Assessment of recharge source to springs in upper Beas basin of Kullu region,Himachal Pradesh,India using isotopic signatures

Journal of Radioanalytical and Nuclear Chemistry - Environmental stable and radioisotope data of springs located in Kullu region of Himachal Pradesh are interpreted to identify the recharge source...     

Distribution patterns of gamma radiation dose rate in the high background radiation area of Odisha,India

Journal of Radioanalytical and Nuclear Chemistry - Absorbed dose rates in air for 20 residential areas in Odisha were measured using a vehicle-mounted NaI(Tl) scintillation spectrometer. The...     

Radon concentration in hot springs of the touristic city of Sarein and methods to reduce radon in water

The aim of this research was to measure the efficiency of various simple methods to decrease the concentration of radon in hot springs of the touristic city of Sarein (a touristic city in northwest Iran). With the aid of “RAD7” radon detector, concentrations in water varied from 212 Bq m^?3 to 3890 Bq m^?3. Using 250 mL vials half-filled with water samples, our research showed that when the temperature of the water increased from 17 °C to 27 °C, the radon concentration decreased from 3230 Bq m^?3 to 745 Bq m^?3. The mixing of the sample at a speed of 500 rpm for 12 min led to a radon reduction of about 70%. Aerating the water sample with 0.2 L min^?1 of ambient air resulted in a 90% decrease in radon concentration in 6 min. Strong exponential correlations (>95%) were reported, which verified that the effectiveness of these methods in reducing dissolved gas in the waters used would be high.     

Uranium,thorium and potassium occurrences in the vicinity of hot springs in the northern neotectonic belt in the Eastern Cape Province,South Africa

Gamma ray measurements were carried out along two parallel lines close to each of the hot springs using a RS 125 spectrometer to find the concentration (ppm) of U, Th, and K at Polile Tshisa, Aliwal North, and Badfontein hot springs. The RS 125 spectrometer is auto-stabilized on the naturally occurring U, Th, and K, and provides concentrations (ppm) of the radioelements. The results show that the concentration of thorium is higher, and is below the world average hazardous threshold of 7.4 ppm. Thorium is related to the occurrence of monazite seen at the scanning electron microscope. Higher ratios of U/K are indicative of an increase of uranium relative to potassium. Binary diagrams (Th–U, K–U, and K–Th) do not show a clear best fit except at Polile Tshisa hot spring where thorium shows a quasi positive correlation to potassium. In general, it can be concluded that the concentrations of these three radioelements are quite low, acceptable for groundwater, and could be hazardous to the health of humans and animals if exposed to long time radiations.     

ICP-MS Measurement of Trace and Rare Earth Elements in Beach Placer-Deposit Soils of Odisha,East Coast of India,to Estimate Natural Enhancement of Elements in the Environment

Inductively coupled plasma mass spectrometry (ICP-MS) has been used to measure the concentration of trace and rare earth elements (REEs) in soils. Geochemical certified reference materials such as JLk-1, JB-1, and JB-3 were used for the validation of the analytical method. The measured values were in good agreement with the certified values for all the elements and were within 10% analytical error. Beach placer deposits of soils mainly from Odisha, on the east coast of India, have been selected to study selected trace and rare earth elements (REEs), to estimate enrichment factor (EF) and geoaccumulation index (I_geo) in the natural environment. Enrichment factor (EF) and geoaccumulation index (I_geo) results showed that Cr, Mn, Fe, Co, Zn, Y, Zr, Cd and U were significantly enriched, and Th was extremely enriched. The total content of REEs (ƩREEs) ranged from 101.3 to 12,911.3 µg g⁻¹, with an average 2431.1 µg g⁻¹ which was higher than the average crustal value of ΣREEs. A high concentration of Th and light REEs were strongly correlated, which confirmed soil enrichment with monazite minerals. High ratios of light REEs (LREEs)/heavy REEs (HREEs) with a strong negative Eu anomaly revealed a felsic origin. The comparison of the chondrite normalized REE patterns of soil with hinterland rocks such as granite, charnockite, khondalite and migmatite suggested that enhancement of trace and REEs are of natural origin.     

Study of uranium contamination of ground water in Punjab state in India using X-ray fluorescence technique

The elemental concentration of uranium in the samples collected from the ground water and the canal water in the Bathinda district of Punjab state, India, have been investigated using X-ray fluorescence technique. The residues obtained after drying the water samples were analysed using the energy dispersive X-ray fluorescence spectrometer consisting of Mo-anode X-ray tube equipped with selective absorbers as an excitation source and an Si(Li) detector. The uranium concentration values in significant fraction of the shallow ground water samples from the hand pumps is found to be above the permissible level of 15?ppb recommended by World Health Organisation for the drinking water, and its values in the canal water samples are below 5?ppb. To investigate the flyash from the coal-fired thermal power plants as a possible source of ground water contamination, the water samples collected from the surroundings of the power plants and the flyash samples were also analyzed. The results rule out flyash as a source of uranium contamination. Agrochemical processes occurring in the calcareous soils in the region are the favoured potential source of uranium contamination of the ground water.     

Characterization of hot carrier cooling and multiple exciton generation dynamics in PbS QDs using an improved transient grating technique

Multiple exciton generation(MEG) dynamics in colloidal PbS quantum dots(QDs) characterized with an improved transient grating(TG) technique will be reported. Only one peak soon after optical absorption and a fast decay within 1 ps can be observed in the TG kinetics when the photon energy of the pump light hν is smaller than 2.7Eg(Eg: band gap between LUMO and HOMO in the QDs), which corresponds to hot carrier cooling. When hν is greater than 2.7Eg, however, after the initial peak, the TG signal decreases first and soon increases, and then a new peak appears at about 2 to 3 ps. The initial peak and the new peak correspond to hot carriers at the higher excited state and MEG at the lowest excited state, respectively. By proposing a theoretical model, we can calculate the hot carrier cooling time constant and MEG occurrence time constant quantitatively. When MEG does not happen for hν smaller than 2.7Eg, hot carrier cools with a time constant of 400 fs. When MEG occurs for hν larger than 2.7Eg, hot carrier cools with a time constant as small as 200 fs, while MEG occurs with a time constant of 600 fs. The detailed hot carrier cooling and MEG occurrence dynamics characterized in this work would shed light on the further understanding of MEG mechanism of various type of semiconductor QDs.     

Structural,optical and magnetic characterization of ZnO nanorods synthesized using hydrothermal technique at low temperature

Pure ZnO nanorods were grown from aqueous solutions at low temperature (90 °C) by hydrothermal growth technique on sapphire (0001) substrate coated with ZnO thin film. X-ray diffraction results show that these nanorods crystallize in the wurtzite structure having space group P6₃mc and that they are oriented along the c-axis. Raman and photo-luminescence studies show the presence of oxygen vacancies in the ZnO nanorods. The ZnO nanorods show room temperature ferromagnetism.     

Preparation of free-standing films of natural polysaccharides using hot press technique and their surface functionalization with biomimetic apatite

This study demonstrated that gel-like polyion complexes obtained by mixing of aqueous solution of chondroitin sulfate, heparin, and hyaluronic acid with that of chitosan were able to form their free-standing films using hot press treatments. These films, having thicknesses ca. 50 and 100 μm, depending on the spacer thickness, were homogeneous and non-porous at the microscopic level, and were not water-soluble. The present fabrication process required neither cross-coupling agents nor introduction of other functional groups to the polysaccharides. Hydroxyapatite deposition on the film surfaces under body fluid conditions was also achieved.     

Microvascularity,blood flow and tissue structure at the subchondral plate using an X-ray fluorescence technique

The measurement of blood flow and blood in bone and cartilaginous tissues is crucial to understanding of the development of various diseases, but it presents a formidable technical challenge. We have therefore developed a method based on the detection of metallized microspheres using X-ray fluorescence. This approach provides unrivalled sensitivity and spatial resolution and also allows us simultaneously to measure other markers of the metabolic status of the tissue.     

Challenges in hydrogen quantification using Kelvin probe technique at different levels of relative humidity

Kelvin probe-based contact potential measurements were conducted with in situ electrochemical hydrogen loading of a Pd membrane with a thickness of 100 μm. The theoretical basis of diffusion coefficient calculation based on measured response time of potential drop, arising from hydrogen arriving at the detection side of the Pd membrane, was discussed. In situ hydrogen loading was also utilized for insertion of different amounts of hydrogen into the Pd sample while monitoring the resulting contact potential difference changes. Measurement of contact potential difference at different final values of hydrogen concentration in the Pd membrane was performed at various atmospheric conditions, focusing in this work on increasing relative humidity (4 to 85% rH). Moreover, the effect of humidity changes on hydrogen effusion kinetics at room temperature and low oxygen content (<1%) was studied.

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Determination of rare-earth elements in Periyar River water (Kerala, India) and seawater (Mumbai, India) using neutron activation analysis

During the present work rare earth elements (REEs) in Periyar River water and in seawater from the region of Mumbai, India, have been measured via neutron activation analysis. To separate and concentrate REEs a pre-irradiation separation approach via ion exchange was adopted. Standard addition and radiotracer studies were carried out to validate the analytical methodology including the recoveries of the separations. The measured REE concentrations in the water samples are presented and discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Natural radioactivity in springs of Sverdlovsk region,Middle Urals,Russia

Journal of Radioanalytical and Nuclear Chemistry - Activity concentrations of natural radionuclides were determined in water from 31 springs of Sverdlovsk region, Middle Urals, Russia. Activity...     

Characterization of active phosphorus surface sites at synthetic carbonate-free fluorapatite using single-pulse 1H, 31P, and 31P CP MAS NMR

The chemically active phosphorus surface sites defined as PO(x), PO(x)H, and PO(x)H2, where x = 1, 2, or 3, and the bulk phosphorus groups of PO4(3-) at synthetic carbonate-free fluorapatite (Ca5(PO4)3F) have been studied by means of single-pulse 1H,31P, and 31P CP MAS NMR. The changes in composition and relative amounts of each surface species are evaluated as a function of pH. By combining spectra from single-pulse 1H and 31P MAS NMR and data from 31P CP MAS NMR experiments at varying contact times in the range 0.2-3.0 ms, it has been possible to distinguish between resonance lines in the NMR spectra originating from active surface sites and bulk phosphorus groups and also to assign the peaks in the NMR spectra to the specific phosphorus species. In the 31P CP MAS NMR experiments, the spinning frequency was set to 4.2 kHz; in the single-pulse 1H MAS NMR experiments, the spinning frequency was 10 kHz. The 31P CP MAS NMR spectrum of fluorapatite at pH 5.9 showed one dominating resonance line at 2.9 ppm assigned to originate from PO4(3-) groups and two weaker shoulder peaks at 5.4 and 0.8 ppm which were assigned to the unprotonated PO(x) (PO, PO2-, and PO3(2-)) and protonated PO(x)H (PO2H and PO3H-) surface sites. At pH 12.7, the intensity of the peak representing unprotonated PO(x) surface sites has increased 1.7% relative to the bulk peak, while the intensity of the peaks of the protonated species PO(x)H have decreased 1.4% relative to the bulk peak. At pH 3.5, a resonance peak at -4.5 ppm has appeared in the 31P CP MAS NMR spectrum assigned to the surface species PO(x)H2 (PO3H2). The results from the 1H MAS and 31P CP MAS NMR measurements indicated that H+, OH-, and physisorbed H2O at the surface were released during the drying process at 200 degrees C.     

Measurement of237Np in the marine environment of coastal nuclear sites in India

Nepturium-237 levels in sea water and sediments from Indian coastal waters receiving radwaste discharges have been investigated. The method used for the estimation is neutron activation and using this method,²³⁷Np activity as low as 10^–7 Bq/l in sea water could be measured. Neptunium-237 levels found are compared with the values reported for other areas.