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Developing novel luminescent materials with ideal properties is an endless project, urged by growing requirements of advances in energy saving, healthy lighting and environmental friendliness. Herein, a series of ScCaOBO3:Ce3+,Mn2+ phosphors with excellent luminescence properties were synthesized by the high temperature solid state method. X-ray diffraction was applied to analyse the phase composition of the obtained phosphors. The morphology and dopant distribution were observed by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS), respectively. The Rietveld refinements and luminescence spectra indicate that Ce3+ preferentially occupies the Sc3+ site and produces a blue emission band at around 460 nm, which originates from the characteristic 5d–4f transitions, while Mn2+ preferentially occupies the Ca2+ site and emits red light due to its characteristic 4T1(4G)–6A1(6S) transitions. Upon excitation at 354 nm, both Ce3+ and Mn2+ emissions can be obtained and further investigations evidenced that the broad and intense light emission of Mn2+ located in the red spectral region is the result of energy transfer from Ce3+ to Mn2+. Theoretical calculations reveal that the energy transfer process from Ce3+ to Mn2+ is of the resonance type and is governed by electric dipole–dipole interactions. Since the ScCaOBO3:Ce3+,Mn2+ phosphors are capable of producing broadband emissions that widely cover the blue and red spectral regions, the introduction of a green light-emitting phosphor CMA:Tb3+ can conveniently generate high quality white light. Therefore, a white light-emitting diode device with extremely high color rendering indices, Ra = 93.7 and R9 = 91.9, was successfully obtained. [ABSTRACT FROM AUTHOR]

The radius of trivalent scandium ions is much smaller than those of other rare earth ions and thus research studies targeting the substitution of the scandium site with other light-emitting rare earth ions are rarely reported. In our present work, special attention is paid to the effect of Dy3+ doping on the crystal structure, atomic site occupancy and luminescence properties of the ScCaBO4 host as Dy3+ often serves as an individual activator for single-phase white light-emitting phosphors. Herein a series of ScCaBO4:Dy3+ phosphors were prepared by solid-state reactions. The phase composition was recorded by X-ray diffraction analysis and XRD refinement reveals that a pure phase could be maintained even when the Dy3+ concentration reaches 11%. Scanning electron microscopy (SEM) was utilized to observe the morphology and EDS mapping was used to investigate elemental distribution. The luminescence performances of the phosphors were investigated using UV-vis diffuse reflectance spectra, steady-state excitation and emission spectra and also transient luminescence decays. Dy3+ luminescence can be ascribed to its 4F9/2 → 6H15/2, 6H13/2 and 6H11/2 transitions, producing blue, yellow and red emissions. The Dy3+ concentration was further optimized at 3%, at which the CIE coordinates and fluorescence lifetimes were (0.425, 0.413) and 0.546 ms, respectively. Thermal quenching studies of the ScCaBO4:0.03Dy3+ phosphor show that Dy3+ luminescence at 400 K can maintain 60.91% of its initial value measured at room temperature. All the results indicate that the ScCaBO4:Dy3+ inorganic phosphors could be a promising single component phosphor for near-UV chip based WLEDs. [ABSTRACT FROM AUTHOR]

A high color rendering index white light emitting diode (WLED) is generally produced by combining yellow and red mixed phosphors on a blue chip. Herein we report a single component phosphor based on CaY2Al4SiO12 (CYAS) to achieve warm white light emission with a high color rendering index (Ra), which can be up to 90.5. Ce3+, Mn2+ singly doped and co-doped CYAS phosphors have been synthesized by solid state reactions, respectively, for comparative investigations. The Rietveld X-ray diffraction (XRD) refinements show that the CYAS host crystallizes in a cubic structure with the Ia3¯d space group. The valence states of Ce and Mn inside the CYAS host have been confirmed by XPS and EPR. Ce3+ occupies the Ca2+/Y3+ site and generates a yellow emission band around 543 nm from its characteristic 5d–4f transition. Mn2+ occupies both the dodecahedron Ca2+/Y3+ and octahedral Al3+ sites, emitting red and deep red lights at 616 nm and 750 nm, respectively. These two emission bands are attributed to the 4T1(4G)–6A1(6S) transitions of Mn2+. Upon 460 nm light excitation, both the Ce3+ and Mn2+ characteristic emissions can be obtained, in which the emissions of Mn2+ result from the occurrence of energy transfer from Ce3+ in CYAS. All the results indicate that the prepared CYAS:Ce3+,Mn2+ could be a promising single component phosphor for blue chip WLEDs. [ABSTRACT FROM AUTHOR]

The upper gastrointestinal (GI) tumors are multifactorial diseases associated with a combination of oncogenes and environmental factors. Currently, surgery, chemotherapy, radiotherapy and immunotherapy are relatively effective treatment options for the patients with these tumors. However, the asymptomatic phenotype of these tumors during the early stages poses as a significant limiting factor to diagnosis and often renders treatments ineffective. Therefore, new early diagnosis and effective therapy for upper GI tumors are urgently needed. Ca2+ is a pivotal intracellular second messenger and plays a crucial role in living cells by regulating several processes from cell division to death. The aberrant Ca2+ homeostasis is related to many human pathological conditions and diseases, including cancer, and thus the changes in the expression and function of plasma membrane Ca2+ permeable channels and sodium/calcium exchangers are frequently described in tumorigenesis and tumor development of the upper GI tract, including voltage-gated Ca2+ channels (VGCC), transient receptor potential (TRP) channels, store-operated channels (SOC) and Na+/Ca2+ exchanger (NCX). This review will summarize the current knowledge about plasma membrane Ca2+ permeable channels and sodium/calcium exchangers in the upper GI tumors and provide a synopsis of recent advancements on the role and involvement of these channels in upper GI tumors as well as a discussion of the possible strategies to target these channels and exchangers for diagnosis and therapy of the upper GI tumors. [ABSTRACT FROM AUTHOR]

Developing novel luminescent materials with ideal properties is an endless project, urged by growing requirements of advances in energy saving, healthy lighting and environmental friendliness. Herein, a series of ScCaOBO 3 :Ce 3+ ,Mn 2+ phosphors with excellent luminescence properties were synthesized by the high temperature solid state method. X-ray diffraction was applied to analyse the phase composition of the obtained phosphors. The morphology and dopant distribution were observed by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS), respectively. The Rietveld refinements and luminescence spectra indicate that Ce 3+ preferentially occupies the Sc 3+ site and produces a blue emission band at around 460 nm, which originates from the characteristic 5d-4f transitions, while Mn 2+ preferentially occupies the Ca 2+ site and emits red light due to its characteristic 4 T 1 ( 4 G)- 6 A 1 ( 6 S) transitions. Upon excitation at 354 nm, both Ce 3+ and Mn 2+ emissions can be obtained and further investigations evidenced that the broad and intense light emission of Mn 2+ located in the red spectral region is the result of energy transfer from Ce 3+ to Mn 2+ . Theoretical calculations reveal that the energy transfer process from Ce 3+ to Mn 2+ is of the resonance type and is governed by electric dipole-dipole interactions. Since the ScCaOBO 3 :Ce 3+ ,Mn 2+ phosphors are capable of producing broadband emissions that widely cover the blue and red spectral regions, the introduction of a green light-emitting phosphor CMA:Tb 3+ can conveniently generate high quality white light. Therefore, a white light-emitting diode device with extremely high color rendering indices, R a = 93.7 and R 9 = 91.9, was successfully obtained.

Intracellular calcium (Ca 2+ ) is a critical cell signaling component in gastrointestinal (GI) physiology. Cytosolic calcium ([Ca 2+ ] cyt ), as a secondary messenger, controls GI epithelial fluid and ion transport, mucus and neuropeptide secretion, as well as synaptic transmission and motility. The key roles of Ca 2+ signaling in other types of secretory cell (including those in the airways and salivary glands) are well known. However, its action in GI epithelial secretion and the underlying molecular mechanisms have remained to be fully elucidated. The present review focused on the role of [Ca 2+ ] cyt in GI epithelial anion secretion. Ca 2+ signaling regulates the activities of ion channels and transporters involved in GI epithelial ion and fluid transport, including Cl - channels, Ca 2+ -activated K + channels, cystic fibrosis (CF) transmembrane conductance regulator and anion/HCO 3 - exchangers. Previous studies by the current researchers have focused on this field over several years, providing solid evidence that Ca 2+ signaling has an important role in the regulation of GI epithelial anion secretion and uncovering underlying molecular mechanisms. The present review is largely based on previous studies by the current researchers and provides an overview of the currently known molecular mechanisms of GI epithelial anion secretion with an emphasis on Ca 2+ -mediated ion secretion and its dysregulation in GI disorders. In addition, previous studies by the current researchers demonstrated that different regulatory mechanisms are in place for GI epithelial HCO 3 - and Cl - secretion. An increased understanding of the roles of Ca 2+ signaling and its targets in GI anion secretion may lead to the development of novel strategies to inhibit GI diseases, including the enhancement of fluid secretion in CF and protection of the GI mucosa in ulcer diseases., (Copyright: © Shan et al.)