Photostimulated Luminescence and Optical Storage in Eu ^(2+)-Doped Fluoride-Oxide Glass Ceramics

Photostimulated luminescence (PSL) phenomenon was observed in a fluoride-oxide glass ceramics doped with Eu 2+. When the UV light irradiated glass ceramic was stimulated by a longer wavelength light, PSL at 447 nm due to the 5d-4f transition of Eu 2+ was observed. The PSl excitation band peaking at 543 nm is due to the electron trap centers which are located either in the Eu 2+-doped crystallites or in the glass; where exactly they are located in is not yet known. The optical storage properties of this kind of glass ceramic were also studied. By comparing with the investigations on PSL phosphor Eu 2+ doped alkali halides, PSL mechanism in glass ceramics which is still an open question and has to be investigated in further experiments was explained.

Photostimulated Luminescence and F-centers of Sr_3Ca_2(PO_4)_3X:Eu^(2+)(X=F,Cl,Br)

This paper reports the F-centers and photostimulated luminescence of Eu^(2+)-activated Sr_3Ca_2(PO_4)_3X crystals.The influence of various halide ions on the F-centers and their energy level is discussed.The mechanism for the photostimulated luminescence and valence change of Eu ion in that process have been investigated.

PHOTOSTIMULATED LUMINESCENCE ON BaFCl: Eu^(2+) THIN FILM

In this paper, we have succesfully prepared the sample of BaFCl: Eu2+thin film using the vacuum thermal evaporation method and first studied photostimulated luminescence on BaFCl: Eu2+thin film.

Long persistent and photostimulated luminescence properties of Sr_2Al_2SiO_7:Eu^(2+)/Tm(3+) phosphors

A series of Sr2A12SiO7 phosphors with fixed Eu2＋ concentration and various Tm3＋ concentrations were synthesized via a high temperature solid state reaction. The structure and luminescence properties of the samples were characterized by X-ray powder diffraction （XRD）, photoluminescence （PL） spectra, decay curves, thermoluminescence （TL） glow curves as well as the photostimu- lated luminescence （PSL） spectra. Sr2A12SiO7：Eu2＋,Tm3＋ phosphors exhibited strong green phosphorescence and photostimulated lu- minescence originating from 4f65d1-4f7 transition of Eu2＋ after ultraviolet light stimulation. Deep traps were found by analyses on the phosphorescence decays and thermoluminescence spectra. It was also found that with increasing the time interval between UV excita- tion turn-off and stimulation turn-on, the photostimulated luminescence became stronger. This phenomenon resulted from the fact that the captured electron was retrapped by the deep traps. Compared with the Tm3＋-free sample, it was found that the PSL intensity was strongly enhanced in Tm3＋ eodoping samples.

V Centers and Hole-photostimulated Luminescence of BaFBr Crystal

In Ref.[1] we reported the V centers and hole-photostimulated luminescence(HPSL) of BaFCl crystal. The result shows that the V centers play an equal role asthe F centers in the X-ray storage and photostimulated luminescence (PSL) processes.Previous research work paid much attention to the F centers but neglected the Vcenters. So the X-ray storage and PSL processes have not been revealed completelyyet. Our research work is significant as a complement to the previous documents.

Colour Centres and Energy Transfer in BaF_(2-x)Cl_x∶Eu^(2+) Phosphors

The optical absorption spectra of BaF2-x Clx ：Eu^2＋ after ultraviolet （UV） light excitation were investigated. The differences between the absorption spectra after and before excitation （DAS） were observed. The DAS increase at both the high and the low energy side of F band in BaF2-xClx ： Eu^2 ＋ after 245 nm UV light excitation. The bleach effect of UV light and the absorption of electrons in the valence band may account for the former and the formation of Fa centres （association of F（Cl^-） centres）, whose absorption band matches the HeNe laser better, may explain the latter. In the write-in process, the transfer of electrons is via tunneling, In the readout process, the transfer of electrons captured in F（F^-） and Fa centres is more likely via tunneling, and that of F（Cl^- ） centres is more likely via conduction band.

Luminescence property of Eu-doped fluorochlorozirconate glass-ceramics

A series of Eu2＋-doped fluorochlorozirconate glass-ceramics were prepared by solid state reaction method. X-ray diffraction, pho- toluminescence, photo-stimulated luminescence （PSL） and the turbidity of fluorozirconate glass containing BaCl2 nano- and micro-crystals were measured for the samples annealed at 290℃ for 10 rain The PSL was attributed to the characteristic emission of Eu2＋ in nano-crystallites of BaCI2, which formed in the glass upon annealing. The PSL efficiency of the glass ceramic was increased by increasing the concentration of BaCl2, which, however, resulted in the decreasing in the transparency of the sample. The sample turned to a semi-transparent glass ceramic or even an opaque and milky white one from a near-transparent glass. The trade-off between optical transparency and PSL intensity over different concentrations of BaCl2 for X-ray imaging plate applications was briefly discussed.

Effect of TSL and PSL in Al^(3+)-Doped BaFBr∶Eu^(2+) at Difference Synthesis Conditions

Thermal stimulated luminescence (TSL) and photostimulated luminescence (PSL) were used to investigate the luminescent performance of Al 3+ doped BaFBr∶Eu 2+ in different synthetic conditions. Theory analysis shows that the decay of TSL spectra is different from that of PSL spectra. Theoretical calculation was used to investigate the effects of energy state in Al 3+ doped BaFBr∶Eu 2+ by different synthetic conditions. The relationship of color center’s energy and different synthetic conditions is discussed.

A New Promising X-Ray Storage Phosphor BaBrCl∶Eu^(2+)

Photostimulated luminescence was observed in X-ray irradiated BaBrCl doped with Eu^2 ＋ . It shows an emission band that peak at 413 nm, and two difference absorption spectra （DAS） bands that peak at - 550 nm and 675 nm respectively. The stimulation energy is lower than that of BaFX：Eu^2＋ （X = Cl, Br）, and matches the cheaper, more portable, and more convenient semiconductor laser better. The results indicate that BaBrCl ： Eu^2＋ shows positive potential as a promising X-ray storage phosphor for practical utilization.

Luminescence studies of MBrCl:Eu^(2+) (M=Ca,Sr,Ba)

Europium doped MBrCl （M=Ca, Sr, and Ba） phosphors were prepared by solid state reaction in reductive atmosphere. Photolu- minescence （PL）, photostimulated luminescence （PSL） after X-ray irradiation and optical absorption studies of MBrCI：Eu2＋ （M=Ca, Sr, and Ba） revealed that： （1） blue light emission, under the excitation of 300 nm, was observed in all these phosphors; （2） the shape of the emission spectra in CaBrCI：Eu2＋ could be changed by varying the bromine/chlorine ratio during synthesis, while that in SrBrCI：Eu2＋ and BaBrCI：Eu2＋ showed no change; and （3） PSL was observed in SrBrCI：Eu2＋ and BaBrCI：Eu2＋ after X-ray irradiation. Difference absorption spectrum （DAS） in SrBrCl：Eu2＋showed two broad bands centered at about 470 and 570 nm, and DAS in BaBrCl：Eu2＋showed two bands at about 550 and 675 nm, respectively. This enabled the use of He-Ne laser （633 nm） or even semiconductor fight-emitting diodes （LED） instead of gas lasers for photostimulation.

A Case History of Treatment of Cutaneous Leishmaniasis by Chromotherapy

Cutaneous Leishmaniasis is endemic in many parts of the world. The disease in most of the cases appears in the form of the open ulcerated lesion on exposed part of the body. The pentavalent antimonial injections (20 mg/kg for 20 days) underneath the lesion for treatment are painful and most of the times unaffordable by the patients, mostly effected by this disease. As a result, most patients give-up early resulting in resistance. Due to high prevalence and the disease taking an epidemic form, there is a need to develop a new simple, cheap and yet an effective alternative treatment for cutaneous Leishmaniasis. Reported here is a case study aimed at alternative treatment regimen for cutaneous leishmaniasis. Here we present a case history of cutaneous leishmaniasis treated with chromotherapy. This seems to be an effective and new method of treatment only using visible range radiations of different wavelengths with no apparent side-effects. Six months follow up was observed and no recurrence was found.

Study of Photostimulable Luminescence Materials Sr_9Ca(PO_4)_6Cl_2:Eu

The polycrystalline Sr_9Ca(PO_4)_6Cl_2:Eu has been synthesized by solid state reaction.The reaction condition,the appropriate raw materials and their quantity used,which may affect the photostimulable luminescence (PSL),have been systematically inves- tigated.The properties of this PSL phosphor as a material for storing and reproducing the X-ray image in computer-aided radiography have been reported briefly.

Analysis of photostimulable phosphor image plate artifacts and their prevalence

BACKGROUND Digital radiography has recently been used in dentistry as a substitute for conventional film radiography worldwide.Digital imaging has many advantages and provides new possibilities for recording and interpreting radiographic data.This system uses different types of digital receptors.AIM To detect the frequency,type,and reasons behind the appearance of intraoral image artifacts acquired by photostimulable phosphor plates(PSP).METHODS This retrospective descriptive study was conducted in the oral and maxillofacial radiology unit of the dental clinics of the College of Dentistry,Princess Nourah University(PNU).All intraoral digital radiographs were acquired using(Gendex Expert DC.,United States)an intraoral X-ray machine with 7-mA,65-kVP using a PSP system(Soredex DIGORA Optime imaging plate)and laser scanners(Soredex DIGORA Optime),which can house all sizes of reusable intraoral PSP sensor plates with image acquisition software(MIPACS Dental Enterprise viewer 3.2.2).A total of 50000 intraoral radiographs were retrieved from the clinical database from April 2018 to April 2020 to evaluate the reason,type,and solutions to these image artifacts.RESULTS Overall,50000 intraoral digital radiographs were acquired in a two-year-period;that is,from April 2018 to April 2020.Of these,3550(7.1%)retakes were performed due to the presence of image artifacts.Periapical radiographs were the most common image type of intraoral retakes(80.8%).Imaging artifacts were divided into three categories:operator,plate and scanning errors.Out of 3550 retakes,5%,1.37%,and 0.73%were related to operator,plate,and scanning errors,respectively.The cone cut was the most common operator error(988 images),Bite marks were the most common plate error(276 images),and delayed scanning artifacts were the most common scanning errors(145 images).The calculated kappa value for interobserver reliability was 0.99,indicating almost perfect interobserver agreement.CONCLUSION Our study discussed intraoral image artifacts that were characteristic of PSP,where the most common artifacts were bitemarks,image size reduction,scratches,and delayed scanning.

Robot Animals Based on Brain-Computer Interface

The study of robot animals based on brain-computer interface （BCI） technology is an important field in robots and neuroscience at present. In this paper, the development status at home and abroad of the motion control of robot based on BCI and principle of robot animals are introduced, then a new animals＇ behavior control method by photostimulation is presented. At last, the application prospect is provided.

New color centers and luminescence of BaFI: Eu^(2+)

MANY publications have appeared on the photostimulated luminescence (PSL) of alkalineearth mixhalides. Color centers play a very important role in the PSL and X-ray storage imag-ing processes. The F centers, V centers and oxygen-related centers in this kind ofcrystals have been investigated. All these reports provide some useful information to the PSLmechanism and thus improve the practical applications of these materials. New color centers

New function of the Yb^(3+) ion as an efficient emitter of persistent luminescence in the short-wave infrared

The trivalent ytterbium(Yb^(3+))ion has been extensively used as an emitter in short-wave infrared(SWIR)lasers,a sensitizer to activate other lanthanide ions for up-conversion luminescence,and a spectral converter in Ln^(3+)-Yb^(3+)doubly doped quantum cutting phosphors.Here we report a new function of the Yb^(3+)ion—as an efficient emitting center for SWIR persistent luminescence.We have developed the first real SWIR persistent phosphor,MgGeO3:Yb^(3+),which exhibits very-long persistent luminescence at around 1000 nm for longer than 100 h.The MgGeO3:Yb^(3+)phosphor is spectrally transparent to visible/near-infrared light(~400–900 nm)and is a promising ultraviolet-to-SWIR spectral convertor.The MgGeO3:Yb^(3+)phosphor also exhibits a photostimulated persistent luminescence capability,where the SWIR persistent emission in an ultraviolet-light pre-irradiated sample can be rejuvenated by low-energy light(white or red light)stimulation.The MgGeO3:Yb^(3+)phosphor is expected to have promising applications in biomedical imaging,night-vision surveillance and photovoltaics.

A neuropsin-based optogenetic tool for precise control of Gq signaling

G_(q)-coupled receptors regulate numerous physiological processes by activating enzymes and inducing intracellular Ca^(2+)signals.There is a strong need for an optogenetic tool that enables powerful experimental control over G_(q) signaling.Here,we present chicken opsin 5(cOpn5)as the long sought-after,single-component optogenetic tool that mediates ultra-sensitive optical control of intracellular G_(q) signaling with high temporal and spatial resolution.Expressing cOpn5 in HEK 293T cells and primary mouse astrocytes enables blue light-triggered,G_(q)-dependent Ca^(2+) release from intracellular stores and protein kinase C activation.Strong Ca^(2+) transients were evoked by brief light pulses of merely 10 ms duration and at 3 orders lower light intensity of that for common optogenetic tools.Photostimulation of cOpn5-expressing cells at the subcellular and single-cell levels generated fast intracellular Ca^(2+)transition,thus demonstrating the high spatial precision of cOpn5 optogenetics.The cOpn5-mediated optogenetics could also be applied to activate neurons and control animal behavior in a circuit-dependent manner.cOpn5 optogenetics may find broad applications in studying the mechanisms and functional relevance of G_(q) signaling in both non-excitable cells and excitable cells in all major organ systems.