triplet-like state with the lifetime ∼57 μs. CASPT2 and RAS-SF calculations have been performed to support the experimental findings. To date, high singlet fission rates have been reported for crystalline and pol…
Huanglongbing modifies quality components and flavonoid content of 'Valencia' oranges.
2014
BACKGROUND: In order to evaluate the effect of citrus greening disease, or Huanglongbing (HLB), on quality components and flavonoid contents of 'Valencia' oranges, fruit from non-infected trees (control), from infected trees but symptom-less (asymptomatic) and from infected trees and showing clear HLB symptoms (symptomatic) were harvested in March and in May, 2013. Fruit peel, pulp and juice were separated, the main quality components were determined, and hesperidin, nobiletin, tangeretin, narirutin and didymin were quantified using liquid chromatography. RESULTS: Peel colour, total soluble solids and citric acid were similar in control and asymptomatic fruits. Symptomatic fruits were small…
Investigation of the Cooling of Hot Walls by Liquid Water Sprays
1999
An experimental study was conducted for the heat transfer from hot walls to liquid water sprays. Four full cone, swirl spray nozzles were used at different upstream pressures, giving mass fluxes impinging on the wall, G, from 8 to 80 kg m(-2) s(-1), mean droplet velocities, U, from 13 to 28 m s(-1) and mean droplet diameters, D, from 0.4 to 2.2 mm. A target consisting of two slabs of beryllium-copper alloy, each 4 x 5 cm in size and 1.1 mm thick, was electrically heated to about 300 degrees C and then rapidly and symmetrically cooled by water sprays issuing from two identical nozzles. The midplane temperature was measured by a fast response, thin-foil thermocouple and the experimental data …
18F-labeling of peptides by means of an organosilicon-based fluoride acceptor.
2006
Fluorine-18 is among the most commonly used radionuclides for positron emission tomography (PET). This non-invasive imaging technique is capable of providing in vivo information about the distribution of radiolabeled biomolecules by 1808 coincidence detection of two simultaneously emitted photons from positron–electron annihilation. Although a number of different radiotracers have been successfully employed in PET, only a few, such as 2-[F]fluoro-2-deoxy-d-glucose (FDG) and [F]fluorodopa, have gained widespread application in nuclear medicine. The reason for this is that the regioselective introduction of F into tracer molecules is often non-specific and radiochemical yields (RCY) of the Fl…
18F-Labeling Using Click Cycloadditions
2014
Due to expanding applications of positron emission tomography (PET) there is a demand for developing new techniques to introduce fluorine-18 (t1/2=109.8 min). Considering that most novel PET tracers are sensitive biomolecules and that direct introduction of fluorine-18 often needs harsh conditions, the insertion of18F in those molecules poses an exceeding challenge. Two major challenges during18F-labeling are a regioselective introduction and a fast and high yielding way under mild conditions. Furthermore, attention has to be paid to functionalities, which are usually present in complex structures of the target molecule. The Cu-catalyzed azide-alkyne cycloaddition (CuAAC) and several copper…
Total synthesis and evaluation of [18F]MHMZ.
2007
Radiochemical labeling of MDL 105725 using the secondary labeling precursor 2-[(18)F]fluoroethyltosylate ([(18)F]FETos) was carried out in yields of approximately 90% synthesizing [(18)F]MHMZ in a specific activity of approximately 50MBq/nmol with a starting activity of approximately 3GBq. Overall radiochemical yield including [(18)F]FETos synthon synthesis, [(18)F]fluoroalkylation and preparing the injectable [(18)F]MHMZ solution was 42% within a synthesis time of approximately 100 min. The novel compound showed excellent specific binding to the 5-HT(2A) receptor (K(i)=9.0 nM) in vitro and promising in vivo characteristics.
Spectroscopic Methods for the Determination of Protein Interactions
2005
This unit provides guidelines on how to use steady-state fluorescence spectroscopy for the quantification of protein-protein interactions. The fluorescence of a protein is characterized by its excitation and emission spectra, quantum yield, and anisotropy. These parameters can change upon interaction with another protein and can be used to measure the extent of complex formation. The source of fluorescence can be an intrinsic fluorophore, such as tryptophan or tyrosine; a covalently attached fluorescent dye; or a fluorescent binding partner, such as a nucleotide or cofactor, that interacts specifically with the complex. Protocols are provided in this unit for determining affinity constants …