Synthesis and optical properties of Gd4Al2O9:Eu3+, a red emitting phosphor with a strong negative thermal quenching effect.

For the purpose of obtaining red-light phosphors with excellent luminescence thermal stability, a series of Gd4Al2O9:Eu3+ (GAO:Eu3+) phosphors were synthesized by combining the sol-gel method with high-temperature calcination, and a detailed series of study and analysis of their room temperature and high temperature luminescence properties was carried out. In GAO, the emission peaks corresponding to the 5D0 → 7F j (j = 0, 1, 2, 3 and 4) transitions of Eu3+ were observed at 578, 590, 610, 654, and 707 nm, with the strongest emission peak at 610 nm, and the obtained samples were red-light phosphors. The sample GAO:Eu3+ synthesized by combining the sol-gel method with high-temperature calcination has a negative thermal quenching (NTQ) effect, and the best doped sample GAO:0.16Eu3+ has an optimal luminescence temperature of 120 °C, and the corresponding integrated PL intensity is 183.2% of the initial value at 30 °C. The presence of the NTQ effect makes GAO:0.16Eu3+ have good luminescence thermal stability, which manifests as thermal-optical energy conversion at the macroscopic level. A detailed study of the thermal quenching mechanism was carried out.

Formation and enhancement of negative thermal quenching in emission of KGdF4:Eu3+, Yb3+@GQDs.

In order to obtain a red emitting phosphor with good luminescence thermal stability, a series of KGdF4:Eu3+, Yb3+@GQD (GQD: Cl-containing graphene quantum dots) red emitting phosphors have been synthesized by the co-precipitation method, and their luminescence thermal properties have also been studied in detail. It is intriguing that the negative thermal quenching (NTQ) effect is induced by the double doping of Yb3+, and the effect is further enhanced by GQD coating. The strongest integrated PL intensities of the optimal double doped sample and the optimal GQD-coated sample are at 130 and 170 °C, in which the corresponding integrated PL intensities are presented as 117.7 and 156.5% of the initial value at 30 °C, respectively. The NTQ effect makes the optimal GQD coated sample have good luminescent thermal stability, so it can be applied for high-power WLEDs. A mechanism of energy conversion from heat to light is discussed and suggested for the effect.

No Increase in HIV Drug Resistance Mutations among Injecting Drug Users on Methadone Maintenance Therapy: A Prospective Cohort Study.

BACKGROUND: Whether HIV-positive injecting drug users (IDUs) are at higher risk of developing drug resistance mutations (DRMs) after methadone maintenance therapy (MMT) than any other HIV-positive population is unclear. OBJECTIVE: To compare the incidence of new DRMs in two population groups: antiretroviraltreatment (ART) HIV-positive IDUs and non-drug users. METHODS: A prospective cohort of ART HIV-positive patients including IDUs who received MMT (MMT group) and non-drug users (N-MMT group) was established from April 2016 to December 2017 in Guangxi, China. RESULTS: Of the 80 participants, 43 were in the MMT group and 37 were in the N-MMT group. Compared with the N-MMT group, the HRs of PIs, NRTIs and NNRTIs for new DRMs in the MMT group was 1.55 (95%CI: 0.28-8.64; P = 0.616), 1.51 (95%CI: 0.44-5.20; P = 0.512) and 0.45 (95%CI: 0.15-1.35; P = 0.155), respectively. There was no dose-response relationship between MMT and new DRMs for PIs, NRTIs and NNRTIs (P > 0.05). The new DRM incidence for NRTIs (138.23 per 104 person-months) was higher than for PIs (94.16 per 104 person-months) and NNRTIs (95.41per 104 person-months) in the MMT group, while the new DRM incidence for NNRTIs (208.24 per 104 person-months) was higher than for PIs (44.13 per 104 person-months) and NRTIs (91.78 per 104 person-months) in the N-MMT group. CONCLUSION: Among ART HIV-positive patients, there is no significant difference in the incidence of new DRMs between IDUs receiving MMT and non-drug users. MMT has little impact on the development of DRMs among IDUs.

Effects of cotrimoxazole prophylaxis on Talaromyces marneffei infection in HIV/AIDS patients receiving antiretroviral therapy: a retrospective cohort study.

The dimorphic fungus Talaromyces marneffei (TM) is a common cause of HIV-associated opportunistic infections in Southeast Asia. Cotrimoxazole (CTX) inhibits folic acid synthesis which is important for the survival of many bacteria, protozoa, and fungi and has been used to prevent several opportunistic infections among HIV/AIDS patients. We question whether CTX is effective in preventing TM infection. To investigate this question, we conducted an 11-year (2005-2016) retrospective observational cohort study of all patients on the Chinese national antiretroviral therapy (ART) programme in Guangxi, a province with high HIV and TM burden in China. Survival analysis was conducted to investigate TM cumulative incidence, and Cox regression and propensity score matching (PSM) were used to evaluate the effect of CTX on TM incidence. Of the 3359 eligible individuals contributing 10,504.66 person-years of follow-up, 81.81% received CTX within 6 months after ART initiation, and 4.73% developed TM infection, contributing 15.14/1,000 person-year TM incidence rate. CTX patients had a significantly lower incidence of TM infection than non-CTX patients (4.11% vs. 7.53%; adjusted hazard ratio (aHR) = 0.50, 95% CI 0.35-0.73). CTX reduced TM incidence in all CD4+ cell subgroups (<50 cells/µL, 50-99 cells/µL, 100-199 cells/µL), with the highest reduction observed in patients with a baseline CD4+ cell count <50 cells/µL in both Cox regression and the PSM analyses. In conclusion, in addition to preventing other HIV-associated opportunistic infections, CTX prophylaxis has the potential to prevent TM infection in HIV/AIDS patients receiving ART.