查找使用阿拉丁产品的科研文献

Strong f–f excitation in hafnium germanate: Near-UV LED and cathode beam–pumped red phosphor with thermal robustness

Quansheng Wu,Shanshan Ye,Xufeng Zhou,Jianyan Ding

Developing narrowband red phosphors has always been a frontier topic in the phosphor community. In this study, a novel hafnium germanate red phosphor, BaHfGe 3 O 9 :Eu 3+ , was successfully synthesized by solid-state reaction method. The phase and crystal structure of BaHfGe 3 O 9 were investigated by the Rietveld refinement of powder X-ray powder diffraction. The band structure was analyzed by density functional theory calculations. Most importantly, the luminescence behavior of phosphors under near-ultraviolet (n-UV) light and cathode rays sources was studied in detail to explore the possibility of their applications in white light-emitting diodes and field emission display. The BaHfGe 3 O 9 :Eu 3+ phosphor exhibits strong f–f excitation and excellent thermal robustness due to Eu 3+ localization in the rigid lattice and asymmetric Ba 2+ sites. Under cathode rays and n-UV light excitation, BaHfGe 3 O 9 :Eu 3+ exhibits narrowband red light emission peaked at 610 nm. Moreover, BaHfGe 3 O 9 :Eu 3+ shows excellent saturation resistance and aging resistance. The performance of the LED lamp encapsulated by the BaHfGe 3 O 9 :Eu 3+ phosphor was studied. The results show that BaHfGe 3 O 9 :Eu 3+ is a potential red phosphor for multifunctional applications.

Assembly of a UV-LED induced fluorescence system for rapid determination of amiloride in pharmaceutical tablet and human serum

Wanchao Chen,Yinran Xiong,Wenming Wang,Ting Wu,Long Li,Qidi Kang,Yiping Du

A simple and sensitive fluorescence method has been developed for the determination of amiloride (AMI) in pharmaceutical tablet and human serum with a portable, cost-effective, and easy-to-operate fluorescence system. The fluorescence system was assembled with some optical and electronic devices mainly including a 370 nm light-emitting-diode (LED) as light source, a fiber spectrometer and a Raspberry Pi computer. With the system, AMI produced a strong fluorescence emission at 413 nm, and the emitted intensity can maintain good stability with in a wide pH range from 2 to 8. The proposed method was successfully applied to the determinations of AMI in pharmaceutical tablet and human serum. Their detection limits were 1.67 ng mL −1 and 1.43 ng mL −1 respectively, and the recovery was in the range of 94.06–114.0%. Those obtained results proved that the proposed methods combined with the developed fluorescence system could be employed for the routine analysis of amiloride in pharmaceutical tablet and human serum, especially for the fast analysis of them under field conditions.

A Compact UV-LED-Induced Fluorescence With Short Metal Capillary and Low Light Leakage: Application to Noninvasive Glucose Detection

Weicheng Cai,Zhaolin Li,Hui Huang,Xuejing Li,Jian Zhao,Pengbo Liu,Yajun Wu,Mingchang Liu,Jian Wang

Enhanced ronidazole degradation by UV-LED/chlorine compared with conventional low-pressure UV/chlorine at neutral and alkaline pH values

Xiang-Yun Zou,Yi-Li Lin,Bin Xu,Tian-Yang Zhang,Chen-Yan Hu,Tong-Cheng Cao,Wen-Hai Chu,Yang Pan,Nai-Yun Gao

Ultraviolet light-emitting diodes (UV-LEDs) are promising alternatives to conventional low-pressure UV (LPUV) lamps, mainly because they contain no toxic mercury and have a potential for less energy consumption and longer lifetime. In this study, UV sources including UV-LEDs (265, 275 and 285 nm) and LPUV (254 nm) were compared in UV/chlorine degradation of an organic contaminant , ronidazole (RNZ). UV-LED/chlorine performed better than LPUV/chlorine at neutral and alkaline pH values for RNZ degradation considering the fluence-based rate constant. However, the wall plug efficiencies of UV-LEDs are relatively low at present and must reach about 20–25% to achieve the same electrical energy per order as the LPUV in UV/chlorine degradation of RNZ at pH 7.5 and 9. Neither the contribution of radical (HO· or Cl·) nor the quantum yield of chlorine could explain the different RNZ degradation rate by UV/chlorine at different wavelengths and pH values, while the chlorine photolysis rate should be the key factor for these phenomena. The effects of common co-existing substances in real water (chloride, bicarbonate and natural organic matter) on UV/chlorine degradation of RNZ were similar at different UV wavelengths. Opposite to other oxidants or reductants, the molar absorption coefficient of chlorine increases when the UV wavelength increases from 254 to 285 nm at neutral and alkaline pH, which makes UV-LED/chlorine one of the best choices for UV-LED-based advanced oxidation/reduction processes.

Deep UV-LED induced nitrate-to-nitrite conversion for total dissolved nitrogen determination in water samples through persulfate digestion and capillary electrophoresis

Dongmei Liu,Yu Xiong,Hui Zeng,Jin Xu,Biyu Tang,Yan Li,Min Zhang

Background Capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C 4 D) is widely used for water quality monitoring. However, there is currently no reported CE method for detecting total dissolved nitrogen (TDN), a crucial parameter for assessing water eutrophication . One challenge is the high sulfate concentration (100 mM) introduced during persulfate digestion, leading to overlap of nitrate (from TDN) and poor electrical stacking of nitrate in CE-C 4 D analysis. Results We introduced an in-capillary UV-LED induced photoreaction to convert nitrate to nitrite, which can be baseline-separated from sulfate via the CE method, enabling accurate quantification of nitrate concentration derived from nitrite. A 2 nL post-persulfate digested sample solution within a fused silica capillary was exposed to UV-LED irradiation at the capillary tip. Subsequently, photoreduction-produced nitrite was electrophoretically separated from sulfate in an acidic buffer (pH = 3.7) within the same capillary, followed by contactless conductivity detection. The nitrate-to-nitrite conversion efficiency was influenced by irradiation wavelength, power, and duration, reaching a maximum efficiency of 77.4% when employing two 230 nm LEDs for 5 min. For more general applications, two 255 nm LEDs were used, providing a conversion efficiency of (66.4 ± 3.3)% ( n  = 11) for 5 min of irradiation. The proposed CE-C 4 D method exhibits a detection limit of 13 μM (0.18 mg N/L) and has been successfully employed for TDN determination in lake water samples. Significance This innovative approach not only enhances the attractiveness of the CE-C4D method for the determination of water quality indicators but also highlights the potential for integrating deep-UV LEDs into environmental analysis .

A miniaturized UV-LED array chip-based photochemical vapor generator coupled with a point discharge optical emission spectrometer for the determination of trace selenium

Mengtian Li,Yi Luo,Zhirong Zou,Fujian Xu,Xiaoming Jiang,Xiandeng Hou

An ultraviolet light emitting diode (UV-LED) array chip as the irradiation source for nano-TiO2 catalyzed photochemical vapor generation (PCVG) was combined with a hollow electrode point discharge microplasma optical emission spectrometer (HEPD-OES) to realize instrumental miniaturization, and utilized for quantitative analysis of trace selenium (Se). Under the irradiation of the UV-LED array chip, Se(IV) and Se(VI) could be effectively converted into volatile species in a miniature quartz coil coating with nano-TiO2 on its inner wall as a photocatalyst. Meanwhile, volatile analyte species were totally guided into the hollow electrode and transported into the inside of micro-discharge plasma for excitation and enhanced sensitivity. Experimental conditions of PCVG and HEPD-OES were investigated in detail using an analytical line of Se at 203.98 nm through the peak area integrated for quantitation. Under optimized experimental conditions of 0.6 mL sample volume, 10% (v/v) acetic acid, 370 nm and 50 W LED, and 75 s UV irradiation, Se(IV) and Se(VI) could be detected with the same LODs, 3.9 μg L−1 and 4.1 μg L−1, respectively. The accuracy of the proposed method was validated by the analysis of the Certified Reference Materials (CRMs, GBW(E)080395 and BWB2427-2016) and real water samples. With the advantages of high compatibility, high efficiency, small size and low power consumption, the integration of UV-LED array chip based PCVG and HEPD-OES would be beneficial to fabricate miniaturized and portable devices for field analysis.

UV-LED-driven photocatalytic chlorine activation with typical spinel ferrites for carbamazepine degradation: Critical role of superoxide radicals, disinfection by-product formation and toxicity evaluation

Lei Wang,Minjie Chen,Anhong Cai,Hanxuan Zeng,Xiaoyan Ma,Qingsong Li,Xueyan Li,Jing Deng

Chlorine activation-inefficiency and the generation of disinfection by-products (DBPs) have indeed limited the application of the UV/chlorine process. In this study, zinc ferrite nanorods (ZFO-R) with excellent photovoltaic properties were successfully prepared for the construction of a novel heterogeneous UV-LED-driven chlorine activation system. The addition of ZFO-R increased the first-order reaction rate constant for the degradation of carbamazepine (CBZ) by the UV-LED/chlorine process by 6 times. Mechanism investigation indicated that superoxide radicals (O 2 − ) dominated the generation of hydroxyl radicals (HO ) and chlorine radicals (Cl ) in the system by promoting the activation of HClO/ClO − , and the increased yields of HO and Cl enhanced their contribution to the degradation of the target pollutants. Importantly, the efficient activation of chlorine not only promoted the generation of reactive species but also inhibited the formation of DBPs by shorting the contact time between chlorine and precursors, which effectively controlled the toxicity of the reaction system. This work proposes a reliable strategy for inhibiting DBPs formation in the UV/chlorine process and broadens the application of spinel ferrites in environmental remediation, achieving efficient and reliable purification of actual micropolluted water bodies.

Long path gas-phase absorption detector using a 235 nm deep-UV LED source for the determination of nitrite, nitrate and total dissolved nitrogen in waters

Yuzhe LI,Hui ZENG,Jin XU,Yan LI,Lishan ZHANG,Ying LIANG,Min ZHANG

A gas-phase absorption detector (GPAD) was developed using a surface-mount 235 nm light-emitting diode (LED) as the light source. Modules for housing the LED and photodiode were three-dimensional printed. A stainless-steel tube was used as the detection cell. To perform long path absorption detection, a fused silica full-ball lens (5 mm diameter) was employed to collimate the light produced by the UV-LED with a viewing angle of 120°. The light attenuation coefficient ( α b ) was measured to be 0.025±0.001 cm −1 . The optimum path length with the maximum signal-to-noise ratio was obtained at ca. 80 cm. This result agreed with the theoretical calculation for optimum path length, i.e., 2/ α b . The GPAD was coupled with an automated analysis system and applied to detect nitrite in water. The automated system added citric acid and ethanol into a water sample, and nitrite was converted to gaseous nitrous acid (HONO), which has a strong absorption at 235 nm. The produced HONO was purged with air, followed by water removal, and then detected with the GPAD. The method was used to detect nitrate and total dissolved nitrogen (TDN) in water as well. Nitrate was reduced to nitrite through a photo-induced reaction with a conversion efficiency of ca. 60%. TDN was converted to nitrate by using an alkaline persulfate digestion method, followed by photoreduction to nitrite, and detected by using the automated system. The limits of detection were 0.4 μM, 3.9 μM, and 6.7 μM (94 μg N/L) for nitrite, nitrate, and TDN, respectively.

Synthesis and properties of photocurable polyurethane acrylate for textile artificial leather

Junxiang Ma,Kunyi Cai,Chao Yang,Meiqi Li,Xiaopeng Pan,Yi Huang,Juming Yao,Jinhuan Zheng,Jianzhong Shao

A new photocurable coating process that combines ultra violet light emitting diode (UV-LED) and deliberately synthesized photocurable polyurethane acrylate (PUA) was developed in this study. The structures of the PUA were characterized by attenuated total reflectance flourier transformed infrared (ATR-FTIR), porton nuclear magnetic resonance ( 1 H NMR) and gel permeation chromatography (GPC). The structure-activity relationship of such PUA was studied by rheological measurements, photopolymerization performance, and mechanical tests. By adjusting the molecular weight and the number of functional groups in the PUA, balanced the wear resistance and flexibility of the photocured coatings were achieved. The optimal formula for photocurable coating was obtained as follows: the R-value (the molar ratio of –NCO/–OH) of PUA was 1.3, the ratio of PUA/HEA (2-hydroxyethyl acrylate) was 60 wt%/40 wt%, and the ratio of end-capped agent HEA/PETA (pentaerythritol triacrylate) was 2/1. With the optimized photocurable coating formula, textile artificial leathers were fabricated and exhibited excellent colorfastness to rubbing, and Martindale abrasion resistance and satisfied fabric handle.