RESUMO
To manipulate the photocatalytic activities of BiOCl photocatalysts, doping and heterojunction engineering are simultaneously adopted. Herein, the photocatalysts Sm3+-doped BiOCl and BiOCl:Sm3+@yg-C3N4 were designed, in which their phase structure, morphology, optical properties and photocatalytic activities were systematically discussed. Excited at 408 nm, red emissions are seen from Sm3+-doped BiOCl microplates and their intensities were impacted by doping content, reaching the maximum value when the Sm3+ content was 1 mol% and the involved concentration mechanism was dominated by quadrupole-quadrupole interaction. Through analyzing the degradation of TC, the visible light triggered photocatalytic behaviors of the resultant compounds were studied. Compared with BiOCl microplates, an improved TC removal ability was seen in Sm3+-doped BiOCl microplates and the products with a Sm3+ content of 0.5 mol% show the best performance. Moreover, through constructing the heterojunction with g-C3N4, the TC removal capacity was further enhanced and the BiOCl:Sm3+@60%g-C3N4 exhibits the optimal photocatalytic activity, which was also much better than that of the commercial SnO2 and TiO2. Accordingly, the ËO2-, h+ and ËOH active species were proven to contribute to the involved visible light driven photocatalytic mechanism. Furthermore, the separation and recombination of photogenerated carries via the Z-scheme transfer process in the designed heterojunction composites, led to splendid photocatalytic properties. Additionally, it was verified that the TC solution treated with synthesized compounds was nontoxic toward plant growth. Our findings may propose an available route to regulate the photocatalytic performance of the visible light driven photocatalysts.
RESUMO
To meet the needs of contactless optical thermometry, Er3+/Yb3+/Ho3+-tridoped La2Mo3O12 (LMO) microparticles were designed and synthesized. Upon exciting with 980 nm light, the synthesized compounds emit glaring upconversion (UC) emissions and their emission colors can be tuned from green to yellow by altering the Ho3+ content. It is found that the optimal doping contents for Yb3+ and Ho3+ in LMO are 9 and 1 mol%, respectively, and the UC emission mechanism involved is a two-photon harvest process. Using the fluorescence intensity ratio (FIR) technique to analyze the temperature responses of the UC emissions arising from thermally coupled levels (TCLs) and non-thermally coupled levels (non-TCLs), the temperature sensing abilities of the synthesized samples were investigated. When the TCLs of Er3+ (2H11/2, 4S3/2) are used, the synthesized microparticles present the highest absolute and relative sensitivities of 0.0085 and 1.0236% K-1, respectively. Moreover, when the non-TCLs of Er3+ (2H11/2) and Ho3+ (5F5) are used, the maximum absolute and relative sensitivities of the synthesized compounds are 0.0296 and 0.6287% K-1, respectively. Clearly, the thermometric characteristics of the final products can be regulated via using different sensing strategies (i.e., TCLs and non-TCLs) and emission combinations (i.e., spatial mode). However, the change of the Ho3+ content has little impact on the temperature sensing capacity of the synthesized products. These results indicate that Er3+/Yb3+/Ho3+-tridoped LMO microparticles are promising candidates for optical thermometers and our findings also provide possible strategies for regulating the thermometric properties of rare-earth ion doped luminescent materials.
RESUMO
Tm3+/Yb3+-codoped ZrScW2PO12 microparticles were prepared in order to solve the problems of the severe thermal quenching and unsatisfactory thermometric properties of most luminescent materials. The synthesized materials exhibit a rarely observed negative thermal expansion (NTE) effect, which was verified by in situ X-ray diffraction experiments, performed under high temperature conditions. Upon excitation with a 980 nm laser, bright blue upconversion (UC) emissions originating from Tm3+ were observed. Moreover, owing to the promoted energy transfer, cross-relaxation and non-radiative decay processes at high temperatures triggered by the NTE effect, the observed UC emissions arising from 1G4 and 3F2,3 levels show non-monotonic responses to temperature. By analysing the temperature-dependent luminescence intensity ratio of these UC emissions originating from the non-thermally coupled levels of Tm3+ (1G4 and 3F2,3), the thermometric properties of the prepared microparticles were investigated in detail. Interestingly, the maximum absolute and relative sensitivities of the synthesized compounds are 0.09 and 1.45% K-1, respectively, which are independent of Yb3+ content, but they can be manipulated by employing different sensing modes. Our results manifest that the exploitation of the NTE effect is an efficient way to control the UC luminescence features of rare earth ions and to realize high performance optical thermometry.
RESUMO
OBJECTIVE: To observe the clinical effect of moxibustion combined with plucking technique at Jiquan (HT 1) for preventing peripherally inserted central catheter (PICC)-related venous thrombosis in the upper limbs of malignant tumor patients. METHODS: A total of 80 malignant tumor patients undergoing PICC were randomized into an observation group and a control group, 40 cases in each one. In the control group, the routine care for PICC was exerted. In the observation group, besides the routine care, moxibustion combined with plucking technique at Jiquan (HT 1) was added. Mild moxibustion was exerted along the venous distribution of PICC (avoiding the entry site) for 10 to 15 min, and then, the circling moxibustion was applied to Quchi (LI 11), Xuehai (SP 10) and Tianfu (LU 3), 3 to 5 min at each acupoint. Finally, plucking technique was given at Jiquan (HT 1) for 5 to 10 min. This combined therapy was intervened since the 2nd day of PICC placement, once daily, 5 times a week, for 3 weeks totally. The incidence of the PICC-related venous thrombosis in the upper limbs was compared between the two groups on day 42 of placement. On day 2, 7, 14, 21, 28, 35 and 42 of PICC placement, the peak systolic velocity (PSV) and the end-diastolic velocity (EDV) of the subclavicular vein on the placement side were observed separately in the two groups. RESULTS: The incidence of the PICC-related venous thrombosis in the upper limbs in the observation group was lower than that in the control group (2.5% [1/40] vs 17.5% [7/40], P<0.05). From day 7 to 35 of PICC placement, PSV of the subclavicular vein on the placement side was higher than that on the day 2 of PICC placement in the observation group (P<0.05). On day 28 and 42 of PICC placement, PSV of the subclavicular vein on the placement side was lower than that on the day 2 of PICC placement in the control group (P<0.05). In the observation group, EDV of the subclavicular vein on the placement side was higher than that on the day 2 of PICC placement from day 7 to 28 of PICC placement (P<0.05). In the control group, EDV of the subclavicular vein on the placement side from day 28 to 42 of PICC placement was lower than that on the day 2 of PICC placement (P<0.05). From day 7 to 42 of PICC placement, PSV and EDV of the subclavicular vein on the placement side in the observation group were all higher than those in the control group (P<0.01, P<0.05). CONCLUSION: The combined treatment of moxibustion with plucking technique at Jiquan (HT 1) can effectively prevent PICC-related venous thrombosis in the upper limbs and improve venous blood flow velocity in malignant tumor patients.