Selectively excited emission and Tb3+-->Ce3+ energy transfer in yttrium aluminum garnet

Impact of Structural Changes on Energy Transfer in the Anion-Engineered Re3+:Y2O3 Through Low-Temperature Synthesis Approach

Anion engineering has proven to be an effective strategy to tailor the physical and chemical properties of metal oxides by modifying their existing crystal structures. In this work, a low-temperature synthesis for rare earth (RE)-doped Y2O2SO4 and Y2O2S was developed via annealing of Y(OH)3 intermediates in the presence of elemental sulfur in a sealed tube, followed by a controlled reduction step. The crystal structure patterns (X-ray diffraction) and optical spectra (UV-IR) of Y2O2SO4, Y2O2S, and crystalline Y2O3 were collected throughout the treatment steps to correlate the structural transformations (via thermogravimetric analysis) with the optical properties. Local and long-range crystallinities were characterized by using X-ray and optical spectroscopy approaches. Systematic shifts in the Eu3+ excitation and emission peaks were observed as a function of SO42- and S2- concentrations resulting from a crystal evolution from cubic (Y2O3) to trigonal (Y2O2S) and monoclinic (Y2O2SO4), which can modify the local hybridization of sensitizer dopants (i.e., Ce3+). Ultimately, Tb3+ and Tb3+/Ce3+ doping was employed in these hosts (Y2O2SO4, Y2O2S, and Y2O3) to understand energy transfer between sensitizer and activator ions, which showed significant enhancement for the monoclinic sulfate structure.

COMPARISON OF CHEMOTHERAPY RESPONSE AND ADVERSE EFFECTS OF DOUBLE-PLATINUM PLUS EGFR-TKI VERSUS DOUBLE-PLATINUM ALONE ON NSLCLC PATIENTS WITH DISEASE PROGRESSION AND EGFR-TKI TREATMENT

EGFR-TKI is the first-line therapy for EGFR-mutant patients. Nevertheless, patients will have disease progression (median PFS 10 – 12 months) due to resistance. The treatment options are still limited in developing countries for such cases, thus double-platinum chemotherapy is the next option. Although IMPRESS study reported no difference in terms of PFS and OS between double-platinum alone and double-platinum plus EGFR-TKI, several local studies reported benefit of continuing EGFR-TKI in combination with double-platinum chemotherapy (treatment beyond progression). This study aimed to compare chemotherapy effects of double-platinum plus EGFR-TKI versus double-platinum alone on patients with NSCLC progression after EGFR-TKI treatment. This was an analytical descriptive study using prospective cohort design, involving 30 patients with disease progression following EGFR-TKI treatment that met inclusion criteria in Dr. Soetomo Hospital. Subjects were divided into two groups: arm A (double-platinum plus EGFR-TKI) and arm B (double-platinum alone). Subjects were observed until 4 cycles of double-platinum chemotherapy. Subjective response (body weight and EQ5D questionnaire) was analyzed, chest CT scans were evaluated using RECIST criteria, and adverse effects were monitored. This study was conducted in accordance with GCP principles and has received ethics certificate from Dr. Soetomo Hospital ethics committee (No. 08/Panke.KKE/I/2017). The results showed that subject characteristics between two arms were insignificantly different (p=0.05). The most common EGFR mutation was exon 21 (50% on arm A and 60% on arm B). Chi square was tested on subjective response parameter (EQ5D (p=0.483)). T2 free sample was tested on semi-subjective parameter (body weight (p=1.00)). Comparison test on both groups after cycle 2 and 4 showed p value=0.05. Statistical test on adverse effect between both groups showed p value=0.526. As a conclusion, there was no significant difference between double-platinum and double-platinum plus EGFR-TKI on patients who had disease progression following EGFR-TKI treatment.

Emission properties of Tb3+ ions in LYSO: evidence of a cross relaxation mechanism explained by a kinetic model

The optical properties of Tb(3+) ions in oxyorthosilicates of lutetium and yttrium (LYSO) are reported. The introduction of a small number of terbium ions (nominal content 10 ppm) generates, in the otherwise transparent absorption spectrum of the matrix, an ultraviolet absorption band peaked at about 240 nm. By exciting within the reported UV band, line shaped emissions in the 350-600 nm range are detected. These transitions are related to the (5)D(3) and (5)D(4) levels of the Tb(3+) ions and are characterized by decay times in the millisecond time domain. Analysis of the decay time measurements allows us to individuate a cross relaxation mechanism among terbium ions even at the low dopant concentration investigated. We propose a three-level kinetic model which is able to successfully reproduce the experimental data, allowing us to discriminate among the radiative and non-radiative contributions to the observed emissions.