ABSTRACT
The existence of so-called blue-green cavities in the luminescence spectrum has been a hindrance to the improvement in the performance of traditional phosphor-converted white light emitting diodes. The commercial phosphors synthesized in reducing atmospheres can also cause problems such as equipment complexity, increased cost, and environmental pollution. Herein, a series of cyan-emitting Lu3GaxAl5-xO12: Ce3+ (x = 0, 1, 2, 3, 4) garnet phosphors were synthesized by a traditional solid-state reaction in a nonreducing atmosphere at different temperatures. The crystal structure, grain morphology, optical properties, and thermal quenching behavior were used to analyze the optical properties of the as-prepared phosphors. The luminescence intensity of samples is affected by the synthesis temperature and energy gap between the conduction band and the lowest energy of the 5d excited state of the host lattice. With the substitution of Al3+ by Ga3+, the regularity of the excitation and emission band movement is determined by the combined effects of crystal field splitting (CFS) and the nephelauxetic effect (NE). The temperature dependence of luminescence was studied. The thermal quenching mechanism was clarified by the thermal ionization model. Finally, by employing Lu2.94Ga2Al3O12: Ce3+0.06 as a cyan component, a w-LED with a high color rendering index of 93.2 and low correlation color temperature of 3880 K based on a blue chip and commercial red phosphors were fabricated in order to explore its possible application in high quality w-LED.
ABSTRACT
AIM: To investigate the effects and mechanism of d-limonene on the growth and metastasis of gastric cancer in vivo. METHODS: Metastatic model simulating human gastric cancer was established by orthotopic implantation of histologically intact human tumor tissue into gastric wall of nude mice. One percent d-limonene was orally administered at dose of 15 ml/kg every other day for seven weeks. Eight weeks after implantation, tumor weight, inhibition rate, apoptotic index (AI), microvessel density (MVD), vascular endothelial growth factor (VEGF), variation of ultrastructure, and the presence of metastasis were evaluated, respectively, after the mice were sacrificed. RESULTS: The tumor weight was significantly reduced in 5-FU group (2.55+/-0.28 g), d-limonene group (1.49+/-0.09 g) and combined treatment group (1.48+/-0.21 g) compared with the control group(2.73+/-0.23 g, P<0.05). In 5-FU group, d-limonene group, combined treatment group, the inhibition rates were 2.60%,47.58% and 46.84% and 0, respectively; AI was (3.31+/-0.33)%, (8.26+/-1.21)%, (20.99+/-1.84)% and (19.34+/-2.19)%, respectively; MVD was (8.64+/-2.81), (16.77+/-1.39), (5.32+/-4.26) and (5.86+/-2.27), respectively; VEGF expression was (45.77+/-4.79), (41.34+/-5.41), (29.71+/-8.92) and (28.24+/-8.55), respectively. The incidences of peritoneal metastasis also decreased significantly in 5-FU group(77.8%), d-limonene group (20.0%) and combined group (22.2%) compared with control group (100%) versus 62.5%,30% and 22.2%) (P<0.05). Liver metastasis was also inhibited and the incidences decreased significantly in 5-FU group, d-limonene group and combined group than that in control group (87.5% vs 55.5%, 20.0% and 22.2% respectively)(P<0.05). The incidence of ascites in control group, 5-FU group, d-limonene group and combined group was 25.0%, 22.2%, 0, 0, respectively and 12.5%, 11.1% 0, 0, with respect to the metastasis rate to other organs. CONCLUSION: d-limonene has antiangiogenic and proapoptotic effects on gastric cancer, thereby inhibits tumor growth and metastasis. Combination of d-limonene with cytotoxic agents may be more effective.
