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Radioluminescence emission spectra of UVC phosphors and BGO powder reference under 50 kVp X-ray excitation at room temperature.
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Germicidal UVC radiation is a highly effective, chemical-free tool for bacteria inactivation, but its application is limited to reactors and open areas that can accommodate lamps/LEDs and wiring. A relevant example of problematic bacterial colonization within UV-inaccessible confines where chemical techniques have found only limited success is biof...
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... the materials chosen were highly stable mineral systems that are non-water-reactive. 45, 46 Figure 3 shows the RL spectra of the phosphors under 50 kVp X-ray excitation, as well as that of BGO powder -a common semiconductor RL reference material with reported light yield of approximately 9000 photons per MeV absorbed. 40 Activator concentration optimization data may be found in Fig. S3, which confirmed 2 mol% Pr 3+ as most effective. ...
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... stable mineral systems that are non-water-reactive. 45, 46 Figure 3 shows the RL spectra of the phosphors under 50 kVp X-ray excitation, as well as that of BGO powder -a common semiconductor RL reference material with reported light yield of approximately 9000 photons per MeV absorbed. 40 Activator concentration optimization data may be found in Fig. S3, which confirmed 2 mol% Pr 3+ as most effective. Luminescence by Pr 3+ is susceptible to concentration quenching via cross-relaxation, 47, 48 as seen in the weaker luminescence at higher concentrations. Furthermore, lithium codoping is well-known to enhance the luminescence properties of oxide-based lanthanide phosphors due to numerous ...
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... petri dishes covered with polystyrene lids. This setup crudely simulated bacteria within a hypothetical membrane module feed channel with RMBC, in that they were concentrated in close proximity to an RL-active surface. We focused on LaPO4:Pr 3+ as a result of its RL showing the best balance of intensity and germicidal emission spectrum (Fig. 3). Figure 4a shows the inactivation that resulted from directing a 150 kVp X-ray beam through the covered dishes at various radiation doses. A dose of 74 Gy resulted in 2.1-log inactivation by the LaPO4:Pr 3+ coating, attributed to a combination of UVC exposure from RL emission, as well as viability loss from X-ray exposure. 58 With no ...
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... RL spectroscopic analysis in Fig. 3 showed that the three phosphor candidates each differ in emitted spectral distribution, as well as emission intensity under 50 kVp excitation. Both intensity and spectral overlap with bacterial DNA action spectra would affect anti-fouling activity in RMBC. Furthermore, as explained above, material density and elemental composition were ...
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Citations
... 33−35 Thus, here, the TSL and PSL methods were utilized to explore the mechanism of X-ray-induced super-long afterglow emission of β-NaYF 4 :Tb 3+ . Figure 3a illustrates the TSL curves (300−650 K, heating rate: 3 k/min) of the sample measured for different afterglow duration periods (12,24,48,120, and 240 h); there is no significant shift in the position of the TSL peaks, and three obvious TSL peaks occur during the process of thermal excitation, indicating that the material has three relatively stable shallow traps corresponding, respectively, to about 353, 446, and 557 K. The part of the fast decay of afterglow after ceasing X-ray excitation may come from the release of electrons from these shallow traps. ...
... In addition, we explored the relationship between the afterglow integration at different times and the fluorescence intensity of DCF at 536 nm and found that they have a good linear correlation, which further indicates that ROS is generated by the afterglow-induced g-C 3 N 4 , and the long-term afterglow irradiation will cause more ROS generation for effective sterilization treatment. It is well known that PAO1 is a common Gram-negative rod-shaped bacterium that is susceptible to cause diseases in organisms 48 and used here as a processing object (Figures S12 and S13). Experimental data indicate that after being irradiated for 2 min by X-rays under 30 mA and 40 kV and treated with the composite β-NaYF 4 :Tb 3+ −g-C 3 N 4 , the viabilities of PAO1 cells decreased rapidly to 67.14% (Figure 5e,g), while the X-ray irradiation hardly induced harm to the growth of PAO1 in the control group (Figure 5a,g). ...
Here, an X-ray-excited super-long afterglow phosphor β-NaYF 4 :Tb 3+ has been discovered for the first time. After X-ray irradiation, the green emission can persist for more than 240 h. After 120 h, the power density of afterglow reached 3.76 × 10 −6 W·m −2 , which can be clearly observed by the naked eye under dark vision. Also, combined with the results of thermoluminescence and photoluminescence, the super-long afterglow emission of β-NaYF 4 :Tb 3+ can be ascribed to the tunneling model associated with F centers. More importantly, the super-long green afterglow emission of β-NaYF 4 :Tb 3+ has been successfully used as an in vivo light source to activate g-C 3 N 4 for photodynamic therapy and bacteria destruction. Furthermore, super-long persistent luminescence of β-NaYF 4 :Tb 3+ could be repeatedly charged by X-rays for many cycles, which indicates that the phosphors have high photostability under repeated cycles of alternating X-ray irradiation.
... However, application of this method is limited to reactors and open areas that can accommodate lamps/LEDs and wiring. 22 Therefore, the necessity for a new and simple method to mitigate biofouling during membrane processes still exists. ...
Among different types of membrane fouling, biofouling is a critical issue which can significantly reduce the process productivity. If the initial phase of the microorganism attachment to the pore wall is prevented, a remarkable reduction in biofilm formation can be obtained. A novel approach to achieve this goal is the infusion of the porous membrane with an infusion liquid (oil) forming liquid-infused membranes (LIMs). It has been shown that the pore wall during permeation is still covered with the infusion liquid forming so-called liquid-lined pores. The liquid-lining can enhance anti-biofouling performance by preventing direct contact between the microorganisms and pore wall. Here, we investigate the capability of LIMs in mitigation of biofouling by conducting long-term cross-flow filtration experiments at constant flow rate for approximately 20 days. The results show significantly lower increase in transmembrane pressure (TMP) values for LIMs compared to non-infused counterparts (dry membranes). The bacterial growth curves are further investigated by fitting a sigmoidal function (logistic model). Approximately 5 times increase in the lag periodand 7 times decrease in the bacterial growth rate are observed for LIMs compared to dry membranes revealing improved anti-biofouling performance of LIMs.
... In the in vitro inactivation experiment, bacterial activities were the consideration of our choice of inactivated organisms. As we know, staphylococcus aureus (SAU) is a common gram-positive, rod-shaped bacterium which can survive in a diversity of environment conditions that causes disease in plants and animals [22]. To effectively inactivate the bacteria in vitro, TiO 2 was used as a separated photosensitizer dissolved in water in order to create a liquid environment to meet the actual conditions for singlet oxygen production. ...
... 33−35 Thus, here, the TSL and PSL methods were utilized to explore the mechanism of X-ray-induced super-long afterglow emission of β-NaYF 4 :Tb 3+ . Figure 3a illustrates the TSL curves (300−650 K, heating rate: 3 k/min) of the sample measured for different afterglow duration periods (12,24,48,120, and 240 h); there is no significant shift in the position of the TSL peaks, and three obvious TSL peaks occur during the process of thermal excitation, indicating that the material has three relatively stable shallow traps corresponding, respectively, to about 353, 446, and 557 K. The part of the fast decay of afterglow after ceasing X-ray excitation may come from the release of electrons from these shallow traps. ...
... In addition, we explored the relationship between the afterglow integration at different times and the fluorescence intensity of DCF at 536 nm and found that they have a good linear correlation, which further indicates that ROS is generated by the afterglow-induced g-C 3 N 4 , and the long-term afterglow irradiation will cause more ROS generation for effective sterilization treatment. It is well known that PAO1 is a common Gram-negative rod-shaped bacterium that is susceptible to cause diseases in organisms 48 and used here as a processing object (Figures S12 and S13). Experimental data indicate that after being irradiated for 2 min by X-rays under 30 mA and 40 kV and treated with the composite β-NaYF 4 :Tb 3+ −g-C 3 N 4 , the viabilities of PAO1 cells decreased rapidly to 67.14% (Figure 5e,g), while the X-ray irradiation hardly induced harm to the growth of PAO1 in the control group (Figure 5a,g). ...
Here, we have discovered a X-ray excited long afterglow phosphor β-NaYF4: Tb3+. After the irradiation of X-ray, the green emission can persist for more than 240 h. After 36 h, the afterglow intensity arrived at 0.69 mcd•m-2, which can clearly be observed by naked eyes. Even after 84 h, the afterglow emission brightness still reached 0.087 mcd•m-2. Also, combined with the results of thermoluminescence and photoluminescence, the super long afterglow emission of β-NaYF4: Tb3+ can be ascribed to the tunneling model associated with F centers. More importantly, the super long green afterglow emission of β-NaYF4: Tb3+ has been successfully used as in vivo light source to activate g-C3N4 for photodynamic therapy（PDT）and bacteria destruction. Furthermore, super long persistent luminescence of β-NaYF4: Tb3+ could be repeatedly charged by X-ray for many circulations, which indicates that the phosphors have high photo stability under repeated cycles of alternating X-ray irradiation.
... Note that the emission corresponding to the transition of 4f5d → 3 H 5 is partially in the UVC spectral range from visible and NIR to UVC opens up a diversity of potential applications. As is well known, Pseudomonas (P.) aeruginosa PAO1 is a common Gram-negative and monoflagellated bacterium that can survive in a diversity of environment conditions 38 . The organism can cause disease not only in animals and plants but also in humans. ...
Phosphors: Persistent luminescence of UVC light A new category of the luminescent compounds called phosphors displays strong and persistent emission of UVC light, with potential applications including disinfection, drug-release, cancer treatment, and anti-counterfeiting measures. Researchers in China and Japan, led by Hong-Tao Sun at Soochow University in China, created several examples of the new generation of phosphors, which are stimulated into luminescence by X-ray irradiation. The bright UVC emission persists for more than two hours. Theoretical and experimental results suggest generally applicable structural explanations for the luminescent properties. The researchers believe this is the first discovery of persistent phosphors luminescing in the germicidal UVC range. The emitted light is sufficiently strong for sterilization applications. The ability to further stimulate the phosphors with near-infrared light, which can pass through biological tissues, suggests potential for treating cancer or triggering drug release.
... Membrane biofouling, i.e., the build-up of microorganisms and their polymeric matrix on a membrane surface (Shi et al. 2014;Zhang et al. 2015), is a long-standing issue in membrane-based processes (Flemming 2002). When compared with biofouling in membrane bioreactor and reverse osmosis (Guo et al. 2012;Johnson et al. 2016;Malaeb et al. 2013), biofouling in drinking water treatment by ultrafiltration (UF) process is much less investigated (Huang et al. 2009;Shi et al. 2014;Sun et al. 2011) with only a handful of studies being reported (refer to the bibliometric analysis in Fig. S1 of the Supplementary material), which could possibly due to the frequent use of chemically enhanced backwash or chemical cleaning in many UF processes (Chang et al. 2017;Gao et al. 2011b;Porcelli and Judd 2010). Nowadays, availability of antifouling membranes, suitable pretreatment methods and optimized operating parameters have enabled much longer intervals of chemical cleaning (N30 days) in the UF process (Field and Pearce 2011;Huang et al. 2009;Zhang et al. 2016). ...
We investigated biofouling in ultrafiltration (UF) for drinking water treatment and its control by backwashing with chlorinated-water or pure water. By using sodium azide to suppress biological growth, the relative contribution of biofouling to total fouling was estimated, and its value (5.3-56.0%) varied with the feed water, and increased with the increases of filtration time and membrane flux. The biofouling layer could partially remove biodegradable organic matter and ammonia (32.9-74.2%). Backwashing using chlorinated-water partly inactivated the microorganisms (23.8%) but increased the content of extracellular polymeric substances (7.7%) in the biofouling layer. In contrast, backwashing using pure water led to a looser and more porous fouling layer according to optical coherence tomography observation. Consequently, the latter was more effective in reducing fouling resistance (33.41% reduction) compared to backwashing by chlorinated-water (8.6%). These findings reveal the critical roles of biofouling in pollutants removal in addition to membrane permeability, which has important implications for addressing seasonal ammonia pollution.
... The contaminants in different water sources vary, resulting in different types of fouling: particle fouling, inorganic scaling, colloidal fouling, organic fouling and biofouling [9]. Due to the growth of microorganisms, biofouling is one of the major types of fouling found in the operation of an RO system [10][11][12]. For example, about 70% of the seawater RO installations at Middle East [7] and almost 75% of more than 600 autopsied RO membranes all over world [13] suffer biological and organic fouling. ...
With the occurrence of global health events such as COVID-19, the development of high-performance ultraviolet-C (UVC) light sources for efficient and convenient sterilization application holds a promising scientific and engineering prospect. However, discovering reliable and stable luminescent materials capable of converting incident excitation energy to UVC radiation remains a challenge. Herein, we report a new Sr2P2O7:Pr3+ phosphor that exhibits exceptional capabilities in X-ray energy absorption, storage, UVC light conversion, and persistent UVC light emission. Specifically, minutes of X-ray excitation can result in more than 24 h of continuous UVC persistent luminescence when monitored 222 nm emission, realizing far-UVC afterglow for the first time. Intense UVC persistent light emission can be detected by a UVC corona camera in bright indoor and outdoor environments without interference from artificial light or natural sunlight, in consideration of avoidance of spectral overlap with ambient light. Utilizing the self-sustained UVC persistent luminescence form demonstrates an optical conversion strategy for sterilization application. The charged Sr2P2O7:Pr3+ persistent phosphor can effectively inactivate infectious methicillin-resistant Staphylococcus aureus (MRSA) within 30 min in an excitation-free manner, offering new insights into developing UVC light sources for sterilization applications. This work expands the field of UV persistent luminescence research to the far-UVC spectral region and is expected to bring new and power-free solutions to some important applications where far-UVC light is needed, such as sterilization and photodynamic therapy.
Lanthanide-doped phosphors with persistent luminescence have attracted much interest owing to their unique “self-luminescing” feature and broad application potentials. Among all lanthanide ions, Pr3+ exhibits versatile persistent luminescence in a...
