Dualistic temperature sensing in Er3+/Yb3+ doped CaMoO4 upconversion phosphor.

Temperature sensing performance of Er3+/Yb3+ doped CaMoO4 phosphor prepared via polyol method is reported herein. The X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy are done to confirm the phase, structure and purity of the synthesized phosphor. The infrared to green upconversion emission is investigated using 980nm diode laser excitation along with its dependence on input pump power and external temperature. The temperature dependent fluorescence intensity ratio of two upconversion emission bands assigned to 2H11/2→4I15/2 (530nm) and 4S3/2→4I15/2 (552nm) transitions has shown two distinct slopes in the studied temperature range - 300 to 760K and therefore, dual nature of temperature sensitivity is observed in this phosphor. This phenomenon in rare earth doped materials is either scarcely reported or overlooked. The material has shown higher sensitivity in the high temperature region (535K

Visible upconversion in Er3+/Yb3+ co-doped LaAlO3 phosphors.

The Er3+ doped and Er3+/Yb3+ co-doped LaAlO3 phosphors have been synthesized by the combustion method and characterized their structural, morphological, elemental, vibrational and optical properties. The optical absorption and upconversion properties of the synthesized phosphors have been studied. Upon co-doping Yb3+ ions into Er3+:LaAlO3, the blue, green and red upconversion emissions of Er3+ ions have been enhanced about ~20, ~54 and ~22 times, under 978nm laser excitation. The observed upconversion emissions could be due to excited state absorption in Er3+:LaAlO3, whereas energy transfer is dominant mechanism in Er3+/Yb3+:LaAlO3 phosphors. The tuning in the color emitted from the synthesized phosphors towards the green region has been found due to incorporation of the Yb3+ ions. With increase in the pump power, the color emitted from the co-doped phosphor is not tuned significantly, showing its applicability in making the green display devices.

Structural and optical properties of thermal decomposition assisted Gd2O3:Ho(3+)/Yb(3+) upconversion phosphor annealed at different temperatures.

The infrared to visible upconversion fluorescent nanoparticles of Ho(3+)/Yb(3+) codoped Gd2O3 phosphor is synthesized via thermal decomposition route. The as-synthesized sample was annealed at 800, 1000 and 1200°C for 3h and then structural and optical properties were studied. The Rietveld refinement of X-ray diffraction (XRD) data was analyzed to probe the effect of Ho(3+)/Yb(3+) dopant on the structural parameters of Gd2O3 host. The upconversion emission spectra of as-synthesized and annealed samples are compared using 980nm diode laser excitation and five emission bands noticed at 490, 539, 550, 667 and 757nm corresponding to the (5)F3→(5)I8, (5)F4→(5)I8, (5)S2→(5)I8,(5)F5→(5)I8 and (5)I4→(5)I8 manifolds, respectively. The local temperature induced by laser light is also calculated. The fluorescence intensity ratio (FIR) of two thermally coupled transitions (5)F4→(5)I8 and (5)S2→(5)I8 is plotted against the sample temperature and sensor sensitivity of sample is calculated.

Enhanced temperature sensing response of upconversion luminescence in ZnO-CaTiO3: Er(3+)/Yb(3+) nano-composite phosphor.

Upconversion emission and temperature sensing of the Er(3+)/Yb(3+) doped ZnO-CaTiO3 nano-composite phosphor is studied by varying the ZnO concentration. The XRD and EDX studies reveal the formation of composite phase when ZnO doping exceeds above 10 mw%. Five prominent upconversion emission bands at 410, 492, 524, 545 and 662 nm corresponding to (2)H9/2→(4)I15/2, (4)F3/2→(4)I15/2, (2)H11/2→(4)I15/2, (4)S3/2→(4)I15/2 and (4)F9/2→(4)I15/2 transitions, respectively are found under 980 nm excitation from a diode laser. On the basis of rise time analysis it was found that energy transfer process is responsible for the intense upconversion emission. Large reduction in decay time of (4)S3/2 level is observed on the ZnO incorporation in host matrix. Moreover, the absolute sensor sensitivity, relative sensor sensitivity and calculated color coordinates of the samples are also determined. These results indicate the potentiality of this composite phosphor for various applications.

Conversion of orange light into blue light.

Frequency upconversion in triply ionized praseodymium doped glass with composition TeO(2)-Na(2)O (TNO) system under the excitation with a laser light from a dye laser has been reported and the covalency, bonding parameter, nephalauxetic effect which provides the information about the nature of bonding between the lanthanide ions and the surrounding oxygens for the present glassy material calculated. The energy transfer route followed by the two excited praseodymium ions is observed to be the leading process for the upconversion emission.

Amphotericin B treatment for Indian visceral leishmaniasis: response to 15 daily versus alternate-day infusions.

BACKGROUND: For patients with Indian visceral leishmaniasis, amphotericin B deoxycholate is usually given as 15 alternate-day infusions of 1 mg/kg over 30 days (total dose, 15 mg/kg); daily treatment with 1 mg/kg for 20 days (total dose, 20 mg/kg) is also used. This study was done to address the unsettled therapeutic questions of administration schedule (alternate-day vs. daily administration) and dose (1 vs. 0.75 mg/kg) and to determine whether the duration of amphotericin B treatment in Bihar, India, can be shortened to 15 days. METHODS: To compare alternate-day versus daily administration and 1-mg/kg versus 0.75-mg/kg doses and to determine whether the duration of treatment could be abbreviated, Indian subjects randomly received 15 infusions of 1 mg/kg (group A; 245 patients) or 0.75 mg/kg (group B; 244 patients) on alternate days or 1 mg/kg (group C; 500 patients) or 0.75 mg/kg (group D; 496 patients) daily. Noninferiority testing compared 6-month cure rates using a 5% margin. RESULTS: Overall, 1439 of the 1485 subjects completed treatment and responded. Treatment interruptions (nephrotoxicity) but not infusion-associated reactions or study removals were more common with daily administration. Final cure rates at 6 months were similar: group A, 234 patients (96%; 95% confidence interval [CI], 92%-98%); group B, 225 patients (92%; 95% CI, 88%-95%); group C, 483 patients (97%; 95% CI, 95%-98%); and group D, 476 patients (96%; 95% CI, 94%-97%; P>.05). CONCLUSIONS: Provided that the serum creatinine level is repeated once, daily treatment with amphotericin B, 0.75 mg/kg for 15 days (total dose, 11.25 mg/kg), is efficient and effective for visceral leishmaniasis in India. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00310505.

Correlative Studies on Plant Growth and Metabolism II. Effect of Light and of Gibberellic Acid on the Changes in Protein and Soluble Nitrogen in Lettuce Seedlings.

Protein and soluble nitrogen distribution in different parts of lettuce seedling was studied in light and darkness and in presence and absence of gibberellic acid. In dark, applied gibberellic acid failed to show any marked effect on the nitrogen changes in lettuce. Light inhibits translocation of nitrogen reserves from the cotyledons. Gibberellic acid reverses the light inhibition of longitudinal growth but has no effect on the inhibition of translocation from the cotyledons. Light grown, gibberellic acid treated seedlings exhibit a pattern of protein and soluble-N which is characteristic of the dark grown seedlings. Thus gibberellic acid not only causes morphological reversal of light inhibition but also shifts the nitrogen metabolism of light grown plants, close to that of plants grown in darkness.