VUV PROPERTIES OF Eu3+- DOPED YBO3 PHOSPHOR PREPARED VIA ALDO-KETO AND SOLID-STATE PROCESS

The Eu3+ doped YBO3 was prepared by the novel aldo-keto method. The structure and VUV luminescence properties of the title compound were studied and compared to the corresponding properties of the materials prepared by a conventional solid state reaction. The use of novel aldo-keto method in preparation lowered the reaction threshold temperature by c.a. 300oC. The YBO3 phosphor from the aldo-keto method look like evenly sized spherical structures, whereas those from the solid-state process look like some agglomerates of little spheres. The Eu3+-doped YBO3 phosphors prepared by both methods showed the red emission with peak around 592, 611 and 627 nm at excitations wavelengths 147 and172 nm, which corresponds to the transitions from the excited 5D0 level to the 7FJ (J = 1, 2, 3, 4) levels of Eu3+ activators. However, the emission intensity of the Eu3+ doped YBO3 from the aldo-keto system is about 2 times as much as that from the sold-state process

EVALUATION OF BIOLOGICAL ACTIVITIES OF NANOCRYSTALLINE TETRAGONAL ZIRCONIA SYNTHESIZED VIA SOL-GEL METHOD

Objective: The objective of the following study was a synthesis of nanocrystalline tetragonal zirconia (ZrO2) using simple sol–gel method and evaluation of its structural and biological properties.Methods: The sample was characterized by X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM) and evaluated for cell growth study using 3T3 mouse fibroblast cells and for degradation using Phosphate Buffered Saline (PBS) solution. The synthesized materials were also evaluated for their antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacterial strains.Results: The XRD pattern shows that the tetragonal phase of nanocrystalline zirconia was obtained at relatively low temperature i.e. 300 °C. The FESEM images showed that the prepared sample consists of particles in the range of 35-69 nm and homogenous particle size distribution. The TEM images confirmed the results shown by FESEM images. The sample of zirconia has excellent tissue biocompatibility, higher cell growth and does not show the toxicity towards normal 3T3 mouse fibroblast cells. The result of qualitative antibacterial tests revealed that the nanocrystalline zirconia had an important inhibitory activity on E. coli and S. aureus. The sample shows stability at the physiological condition and does not show degradation.Conclusion: Nanocrystalline tetragonal zirconia shows higher cell growth and efficient antibacterial activity against E. coli and S. aureus bacterial pathogen and also it is stable at the physiological condition. Hence, it can be used for various biomedical applications.Keywords: Nanocrystalline zirconia, Sol-gel route, Antimicrobial action, Biomedical applicatio

Direct and sensitive detection of Trypanosoma evansi by polymerase chain reaction

The mechanically transmitted haemoflagellate,Trypanosoma evansicauses 'surra', a wasting disease of domestic animals and is highly endemic in distribution in Southeast Asia. The detection ofT. evansiis important for improving the epizootiological and animal health status of the region. The specificity and sensitivity of polymerase chain reaction (PCR) using oligonucleotide primers constructed fromT. evansirepetitive DNA sequences were studied in the present investigation. Using the assay, it was possible to amplify template DNA ofT. evansiderived from buffaloes, camels and horses to a threshold sensitivity level of 0.5 pg and to detect DNA from as few as five organisms in 10 (l crude blood samples. Following experimental infection of calves with 5 × 105T. evansi, positive signals could be observed as early as 12 h post-infection. DNAs from two common haemoflagellates of cattle,Babesia bigeminaandTheileria annulatawere not amplified with the primers

Photoluminescence study of Sr3Y1-X(BO3)3:xTb3+ green emitting phosphor

143-147Terbium doped strontium yttrium borate phosphor is prepared by solution combustion method. Structural characterization of Sr3Y(BO3)3:Tb3+ (SYB:Tb) has been carried out with X-ray powder diffraction (XRD) analysis. Particle size of 0.5–2 µm and perfect element composition were seen in SEM-EDS. Using FTIR at room temperature the presence of [BO3]- group; complete combustion of nitrates, organic material, absence of O-H bond were firmed up. Photoluminescence properties of the phosphor have been investigated by measuring the excitation and emission spectra. Several luminescence bands of Tb3+ ions are observed under 233 nm excitation wavelengths in 350–700 nm spectral region. The emission spectra were composed of three bands, in which the dominated emission of green luminescence SYB:Tb attributed to the transition 5D4→7F5 is centered at 543 nm. The dependence of the emission intensity on the Tb3+ concentration for the Sr3Y1-X(BO3)3:xTb3+ (0.01 ≤ x ≤ 0.05) was studied and observed that the optimum concentration of Tb3+ in phosphor was 3 mol% for the highest emission intensity at 543 nm. The CIE coordinates (X=0.251363409, Y=0.736605581) fall at the border of green region in the CIE 1931 chromaticity

Photoluminescence study of Sr3Y1-X(BO3)3:xTb3+ green emitting phosphor

Terbium doped strontium yttrium borate phosphor is prepared by solution combustion method. Structural characterization of Sr3Y(BO3)3:Tb3+ (SYB:Tb) has been carried out with X-ray powder diffraction (XRD) analysis. Particle size of 0.5–2 µm and perfect element composition were seen in SEM-EDS. Using FTIR at room temperature the presence of [BO3]- group; complete combustion of nitrates, organic material, absence of O-H bond were firmed up. Photoluminescence properties of the phosphor have been investigated by measuring the excitation and emission spectra. Several luminescence bands of Tb3+ ions are observed under 233 nm excitation wavelengths in 350–700 nm spectral region. The emission spectra were composed of three bands, in which the dominated emission of green luminescence SYB:Tb attributed to the transition 5D4→7F5 is centered at 543 nm. The dependence of the emission intensity on the Tb3+ concentration for the Sr3Y1-X(BO3)3:xTb3+ (0.01 ≤ x ≤ 0.05) was studied and observed that the optimum concentration of Tb3+ in phosphor was 3 mol% for the highest emission intensity at 543 nm. The CIE coordinates (X=0.251363409, Y=0.736605581) fall at the border of green region in the CIE 1931 chromaticity

Identification of Trypanosoma evansi by DNA hybridisation using a non-radioactive probe generated by arbitrary primer PCR: Short communication

A highly reproducible, dominant, monomorphic fragment of 473 base pair (bp) amplified from the genome of Trypanosoma evansi by arbitrary primer — polymerase chain reaction (AP-PCR) was labelled with digoxigenin and investigated for its potential as DNA probe. Dot-blot hybridisation of total genomic DNA with the probe proved useful in detecting bubaline, cameline and equine strains of T. evansi down to 10 pg of parasite template DNA. No cross-hybridisation was seen with Babesia bigemina, Theileria annulata and the bubaline host DNA. This probe may facilitate laboratory identification of T. evansi in developing countries, without the inherent risk associated with radioisotopes

Studies on optical properties of LiCaBO3: Tb3+ phosphor

458-462The green emitting phosphor LiCaBO3:Tb3+ has been synthesized by easy, time saving, cost effective modified method of solution combustion synthesis at comparatively lower temperature using urea as fuel. X-ray power diffraction (XRD) analysis confirms the formation of the said phosphor. Photoluminescence measurements show that the phosphor has exhibited emission peak with good intensity at 547 nm, corresponding to 5D4–7F5 (547 nm) green emission and weak 5D4–7F5 (486 nm) blue emission. The excitation spectra monitored at 547 nm show broad band from 250 to 300 nm ascribed to spin-allowed 4f8–4f75d transitions of Tb3+. Also, no charge-transfer (CT) transition related to Tb3+-O2- has been observed. For the excitation wavelength of 240 nm the emission intensity increases initially with the increase of Tb3+ concentration and reaches to the maximum at x=0.005. The concentration quenching observed after that is mainly due to quadrupole–quadrupole interaction. The as synthesized phosphor LiCaBO3:Tb3+ by this method shows CIE colour coordinates of (0.28, 0.71) with good intensity

UV emitting borate phosphors for phototherapy lamps

77-81Photoluminescence properties of UV and blue emitting borate phosphors prepared by simple and time saving combustion synthesis technique are presented and discussed in the context of application in phototherapy lamps. Emission characteristics of these phosphors are found to be similar to those of commercial lamp phosphors used for phototherapy

Design Parameters of Different Configurationof Optical Filters Made up of MgF 2 and Ta 2 O 5

ABSTRACT:In this paper, an improved design of a tunable optical filter device made up of alternating layers of MgF 2 and Ta 2 O 5 is proposed. Different configurations of this narrow band pass (NBP) optical filter are used for whole visible spectral range (400nm-700nm).We report on the calculated values of the design parameters, such as pass band wavelength, 3-dB bandwidth and quality factor for different configurations of narrow band pass optical filter. The design parameters are also evaluated when varying the angle at which the optical wave is incident on the input layer of the filter