Available online xxxKeywords: Radionuclide Uranium Radiological risk Toxicity Laser a b s t r a c tIn the present investigations, Laser Fluorimetry technique has been used for the microanalysis of uranium content in drinking water samples collected from different sources like the hand pumps, tube wells of various depths from wide range of locations in the four districts of SW-Punjab, India. The purpose of this study was to investigate the uranium concentration levels of ground water being used for drinking purposes and to determine its health effects, if any, to the local population of this region. Corresponding radiological and chemical risks have also been calculated for the uranium concentrations in ground water samples. Some other heavy elements have also been analysed using the Atomic Absorption Spectrometry. In this region, uranium concentration in 498 drinking water samples has been found to vary between 0.5e579 mgl À1 with an average of 73.5 mgl À1 . Data analysis revealed that 338 of 498 samples had uranium concentration higher than recommended safe limit of 30 mgl À1 (WHO, 2011) while 216 samples exceeded the threshold of 60 mgl À1 recommended by AERB, DAE, India, 2004.
Background
Corticotrophin releasing hormone (CRH) is the major regulator of ACTH secretion from the anterior pituitary and acts via CRH-1 receptors (CRH-1R). Corticotropinoma though autonomous still retain their responsiveness to CRH and hence, we hypothesize that in vivo detection of CRH-1 receptors on pituitary adenoma using Gallium-68 ( 68Ga) tagged CRH can indicate the functionality of adenoma and combining it with Positron emission tomography-computed tomography (PET-CT) can provide requisite anatomical information.
Methods
Subjects with ACTH dependent Cushing's syndrome (CS) [n = 27, 24: Cushing's disease (CD), 3: ectopic Cushing's syndrome (ECS)] underwent 68Ga CRH PET-CT. Two nuclear medicine physicians read these images for adenoma delineation and superimposed them on MRI sella. The information so provided was used for intra-operative navigation and compared with operative and histopathological findings.
Findings
68Ga CRH PET-CT correctly delineated corticotropinoma in all the 24 cases of CD, including the ten cases with size < 6mm (four cases negative on MRI). Corticotropinoma location on 68Ga CRH PET fusion images with MRI were concordant with operative findings and further confirmed on histopathology. There was no tracer uptake in pituitary in two patients with ECS while in another, the diffuse uptake in pituitary suggested ectopic CRH production.
Conclusion
68Ga CRH PET-CT represents a novel non-invasive molecular imaging targeting CRH receptors that not only delineates corticotropinoma and provides surgeon with valuable information for intra-operative tumour navigation but also helps in differentiating pituitary from extra-pituitary source of ACTH dependent Cushing’s syndrome.
Exposure due to natural radiation is of particular importance because it accounts for the largest contribution (nearly 85 %) to the total collective dose of the world population. An attempt has been made to present the feasibility of uranium occurrence in drinking water samples from different states of India, by laser-induced fluorimetry. The associated age-dependent radiation dose was estimated by taking the prescribed water intake values of different age groups. The concentration of uranium obtained, i.e. 0.1 +/- 0.01 to 19.6 +/- 1.8 microg l(-1), is well below the drinking water guideline value of 30 microg l(-1). The annual ingestion dose due to uranium in drinking water for various age groups is found to vary from 0.14 to 48 microSv y(-1).
The piezoelectric (PZ) polarization property present in the wurtzite nitrides modifies the group velocity of phonons. As a result, the relaxation rates of phonons are changed. In this paper, we have calculated the relaxation rate of phonons as functions of the phonon frequency in binary wurtzite nitrides (GaN, AlN and InN) using the modified phonon group velocity. Different scattering mechanisms such as Umklapp, point defect, dislocation, boundary and phonon-electron scattering processes have been considered. The percentage change in phonon relaxation rates is found to be maximum for InN and minimum for GaN.
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