[en] Highlights: • Heavy metal accumulation in marine sediments of Veraval harbour • Mobilization of Fe and Mn due to reduction of FeMn oxyhydroxides • Formation of metal sulfides in anoxic sediments - Abstract: The purpose of the present study is to investigate the behaviour of trace metals in anoxic environment. Water column of the harbour was found to be anoxic (DO − 1) with high concentration of NH₄⁺-N (av. 459 ± 21 μmol l^{− 1}) and H₂S (av.73 ± 2.5 μmol l^{− 1}) irrespective of season and tide. High concentrations of Fe, Mn in bottom water indicated that Fe, Mn were diagenetically mobilized under the anoxic conditions prevailing in the harbour. In harbour sediments significant correlation of metals with TOC and TS indicated their diagenetic immobilization in anoxic environment. Fe was positively correlated with TS suggesting FeS formation in anoxic condition. TOC/TN ratio of sediments was higher (16 ± 5.2) than the normal marine planktonic sediments suggesting an increased burden of terrestrial carbon in the harbour. A sediment core collected 10 km away from the shore indicated build-up of trace metals in recent years, showing diagenetically upward movement of metals.

[en] Dhruva, 100 MWth high flux vertical tank type research reactor joined research reactors fleet of BARC Trombay in the year 1985 and proved its versatility by rendering various experimental/irradiation facilities. One of the irradiation facility is Self Serve Facility which is designed to facilitate irradiation of small samples of material having intermediate half-life ranging from few hours to a few days. Irradiation is aimed from radio-isotope production having intermittent half-life as well as for Neutron Activation Analysis (NAA). The sample is being send in to reflector region of the reactor for irradiation using a special setup. Self serve facility consists of two state of the art and well engineered self serve units (i.e. SS-1, SS-2) which are located on either end of upper through tube which passes through calandria. Presently SS-2 unit is in use and it provides three positions for irradiation. For irradiation, target sample is placed in aluminium sealed container which is in turn placed inside a spherical aluminium ball having lid. The spherical balls are rolled into required position by gravity though inlet channel made in to biological shield of the reactor. After predefined irradiation period, sample is rolled out from outlet channel after completion of irradiation by gravity. A wide variety of samples are being irradiated in self serve facility for research application. This poster describes overview of self serve utilization along with operational procedures, operational experiences and safety enhancements. (author)

[en] The aqueous chemistry of Mo (VI) is quite complicated due to the rich coordination chemistry of this transition metal. Mo (VI) has a pronounced affinity for the oxygen atom and tends to form different types of oxo-complexes and a variety of polymeric, anionic, neutral and cationic species can occur in the solution. During uranium purification by solvent extraction (SX), Mo is co-extracted significantly with U in TBP-HNO₃ medium. For nuclear fuel materials general limit of Mo content is < 2 ppm

[en] Highlights: • Tesla type valve is used in natural circulation loop (NCL) to mitigate instability. • Effect of heat input on the stability at supercritical pressures is studied. • Tesla valve reduces flow reversal and prescribes flow direction in NCL. • Fluctuations in temperature and velocity get reduced with Tesla-NCL. • Maximum reduction in heat transfer capability with Tesla NCL is ≤3%. Flow instability in supercritical fluid based natural circulation loop (NCL) is still an investigation aspect of physical and mathematical problems to comprehend. Therefore, NCLs require precise design assessment that focuses on the interaction of all the transient responses of buoyancy and friction forces which can ensure a stable zone of operation. To promote the uni-directional circulatory movement of loop fluid and to decrease the magnitude of instability, this research emphasizes the development of NCL integrated with two modified Tesla type valves. In this article, numerical simulations have been carried out for a range of supercritical pressures (80–100 bar) and heat inputs (500–2000 W) to do the comparative investigation of instability phenomenon in supercritical carbon dioxide based regular natural circulation loop and a new modified twin Tesla NCL. Results show that the use of modified Tesla valves leads to better stabilization for all supercritical pressures and heat inputs considered in the study. It is also found that the proposed Tesla NCL mitigates the temperature and velocity oscillations with a marginal drop of $⩽$3% in the heat transfer performance. Using asymmetrical flow resistance to stimulate directional circulation is an efficient technique to combat this instability issue. Obtained results are validated with the existing correlations, and a good agreement is obtained.

[en] The aqueous chemistry of Mo (VI) is quite complicated due to the rich coordination chemistry of this transition metal. Mo (VI) has a pronounced affinity for the oxygen atom and tends to form different types of oxo- complexes and a variety of polymeric, anionic, neutral and cationic species can occur in the solution. During uranium purification by solvent extraction (SX), Mo is co-extracted significantly with U in TBP-HNO₃ medium. For nuclear fuel materials general limit of Mo content is < 2 ppm. Most of the SX studies are concentrated on separation/recovery of Mo from leach liquor generated from different non-U ore bodies and liquid wastes using mainly other extractant & acids/alkalis except combination of TBP as extractant (Organic phase) and HNO₃ (Aqueous phase). With increase in (Mo), DMo decreases gradually. But this change is so gradual that (Mo) in extract is higher in spite of lower DMo because of higher (Mo) in the feed. This can be explained form the fact that, at higher (Mo), such as above 0.001 M, it starts polymerization, hence it doesn't easily get extracted in TBP. But this polymerization is not dominant enough to cause drop in (Mo) in extract with increase of (Mo) in the feed. Typical values obtained for DU and DMo are in consonance with values reported in literature. Hence, an implementable methodology to separate Mo from concentrated U solution to arrive at (Mo) < 2 ppm before production of purified U solid intermediates in U refining technology has been developed

[en] Highlights: • A novel mechanism is discussed for the instability in natural circulation loop. • Instability in supercritical CO₂ based NCL is analysed. • CFD study at different heat inputs and operating pressures is carried out. • Heat transfer capability of the loop is obtained. Three-dimensional computational fluid dynamics (CFD) simulation on a supercritical CO₂ based natural circulation loop (scCO₂-NCL) is carried out to explore the effects of various parameters (i.e., pressure and heat inputs) on the loop’s transient and stability behaviour. Results show that for supercritical CO₂, there is a threshold point that decides the flow’s nature. Lower than threshold heat inputs flow shows repetitive-reversal flow while at higher heat input the flow changes to stable or single-direction flow. With an increase in heat input, the system attains stability for a given operating pressure. In addition, a possible mechanism for continuous flow oscillation and measurement of instability with different pressure in unstable loops is also proposed in this study. It is found that the Nusselt number decreases with an increase in operating pressure for given heat input. Obtained simulation results are validated with the two existing correlations and found a good agreement.

[en] Highlights: • Preheating of VIME biodiesel for better atomization is introduced for CI engine. • Various diesel-biodiesel blends (B0, B30, B50 and B100) are considered for study. • Drastic drop in viscosity is observed by heating the biodiesel up to 95 °C. • Engine performance, combustion and emission characteristics are investigated. The present study investigates the suitability of preheated Vateria indica methyl ester (VIME) as an alternative fuel for a diesel engine. VIME is a renewable, non-toxic and sustainable alternative biodiesel obtained from Dhupa fat by transesterification. This study aims to evaluate the combustion, performance, and emission characteristics of four different blends such as B0 (0% VIME and 100% mineral diesel), B30, B50 and B100 at elevated fuel inlet temperatures ranging from 35 °C to 95 °C. The tests are carried out in a single cylinder diesel engine at optimum loading condition and fixed speed. Results are obtained in terms of brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), in-cylinder pressure, heat release rate and exhaust emissions (CO, HC, NO_X, CO₂ and soot). It is observed that the preheating of blends decreases the viscosity which enhances fuel spray characteristics, leading to higher engine performance, lower CO and HC emissions with a slight increase in NO_X and CO₂ emissions. BTE and peak in-cylinder pressure for B100 at 95 °C and 75% load are increased by 7.44%, 2.97% respectively compared to unheated B100 biodiesel. BSFC, CO, HC emissions at 75% load for B100 at 95 °C are reduced by 26.73%, 28.08%, 42.7% respectively compared to unheated B100.

[en] Dengue is a common viral infection worldwide with presentation varying from clinically silent infection to dengue fever, dengue hemorrhagic fever, and severe fulminant dengue shock syndrome. Neurological manifestation usually results from multisystem dysfunction secondary to vascular leak. Presentation as hemorrhagic encephalitis is very rare. Here we present the case of a 13-year-old female admitted with generalized tonic clonic seizures. Plain computed tomography (CT) scan of head revealed hypodensities in bilateral deep gray matter nuclei and right posterior parietal lobe without any hemorrhage. Cerebrospinal fluid (CSF) and serology were positive for IgM and IgG antibodies to dengue viral antigen. Contrast-enhanced magnetic resonance imaging (MRI) revealed multifocal T2 and fluid attenuated inversion recovery (FLAIR) hyperintensities in bilateral cerebral parenchyma including basal ganglia. No hemorrhage was seen. She was managed with steroids. As her clinical condition deteriorated, after being stable for 2 days, repeat MRI was done which revealed development of hemorrhage within the lesions, and diagnosis of acute hemorrhagic encephalitis of dengue viral etiology was made

[en] Posttreatment detection of residual/recurrence disease in the head and neck cancers is not an easy task. Treatment induces changes create difficulties in diagnosis on conventional imaging (computed tomography, magnetic resonance imaging) as well as macroscopic inspection (direct laryngoscopy). Hence, we evaluate the diagnostic performance of contract-enhanced F-18 fluorodeoxyglucose positron emission tomography (FDG PET)/CT in restaging of laryngeal carcinoma Postchemotherapy-surgery and/or radiation therapy. We retrospectively analyzed patients of carcinoma larynx (n = 100) who has completed treatment and were referred for FDG PET/CT. Two reviewers performed image analysis to determine recurrence at primary site and/lymph nodes and distant metastases. Receiver operating characteristic (ROC) was used to determine the maximum standardized uptake value (SUVmax) cut off for disease detection. Histopathological examination and clinical or imaging follow-up were taken as gold standard for recurrence. One hundred laryngeal carcinoma patients with mean age of 57.2 years (range of 40–76) were included in the present study. Among the 100 patients, 96 were male and remaining 4 were female. The average interval between completion of treatment and FDG PET/CT scan was 8.5 months (minimum 6 months). Of the 100 patients, FDG PET/CT detected FDG avid lesions in 66 patients. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of FDG PET/CT for residual/recurrence disease detection was 90.3%, 73.7%, 84.8%, 82.3%, and 84.0%, respectively (P < 0.05). In addition, in 10 patients, metachronous primaries were detected (lung-4, thyroid-2, tongue, colon, esophagus, and lymphoma-one each). On ROC curve analysis, SUVmax >6.1 had sensitivity and specificity of 80.6% and 94.7% respectively for detection of recurrent/metastatic disease. FDG PET/CT demonstrates high diagnostic accuracy for detection of residual/recurrent disease in treated laryngeal cancer patients and our findings suggest that this imaging modality should be the first-line diagnostic investigation in this cohort of patients. (author)

[en] We study the interplay between the contributions of electron thermal flux and interface scattering to the Kapitza conductance across metal-metal interfaces through measurements of thermal conductivity of copper-niobium multilayers. Thermal conductivities of copper-niobium multilayer films of period thicknesses ranging from 5.4 to 96.2 nm and sample thicknesses ranging from 962 to 2677 nm are measured by time-domain thermoreflectance over a range of temperatures from 78 to 500 K. The Kapitza conductances between the Cu and Nb interfaces in multilayer films are determined from the thermal conductivities using a series resistor model and are in good agreement with the electron diffuse mismatch model. Our results for the thermal boundary conductance between Cu and Nb are compared to literature values for the thermal boundary conductance across Al-Cu and Pd-Ir interfaces, and demonstrate that the interface conductance in metallic systems is dictated by the temperature derivative of the electron energy flux in the metallic layers, rather than electron mean free path or scattering processes at the interface