The luminescence properties of yttria based phosphors and study of YBO3 formation via H3BO3 addition

In this paper, Y2O3:Eu3+ nano-phosphor was synthesized through the facile solid-state method and influence of H3BO3 addition to the prepared Y2O3:Eu3+ powder was investigated. The consumption of boric acid resulted in the formation of YBO3 by changing the crystal structure from cubic to hexagonal. Noteworthy, through the use of specific quantities of H3BO3 (medium amount), Y3BO6 impurity with the monoclinic crystal structure and the space group C2/m was formed. FESEM observations showed that the addition of H3BO3 leads to the coarsening of the synthesized particles; changing from approximately 80 nm to 1 µm. Also, it was concluded that the transformation of the crystal structure causes a dramatic change of phosphor emission colours from reddish to orange

تأثير كفي با گوه خارجي پاشنه بر استئوآرتريت كمپارتمنت

مقدمه :استئوآرتريت زانو يكي از علل شايع زانو درد در سالمندان بوده كه باعث درد و اشكال راه رفتن در آن‌ها مي‌شود و شيوع آن در زنان بيشتر از مردان می‌باشد. شيوع اين عارضه در كمپارتمنت داخلي بيشتر است و اغلب منجر به تخريب فضاي داخلي مفصل مي‌شود. با تجويز كفي با گوه خارجي خط وزن از روي بخش داخلي به سمت خارج منتقل شده و در نتيجه باعث كاهش فشار روي سمت داخل زانو و كاهش درد مي‌شود .هدف از این مطالعه، بررسي ميزان تأثير كفي با گوه خارجي پاشنه در افراد مبتلا به استئوآرتريت كمپارتمنت داخلي زانو بود. مواد و روش‌ها: در اين مطالعه 36 بيمار مبتلا به استئوآرتريت كمپارتمنت داخلي زانو پس از گذراندن مراحل غربالگري به دو گروه 18 نفره تقسيم شدند. گروه اول از كفي با گوه خارجي 3 ميلي‌متر در پاشنه و گروه دوم از كفي با گوه خارجي 7 ميلي‌متر در پاشنه استفاده كردند. ميزان درد و كيفيت زندگي بيماران با استفاده از پرسش‌نامه‌هاي تنظيم شده و بر اساس سيستم WOMAC و شدت استئوآرتريت و ميزان زاويه تيبيوفمورال با استفاده از عكس راديوگرافي اندازه‌گيري شد . يافته‌ها: ميزان درد، كيفيت زندگي و زاويه تيبيوفمورال به طور معني‌داري بهبود يافت؛ در حالي كه شدت استئوآرتريت پس از استفاده از كفي تفاوتي با قبل نداشت. در بين دو گروه كفي‌هاي 7 ميلي‌متر به طور معني‌داري نسبت به كفي 3 ميلي‌متر باعث كاهش درد شدند . نتيجه‌گيري :طبق نتايج به دست آمده از اين تحقيق، استفاده از كفي با گوه خارجي پاشنه باعث تصحيح زاويه تيبيوفمورال، كاهش درد و افزايش كارايي مفصل زانو مي‌شود . كليد واژه‌ها: استئوآرتريت زانو، كفي طبي، گوه خارج

Magnetically recoverable graphene oxide supported Co@Fe 3 O 4 /L-dopa for C-C cross-coupling and oxidation reactions in aqueous medium

We report the synthesis of inexpensive and environmentally benign cobalt(0) nanoparticles on L-3,4-dihydroxyphenylalanine (L-dopa) functionalized and magnetite (Fe 3 O 4 ) grafted graphene oxide (Co@GO/Fe 3 O 4 /L-dopa) which was fully characterized with different techniques such as Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HR-TEM), X-Ray Photoelectron Spectroscopy (XPS), X-ray Powder Diffraction (XRD), Thermogravimetric analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), Vibrating Sample Magnetometer (VSM), Carbon Hydrogen Nitrogen (CHN) analysis, Energy Dispersive X-ray (EDX) and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). Graphene oxide was used as the core material due to its mechanical, electrical and thermal properties. In order to avoid the cumbersome process of separation, magnetite nanoparticles were coated over the graphene oxide. After the successful preparation of graphene oxide based magnetic nanoparticles, L-dopa was grafted over Fe 3 O 4 nanoparticles so as to provide firm anchoring agent for cobalt nanoparticles. Finally, cobalt(0) nanoparticles were immobilized on the developed magnetic support. The catalytic efficiency of the synthesized catalyst was tested for Suzuki cross-coupling and oxidation reactions, usually carried out by precious and expensive second and third row transition metals; products were obtained in good to excellent yields. The synthesized catalyst represents an attractive alternative to conventional catalysts for Suzuki cross-coupling and oxidation reactions, and is recyclable up to five runs

Solid State Synthesized YVO4:Dy3+/ SiO2 Composites: Microstructures and Optical Characteristics

In this paper YVO4:Dy3+ was synthesized via solid state method at 1100°C and effects of different quantities of SiO2 particles on microstructure and photoluminescence properties were investigated in details. To study the microstructure and properties of these composites XRD, SEM, TEM, HRTEM, XPS and PL equipments were employed. It was found that via addition of SiO2 particles to YVO4:Dy3+ phosphors, strong bonding is made between SiO2 particles and phosphors. Furthermore, based on stronger electronegativity of Si 2p element compared to Y 3d and V 2p elements, increase of SiO2 causes the increase of binding energy. Moreover, this research showed that the addition of 10 wt% SiO2 particles to YVO4:Dy3+ material enhances the excitation and emission luminescence properties, significantly. Further increase of SiO2 particles results in suppress of emission intensity

Isotope-like effect in YVO4:Eu3+ nanopowders: Raman spectroscopy

In this paper, we describe synthesis and characterization of YVO 4 and Eu 3+ -doped YVO 4 nanopowders. Two methods of preparation were used—solution combustion synthesis (SCS) and classical ceramic method (CCM)—and compared. Morphology and structure of all samples were characterized with atomic-force microscopy (AFM), X-ray diffraction (XRD), and field-emission scanning electron microscopy (SEM). Raman spectroscopy was used to discuss the isotope-like effect. It is confirmed that doping with Eu ions results in a change of Raman spectra of doped samples—new modes arise, and intensity of existing ones change. Influence of different preparation methods on isotope-like effect is presented with detailed calculations of shifted modes. © 2019 John Wiley & Sons, Ltd