scholarly journals Production of 128I Atoms through 127I (n,γ) 128I Reactions in some Solid Iodocompounds using an (241Am-Be) Neutron Source

2011 ◽  
Vol 3 (2) ◽  
pp. 357-366 ◽  
Author(s):  
M. R. Zaman ◽  
M. A. Hossain ◽  
M. J. A. Sarkar
Keyword(s):  
Solid State ◽  
Neutron Source ◽  
Half Life ◽  
Irradiation Time ◽  
Volume Element ◽  
Nuclear Transformation ◽  
Time Decay ◽  
Chemical Effects ◽  
Counting Geometry ◽  
Zero Time

 Present work reports the production of 128I atoms through 127I (n,g) 128I reactions in six iodine containing compounds (viz. NaI, NaIO3, NaIO4, KI, KIO3 and KIO4) in solid state. An  241Am-Be neutron source has been used for the production of 128 I atoms. The radioactivities produced have been measured by a thin end-window G.M. Counter. The irradiation time and counting geometry were constant throughout the present sets of experiments. Results obtained have been analyzed through time-decay analyses. From the decay curves, the half life of 128I  has been estimated ~25 minutes. The average zero time activities of 128I from three independent measurements in each of NaI, NaIO3.H2O, NaIO4, KI, KIO3 and KIO4 target, have been found 116 ± 2, 92 ± 4, 88 ± 6, 102 ± 6, 98 ± 1 and 93 ± 5 cpm respectively. It is interesting to note that the activities show a decreasing trend while passing through either from NaI to NaIO4 or from KI to KIO4. Results are attributed to the quantity of 128I produced in a specified volume element and, self absorption and self scattering of radiations within the target compounds studied.  Keywords: Iodocompounds; 128I; 241Am-Be neutron source; Chemical effects of nuclear transformation.© 2011 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi:10.3329/jsr.v3i2.6385                 J. Sci. Res. 3 (2), 357-366 (2011)

Development and Characterization of LBG-PVA Interpenetrating Networks Incorporating Gliclazide for Sustained Release

2020 ◽  
Vol 15 ◽  
Author(s):  
Ashish Katoch ◽  
Manju Nagpal ◽  
Malkiet Kaur ◽  
Manjinder Singh ◽  
Geeta Aggarwal ◽  
...  
Keyword(s):  
Solid State ◽  
Sustained Release ◽  
Half Life ◽  
Solid State Nmr ◽  
Oral Dosage ◽  
Cross Linking ◽  
Interpenetrating Networks ◽  
Dsc Studies ◽  
Biological Half Life ◽  
Percentage Yield

Background: Controlled oral dosage forms have always been preferred for drugs with variable absorption, and short biological half life and frequent dosing. The prime goal with sustained release systems is to maintain uniform therapeutic blood levels for longer periods of time. Interpenetrating networks (IPNs) have been evidenced as uniform sustained release systems. In current study, polyvinyl alcohol (PVA) and locust bean gum (LBG) based IPNs were developed for the oral sustained release drug delivery of gliclazide (shows variable absorption). Method: The IPNs were synthesized by emulsion cross-linking method using glutaraldehyde (GA) as a cross linking agent. Gliclazide is a potential second generation, short-acting sulfonylurea oral hypoglycemic agent is having a short biological half-life (2-4 h), variable absorption and poor oral bioavailability. Various batches of IPNs were formulated by varying LBG: PVA ratio and evaluated for percentage yield, drug entrapment efficiency (DEE), swelling properties and in vitro drug release studies. Further characterizations were done by Fourier Transform Infrared Spectroscopy (FTIR), C13 Solid state NMR, X-Ray diffraction study (XRD), Scanning electron microscopy (SEM), and Differential scanning microscopy (DSC) studies. Results: The percentage yield, drug entrapment and equilibrium swelling was observed to be dependent on PVA-LBG ratio and GA amount. Sustained release of drug was observed in all IPN formulations (approx 59 - 86% in 8 h in various batches) with variable release kinetics. SEM studies revealed the regular structures of IPNs. FTIR, XRD, C13 Solid state NMR and DSC studies proposed that drug was successfully incorporated into the formed IPNs. Conclusion: IPNs of LBG and PVA can be used as a promising carrier with uniform sustained release characteristics.

scholarly journals Fluorinated azobenzenes as supramolecular halogen-bonding building blocks

2019 ◽  
Vol 15 ◽  
pp. 2013-2019 ◽  
Author(s):  
Esther Nieland ◽  
Oliver Weingart ◽  
Bernd M Schmidt
Keyword(s):  
Solid State ◽  
Dft Calculations ◽  
Visible Light ◽  
Half Life ◽  
Photophysical Properties ◽  
Bathochromic Shift ◽  
Halogen Bonding ◽  
Building Blocks ◽  
Partial Overlap

ortho-Fluoroazobenzenes are a remarkable example of bistable photoswitches, addressable by visible light. Symmetrical, highly fluorinated azobenzenes bearing an iodine substituent in para-position were shown to be suitable supramolecular building blocks both in solution and in the solid state in combination with neutral halogen bonding acceptors, such as lutidines. Therefore, we investigate the photochemistry of a series of azobenzene photoswitches. Upon introduction of iodoethynyl groups, the halogen bonding donor properties are significantly strengthened in solution. However, the bathochromic shift of the π→π* band leads to a partial overlap with the n→π* band, making it slightly more difficult to address. The introduction of iodine substituents is furthermore accompanied with a diminishing thermal half-life. A series of three azobenzenes with different halogen bonding donor properties are discussed in relation to their changing photophysical properties, rationalized by DFT calculations.

scholarly journals OPTIMIZATION OF COLLIMATOR APERTURE GEOMETRY FOR BNCT KARTINI RESEARCH REACTOR USING MCNPX

2019 ◽  
Vol 21 (1) ◽  
pp. 9
Author(s):  
Ramadhan Valiant Gill S.B. ◽  
Yohannes Sardjono
Keyword(s):  
Neutron Source ◽  
Research Reactor ◽  
Irradiation Time ◽  
Base Point ◽  
Cell Diameter ◽  
Cylindrical Shape ◽  
Trace Distance ◽  
Optimal Output ◽  
Boron Neutron Capture ◽  
High Ionization

Boron Neutron Capture Therapy (BNCT) is one of the promising cancer therapy modalities due to its selectivity which only kills the cancer cells and does not damage healthy cells around cancer. In principle, BNCT utilizes the high ionization properties of alpha (4He) and lithium (7Li) particles derived from the reaction between epithermal and boron-10 neutrons (10B + n → 7Li + 4He) in cells, where trace distance of alpha and lithium particles is equivalent with cell diameter. The neutron source used in BNCT can come from a reactor, as a condition for conducting BNCT therapy tests, there are five standard parameters that must be met for a neutron source to be used as a source, and the standards come from IAEA. This research is based on simulation using the MCNPX program which aims to optimize IAEA parameters that have been obtained in previous studies by changing the shape of the collimator geometry from cone shape to cylinder with variations diameter from 3, 5 and 10 cm and also the simulation divided into two schemes namely first moderator Al is placed in a position 9.5 cm behind the collimator and the second is the moderator Al is pressed into the base point of the aperture in the collimator. In this work, neutrons originated from Yogyakarta Kartini research reactor have the energy range in the continuous form. The results of the optimization on each scheme of the collimator are compared with the outputs that have been obtained in previous studies where the aperture of the collimator is in the cone shape. The most optimal output obtained from the results is a collimator with a diameter of 5 cm in the second scheme where the results of IAEA parameters that are produced (n/cm2 s) = 2.18E+8, / (Gy-cm2/n) = 6.69E-13, / (Gy-cm2/n) = 2.44E-13,  = 4.03E-01, and J/ = 6.31E-01. These results can still be used for BNCT experiments but need a long irradiation time and when compared to previous studies, the output of the collimator with the diameter of 5 cm is more optimal.Keywords: BNCT, Collimator, IAEA Parameters, MCNPX, Cylindrical shape 

Photocatalytic Degradation of Methyl Orange on Iron Niobate Prepared by Solid-State Reaction

2010 ◽  
Vol 113-116 ◽  
pp. 2021-2024 ◽  
Author(s):  
Wen Jie Zhang ◽  
Xin Sun ◽  
Bai Han Chen
Keyword(s):  
Methyl Orange ◽  
Solid State ◽  
Photocatalytic Degradation ◽  
Solid State Reaction ◽  
Irradiation Time ◽  
Molar Ratio ◽  
Preparation Conditions ◽  
New Type ◽  
Iron Niobate ◽  
Degradation Of Methyl Orange

Iron niobate photocatalyst as a new type of photocatalyst was prepared by solid-state reaction of Fe3O4 and Nb2O5 and its activity was evaluated using photocatalytic degradation of methyl orange. Preparation conditions such as calcination temperature and time, and irradiation time were investigated according to photocatalytic efficiencies. FeNb2O6 was produced during calcination below 700 oC and FeNbO4 was produced above 800 oC. Iron niobate with optimum activity could be prepared after calcination at 700 oC for 8 h when Fe:Nb molar ratio was 0.8:1. Methyl orange degradation rate was 72.7% after 180 min of irradiation at photocatalyst concentration of 4 g/l.

Half-life measurements on 29P and 33Cl

1970 ◽  
Vol 48 (13) ◽  
pp. 1578-1584 ◽  
Author(s):  
P. J. Scanlon ◽  
D. Crabtree
Keyword(s):  
Fourier Transform ◽  
Solid State ◽  
Half Life ◽  
Time Distribution ◽  
Transform Method ◽  
Solid State Detector ◽  
Life Values ◽  
The Fourier Transform ◽  
State Detector ◽  
Crystal Clock

The half-life values for the β+ emitters 29P and 33Cl reported in the literature show a wide variation (4.6 ± 0.2 to 4.19 ± 0.02 s for 29P and 2.9 ± 0.1 to 2.51 ± 0.02 s for 33Cl). We have remeasured these activities via the Si(p,γ)P and S(p,γ)Cl reactions with protons from a 3 MV Van de Graaff. The decay positrons were detected in a solid-state detector telescope and the time distribution of the pulses was determined with a multiscaler controlled by a crystal clock. Data were analyzed by an iterative least-squares procedure and by the Fourier transform method. Values obtained were 4.15 ± 0.03 s for 29P and 2.47 ± 0.02 s for 33Cl.

scholarly journals U. S. Geological Survey Radiocarbon Dates VII

Radiocarbon ◽  
1964 ◽  
Vol 6 ◽  
pp. 37-76 ◽  
Author(s):  
Patricia C. Ives ◽  
Betsy Levin ◽  
Richard D. Robinson ◽  
Meyer Rubin
Keyword(s):  
Solid State ◽  
External Field ◽  
Half Life ◽  
Geological Survey ◽  
Radiocarbon Dates ◽  
Solid State Electronics ◽  
Counting Error ◽  
Atmospheric Variations ◽  
The One

This date list contains the results of measurements made during 1961, 1962 and 1963. The method of counting, utilizing acetylene gas, remains essentially unchanged, except for the addition of some solid state electronics. The method of computation, using the Libby half-life of 5568 ± 30 yr, is continued. The error listed is always larger than the one-sigma statistical counting error commonly used, and takes into account known uncertainty laboratory factors, and does not include external (field or atmospheric) variations.Unless otherwise stated, collectors of all samples are members of the U. S. Geological Survey.

Chemical Effects of Nuclear Recoil. Alkali Bromates

1963 ◽  
Vol 1 (4) ◽  
Author(s):  
D. J. Apers ◽  
F. G. Dejehet ◽  
B. S. van Outryve D'ydewalle ◽  
P. C. Capron ◽  
J. Jach ◽  
...  
Keyword(s):  
Isotope Effect ◽  
Thermal Annealing ◽  
Irradiation Time ◽  
Natural Abundance ◽  
Potassium Bromate ◽  
Nuclear Recoil ◽  
Chemical Effects ◽  
Influence Of Solvent

SummaryAn attempt is made to explain some of the discrepancies which have been observed when studying the retention of bromine in neutron irradiated bromates. In particular the influence of solvent, irradiation time and thermal annealing is investigated in potassium bromate, lithium (natural abundance) bromate and lithium (depleted inAn explanation is put forward on the basis of an oxygen free intermediate recoil bromine fragment. The isotope effect on bromine recoil is confirmed.

SALICYLATE INTOXICATION

PEDIATRICS ◽  
1960 ◽  
Vol 26 (5) ◽  
pp. 800-807 ◽  
Author(s):  
Alan K. Done
Keyword(s):  
Half Life ◽  
Clinical Severity ◽  
Poor Correlation ◽  
Excellent Correlation ◽  
First Order ◽  
Salicylate Level ◽  
Salicylate Intoxication ◽  
The Mean ◽  
Serial Measurements ◽  
Zero Time

Studies on 38 children and adults who ingested large amounts of salicylate revealed a poor correlation of salicylate level in serum with clinical severity of salicylate intoxication. Serial measurements of serum salicylate levels in dogs and in 17 previously well patients revealed that the disappearance of salicylate from circulation is a first-order reaction in the post-absorptive period. It is possible, therefore, to calculate the half-life of circulating salicylate. In the present study the mean salicylate half-life in 17 patients was 20 hours. It is possible to eliminate the variable of time since ingestion by utilizing the rate of removal (half-life) of salicylate to extrapolate from the observed salicylate level at any time following ingestion to a theoretical zero-time salicylate concentration (So). There was found to be an excellent correlation of So with the clinical severity of salicylate intoxication. A nomogram that eliminates the necessity for calculating So is presented. Calculation of So or use of the nomogram provide better means than were previously available for predicting the severity of salicylate intoxication on the basis of measurements of blood salicylate. Particularly noteworthy was the fact that four patients who died despite intensive conventional treatments had So values which greatly exceeded those found in patients who recovered. This observation suggests that an So of greater than 160 is essentially incompatible with life and that measures for rapidly reducing salicylate levels, such as hemodialysis or exchange transfusion, should be instituted. The data are not sufficient to permit conclusions to be drawn concerning the influence of various factors on salicylate removal and toxicity. However, the use of So and salicylate half-life should facilitate such studies.

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