Comparative spectroscopic study of Tb:Ce(Sal)3Phen complex inhibited PVA nanofibres for flexible moisture sensor.

In the present work, we report a systematic study on optical alteration in Tb:Ce(Sal)3Phen, Tb(Sal)3Phen complexes, and TbCl3·6H2O inhibited in polyvinyl alcohol (PVA) polymeric nanofibres. We also report the feasibility of Tb:Ce(Sal)3Phen complex dispersed electrospun nanofibres for opto-humidity sensor. Structural, morphological, and spectroscopic properties of the synthesized nanofibres were systematically compared using Fourier transform infrared spectroscopy, scanning electron microscopy, and Photoluminescence analysis. Synthesized Tb(Sal)3Phen complex inhibited in nanofibres yields characteristic bright green photoluminescence of Tb3+ under UV excitations, which is at least two manifolds enhanced on the addition of Ce3+ ions in the same complex. The presence of Ce3+ ions, the salicylate ligand, and the Tb3+ ion help to expand the absorption range (290 nm-400 nm) and, subsequently, the photoluminescence in blue and green regions. Our analysis revealed the linear enhancement of photoluminescence intensity with the addition of Ce3+ ions. Upon exposing the flexible Tb:Ce(Sal)3Phen complex dispersed nanofibres mat in different humidity environments, photoluminescence intensity shows a linear variation. The prepared nanofibres film shows good reversibility, small hysteresis, cyclic stability, and acceptable response and recovery times i.e. 35 and 45 s. The humidity sensing mechanism was proposed on the basis of infrared absorption analysis of dry and humid nanofibres.

Dual interactions and thermo-optical analysis of YAGG:Ce/Eu nanophosphor.

Present article report on structural and optical investigations of doubly doped Y3(Al5-xGax)O12:Ce/Eu nanophosphor. Efforts have been made to explore the interaction between the Ce3+ and Eu3+ ions and subsequently variation in overall color perception. Experimental techniques namely XRD, HR-TEM, and SEM reveal precipitation of tiny particles with diameter ~22 nm. Structural refinement has been carried out by Rietveld refinement. Photo-excitation by 342, 405, 450, and 464 nm wavelengths triggers the emission from Eu3+ and Ce3+ ions. Further, the laser excitations by 405 nm and 450 nm radiations, induced YAGG:Ce/Eu nanophosphor to yield combinatorial emission of both Ce3+ and Eu3+ ions; though, the intensity was found to be altered due to the two-way ionic interaction between the doped ions. The resultant emission extended in the red region. Also, the doubly doped sample exhibits strong temperature reliance on the emission intensity in the temperature range extended over 273-388 K. The color perception of the nanophosphor was observed to be significantly modified at different excitation wavelengths, temperatures, and laser powers as reflected by CIE coordinates.

White light color tuning ability of hybrid Dibenzoylmethane/YAG:Ce nanophosphor.

In this study, we have considered the synthesis of a novel hybrid material consisting of cerium-doped yttrium aluminium garnet (YAG:Ce) nanophosphor surface decorated by UV/blue sensitizing Dibenzoylmethane (DBM) organic molecule. A comparative evaluation of synthesized hybrid material YAG:Ce/DBM nanophosphor and YAG:Ce nanophosphors was made using a combination of different analytical techniques like X-ray diffraction, Scanning electron microscopy, UV-Visible-Infrared absorption, Photoluminescence techniques etc. Due to the presence of organic ligand, the hybrid nanophosphor has extended excitation. We have monitored the emission spectra at excitation with 355 nm, 375 nm, 405 nm, and 465 nm. The synthesized luminescent hybrid material was characterized by various spectroscopic techniques and its photophysical properties were thoroughly investigated. The color perception of hybrid YAG:Ce/DBM nanophosphor is significantly modified due to the mixing of blue color in the green-yellow emission of YAG:Ce nanophosphor at different excitations which yield CIE coordinates (0.37, 0.59).

Animal models to improve our understanding and treatment of suicidal behavior.

Worldwide, suicide is a leading cause of death. Although a sizable proportion of deaths by suicide may be preventable, it is well documented that despite major governmental and international investments in research, education and clinical practice suicide rates have not diminished and are even increasing among several at-risk populations. Although nonhuman animals do not engage in suicidal behavior amenable to translational studies, we argue that animal model systems are necessary to investigate candidate endophenotypes of suicidal behavior and the neurobiology underlying these endophenotypes. Animal models are similarly a critical resource to help delineate treatment targets and pharmacological means to improve our ability to manage the risk of suicide. In particular, certain pathophysiological pathways to suicidal behavior, including stress and hypothalamic-pituitary-adrenal axis dysfunction, neurotransmitter system abnormalities, endocrine and neuroimmune changes, aggression, impulsivity and decision-making deficits, as well as the role of critical interactions between genetic and epigenetic factors, development and environmental risk factors can be modeled in laboratory animals. We broadly describe human biological findings, as well as protective effects of medications such as lithium, clozapine, and ketamine associated with modifying risk of engaging in suicidal behavior that are readily translatable to animal models. Endophenotypes of suicidal behavior, studied in animal models, are further useful for moving observed associations with harmful environmental factors (for example, childhood adversity, mechanical trauma aeroallergens, pathogens, inflammation triggers) from association to causation, and developing preventative strategies. Further study in animals will contribute to a more informed, comprehensive, accelerated and ultimately impactful suicide research portfolio.

Vibrational and spectroscopic analysis of white light emitting Bi2SiO5 nanophosphor.

A series of Dy3+ ion activated Bi2SiO5 nanophosphors were synthesized by the hydrothermal and coprecipitation methods. Various structural and optical characterizations were made using X-ray diffraction, Scanning and Transmission electron microscopy, UV-Visible-Infrared absorption, Raman Spectroscopy, Photoluminescence, Time resolved luminescence techniques etc. Dy3+ ion doped samples yields characteristic bright yellow and blue emissions, on resonant excitation with 349nm and 386nm. The intensity ratio of the yellow/blue peaks was found to be function of Dy ion concentration and synthesis method. We have achieved white colour emission at 1.5mol% Dy concentration, CIE coordinate (0.36, 0.4) of which fall well within gamut of white light. The time-resolved fluorescence reveals decrease in radiative lifetime values with increasing Dy3+ ions concentration. A comparison between the samples synthesized by different methods, and Dy ion concentrations has been made and detail photo-physics involved is presented in the article.

Dissecting bipolar disorder complexity through epigenomic approach.

In recent years, numerous studies of gene regulation mechanisms have emerged in neuroscience. Epigenetic modifications, described as heritable but reversible changes, include DNA methylation, DNA hydroxymethylation, histone modifications and noncoding RNAs. The pathogenesis of psychiatric disorders, such as bipolar disorder, may be ascribed to a complex gene-environment interaction (G × E) model, linking the genome, environmental factors and epigenetic marks. Both the high complexity and the high heritability of bipolar disorder make it a compelling candidate for neurobiological analyses beyond DNA sequencing. Questions that are being raised in this review are the precise phenotype of the disorder in question, and also the trait versus state debate and how these concepts are being implemented in a variety of study designs.

Chronic corticosterone-mediated dysregulation of microRNA network in prefrontal cortex of rats: relevance to depression pathophysiology.

Stress plays a major role in inducing depression, which may arise from interplay between complex cascades of molecular and cellular events that influence gene expression leading to altered connectivity and neural plasticity. In recent years, microRNAs (miRNAs) have carved their own niche owing to their innate ability to induce disease phenotype by regulating expression of a large number of genes in a cohesive and coordinated manner. In this study, we examined whether miRNAs and associated gene networks have a role in chronic corticosterone (CORT; 50 mg kg(-1) × 21 days)-mediated depression in rats. Rats given chronic CORT showed key behavioral features that resembled depression phenotype. Expression analysis revealed differential regulation of 26 miRNAs (19 upregulated, 7 downregulated) in prefrontal cortex of CORT-treated rats. Interaction between altered miRNAs and target genes showed dense interconnected molecular network, in which multiple genes were predicated to be targeted by the same miRNA. A majority of altered miRNAs showed binding sites for glucocorticoid receptor element, suggesting that there may be a common regulatory mechanism of miRNA regulation by CORT. Functional clustering of predicated target genes yielded disorders such as developmental, inflammatory and psychological that could be relevant to depression. Prediction analysis of the two most prominently affected miRNAs miR-124 and miR-218 resulted into target genes that have been shown to be associated with depression and stress-related disorders. Altogether, our study suggests miRNA-mediated novel mechanism by which chronic CORT may be involved in depression pathophysiology.

Structural and optical properties of Eu3+, Sm3+ co-doped La(OH)3 nano-crystalline red emitting phosphor.

We report Eu3+, Sm3+ co-doped La(OH)3 nano-crystalline red emitting phosphor prepared following combustion synthesis protocol. The structural and morphological information about the synthesized samples have been explored using X-ray diffraction (XRD) and transmission electron microscopic (TEM) techniques. The optical properties of the samples have been investigated under 355 nm laser excitations. The sample emits intense red emissions at 625 and 707 nm due to 5D0→7F2 and 5D0→7F4 transitions in Eu3+ ion, respectively. The concentrations of both, Eu3+ and Sm3+ in the samples were optimized at 1 mol% to get maximum fluorescence. The presence of Sm3+ in the Eu3+ doped sample enhances the emission intensity up to two times. The samples annealed at higher temperature show significant enhancement in the emission intensity. The life time studies show an efficient energy transfer from Sm3+ to Eu3+ ions and have been discussed with the help of schematic energy level diagram. This enhancement in the emission intensity is discussed in terms of the rare earth ion concentration, annealing temperature and energy transfer.

Advances in rare earth spectroscopy and applications.

Rare earth (RE) elements are prime constituents in a large amount of innovative materials and several technological advances would not be possible without their contribution. In this review, recent progress in the field of rare earth spectroscopy is highlighted, with a special emphasis on clean energy, sensors and telecommunications, providing a broad view on past and recent developments.

Enhanced luminescence and energy transfer study in Tb:Sm codoped lead fluorotellurite glass.

Spectroscopic properties of Sm(3+), Tb(3+) doped and Tb(3+):Sm(3+) co-doped lead fluorotellurite glasses have been studied in detail. On the excitation with 355 and 532 nm laser wavelengths, the luminescence properties of the singly and doubly doped glasses have been analyzed. Intensity of characteristic emission bands due to Sm(3+) ions is appreciably enhanced in the presence of Tb(3+) ions. This is due to the energy transfer from Tb(3+) to Sm(3+) ions. Different energy transfer parameters have also been calculated, which affirm an efficient energy transfer from Tb(3+) to Sm(3+) ions.

Optical properties of cerium doped oxyfluoroborate glass.

Cerium doped oxyfluoroborate glasses have been prepared and its spectroscopic properties have been discussed. It is found that the absorption edge shifts towards the lower energy side for the higher concentration of cerium dopant. Optical band gap for these glasses have been calculated and it is found that the number of non-bridging oxygen increases with cerium content. The emission spectra of these glasses have been recorded using UV laser radiations (266 and 355 nm) and it is observed that these glasses show bright blue emission. On the basis of excitation and emission spectra we have reported the existence of at least two different emission centers of Ce(3+)ions.

Infrared cascade and cooperative multicolor upconversion emissions in Y8V2O17:Eu:Yb nanophosphors.

This work reports on the efficient cooperative upconversion and infrared cascade downconversion emissions in a novel Y8V2O17:Eu:Yb nanophosphor. The excitation with UV light produces emission in the 950-1000 nm region, corresponding to the Yb³âº:²F5/2-->²F7/2 transition, as well as visible emissions of the Eu³âº ion. Time-resolved spectroscopy measurements revealed that the mechanism responsible for this transition is the efficient cascade nonresonant energy transfer from VO4³-->Eu-->Yb. When the same nanophosphor is excited with 976 nm radiation, bright reddish upconversion emission of the Eu³âº:5DJ-->7FJ transition is observed as consequence of the Yb + Yb-->Eu cooperative energy transfer mechanism, which was established by analyzing the emission power dependence and the time-resolved spectroscopy of radiative transitions.

Experimental and theoretical investigation of optical nonlinearities in (nitrovinyl)-1H-pyrazole derivative.

This work reports on the optical nonlinearities of a newly synthesized pyrazole derivative, namely (E)-1-(4-chlorophenyl)-4-(2-nitrovinyl)-1H-pyrazole. The Z-scan technique with femtosecond laser pulses was used to determine the two-photon absorption (2PA) cross-section spectrum, which presents a maximum of 67 GM at 690 nm. We have combined hyper-Rayleigh scattering (HRS) experiments and second-order Møller-Plesset perturbation theory (MP2) calculations to study the first hyperpolarizability (ß(HRS)). It was found that the MP2/6-311+G(d) model, taking into account solvent and dispersion effects, provides the ß(HRS) value of 40×10(-30) cm(5)/esu for the compound, in good agreement with the experimental result of 45±2×10(-30) cm(5)/esu.

Structural and optical characterization of nanosized La(OH)3:Sm3+ phosphor.

In the present work, Sm(3+) doped La(OH)(3) nano-phosphor (~40 nm) has been synthesized using combustion synthesis method and detailed structural and spectroscopic characterizations are carried out. On excitation with 532 nm, several photoluminescence peaks extending over green to NIR regions have been observed and assigned to be due to 4f-4f transitions of Sm(3+) ions. A bright orange-red perception is observed in annealed sample, which is 10 times higher than as synthesized sample. Time resolved emission spectroscopy reveals pronounced effect of heating, which induce good crystalline in the host.

Green and NIR sensitized luminescent nanophosphor: preparation, characterization and application.

Luminescent nanophosphor of Er, Yb: Gd(2)O(3) has been synthesized by well known combustion synthesis. Along with strong UV-Vis upconversion emission, sensor for temperature and magnetic field, nano-heater etc., it can also be used as luminescent ink by dispersing the nanophosphor in aqueous polyvinyl alcohol solution. The stability of the ink has been found to depend strongly on the mixing process of the phosphor powder in the polymer solution. The X-ray diffraction results and TEM images with diffraction pattern show that the particles are in cubic phase of Gd(2)O(3) with particles of average size <40 nm. SEM images show flaky structure which makes it suitable for dispersing in PVA and useful for luminescent ink purposes on NIR excitation. The FT-IR and the thermal analysis support the presence of PVA. Upconversion and downconversion luminescence has also been observed with 532 nm excitation and energy transfer mechanism has been explained. The NIR pumping gives strong UC emission bands in red and green regions extending up to extreme UV (240 nm) in this host.

Structural and spectroscopic diagnosis of Eu:ZnO and Eu:Yb:ZnO glass and ceramics.

Eu and Eu:Yb codoped ZnO nanocrystals embedded in B(2)O(3) glass matrix were synthesized and their structural, optical properties were discussed. On excitation with 532 nm laser radiation intense orange/red emissions from Eu(3+) ions were observed. The fluorescence intensity was found to enhance on annealing. Frequency upconversion emissions from Eu(3+) ions were observed in presence of Yb(3+) ions on excitation with NIR (976 nm) laser. The enhancement in emission intensity was explained and the photo-physics involved is linked with the unique structural properties of the crystallites formed. Ion interactions and the different energy transfer parameters were also calculated.

Yb3+ sensitized Tm3+ upconversion in tellurite lead oxide glass.

Triply ionized thulium/thulium--ytterbium doped/codoped TeO2-Pb3O4 (TPO) glasses have been fabricated by classical quenching method. The upconversion emission spectra in the Tm3+/Tm3+-Yb3+ doped/codoped glasses upon excitation with a diode laser lasing at ∼980 nm has been studied. Effect of the addition of the Yb3+ on the upconversion emission intensity in the visible and near infrared regions of the Tm3+ doped in TPO glass has been studied and the processes involved explored.

Synthesis, physicochemical and optical characterization of novel fluorescing complex: o-phenylenediamine-benzoin.

The complex of o-phenylenediamine (o-PDA) and benzoin (BN) was synthesized adopting solid state reaction by mixing of their melt together followed by chilling. The phase diagram study shows the formation of a complex in 1:1 molar ratio with congruent melting point and two eutectics lying on either side of complex. The formation of complex was confirmed using the FTIR, NMR, mass spectroscopy, powder XRD and DSC studies. The optical properties of the parent component, their complex and few other compositions nearby the complex were studied using absorption and laser luminescence techniques. The significantly higher green/yellow emission was noted with newly synthesized complex as compared to that of their parents as well as other compositions of o- PDA and BN.

Gd3+ sensitized enhanced green luminescence in Gd:Tb(Sal)3Phen complex in PVA.

Ternary and tertiary complexes of Tb(Sal)(3)Phen and Gd:Tb(Sal)(3)Phen were synthesized and characterized in PVA polymer. The structural properties of these systems were evaluated on the basis of NMR and FT-IR techniques. The absorption, excitation and emissive properties of the Tb(3+) ion were improved when coordinated with Sal and Phen ligands. Photoluminescence properties of the complexes in solution, crystals and dispersed in PVA film were explored in steady state and in time domain. Selective excitations (487, 355, 310 and 266 nm) of Tb(3+), Sal and Gd(3+) ions reveal an intramolecular energy transfer process. The emission of Gd:Tb(Sal)(3)Phen complex in PVA indicates the contribution of Gd(3+) ion to enhance the emission intensity of Tb(3+) ion. On the basis of these investigations, photophysics was widely discussed in terms of energy transfer and encapsulation effect.

Spectroscopic study of Er:Sm doped barium fluorotellurite glass.

In this paper, we report the physical and spectroscopic properties of Er(3+), Sm(3+) and Er(3+):Sm(3+) ions codoped barium fluorotellurite (BFT) glasses. Different Stokes and anti-Stokes emissions were observed under 532 nm and 976 nm laser excitations. Energy transfer from Er(3+) ion to Sm(3+) ion was confirmed on the basis of luminescence intensity variation and decay curve analysis in both the cases. Under green (532 nm) excitation emission intensity of Sm(3+) ion bands improves whereas on NIR (976 nm) excitation new emission bands of Sm(3+) ions were observed in Er:Sm codoped samples. Ion interactions and the different energy transfer parameters were also calculated.