Radioactivity level evaluation in granite building raw material production area in Cenxi, China.

This study was conducted to evaluate the radioactivity level in the granite building raw material production area in Cenxi, China. Natural radionuclide concentrations, γ absorbed dose rates (ADRs) and radon exhalation rates were measured in the area. The spatial distribution of natural radionuclides, γ ADR and radon exhalation rate were mapped with GPS information. The radioactivity levels in the study area were analysed based on the descriptive statistics and frequency distribution of measurement data. According to the Chinese standard, the granite raw materials used for building and decoration in this region were classified based on their radiological hazards. In addition, radiation protection measures were proposed for the mining of local granite building materials products as well as environmental protection around the work area and resident safety.

Efficient and zero thermal quenching Sm3+-activated Li2LaTiTaO7 phosphor for white LEDs.

In this work, we prepared a new orange-red phosphor Li2La1-xTiTaO7:xSm3+ (abbreviated as LLTT:Sm3+) for white light-emitting diodes (w-LEDs). Its crystal structure, microstructure, photoluminescence characteristics, luminescence lifetime and thermal quenching properties were studied in depth. The LLTT:Sm3+ phosphor shows four intense emission peaks at 563, 597, 643, and 706 nm when excited at 407 nm. Thermal quenching is caused by the dipole-quadrupole (d-q) interaction of Sm3+ ions, and the optimum doping concentration of Sm3+ is x = 0.05. Meanwhile, the LLTT:0.05Sm3+ phosphor has a high overall quantum yield (QY = 59.65%) and almost no thermal quenching. The emission intensity at 423 K is 101.5% of the initial value at 298 K, while the CIE chromaticity coordinates barely change as the temperature rises. The fabricated white LED device exhibits excellent CRI and CCT values of 90.4 and 5043 K, respectively. These findings demonstrate that the LLTT:Sm3+ phosphor has promise in w-LED applications.

A broadband near-infrared Cr3+-doped phosphor applied to near-infrared light-emitting diodes: enhanced luminescence and thermal stability by annealing.

Cr3+-activated phosphors with high quantum efficiency show excellent promise in the field of near-infrared (NIR) phosphor converted light-emitting diodes (pc-LEDs). Here, we design an annealing program for Cr3+-doped phosphors containing variable valence elements that cannot be prepared in a reducing atmosphere to enhance their luminescence efficiency and thermal stability. A novel phosphor, Li2Mg3SnO6:Cr3+, developed by this annealing design, containing variable valence element Sn, exhibits higher quantum efficiency and better thermal stability than the one prepared by the conventional solid-state reaction. The Li2Mg3SnO6:0.03Cr3+ sample exhibits broadband NIR emission with a full width at half-maximum (FWHM) of 201 nm. After annealing, the internal quantum efficiency (IQE) and external quantum efficiency (EQE) of the Li2Mg3SnO6:0.03Cr3+ sample are enhanced from 48.5% to 84.7% and from 22.7% to 32.6%, respectively, and the thermal quenching temperature at which the luminescence intensity of the phosphor reduces to half of its initial value is promoted from ∼400 K to ∼425 K. The luminescence intensity of the optimized Li2Mg3SnO6:0.03Cr3+ sample at 425 K (∼152 °C) remains 49.2% of its initial intensity at 300 K. A NIR pc-LED is fabricated by combining the optimized Li2Mg3SnO6:0.03Cr3+ sample with a blue LED (455 nm blue chip), and the NIR radiant fluxes of 3.676 mW (at 10 mA) and 29.21 mW (at 100 mA), as well as a maximum NIR photoelectric efficiency of 14.2%, are obtained. The results show that this novel phosphor has great application potential in NIR pc-LEDs, and the annealing design exhibits huge potential for improving the optical properties of Cr3+-activated phosphors.

Multiple site occupancy induced yellow-orange emission in an Eu2+-doped KSr6Sc(SiO4)4 phosphor towards optical temperature sensors.

Phosphors have attracted significant interest as potential optical temperature sensors in recent years. In our work, a new blue-light stimulated KSr6Sc(SiO4)4:Eu2+ phosphor with decorative kröhnkite-like octahedral tetrahedral chains was successfully synthesized. Multiple site occupancy occurred in KSr6Sc(SiO4)4:Eu2+ and induced a yellow-orange emission band with a peak at 571 nm and an FWHM of 91 nm. Gaussian fitting and time-resolved photoluminescence mapping were combined to analyze the occupation of Eu2+ in five Sr2+ sites. In the meantime, the site occupation preference, energy transfer process, and thermal quenching mechanism of Eu2+ emission centers have been comprehensively examined. Under 450 nm excitation, the optimal sample possesses an acceptable quantum efficiency (EQE = 17.3%) and a high sensitivity between luminescence properties and temperature variation ranging from 200 to 475 K. The optimal sample's relative sensor sensitivity achieves a maximum value of 3.53% K-1 at 475 K. The phosphor KSr6Sc(SiO4)4:0.07Eu2+ presents the potentiality as an optical thermometer.

Achieving High Quantum Efficiency Broadband NIR Mg4 Ta2 O9 :Cr3+ Phosphor Through Lithium-Ion Compensation.

Ultra-efficient broadband near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) are urgently needed to improve the detection sensitivity and spatial resolution of current smart NIR spectroscopy-based techniques. Nonetheless, the performance of NIR pc-LED has severely limited owing to the external quantum efficiency (EQE) bottleneck of NIR light-emitting materials. Herein, a blue LED excitable Cr3+ -doped tetramagnesium ditantalate (Mg4 Ta2 O9 , MT) phosphor is advantageously modified through lithium ion as a key efficient broadband NIR emitter to achieve high optical output power of the NIR light source. The emission spectrum encompasses the 700-1300 nm electromagnetic spectrum of first biological window (λmax  = 842 nm) with a full-width at half-maximum (FWHM) of ≈2280 cm-1 (≈167 nm), and achieves a record EQE of 61.25% detected at 450 nm excitation through Li-ion compensation. A prototype NIR pc-LED is fabricated with MT:Cr3+ , Li+ to evaluate its potential practical application, which reveals an NIR output power of 53.22 mW at a driving current of 100 mA, and a photoelectric conversion efficiency of 25.09% at 10 mA. This work provides an ultra-efficient broadband NIR luminescent material, which shows great promise in practical applications and presents a novel option for the next-generation high-power compact NIR light sources.

Enhanced blue-light excited cyan-emitting persistent luminescence of BaLu2Al2Ga2SiO12:Ce3+, Bi3+ phosphors for AC-LEDs via defect modulation.

Alternating current light-emitting diodes (AC-LEDs) have received significant attention from both academia and industry due to their remarkable benefits of more compact volume, cheaper manufacturing cost, greater energy usage efficiency, and longer service life. One of the most significant challenges for AC-LEDs is the flicker effect, which is mainly caused by the unavoidable 5-20 ms dimming time. Aiming to reduce the flicker effect, we designed a series of excellent blue-light excited cyan-emitting persistent luminescence (PersL) phosphors BaLu2Al2Ga2SiO12:Ce3+, Bi3+ via defect engineering of co-doping Bi3+. Interestingly, we found that co-doping Bi3+ not only effectively enhanced the PersL intensity, but also regulated the PersL lifetime of this phosphors. As the Bi3+ co-doping concentration increases to 0.01, the τ80 value (the time when the PersL intensity decreases to 80% of the initial intensity) increases from 0.24 to 19.61 ms, which proves to be effective in compensating the flicker effect of AC-LEDs. A new method of generating white light emission during the dimming time through adding the blue-light excited cyan PersL phosphor to the original orange-red PersL phosphor was proposed and an AC-LED lamp with a decreased percent flicker of 48.15% was fabricated, which is significantly better than the other currently reported AC-LED devices based on PersL phosphors. These results demonstrate that BaLu2Al2Ga2SiO12:Ce3+, Bi3+ might be an attractive material for low-flicker AC-LEDs.

Design and synthesis of a novel blue-emitting CaNaSb2O6F:Bi3+ phosphor for optical temperature sensing.

Bi3+ has gained increasing attention due to its abundant reserves, adjustable luminous colour and high chemical stability, therefore, Bi3+-activated luminescent materials have already been extensively applied in various fields. Herein, a novel blue-emitting CaNaSb2O6F:Bi3+ (CNSOF:Bi3+) phosphor with a pyrochlore-type structure with the space group Fd3̄m (277) was successfully synthesized. It exhibits a broad absorption band in the n-UV region (290-390 nm) and an ideal blue emission band centered at 441 nm. Interestingly, the wide emission peak of CNSOF:Bi3+ shows strongly temperature-dependent fluorescence properties and good thermal degradation resistance in the cycle temperature range from 298 K to 473 K, and the relative sensitivity is calculated to reach the maximum value of 2.34% K-1 at 423 K. Besides, the phosphor is different from a traditional optical temperature sensing material which shows the emission peak of trivalent rare earth ions. The wide emission peak makes the instrument insensitive to the peak shift, which dramatically reduces the requirement of the instrument, and the emission peak does not shift with the temperature to enhance the measurement stability, thus saving the cost. These results indicate that the CNSOF:Bi3+ blue emitting phosphor has potential applications in temperature sensing.

Tuning emission color and improving the warm-white persistent luminescence of phosphor BaLu2Al2Ga2SiO12:Pr3+via Zn2+ co-doping.

In this article, we synthesized a series of new warm-white emitting persistent luminescent phosphors by co-doping Zn2+ into Pr3+ activated BaLu2Al2Ga2SiO12, and systematically investigated the effect of Zn2+ co-doping on both their photoluminescence and persistent luminescence properties. Following the removal of UV excitation, the phosphor emits warm-white persistent luminescence consisting of greenish-blue and red emissions originating from 3P0 and 1D2 multiplet electron transitions at the 4f level of Pr3+. The luminescence properties of the Ba1-xZnxLu2Al2Ga2SiO12:Pr3+ phosphors can be modified by changing the content of Ba/Zn in the host, which affects the non-radiative energy flow between 5d1-3P0-1D2 levels and resultantly enhances the intensity of the 4f → 4f transition. Compared with the undoped sample, Zn2+ co-doping can significantly enhance the persistent luminescence intensity of the phosphors in the range of 400-800 nm and reduce the intensity in the UV region. Meanwhile, Zn2+ co-doping can also change the intensity ratio between the greenish-blue and red emissions, and the persistent luminescence color can be tuned from red to warm-white with the increase of Zn2+ concentration. Besides, the Zn2+ ions entering the crystal lattice also enhance the persistent luminescence performance by modifying the defect levels in the phosphor. For the optimized phosphor, bright warm-white persistent luminescence can be observed by the naked eye in the dark after the removal of the excitation source for 4 h. Based on the experimental results, a feasible mechanism was also proposed to reveal the persistent luminescence generation process for the BaLu2Al2Ga2SiO12:Pr3+,Zn2+ phosphor.

The effects of CPET-guided cardiac rehabilitation on the cardiopulmonary function, the exercise endurance, and the NT-proBNP and hscTnT levels in CHF patients.

OBJECTIVE: To explore the effects of cardiopulmonary exercise testing (CPET) on the cardiopulmonary function, the exercise endurance, and the NT-proBNP and hscTnT levels in chronic heart failure (CHF) patients. METHODS: Altogether 98 patients with CHF were randomly divided into a control group and a CPET group, with 49 cases in each group. The control group was administered routine treatment, and the CPET group was administered CPET cardiac rehabilitation training in addition to the routine treatment. Heart and lung function, exercise endurance, and the peripheral blood NTproBNP, hscTnT, and CRP levels were observed. The patients' quality of life, anxiety, and depression were observed using the scale. RESULTS: After the treatment, the left ventricular end systolic diameters (LVESD) and the left ventricular end diastolic diameters (LVEDD) were significantly decreased, the left ventricular ejection fractions (LVEF), the stroke volumes (SV), and the CI levels were significantly increased, and there were significant differences in these indexes between the CPET group and the control group (all P<0.05). After the treatment, the carbon dioxide ventilation equivalent slope (VE/VCO2slop) decreased significantly, the peak oxygen consumption (peakVO2) and anaerobic threshold oxygen consumption (VO2AT) levels increased significantly, and there were significant differences in these indicators between the CPET group and the control group (all P<0.05). Compared with the control group, the exercise endurance, the maximum oxygen uptake capacity (VO2max), the maximum power, the exhaustion times, and the six-minute walking test (6MWT) levels in the CPET group increased significantly (all P<0.05). After the treatment, the N-terminal precursor brain natriuretic peptide (NTproBNP), the high sensitivity cardiac troponin (hscTnT), and the C-reactive protein (CRP) levels in the two groups were decreased compared with their pre-treatment levels, and there were significant differences in these indexes between the CPET group and the control group (all P<0.05). After the treatment, the Minnesota living with heart failure questionnaire (MLHFQ), the self-rating anxiety scale (SAS), and the self-rating depression scale (SDS) scores in the two groups were significantly lower than they were before the treatment, and there were significant differences in the two scores between the CPET group and the control group (all P<0.05). CONCLUSION: CPET for patients with CHF helps increase heart and lung function, improves exercise endurance, reduces the NT-proBNP and hscTnT levels, and improves patients' quality of life.

Hybrid-functional calculations of electronic structure and phase stability of MO (M = Zn, Cd, Be, Mg, Ca, Sr, Ba) and related ternary alloy M x Zn1-x O.

Using the hybrid exchange-correlation functional within the density-functional theory, we have systematically investigated the structural and electronic properties of MO (M = Be, Mg, Ca, Sr, Ba, Zn, Cd) in binary rock salt (B1), zinc-blende (B3) and wurtzite (B4) phases, including the structural parameters, bulk moduli, band gaps and deformation potentials. Our results agree well with the experimental data and other theoretical results, and give a better understanding of the relationship between the geometric and electronic structure. After calculating the band alignment, we find that in both the B1 and B3 structures, the valence band maximum (VBM) has an obvious decrease from BeO to MgO to CaO, then it goes up from SrO to BaO to ZnO to CdO. Moreover, the properties of the ternary alloys M x Zn1-x O were studied through the application of the special quasi-random structure method. The critical value of the ZnO composition for the transition from the B3 structure to the B1 structure gradually increases from (Ca, Zn)O to (Mg, Zn)O to (Sr, Zn)O to (Ba, Zn)O to (Cd, Zn)O, indicating that (Ca, Zn)O can exist in the B3 structure with the lowest ZnO composition. These results provide a good guideline for the accessible phase space in these alloy systems.

[Effect of comprehensive schistosomiasis control measures based on infection source control in mountainous areas of Yunnan Province].

OBJECTIVE: To evaluate the effect of comprehensive schistosomiasis control measures based on infection source control in plateau mountain areas of Yunnan Province. METHODS: From 2006 to 2004, four administrative villages were selected as test areas from plateau canyon and plateau basin endemic areas in Jindun Town, Heqing County, two villages each type, and the comprehensive control measures were implemented, including the examination and treatment of schistosomiasis, Oncomelania hupensis snail survey and control, health education, improving drinking water and lavatories, banning grazing, constructing sanitary pen of livestock, replacing cattle with machine, etc. The schistosome infection state and snail status in 2006 were treated as the baseline information, and the effect of the comprehensive measures were evaluated. Results The infection rate of human in plateau canyon areas decreased from 4.94% in 2006 to 0.06% in 2014, and that of livestock decreased from 1.11% to 0. In plateau basin areas, there was only 1 case of schistosomiasis found in Xiaolian Village in 2007, and no any other cases found in the other years, the infection rates of livestock dropped from 7.38% to 0. Compared with 2006, the snail areas in the two type areas decreased by 74.89% and 75.30%, respectively, meanwhile, the percentage of snail area, the occurrence rate of frames with snails, as well as the average density of living snails also decreased, and no infected snails were found since 2008. Xidian and Xinzhuang villages in plateau canyon area reached the criteria of schistosomiasis transmission controlled in 2009, and Xiao-lian and Kangfu villages in plateau basin reached the criteria of transmission interrupted in 2014. CONCLUSIONS: The comprehensive schistosomiasis control measures based on infection source control can effectively control the endemic situation of schistosomiasis in plateau areas of Yunnan Province. In the future, we should pay an equal attention to the infection sources control and snail control to consolidate and amplify the achievement of schistosomiasis control.

[Molluscicidal effect of buried niclosamide sustained-release method in plateau mountainous areas].

OBJECTIVE: To evaluate the molluscicidal effect of the buried niclosamide sustained-release method in Oncomelania snail-infested terraced environments of mountainous areas in Yunnan Province. METHODS: A piece of relatively isolated snail-infested terraced environment was selected as experimental plot and randomly divided into four groups. The buried niclosamide sustained-release methods were performed in Group A, B, C with the doses of 6 g/m2, 12 g/m2, 24 g/m2 respectively, and Group D was sprayed with 50% niclosamide ethanolamine salt wettable powder (2 g/m2) as the control. RESULTS: In Group C (with the buried niclosamide sustained-release method of 24 g/m2), the half-year reduction of living snail density was 89.90%, and one-year reduction of living snail density was 96.80%, which were significantly higher than those of Group D (40.35% and 59.11%) (Both P < 0.01) CONCLUSION: The buried niclosamide sustained-release method is effective and suitable for snail control in mountainous terrace areas.

[Molluscicidal effect of WPN and MNSC on Lymnaea].

OBJECTIVE: To evaluate the molluscicidal effect of wettable powder of 50% niclosamide ethanolamide salt (WPN) and suspension concentrate of 26% metaldehyde and niclosamide (MNSC) on Lymnaea. METHODS: WPN and MNSC were prepared as a series of solutions containing the active ingredient concentrations of 0.06, 0.13, 0.25, 0.50, 1.00, 2.00 mg/L and 4.00 mg/L, and the adult Lymnaea snails were soaked in the above mentioned series of solutions in the laboratory, and the LC50 values were calculated. The doses of active ingredient concentrations of 0.03, 0.06, 0.13, 0.25, 0.50, 1.00 g/m2 and 2.00 g/m2 of WPN and MNSC were adopted to spray on Lymnaea snails in the laboratory, and the LC50 values were calculated. A series of solutions containing the active ingredient concentrations of 1.00 mg/L, 0.50 mg/L, 0.25 mg/L, and 0.13 mg/L of WPN and MNSC were prepared, and the adult Lymnaea snails were put into the bowls with each concentration solution above mentioned and the climbing situation of the snails was observed at different time. RESULTS: By the immersion method, LC50 values of WPN at 48 h and 72 h were 0.93 mg/L and 0.64 mg/L respectively; LC50 values of MNSC at 48 h and 72 h were 0.74 mg/L and 0.51 mg/L respectively; by the spray method, when active ingredient concentrations of WPN and MNSC were 1.00 g/m2 or more, the death rates were both 100% after 3 days. In the climbing test, the Lymnaea snails did not climb in the solutions containing the active ingredient concentration of 1.00 mg/L of WPN and MNSC, however, a few snails climbed in the low concentrations. CONCLUSIONS: WPN and MNSC both have the effect of killing Lymnaea snails and inhibiting their climbing. By using the immersion method in the field, the active ingredient concentration of 2.00 mg/L of WPN and MNSC for 48 h is appropriate; by using the spray method, the active ingredient content of 1.00 g/m2 of WPN and MNSC for 3 days is appropriate.

[Effect of comprehensive control and management of schistosomiasis at plateaus regions in Yunnan Province].

OBJECTIVE: To evaluate the effect of comprehensive control and management of schistosomiasis at plateaus regions in Yunnan Province. METHODS: Xiaolian and Kangfu villages at plateaus regions where schistosomiasis was endemic were selected as study areas from 2006 to 2011, the schistosomiasis comprehensive control measures were conducted, and these measures included the health education, chemotherapy, stool and water management, grazing forbidden, Oncomelania snail control, etc. combined with the infrastructure of farmland water conservancy, agricultural comprehensive development, adjustment of industry structure, returning farmland to forest, ditch hardening, and aquaculture. RESULTS: At Xiaolian Village, no schistosomiasis patient and livestock were found from 2008; and at Kangfu Village, no schistosomiasis patient was detected from 2006 and no schistosomiasis domestic animal was found from 2008. In 2011, the snail area, percent of frames with living snails, the number of snails, average concentration of living snails, and the highest concentration of living snails descended by 69.99%, 81.86%, 88.86%, 89.71%, 57.95% at Xiaolian Village, and descended by 27.65%, 1.11%, 94.71%, 92.16%, 88.00% at Kangfu Village, respectively, compared with those in 2006. The ratios of infected snail area to snail area were 68.91% in 2006 and 69.13% in 2007 at Xiaolian Village, and 61.73% in 2006 and 43.24% in 2007 at Kangfu Village. There were no infected snails from 2008 in the two villages. CONCLUSION: The comprehensive control and management measures can effectively control the schistosomiasis prevalence at plateaus regions.