New lanthanide-free self-activated full-color emission phosphor in Y3+ doped Sr3 Bi(VO4 )3 system for white light emitting diode applications.

Commercially used inorganic phosphors heavily depend on lanthanide doped host materials which are becoming more expensive and also their availability is limited due to scarcity. In this regard, a new lanthanide-free self-activated full-color emission phosphor in Y3+ doped Sr3 Bi(VO4 )3 system was developed by the conventional ceramic route. These phosphors crystallize into a hexagonal-type palmierite mineral structure. They exhibit broad excitation bands in the wavelength region of 250-400 nm, owing to the charge transfer transitions from both O2- and Bi6s2 electrons to V5+ . Upon excitation, these phosphors show bright broad emissions in the 400-750 nm wavelength range, peaking around 535 nm, with a large full width half maximum of 160 nm. The Y substitution allows tuning of the emission from yellowish green to bluish white due to increased distortion of [VO4 ]3- tetrahedron. Consequently, the CIE color coordinates changed from (0.42, 0.50) to (0.31, 0.35) which lies in the near-white region in the chromaticity diagram. Thus, the newly developed Y doped Sr3 Bi(VO4 )3 is a promising lanthanide-free full-color emission phosphor for applications in pc-white light emitting diodes.

Exploitation of Eu3+ red luminescence through order-disorder structural transitions in lanthanide stannate pyrochlores for warm white LED applications.

Eu3+ ions epitomize excellent structural probes for the detection of disorder induced by structural variations in stannate pyrochlores due to their relatively simple energy level structure. In this context, we have synthesized a series of Eu3+ doped Ln2.85YSnNbO10.5:0.15Eu3+ (Ln = La, Gd, Y, and Lu) red phosphors via a high temperature solid state reaction method to explore the influence of phase evolution on the luminescence properties. The substitution of Ln3+ ions in the A sites of the pyrochlore induces a structural transition from an ordered pyrochlore to a disordered fluorite structure with decreasing ionic radius. The diminishing trend of the characteristic superstructure peaks in the XRD pattern and the broadening of Raman modes with lanthanide substitution clearly substantiate the disorder induced in the cationic sublattice. These phosphors exhibit strong absorption in the near UV region and emit red luminescence under 392 nm excitation, which also correlates to their crystal structures. Their luminescence properties were enhanced with the increased ordering of cations from Lu to La. The more ordered structure of the La system favors a more uniform distribution of Eu3+ ions, preventing cluster formation, and thus improving the luminescence properties. The splitting of the 5D0-7F1 transition of the Eu3+ ions further provides a clue for the structural transition in support of the XRD and Raman analysis. The long range ordering, ligand polarizability, and covalent nature of the Eu3+ bonding influence the emission probability and improve the quantum efficiency of the La host. Eu3+ emissions resulting from 5D0-7FJ transitions are significantly improved with increases in the concentration of Eu3+ ions in the La host. The distortion of the A site symmetry and the red shift of the charge transfer band with Eu3+ doping in the La3YSnNbO10.5 system leads to an enhanced electric dipole transition. The extent of the distortion in the EuO8 polyhedra is reflected in the quantum efficiency values and J-O intensity parameters, Ω2 and Ω4, which are a measure of the degree of polarizability of the Eu-O bonds in the lattice. Our results suggest that we can manipulate the Eu3+ red luminescence in lanthanide stannate pyrochlores through order-disorder structural transitions.

Influence of local structure on photoluminescence properties of Eu3+ doped CeO2 red phosphors through induced oxygen vacancies by contrasting rare earth substitutions.

A new family of red phosphors, Ce0.9-xRExO2-δ:0.1Eu3+ (RE = Y and La; x = 0, 0.20, 0.40, 0.60, 0.80, and 0.90), was synthesized by a conventional solid-state route. The influence of contrasting rare earth substitutions (Y and La) in the system was investigated on the local structure and associated photoluminescence properties by various characterization techniques. Both trivalent ion substitutions lead to the same kind of variation during phase transformation from fluorite to the respective parent oxide structure (x ≥ 0.6). On the other hand, the substitutions have a distinct effect on local structure, absorption, luminescence and lifetimes. The smaller Y3+ ion substitution enables the ordering of oxygen vacancies in a lattice, inhibiting the defect formation of Ce3+ oxidation states. In contrast, the larger La3+ ion substitution liberates oxygen vacancies, allowing defect formation. Consequently, the concentration of Ce3+ is dependent on the ionic radius of the metal ions and it has a bearing on the band gap and luminescence properties of the system. Ce0.1Y0.8O2-δ:0.1Eu3+ phosphor exhibited maximum red emission intensity at 612 nm, which is 8 times higher than that of Ce0.9O2-δ:0.1Eu3+ and better than that of commercial Philips red phosphor, whereas La substitution yielded poor emission intensities with higher concentrations. The co-substitution of contrasting rare earth metals with Eu3+ allow the understanding of local structure and a smaller ion like Y3+ greatly functionalizes CeO2:Eu3+ phosphor.

Remarkable changes in the photoluminescent properties of Y2Ce2O7:Eu(3+) red phosphors through modification of the cerium oxidation states and oxygen vacancy ordering.

A new series of red phosphors based on Eu(3+)-doped yttrium cerate [Y1.9Ce2O7:0.1Eu(3+), Y2Ce1.9O7:0.1Eu(3+) and Y2Ce2-xO7:xEu(3+) (x = 0.05, 0.10, 0.15, 0.20, 0.25 and 0.50)] was prepared via a conventional solid-state method. The influence of the substitution of Eu(3+) at the aliovalent site on the photoluminescent properties was determined by powder X-ray diffraction, FT Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy with energy-dispersive spectroscopy, UV-visible absorption spectroscopy, photoluminescence spectroscopy and lifetime measurements. The substitution of Eu(3+) at the Ce(4+) site induces a structural transition from a defect fluorite to a C-type structure, which increases the oxygen vacancy ordering and the distortion of the Eu(3+) environment, and decreases the formation of Ce(3+) states. In contrast, phosphors with isovalent substitution at the Y(3+) site exhibit the biphasic nature of defect fluorite and a C-type structure, thereby increasing the number of Ce(3+) oxidation states. These modifications resulted in remarkable changes in the photoluminescent properties of Y2Ce1.9O7:0.1Eu(3+) red phosphors, with emission intensities 3.8 times greater than those of the Ce0.9O2:0.1Eu(3+) and Y1.9Ce2O7:0.1Eu(3+). The photoluminescent properties of Y2Ce2-xO7:xEu(3+) were studied at different Eu(3+) concentrations under excitation with blue light. These phosphors emit intense red light due to the (5)D0-(7)F2 transition under excitation at 466 nm and no concentration quenching is observed with up to 50 mol% Eu(3+). They show increased lifetimes in the range 0.62-0.72 ms at Eu(3+) concentrations. The cation ordering linked to the oxygen vacancy ordering led to the uniform distribution of Eu(3+) ions in the lattice, thus allowing higher doping concentrations without quenching and consequently increasing the lifetime of the (5)D0 states. Our results demonstrate that significant improvements in the photoluminescence properties can be achieved by the structural alteration of a fluorite CeO2 to a C-type lattice.

Pharmacogenetics of selective serotonin reuptake inhibitors (SSRI): A serotonin reuptake transporter (SERT)-based approach.

Neuropsychiatric disorders are considered to be the most common cause of disability worldwide. Serotonin and its transporter is a prominent paradigm in mood disorders. Response to selective serotonin reuptake inhibitors (SSRI) is altered due to heterogeneity in the serotonin transporter gene, SLC6A4 (solute carrier family 6 member 4). The reported polymorphisms are found to be in different regions of the transporter gene: promoter region (5-HTTLPR and various single nucleotide polymorphisms within it), intron (STin2), and exon 9 (I425V). The long and short alleles of the 5-HTTLPR gene, which are prevalent among variations, may mediate differential effects. In long allelic variant carriers, an increased response to SSRI and timely recovery is due to increased availability of SERT. Whereas, SERT availability is significantly decreased in short allelic carriers, necessitating a reduction in SSRI dosage due to the increased risk of adverse drug reactions. Thus, pharmacogenetic investigations are required to understand the impact of functional variations on the efficacy and tolerability of SSRI. Identifying the carrier variants may aid in clear-decision making of the treatment regimen, aiding the approach of personalized medication.

Repurposing Vorinostat for the Treatment of Disorders Affecting Brain.

Based on the findings in recent years, we summarize the therapeutic potential of vorinostat (VOR), the first approved histone deacetylase (HDAC) inhibitor, in disorders of brain, and strategies to improve drug efficacy and reduce side effects. Scientific evidences provide a strong case for the therapeutic utility of VOR in various disorders affecting brain, including stroke, Alzheimer's disease, frontotemporal dementia, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, spinal muscular atrophy, X-linked adrenoleukodystrophy, epilepsy, Niemann-Pick type C disease, and neuropsychiatric disorders. Further elucidation of the neuroprotective and neurorestorative properties of VOR using proper clinical study designs could provide momentum towards its clinical application. To improve the therapeutic prospect, concerns on systemic toxicity and off-target actions need to be addressed along with the improvement in formulation and delivery aspects, especially with respect to solubility, permeability, and pharmacokinetic properties. Newer approaches in this regard include poly(ethylene glycol)-b-poly(DL-lactic acid) micelles, VOR-pluronic F127 micelles, encapsulation of iron complexes of VOR into PEGylated liposomes, human serum albumin bound VOR nanomedicine, magnetically guided layer-by-layer assembled nanocarriers, as well as convection-enhanced delivery. Even though targeting specific class or isoform of HDAC is projected as advantageous over pan-HDAC inhibitor like VOR, in terms of adverse effects and efficacy, till clinical validation, the idea is debated. As the VOR treatment-related adverse changes are mostly found reversible, further optimization of the therapeutic strategies with respect to dose, dosage regimen, and formulations of VOR could propel its clinical prospects.

Flavonoids, the emerging dietary supplement against cisplatin-induced nephrotoxicity.

The letter illustrates the emerging potential of flavonoids as dietary supplement to ameliorate cisplatin-induced nephrotoxicity and refers to the recent article on ''Anti-apoptotic and anti-inflammatory effects of naringin on cisplatin-induced renal injury in the rat'' by Chtourou et al. They demonstrated that supplementation of naringin, a flavanone glycoside, found in grape and citrus fruit species, can attenuate cisplatin-induced renal dysfunction via restoration of redox balance and suppression of inflammation, NF-κB activation and apoptosis. The chemotherapeutic efficacy of cisplatin has always compelled the researchers to find solution to ameliorate its side effects. In recent years, numerous candidates have been evaluated for their protective potential against cisplatin-induced nephrotoxicity and flavonoids have come up with promising results. The future prospects might be promising with a proper refinement and collective integration of the preclinical and clinical research in the field of flavonoid supplementation to cisplatin therapy.

Structural and photoluminescence properties of stannate based displaced pyrochlore-type red phosphors: Ca(3-x)Sn3Nb2O14:xEu³âº.

New stannate based displaced pyrochlore-type red phosphors, Ca(3-x)Sn3Nb2O14:xEu(3+), were prepared via a conventional solid state method. The influence of partial occupancy of Sn in both A and B sites of the pyrochlore-type oxides on the photoluminescence properties was studied using powder X-ray diffraction, FT-Raman, transmission electron microscopy, scanning electron microscopy with energy dispersive spectrometry, UV-visible absorption spectroscopy, and photoluminescence excitation and emission spectra with lifetime measurements. The structural analysis establishes that these oxides belong to a cubic displaced pyrochlore type structure with a space group Fd3̄m. These phosphors exhibit strong absorptions at near UV and blue wavelength regions and emit intense multiband emissions due to Eu(3+ 5)D0-(7)F(0, 1, 2) transitions. The absence of characteristic MD transition splitting points out that local cation disorder exists in this type of displaced pyrochlores, reducing the D(3d) inversion symmetry, which is not evidenced by such disorder in the X-ray diffraction analysis. The unusual forbidden intense sharp (5)D0-(7)F0 transition indicates single site occupancy of Eu(3+) with a narrower range of bonding environment, preventing the cluster formation. This is supported by the stable (5)D0 lifetime with Eu(3+) concentration. The Judd-Ofelt intensity parameter assessment corroborates these results. The CIE color coordinates of these phosphors were found to be (0.60, 0.40), which are close to the NTSC standard values (0.67, 0.33) for a potential red phosphor.

Probing structural variation and multifunctionality in niobium doped bismuth vanadate materials.

Multifunctional materials are developed in BiV1-xNbxO4 solid solutions via structural variations. A citrate gel route has been employed to synthesize these materials followed by calcination at various temperatures leading to fine particles. The effects of niobium doping over the structural variation and its influence on the optical properties are assessed by powder X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis-NIR spectroscopy. These solid solutions exhibit superior coloristic properties which are comparable to commercially available yellow pigments. These materials also show remarkable reflectance in the NIR region which makes them potential candidates for cool roof applications. A notable methylene blue dye degradation property is observed in Nb(5+) doped BiVO4 under sunlight irradiation.