Changes in the thermodynamical profiles of the subsurface ocean and atmosphere induce cyclones to congregate over the Eastern Arabian Sea.

The Arabian Sea accounts for a small fraction of Tropical Cyclones-about 2% of the annual global mean. However, the damage they might inflict there and along its coastlines, which are thickly populated, is considerable. This study explores the influence of the changes in the vertical profiles of atmosphere and oceanic environment throughout the seasons of March-June (MAMJ) and October-December (OND) in clustering the cyclogenesis over the Eastern Arabian Sea (EAS) next to the Indian West coast in recent decades. Further investigation has been done into the precise contribution of atmospheric and oceanic factors to fluctuations in cyclone intensity throughout the MAMJ and OND seasons separately. Two seasons have been studied independently in order to better understand the distinct influences of the vertical fluctuation of atmospheric factors and the thermal structure of the oceanic subsurface on cyclogenesis. More severe cyclones are caused by high tropical cyclone heat potential, and ocean subsurface warming present in this sea region influences the genesis of storms mostly during MAMJ. On the other hand, mid tropospheric relative humidity and thermal instability influences more on increasing cyclogenesis and its clustering over EAS during OND season. The findings suggest that large-scale oceanic subsurface conditions have a crucial influence on cyclogenesis over EAS through oceanic sensitivity to atmospheric forcing. This cyclone tendency and its clustering over EAS needs attention in terms of forecasting, catastrophe risk reduction, and climate change adaptation due to the security of coastal urban and rural habitats, livelihoods, and essential infrastructure along the coasts.

Pacific decadal oscillation causes fewer near-equatorial cyclones in the North Indian Ocean.

Tropical cyclones do not form easily near the equator but can intensify rapidly, leaving little time for preparation. We investigate the number of near-equatorial (originating between 5°N and 11°N) tropical cyclones over the north Indian Ocean during post-monsoon season (October to December) over the past 60 years. The study reveals a marked 43% decline in the number of such cyclones in recent decades (1981-2010) compared to earlier (1951-1980). Here, we show this decline in tropical cyclone frequency is primarily due to the weakened low-level vorticity modulated by the Pacific Decadal Oscillation (PDO) and increased vertical wind shear. In the presence of low-latitude basin-wide warming and a favorable phase of the PDO, both the intensity and frequency of such cyclones are expected to increase. Such dramatic and unique changes in tropical cyclonic activity due to the interplay between natural variability and climate change call for appropriate planning and mitigation strategies.

Stabilization of Eu2+ in Li2B4O7 with the BO3 network through U6+ co-doping and defect engineering.

Owing to the unique 4f-5d transitions and the involvement of 5d electrons, the divalent europium (Eu2+) ion is extensively used as a dopant ion in luminescent materials for phosphor-converted light emitting diodes (pc-LEDs) and other technological applications. Earlier reports in most of the cases have shown that the reduction of Eu3+ to Eu2+ requires very high temperatures and large hydrogen flux. In this study, a co-doping strategy with higher valent U6+ ions was utilized to successfully stabilize Eu2+ ions in the Li2B4O7 (LTB) host with both the BO3 and BO4 network in low H2 flux of only 8%. It is postulated that charge transfer occurs from U to Eu, resulting in the reduction of the charged state of Eu and the reaction probably proceeds via the formation of paramagnetic transient [U5+-Eu3+] species in the co-doped LTB. The same is also believed to be facilitated by the enhanced formation of Li-O type vacancy clusters in co-doped samples and enhanced oxygen vacancies in a reducing atmosphere. We believe this work will pave a new pathway for stabilizing the unusual oxidation state of lanthanides and transition metal ions through co-doping with hexavalent uranium ions.

Hot weather hazard analysis over India.

Heat waves are often termed as the silent killer and have become even more important as recent studies suggest that the heat wave have become second most devastating extreme weather events in terms of human deaths and losses. It is also been largely realised by scientific community that it is not just the high temperatures which are responsible for the gruesome effect of heat waves but several other meteorological parameters play a vital role in aggravating the impact and causing much more damages. In view of the above the attention of scientific community, weather forecasters as well as disaster managers has shifted to also take into account the different meteorological parameters like maximum and minimum temperatures, relative humidity, wind speed, duration/spell of heat waves and its intensity which are aggravating the impact of heat stress. In this background, this study is undertaken as an attempt to quantify the effect of different meteorological parameters on heat wave on different regions of India for different summer months (March, April, May and June). In this study the impact of individual meteorological parameter as well their cumulative effect is studied based on data of 30 years (1981-2010) for 300 stations. The effect of different meteorological parameters is identified for different months for different regions of the country. Also the cumulative scores are calculated for different regions considering different meteorological parameters, as a first initiative to perform heat hazard analysis and zonation over the entire country. This could serve as initial step for planning mitigation and adaptation strategies throughout the country. These scores as thresholds for different regions may be also useful for operational forecaster's for early impact based warning services as well as for the disaster managers, for taking effective and timely actions.

Design of need-based phosphors and scintillators by compositional modulation in the ZnGa2-xAlxO4:Cr3+ spinel: pure compound versus solid solutions.

Materials that can depict persistent deep red light under both ultraviolet (UV) and X-ray illumination can be a boon to sustainable economy, particularly for optical imaging, solid state lighting, and anticounterfeiting applications. Herein, we have made a series of compounds starting from ZnGa2O4:Cr3+ to ZnAl2O4:Cr3+ (individual spinel) by substituting the varied concentration of Al3+ in place of Ga3+ in ZnGa2-xAlxO4:Cr3+ (solid solution). By virtue of the structural and defect engineering doping strategy, the photo and radioluminescence are expected to be improved. Both Cr and Al doping was found to be energetically favorable in ZnGa2O4, where the same does not hold true for Ga doping in ZnAl2O4, as indicated by the DFT-calculated defect formation energies. There seems to be ordering around the dopant ion in the solid solutions compared to either ZnGa2O4 or ZnAl2O4 and is also reflected to as lower persistent luminescence (PerL) lifetimes. PerL under UV, in general. was found to be lower with the enhancement in the Al3+ content endowed by the formation of Cr-Cr ion pair, lower probability of antisite formation, and widening band gap. On the other hand, X-ray excited emission enhances in the solid solution due to the decrease in cation inversion and associated defects. Confocal Microscopy showed that larger particles depicted much brighter deep red emission but failed to percolate to the human cells to a detectable limit; hence, future work is needed for the functionalization of the ZnGa2-xAlxO4:Cr3+ spinel. This work could be of great implication in designing need-based materials, where UV and X-ray excitation is required, for deep red emission with persistent characteristics from chromium-doped spinels.

Photophysical Behaviour of Novel Quaternary Pyrenoyl Salts and Their Sensitivity Towards Bile Salt Micellization.

The present work describes the synthesis and characterization of pyrene derivatives, N-(1-Pyrenoylmethyl) pyridinium bromide (PM-PB) and N-(1-Pyrenoylmethyl)-N,N,N-triethylammonium bromide (PM-TAB). The photophysical behavior of these molecules has been studied in various protic and aprotic solvents. Using steady state fluorescence intensity, fluorescence anisotropy and dynamic fluorescence lifetime studies, the sensitivity of these molecules towards the micellization process of bile salts has been monitored. These derivatives have been effectively used in estimating critical micellar concentration (CMC) of bile salt, sodium deoxycholate (NaDC).

Defect engineering in trivalent ion doped ceria through vanadium assisted charge compensation: insight using photoluminescence, positron annihilation and electron spin resonance spectroscopy.

Pair matching charge compensation with trivalent and pentavalent dopants in ceria was found to be an attractive strategy in engineering defects with minimal distortions in the lattice and obtaining enhanced catalytic properties. In the present study, charge compensation with a vanadium codopant in trivalent ion doped ceria is studied. Defect evolution in the trivalent ion doped ceria with vanadium codoping has been studied in CeO2:Eu3+, CeO2:La3+,Eu3+ and CeO2:Y3+,Eu3+ systems and the choices of the dopant and co-dopant are triggered by their ionic radius. Eu3+ photoluminescence (PL) is used as a spectroscopic probe to monitor local structural changes around the dopants. Positron lifetime studies showed that oxygen vacancies formed due to trivalent ion doping are weakly associated when larger ions are doped and result in the formation of vacancy aggregates. Positron lifetime studies along with XRD studies show that vanadium codoping effectively removes the vacancies but the distortions are significant when the size mismatch between the pair match used for charge compensation is higher. Photoluminescence demonstrated that the oxygen vacancies associated with Eu are more effectively removed in the case of Y codoped samples. Electron Spin Resonance (ESR) studies suggested that vanadium in excess over the stoichiometric concentration of the trivalent ion can lead to additional defects. These studies are expected to help in tuning the vacancy concentrations as well as controlling the lattice distortions for technological applications such as catalysis, ionic conductivity, etc.

Structural and Magnetic Properties of Dilute Ca²âº Doped Iron Oxide Nanoparticles.

Undoped and calcium substituted hematite (α-Fe2O3) nanoparticles are synthesized by surfactant-directed co-precipitation and post annealing method. The annealed nanoparticles were found to be in single phase in nature and crystallize in the rhombohedral structure with space group R3c as confirmed by Rietveld refinement of the X-ray diffraction (XRD) data. Average crystallite sizes are calculated to be 20 to 30 nm and 50 to 60 nm for the nanoparticles annealed at 400 and 600 °C respectively. Mössbauer spectra for all the nanoparticles could be fitted with a sextet corresponding to the single magnetic state of the iron atoms in its Fe³âº state in the hematite matrix. The FTIR and Raman spectra of all the samples correspond to specific modes of α-Fe2O3. UV-Vis spectra of annealed samples showed broad peaks in the range of 525-630 nm resulting from spin-forbidden ligand field transition together with the spin-flip transition among the 2t2g states. The estimated band gap energies were in the range of 1.6 to 1.9 eV which are much lower than the reported values for nano hematite. From the room temperature magnetic hysteresis loop measurements, weak ferromagnetic behavior is observed in all undoped and Ca²âº doped hematite samples. Morin temperature (T(M)) is calculated to be 257 and 237 K for 1.45% doped samples with particle size 54 and 27 nm respectively. The sample with Ca content of 1.45 wt% when annealed at 400 °C showed that the particles were of different shapes which included both quasi spherical and rod shaped. On annealing the same sample at 600 °C, the nanorods collapsed to form bigger spherical and ellipsoidal particles.

Uranium luminescence in La2 Zr2 O7 : effect of concentration and annealing temperature.

The speciation of a particular element in any given matrix is a prerequisite to understanding its solubility and leaching properties. In this context, speciation of uranium in lanthanum zirconate pyrochlore (La2 Zr2 O7 = LZO), prepared by a low-temperature combustion route, was carried out using a simple photoluminescence lifetime technique. The LZO matrix is considered to be a potential ceramic host for fixing nuclear and actinide waste products generated during the nuclear fuel cycle. Special emphasis has been given to understanding the dynamics of the uranium species in the host as a function of annealing temperature and concentration. It was found that, in the LZO host, uranium is stabilized as the commonly encountered uranyl species (UO22+ ) up to a heat treatment of 500 °C at the surface. Above 500 °C, the uranyl ion is diffused into the matrix as the more symmetric octahedral uranate species (UO66- ). The uranate ions thus formed replace the six-coordinated 'Zr' atoms at regular lattice positions. Further, it was observed that concentration quenching takes place beyond 5 mol% of uranium doping. The mechanism of the quenching was found to be a multipolar interaction. Copyright © 2016 John Wiley & Sons, Ltd.

A case study of energy transfer mechanism from uranium to europium in ZnAl3O4 spinel host by photoluminescence spectroscopy.

Zinc aluminate (ZAO), a member of spinel class of inorganic compounds has been of much interest of late due to its wide range of use in catalysis, optical, electronic and ceramic industries. When doped with several lanthanides, this material has proved to be a potential host matrix for phosphors. As lanthanides suffer from poor (direct) excitation and emission cross sections, the use of a co-dopant ion can help to circumvent this and extract better emission from a lanthanide doped ZAO system. In this connection, energy transfer mechanism from uranium to europium in the ZAO host was investigated by photoluminescence spectroscopic technique. It was seen that uranium gets stabilized in the hexavalent state as UO6(6-) (octahedral uranate) where as the lanthanide ion, Eu is stabilized in its trivalent state in the ZAO host. In the co-doped system, an efficient energy transfer pathway from the uranate to europium ion was observed. Based upon emission and life time data a suitable mechanism was proposed for the energy transfer (quenching) process. It was proposed that after excitation by photons, the uranate ions transfer their energy to nearby (5)D1 level of Eu(3+) ions which non-radiatively de-excites to the corresponding lower levels of (5)D0. Further this (5)D0 level decays in a radiative mode to the (7)F manifold giving the characteristic emission profile of trivalent Eu. It was proposed that both static and dynamic types of energy transfer mechanism were responsible for this process.

Evaluation of clinico: pathologic findings of breast carcinoma in a general hospital in Southern India.

BACKGROUND AND OBJECTIVES: Breast cancer is the second most common cancer in the Indian female population. As per our hospital data, breast cancer is also found to be the second leading malignancy in women. Hence, we undertook this study to evaluate the clinical profile, histopathologic types, grade, stage and the prognosis of the disease in our patients. Majority of our patients are from rural areas. MATERIALS AND METHODS: This study was undertaken over a period of three years comprising of 178 patients who underwent modified radical mastectomy following preliminary diagnosis of carcinoma on fine needle aspiration cytology or histopathological examination of the lumpectomy or trucut biopsy specimens. Clinico-pathological evaluation was done in all of these cases following standard protocols. RESULT: The study comprised of 175 female patients and 3 male patients in the age range of 28 to 76 years. Majority (111/62.3%) of the cases were within the age range of 31-50 years of age with mean age of 48.7 years. Two females had bilateral breast cancer and one female had synchronous papillary serous cystadenocarcinoma of the ovary. Invasive ductal carcinoma no special type was the most common histopathologic pattern, and was seen in 172 (95.5%) cases. Most tumors were Scarff Bloom Richardson grade II and American Joint Committee on Cancer pathologic stage II. Prognostically, majority of tumors (49.5%) was assessed as 'good' as per the Nottingham prognostic index score. CONCLUSIONS: This study gave an insight to the clinico-pathological profile of breast cancer in our area. Long term study with follow up of the patient is needed for better understanding of the case.

Photoluminescence studies on the complexation of Eu(III) and Tb(III) with acetohydroxamic acid (AHA) in nitrate medium.

UREX process has been proposed for selective extraction of U(VI) and Tc(VII) from nitric acid medium (∼1M HNO3) using tri-n-butyl phosphate (TBP) as extractant and retaining Pu, Np and fission products in the aqueous phase. The feasibility of the use of luminescence spectroscopy as a technique to understand the complexation of trivalent f-elements cations viz. Eu(III) and Tb(III) with acetohydroxamic acid (AHA) in nitric acid medium has been examined. The luminescence lifetimes for the 1×10(-3)M Eu(III) and AHA complex system decreased with increased AHA concentration from 116±0.2µs (no AHA) to 1.6±0.1µs (0.1M AHA) which was attributed to dynamic quenching. The corrected fluorescence intensities were used to calculate the stability constant (log K) for the formation of 1:1 Eu(3+)-AHA complex as 1.42±0.64 under the conditions of this study. By contrast, the Tb(III)-AHA system at pH 3 (HNO3) did not show any significant variation in the life times of the excited state (364±9µs) suggesting the absence of dynamic quenching. The spectral changes in Tb(III)-AHA system showed the formation of 1:1 complex (log K: 1.72±0.21). These studies suggest that the extent of AHA complexation with the rare earth elements will be insignificant as compared to tetravalent metal ions Pu(IV) and Np(IV) under UREX process conditions.

Mössbauer and magnetic studies of surfactant mediated Ca-Mg doped ferrihydrite nanoparticles.

Ultrafine (2-5 nm) particles of amorphous Ca-Mg co-doped ferrihydrite have been synthesized by surfactant mediated co-precipitation method. The evolution of the amorphous ferrihydrite by Ca-Mg co-doping is quite different from our earlier investigations on individual doping of Ca and Mg. Amorphous phase of ferrihydrite for the present study has been confirmed by X-ray diffraction (XRD) and Mössbauer spectroscopy at room temperature and low temperatures (40 K and 20 K). Hematite nanoparticles with crystallite size about 8, 38 and 70 nm were obtained after annealing the as-prepared samples at 400, 600 and 800 degrees C respectively in air atmosphere. Superparamagnetism has been found in 8 nm sized hematite nanoparticles which has been confirmed from the magnetic hysteresis loop with zero remanent magnetization and coercive field and also from the superparamagnetic doublet of its room temperature Mössbauer spectrum. The magnetic properties of the 38 and 70 nm sized particles have been studied by room temperature magnetic hysteresis loop measurements and Mössbauer spectroscopy. The coercive field in these hematite nanoparticles increases with increasing particle size. Small amount of spinel MgFe2O4 phase has been detected in the 800 degrees C annealed sample.

Nano-structured Mg-doped Fe2O3-ferrihydrite powder--a new adsorbent for cation removal from aqueous solutions.

The present studies were undertaken with a view to developing a low-cost, efficient adsorbent for removal of heavy metal ions from aqueous solutions. A new cost-effective nano-structured Mg-doped Fe2O3-ferrihydrite adsorbent exhibiting high uptake capacities for various cations was synthesized. After preliminary testing of a series of Mg-doped (0.38 to 0.98%) samples for Pb(II), Cd(II), Cu(II) or Co(II) adsorption, a typical sample containing 55.7% Fe and 0.38% Mg was chosen for detailed characterization studies (XRD, TG-DTA, FTIR and TEM techniques). The adsorption behaviour of cations on the prepared nano powder was studied under various experimental conditions. The generated data were fitted to kinetic and isotherm models. The Langmuir monolayer capacities were 99.1, 83.3, 111.1 and 151.5 mg/g for Pb(II), Cd(II), Cu(II) and Co(II), respectively. It is the first time that such a high loading capacity for Co(II) has been reported. The effect of the presence of chloride or sulphate was dependent on the nature of the cation. Lead(II) adsorption was endothermic in nature with increased randomness at the solid-liquid interface, while for the rest of the three cations the adsorption process was exothermic. The XRD and FTIR studies on the loaded samples revealed structural changes during the adsorption process. The high cation loading capacities along with the stability of the loaded adsorbent make the synthesized ferrihydrite-Fe2O3 nano powder a potential candidate for contaminated water purification.

2-line ferrihydrite: synthesis, characterization and its adsorption behaviour for removal of Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions.

Nano-structured 2-line ferrihydrite was synthesized by a pH-controlled precipitation technique at 90 °C. Chemical, X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman analyses confirmed the sample to be 2-line ferrihydrite. The nano nature of the prepared sample was studied by transmission electron microscopy (TEM). The surface area obtained by the Brunauer-Emmett-Teller (BET) method was 175.8 m(2) g(-1). The nanopowder so obtained was used to study its behaviour for the removal of Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions. The relative importance of experimental parameters such as solution pH, contact time and concentration of adsorbate on the uptake of various cations was evaluated. By increasing the pH from 2.0 to 5.5, adsorption of the four cations increased. The kinetics parameters were compared by fitting the contact time data to both linear as well as non-linear forms of pseudo-second-order models. Linear forms of both Langmuir and Freundlich models fitted the equilibrium data of all the cations except for Pb(II) which was also fitted to the non-linear forms of both the models as it gave a low R(2) value of 0.85 for the Langmuir model. High Langmuir monolayer capacities of 366, 250, 62.5 and 500 mg g(-1) were obtained for Pb(II), Cd(II), Cu(II) and Zn(II), respectively. Presence of chloride or sulfate had an adverse effect on cation adsorption. The interactive effects on adsorption from solutions containing two, three or four cations were studied. Surprisingly no Cd(II) adsorption was observed in Pb(II)-Cd(II), Pb(II)-Cd(II)-Zn(II) and Pb(II)-Cd(II)-Cu(II)-Zn(II) systems under the studied concentration range. The overall loading capacity of the adsorbent decreased in mixed cation systems. Metal ion loaded adsorbents were characterized by XRD, FTIR and Raman techniques. The high adsorption capability of the 2-lines ferrihydrite makes it a potentially attractive adsorbent for the removal of cations from aqueous solutions.

Delayed gastric emptying time in adult cerebral Falciparum malaria.

OBJECTIVE: We hypothesize that upper gastrointestinal symptoms in cerebral malaria are due to gastric motor dysfunction. But gastric motility studies in cerebral malaria are scarce. METHODS: We determined gastric emptying half-time (GET½) of liquid meals quantitatively by radio isotope scintigraphy in 25 patients of cerebral malaria and 10 healthy controls. RESULTS: GET½ was prolonged (46.5 ± 4.8 min) significantly (p <0.001) in patients of cerebral malaria compared to healthy controls (27.6 ± 5.3 min). CONCLUSION: Cerebral malaria can cause prolongation of gastric emptying time of liquid foods.

Manifestation and outcome of concurrent malaria and dengue infection.

OBJECTIVE: Studies on concurrent infection of dengue and malaria are uncommon in India. Therefore, in this study, we compared the clinical features and outcome of concurrent infection with mono-infection of dengue and malaria. METHODS: All the patients of fever within 7 days duration were investigated for dengue, malaria and other causes of fever. Patients of concurrent dengue and malaria (Group A) were compared with dengue mono-infection (Group B) and malaria mono-infection (Group C). Biochemical and haematological investigations were done and compared. RESULTS: During the study period 367 patients of dengue were admitted. Concurrent infection of dengue and malaria was found in 27 (7.4%) patients. There were 27 (5.8), 340 (72.5), and 102 (21.7%) patients in Groups A, B, and C respectively. The clinical features of concurrent infection were more like dengue than malaria. Unlike malaria the outcome of concurrent infection is good. CONCLUSION: Concurrent infection of dengue and malaria is not uncommon. For the diagnosis investigations for both the infections should be carried out routinely.

Profile of mixed species (Plasmodium vivax and falciparum) malaria in adults.

OBJECTIVE: Studies on malaria due to co-existent P. falciparum and P. vivax infections are negligible in India. Therefore, this study was undertaken to find out the clinical profile, prognostic factors, and outcome of mixed species malaria and to compare it with P. falciparum malaria. METHODS: This prospective, comparative study has been conducted in a tertiary health care institution with high prevalence of malaria. A cohort of 888 patients of malaria was enrolled in this study. The diagnosis of malaria was made either by Giemsa stained peripheral blood smear or RDT. Mixed species (MS) malaria was diagnosed when both P. vivax and P. falciparum were detected either from peripheral blood smear or RDT. Patients with P. falciparum malaria were grouped in to Pf group. The differences in clinical presentation, biochemical and haematological findings, occurrence of severe malaria, and outcome were recorded, compared, and analyzed. The severity of complication was assessed and Malaria Severity Score (MSS) was calculated. All the patients were treated according to WHO guidelines. RESULTS: Of them MS and Pf malaria constituted 118 (13.2%) and 770 (86.7%) patients respectively. Severe malaria was found in 17.8% (21 of 118) patients of MS and 57.1% (440 of 770) patients Pf malaria. Pf constituted 440 (95.5%) cases where as MS constituted 21 (4.5%) respectively. The number of severe malaria was significantly (p < 0.001) more in Pf than MS. Out of 21 cases of severe malaria in MS infection, 14 (66.6%) had single complication and 7 (33.3%) cases had multiple complication. However, in Pf mono infection there were 200 (45.5%) patients with single and 240 (54.5%) with multiple complication. There were 4 independent risk factors for a patient of developing complicated malaria. They were: presenting without fever, high parasite count, Pf mono infection, and fever to treatment interval. Multiple complications and high MSS are associated with increased death in Pf malaria. The outcome of patients of MS was good. CONCLUSION: In conclusion mixed species infection is not uncommon in the locality where both species coexists. Mixed species infection can complicate with severe malaria. However, its incidence and severity is less than severe falciparum malaria. In mixed infection, P.vivax malaria has a protective effect against the severity of falciparum malaria.