Multisite Cation Regulation of Broadband Cyan-Emitting (Ba1-xSrx)9Lu2Si6O24/Eu2+ Phosphors for Full-Spectrum wLEDs.

Developing broadband cyan-emitting phosphors is an essential issue to achieve high-quality full-spectrum phosphor-converted white light-emitting diodes. Multisite cation regulation to modify the photoluminescence spectrum is a valid way to achieve broadband emission for phosphors. The Ba9Lu2Si6O24 lattice with various cation sites for activator ions is a preferred host for broadband emitting phosphors. The preferential crystallographic sites of Eu2+ in the Ba9Lu2Si6O24 lattice are identified based on the crystal field theory, crystal structure, and bond indices (such as NAC and SBOs) of the cations. Sr substitution in Ba9Lu2Si6O24/Eu2+ phosphor affects the location of Eu2+ activator ions, which is investigated via the first-principles density functional theory calculations, Rietveld refinement, and luminescence decay curves, and results in the modification of luminescence properties and thermal stability. The Sr-substituted (Ba0.8Sr0.2)9Lu2Si6O24/Eu2+ sample exhibits a broadband emission spectrum peaked at 471 and 518 nm with a large full width half maximum of 139 nm, covering blue-cyan-green regions, which can be an excellent candidate as broadband cyan-emitting phosphors for high-quality full-spectrum wLEDs.

Influence of Mixed Valence on the Formation of Oxygen Vacancy in Cerium Oxides.

Ceria is one of the most important functional rare-earth oxides with wide industrial applications. Its amazing oxygen storage/release capacity is attributed to cerium's flexible valence conversion between 4+ and 3+. However, there still exists some debate on whether the valence conversion is due to the Ce-4f electron localization-delocalization transition or the character of Ce-O covalent bonds. In this work, a mixed valence model was established and the formation energies of oxygen vacancies and electronic charges were obtained by density functional theory calculations. Our results show that the formation energy of oxygen vacancy is affected by the valence state of its neighboring Ce atom and two oxygen vacancies around a Ce4+ in CeO2 have a similar effect to a Ce3+. The electronic charge difference between Ce3+ and Ce4+ is only about 0.4e. Therefore, we argue that the valence conversion should be understood according to the adjustment of the ratio of covalent bond to ionic bond. We propose that the formation energy of oxygen vacancy be used as a descriptor to determine the valence state of Ce in cerium oxides.

Cerebral syphilitic gumma masquerading as cerebral metastatic tumors: case report.

A 45-year-old man was admitted with severe headache and left-sided weakness, which worsened over 1 week. Brain imaging revealed a small lesion close to the sagittal sinus in the right frontal lobe with severe perilesional edema and showed enhancement on both CT and MRI obtained with contrast. Serological findings were positive for toluidine red unheated serum test (TRUST) positivity and Treponema pallidum particle agglutination assay. The patient was first suspected of having a malignant brain tumor and subsequently received emergency craniotomy. Brain biopsy suggested a diagnosis of syphilitic cerebral gumma; meanwhile the postoperative CSF TRUST titer was positive, and the patient's improvement with high-dose intravenous aqueous crystalline penicillin further supported this etiology. Finally, the lesion on the right frontal lobe had disappeared during the follow-up imaging examination and the myodynamia of the left limbs gradually improved. The authors recommend that diagnostic penicillin treatment should be first implemented. When a patient's history, clinical manifestations, syphilis serology, CSF examination, and other physiological changes indicate a diagnosis of syphilitic cerebral gumma, there is no doubt that surgery should be performed in patients with acute intracranial hypertension, but unnecessary craniotomy should be avoided as far as possible.

Clinical device-related article evaluation of morphology and functions of a foldable capsular vitreous body in the rabbit eye.

We previously proposed a new strategy to replace a vitreous body with a novel foldable capsular vitreous body (FCVB). In this study, the FCVB was designed to mimic natural vitreous morphology, and evaluate its physiological functions compared with traditional silicone oil substitutes, in an established rabbit model of proliferative vitreoretinopathy. We found that FCVB was a very good replacement for closely mimicking the morphology and restoring the physiological functions, such as the support, refraction, and cellular barriers, of the rabbit vitreous body. The study has provided us with a novel research and therapy strategy that could effectively mimic the morphology and physiological function of the rabbit vitreous body.