Significantly enhanced photoluminescence and thermal stability of La3Si8N11O4:Ce3+,Tb3+ via the Ce3+ → Tb3+ energy transfer: a blue-green phosphor for ultraviolet LEDs.

A series of Ce3+-, Tb3+- and Ce3+/Tb3+-doped La3Si8N11O4 phosphors were synthesized by gas-pressure sintering (GPS). The energy transfer between Ce3+ and Tb3+ occurred in the co-doped samples, leading to a tunable emission color from blue to green under the 360 nm excitation. The energy transfer mechanism was controlled by the dipole-dipole interaction. The Ce3+/Tb3+ co-doped sample had an external quantum efficiency of 46.7%, about 5.6 times higher than the Tb-doped La3Si8N11O4 phosphor (8.3%). The thermal quenching of the Tb3+ emission in La3Si8N11O4:Tb,Ce was greatly reduced from 74 to 30% at 250 °C, owing to the energy transfer from Ce3+ to Tb3+. The blue-green La3Si8N11O4:0.01Ce,0.05Tb phosphor was testified to fabricate a warm white LED that showed a high color rendering index of 90.2 and a correlated color temperature of 3570 K. The results suggested that the co-doped La3Si8N11O4:Ce,Tb phosphor could be a potential blue-green down-conversion luminescent material for use in UV-LED pumped wLEDs.

Synthesis and Photoluminescence Properties of a Blue-Emitting La3Si8N11O4:Eu2+ Phosphor.

Eu2+-doped La3Si8N11O4 phosphors were synthesized by the high temperature solid-state method, and their photoluminescence properties were investigated in this work. La3Si8N11O4:Eu2+ exhibits a strong broad absorption band centered at 320 nm, spanning the spectral range of 300-600 nm due to 4f7 → 4f65d1 electronic transitions of Eu2+. The emission spectra show a broad and asymmetric band peaking at 481-513 nm depending on the Eu2+ concentration, and the emission color can be tuned in a broad range owing to the energy transfer between Eu2+ ions occupying two independent crystallographic sites. Compared to the Ce3+-doped La3Si8N11O4, the Eu2+-doped one shows a larger thermal quenching, predominantly owing to photoionization. Under 320 nm excitation, the internal and external quantum efficiencies are 44 and 33%, respectively.

Preventive and therapeutic effect of N-Acetyl-l-cysteine on infection-associated preterm labor in mice.

OBJECTIVE: To study the preventive and therapeutic effect of N-Acetyl-l-cysteine on infection-associated preterm labor in mice. METHODS: A total of 66 C57BL/6 inbred strain pregnant mice were selected and randomly divided into groups A, B and C, with 22 cases in each group. Group A, B and C were regarded as model group, prevention group and treatment group, respectively. The model of infection-associated preterm labor was built by intraperitoneal injection of Escherichia coli. Ten mice of each group were taken and observed the preterm birth rates and live birth rates, respectively. Three mice of each group were killed at 3 h, 6 h, 12 h and 24 h after building the model. Their uterus tissues were collected and the expressions of the AP-1 and MCP-1 in those tissues were assayed with immunohistochemical method and the expressions of NF-κBp65 and TNF-α protein in the placenta tissues of those mice were also detected with immunohistochemical method. RESULTS: The preterm birth rates of mice in groups B and C were significantly lower than that in group A, while their live birth rates were distinctly higher than that in group A (P < 0.05); the expressions of the AP-1 and MCP-1 in the uterus tissues and NF-κBp65 and TNF-α protein in the placenta tissues of mice in groups B and C were evidently lower than those in group A (P < 0.05); the comparison of the expressions of the NF-κBp65 and TNF-α between group B and C showed no statistical differences (P > 0.05). CONCLUSIONS: N-Acetyl-l-cysteine can lower the incidence rate of infection-associated preterm labor by prohibiting the activation of the protein AP-1/MCP-1 and decreasing the expression of NF-κBp65 and TNF-α in the pregnant tissues of premature mice to reduce the inflammatory reactions.

Anti-tumor effect of matrine combined with cisplatin on rat models of cervical cancer.

OBJECTIVE: To observe the anti-tumor effect of matrine combined with cisplatin on U14 rat models of cervical cancer. METHODS: A total of 80 female Kunming rats were used to establish U14 rat models of cervical cancer and then divided into groups I, II, III, IV, with 20 rats in each. For Group I, the control group, injection of normal saline was given around the tumors. For Group II, injection of 2 mg/kg cisplatin was given around the tumors. For Group III, injection of 75 mg/kg matrine was given around the tumors while the combined injection of matrine and cisplatin was given for Group IV with the same doses as Groups II and III. The animals were sacrificed 10 d after the injection and tumors were taken out for the comparisons of tumor weights after injection and calculation of anti-tumor rates, while thymus and spleen were taken for thymus index and spleen index. Blood in eyeball was collected for determination of changes in serum creatinine and urea nitrogen levels. Sections of tumor issue were prepared and morphological changes in tumor tissue cells were observed by using immunohistochemistry technique. RESULTS: After injection, the thymus index and spleen index in Groups III and IV were significantly higher than those in Groups I and II (P < 0.05) while the two indexes in Group II were significantly lower than Group I (P < 0.05). The tumor weights in Groups II and IV were significantly smaller than those in Groups I and III (P < 0.05) with significantly higher anti-tumor rates than Groups I and III (P < 0.05). The serum creatinine and urea nitrogen levels in Groups III and IV were significantly lower than Group II (P < 0.05) and the two indicators in Group III were significantly lower than those in Group IV (P < 0.05). The observation under the histological microscope showed densely arranged tumor cells in Group I, growing as a crumby structure and diffuse appearance, with hyperchromatic and large nuclei, and abundant cytoplasm. In the case of Group II, it showed less tumor cells, with extensive degenerative necrosis, sparse arrangement and karyopyknosis as well as karyoclasis. For Group III, necrosis of tumor cells in different sizes and heterogeneous color in nuclei were observed. For Group IV, the number of tumor cells was significantly smaller than Groups I and III and the tumor cells presented an appearance of crumby structure as cancer nests, with more proliferation of connective tissue. CONCLUSIONS: The treatment of matrine combined with cisplatin can significantly improve the anti-tumor effect on U14 rats with cervical cancer, which can be a new option for the treatment for cervical cancer.

Synthesis and biological evaluation of hydroxycinnamic acid hydrazide derivatives as inducer of caspase-3.

In order to generate compounds with superior antitumor activity and reduced toxicity, twelve new hydroxycinnamic acid hydrazide derivatives were synthesized and evaluated for their antiproliferative activities against two cancer cell lines (H1299 lung carcinoma cells and MCF-7 breast cancer cells), and compared to two normal counterparts (NL-20 lung epithelial cells and H184B5F5/M10 breast cells) by MTT method. The results demonstrated that some of these compounds possessed good antiproliferative activity against the two cancer cell lines. Among them, compound 2c was active against the growth of H1299 lung carcinoma cells with IC50 values of 1.50 µM, which was more active than the positive topotecan (IC50 = 4.18 µM). Simultaneously, it showed lower cytotoxic effects on normal NL-20 lung epithelial cells (IC50 > 10 µM). Mechanism studies indicated that it induced cell cycle arrest at G2/M phase followed by activation of caspase-3, and consequently caused the cell death. Further studies on the structure optimization are ongoing.

[Genetic diversity based on swine leukocyte antigen complex mi-crosatellites(SLA-MS) in five pig populations].

The genetic diversity of swine leukocyte antigen complex (SLA) was studied among Guangdong local pigs, Huanan wild boars (S.s. chirodontus) and introduced pigs, which aimed at providing a theoretical foundation for further pig anti-disease resistance breeding. Pietrain pigs, Duroc pigs, Large black-white pigs, Lantang pigs, and Huanan wild boars were genotyped by employing 18 microsatellites in swine leukocyte antigen complex (SLA-MS). The result showed that the average diversity in SLA II was higher (He=0.628, PIC=0.581) than that in SLA I (He=0.530, PIC=0.474) and in SLA III (He=0.526, PIC=0.458). The molecular diversity indices (MDI) of Huanan wild boars was the highest(0.716), followed by Lantang pigs (0.614), Large black-white pigs (0.559), Pietrain pigs (0.550) and Duroc pigs (0.507). As a whole, the genetic diversity of Huanan wild boars was the highest over Guangdong native pigs and introduced pigs. Large black-white pigs and Duroc pigs had ever happened a severe bottleneck by comparison with the Garza-Williamson index (GWI) in Huanan wild boar. From the genetic distance, one clade was that Lantang pigs were first clustered with Huanan wild boar, and then grouped together with Large black-white pigs; another clade was that Pietrain pigs were independently clustered with Duroc pigs in the NJ tree. The results would establish the foundation for pig conservation of germplasm resource, disease resistance breeding, and multiplicative strains.