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1.
Plant Physiol ; 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38758108

RESUMO

Acidity is a key factor controlling fruit flavor and quality. In a previous study, combined transcriptome and methylation analyses identified a P3A-type ATPase from apple (Malus domestica), MdMa11, which regulates vacuolar pH when expressed in Nicotiana benthamiana leaves. In this study, the role of MdMa11 in controlling fruit acidity was verified in apple calli, fruits, and plantlets. In addition, we isolated an AP2 domain-containing transcription factor, designated MdESE3, based on yeast one-hybrid (Y1H) screening using the MdMa11 promoter as bait. A subcellular localization assay indicated that MdESE3 localized to the nucleus. Analyses of transgenic apple calli, fruits, and plantlets, as well as tomatoes, demonstrated that MdESE3 enhances fruit acidity and organic acid accumulation. Meanwhile, chromatin immunoprecipitation quantitative PCR (ChIP-qPCR), luciferase (LUC) transactivation assays, and GUS reporter assays indicated that MdESE3 could bind to the ethylene-responsive element (ERE; 5'-TTTAAAAT-3') upstream of the MdMa11 transcription start site, thereby activating its expression. Furthermore, MdtDT, MdDTC2, and MdMDH12 expression increased in apple fruits and plantlets overexpressing MdESE3 and decreased in apple fruits and plantlets where MdESE3 was silenced. The ERE was found in MdtDT and MdMDH12 promoters, but not in the MdDTC2 promoter. The Y1H, LUC transactivation assays, and GUS reporter assays indicated that MdESE3 could bind to the MdtDT and MdMDH12 promoters and activate their expression. Our findings provide valuable functional validation of MdESE3 and its role in the transcriptional regulation of MdMa11, MdtDT, and MdMDH12 and malic acid accumulation in apple.

2.
Dalton Trans ; 52(35): 12526-12533, 2023 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-37608690

RESUMO

Sunlight-like full-spectrum phosphor-converted light-emitting diodes (pc-LEDs) require near-infrared (NIR) emission bands to fill the spectrum gap and consequently propel their widespread applications. Although fluoride NIR phosphors have been increasingly investigated, balancing high quantum efficiency (QE), high thermal stability, and wideband NIR emission to obtain excellent overall performance in a single system is still a challenge for Cr3+-doped fluoride NIR phosphor and is significant for direct utilization. Herein, a high-efficiency and thermally stable broadband NIR emission was realized in a novel LiSrGaF6:Cr3+ fluoride phosphor benefitting from a relatively weak crystal field and electron-phonon coupling effect. Upon blue light excitation, the ultra-broad NIR luminescence ranging from 650 to 1150 nm can be achieved with an FWHM of 149 nm peaking at ∼813 nm. Furthermore, this system possesses a high QE of up to 76.88% and its emission intensity at 423 K still maintains 61.62% of its initial intensity at room temperature. An NIR output power of 42.82 mW and photoelectric conversion efficiency of 14.27% of NIR pc-LED devices have also been presented based on this NIR phosphor, demonstrating its possible application in compact nonvisible light sources. In addition, a highly continuous sunlight-like vis-NIR pc-LED was further constructed by employing a blue chip with commercial cyan (BaSi2O2N2:Eu2+), yellow (Y3Al5O12:Ce3+), red (CaAlSiN3:Eu2+), and this LiSrGaF6:Cr3+ NIR phosphor. The as-obtained pc-LED exhibits an ultra-broad spectrum ranging from 400 nm to 1000 nm, exhibiting a higher color reproduction with a color rendering index (CRI) of 95.1 and luminous efficiency (LE) of 50.22 lm W-1. These results indicate that LiSrGaF6:Cr3+ phosphor can be a promising NIR phosphor candidate for high-quality sunlight-like full-spectrum lighting and infrared night vision technology.

3.
Dalton Trans ; 52(17): 5587-5596, 2023 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-37013912

RESUMO

For high-efficiency lighting and wide color gamut backlight display, high-quality narrow-band red phosphors for WLEDs are still in high demand. Herein, a novel red-emitting fluoride phosphor Cs2NaGaF6:Mn4+ was successfully synthesized by a simple two-step co-precipitation method and exhibits ultra-intense zero-phonon lines (ZPLs) and long wavelength phonon sidebands under 468 nm blue light irradiation. The ZPL emission peak of Cs2NaGaF6:Mn4+ was located at 627 nm, which is much stronger than its υ6 vibration peak, more matchable with the eye-sensitive region of humans, and beneficial for obtaining higher luminous efficiency of WLEDs. Interestingly, the υ6 vibration peak of this red phosphor is at 636.5 nm, which is larger than that of the common fluoride phosphor A2BF6:Mn4+ (usually at about 630 nm, represented by K2SiF6:Mn4+) at about 6.5 nm. Thanks to the longer wavelength of the υ6 vibration peak, the chromaticity coordinates (0.7026, 0.2910) with a larger x-coordinate value were realized, leading to a potentially wider color gamut of WLEDs. In addition, this phosphor has high thermal stability and its emission intensity at 423 K remains 93.7% of the initial intensity at room temperature. The lumen efficiency of WLED1 packaged with a mixture of Cs2NaGaF6:Mn4+ and YAG:Ce3+ on the InGaN blue chip is 115.7 lm W-1 with the color temperature (Tc) = 3390 K and the colour rendering index (Ra) = 92.5 under 20 mA driving current. The chromaticity coordinates of WLED2 packaged with Cs2NaGaF6:Mn4+ and ß-SiAlON:Eu2+ on the InGaN blue chip are (0.3149, 0.3262) and the calculated color gamut is up to 118.4% (NTSC). These results indicate that Cs2NaGaF6:Mn4+ red phosphors have promising applications in the high-quality lighting and display fields.

4.
Int Urol Nephrol ; 54(1): 225-235, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34138419

RESUMO

OBJECTIVE: To explore the effect of miR-93-mediated Wnt/ß-catenin pathway on the vascular calcification (VC) of chronic renal failure (CRF). METHODS: SD rats were utilized to construct CRF models and divided into Control, CRF, CRF + LV (lentiviral vector)-miR-93 and CRF + LV-Con groups. Renal tissues collected from rats were performed hematoxylin and eosin (HE) staining and Masson staining, while the abdominal aorta was dissected for alizarin red staining and Von Kossa staining. VC-related genes were determined by qRT-PCR while Wnt/ß-catenin pathway-related proteins were examined by Western blotting. RESULTS: As compared to Control group, the serum levels of blood urea nitrogen (BUN), serum creatinine (Scr), phosphorus (P), cystatin C (Cys-C) and 24-h urea protein (24 h Upro), and the scores of renal interstitial lesion and fibrotic area in rats from CRF group were elevated, with the increased calcified area of aorta as well as the enhanced calcium content and ALP. Meanwhile, rats in the CRF group had up-regulated expression of OPN, OCN, RUNX2 and BMP-2 and down-regulated expression of miR-93. As for the expression of Wnt/ß-catenin pathway, rats in the CRF group had sharp increases in the protein expression of TCF4 and ß-catenin, while α-SMA was down-regulated. However, changes of the above were reversed in rats from CRF + LV-miR-93 group, and TCF4 was confirmed to be a target gene of miR-93. CONCLUSION: MiR-93, via inhibiting the activity of Wnt/ß-catenin pathway by targeting TCF4, can improve the renal function of CRF rats, thereby mitigating the vascular calcification of CRF.


Assuntos
Falência Renal Crônica/complicações , MicroRNAs/fisiologia , Calcificação Vascular/etiologia , Via de Sinalização Wnt/fisiologia , beta Catenina/fisiologia , Animais , Masculino , Ratos , Ratos Sprague-Dawley
5.
Kidney Int Rep ; 6(9): 2525, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34490410

RESUMO

[This corrects the article DOI: 10.1016/j.ekir.2020.07.010.][This corrects the article DOI: 10.1016/j.ekir.2021.07.022.].

6.
Kidney Int Rep ; 6(9): 2526-2531, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34490411

RESUMO

[This corrects the article DOI: 10.1016/j.ekir.2021.07.021.][This corrects the article DOI: 10.1016/j.ekir.2020.07.010.].

7.
BMC Nephrol ; 22(1): 304, 2021 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-34493223

RESUMO

BACKGROUNDS: Diabetic nephropathy (DN) is one of the most important clinical complications of diabetes mellitus (DM) and is the most common cause of end-stage renal disease. Currently, there is no highly effective medicine that can prevent, halt, or reverse the progressive course of DN. Initial clinical data showed that Tripterygium glycosides (TGs), a traditional Chinese medicine, can decrease proteinuria in patients with DN. OBJECTIVES: The objective of the present study is to investigate the efficacy and safety of TGs for the treatment of DN through meta-analysis of randomized controlled trials (RCTs). METHODS: All RCTs of TGs for DN were collected from The China National Knowledge Infrastructure (CNKI), PubMed, Web of Science, Wanfang Data, Chinese Biomedical Literature Database (CBM), China Science and Technology Journal Database (VIP) by setting the study inclusion and elimination standards. Two reviewers evaluated the quality of the trials and extracted the data independently. RevMan 5.4 software was used for meta-analyses. The primary outcome was a change in 24-hours urinary total protein (24 h TUP). RESULTS: 26 RCTs with 1824 participants were identified. Studies were assessed using the Cochrane risk of bias tool. The overall effects showed that TGs was compared with the controls, TGs showed significant effects in reducing 24 h TUP [WMD = -0.84, 95 % CI (-1.09, -0.59)], elevating serum albumin [WMD = 2.88, 95 % CI (1.87, 3.90)], and the total efficiency [OR = 4.08, 95 % CI (2.37, 7.04)]. This effect was consistent across the subgroups of period of intervention. CONCLUSIONS: The present research showed that TGs was significantly associated with improvement of renal function in patients with DN. TGs offers a novel approach to the treatment of DN, more high-quality RCTs are needed for a better understanding of the role of TGs in DN therapy.


Assuntos
Nefropatias Diabéticas/tratamento farmacológico , Glicosídeos/uso terapêutico , Tripterygium , Viés , Nitrogênio da Ureia Sanguínea , Creatinina/sangue , Nefropatias Diabéticas/fisiopatologia , Glicosídeos/efeitos adversos , Humanos , Proteinúria/tratamento farmacológico , Ensaios Clínicos Controlados Aleatórios como Assunto
8.
Dalton Trans ; 49(32): 11290-11299, 2020 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-32761036

RESUMO

An oxyfluoride red phosphor Cs2MoO2F4:Mn4+ was synthesized via a facile co-precipitation route with a certain molecular ratio of CsF and MoO3. X-ray diffraction analysis and its Rietveld refinement reveal that Cs2MoO2F4:Mn4+ crystallized in an orthorhombic structure with the Amam (63) space group. Upon blue light excitation, Cs2MoO2F4:Mn4+ exhibits a series of sharp red emission lines around ∼634 nm and the zero-phonon line (ZPL) is visible at 619 nm. The optimal doping amount of Mn4+ in Cs2MoO2F4 is 1.12%, and the decay curves show a good fit with the single exponential decay model. The fluorescence lifetime of the synthesized phosphors is relatively short and calculated as 3.18 to 2.46 ms, the Mn4+ ions in Cs2MoO2F4 experience a strong crystal field strength with a Dq/B of ∼4.87, and the distinct nephelauxetic ratio ß1 is determined to be ∼1.0226. The thermal quenching mechanism of Mn4+ was also studied. Furthermore, by using the as-synthesized Cs2MoO2F4:Mn4+ phosphor as a red component and ß-SiALON as a green light component, a WLED was fabricated with a high luminous efficacy of 114.70 lm·W-1 and wide color gamut of 109.1% of the National Television Standard Committee (NTSC) value. Hence, the Cs2MoO2F4:Mn4+ phosphor with a short fluorescence lifetime could potentially be an efficient red compensator for application in rapid-response backlight displays.

9.
Chem Asian J ; 15(20): 3326-3337, 2020 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-32776694

RESUMO

Fluoride phosphors as red components for warm white LEDs have attracted a tremendous amount of research attention. But these phosphors are extremely sensitive to moisture, which seriously limits their practical industrial applications. To tackle this problem, unlike all the straightforward preventive strategies, a reverse strategy "Good comes from bad" was successfully developed to treat the degraded K2 SiF6 : Mn4+ (D-KSFM) phosphor in the present study, which not only completely restores the luminescence properties, but also significantly enhances the moisture resistance at the same time. After treatment with an oxalic acid solution as restoration modifier, the emission intensity of the D-KSFM phosphor can be restored to 103.7% of the original K2 SiF6 : Mn4+ red phosphor (O-KSFM), and the moisture resistance is remarkably improved. The restored K2 SiF6 : Mn4+ (R-KSFM) maintains approximately 62.3% of its initial relative emission intensity after immersing in deionized water for 300 min, while the reference commercial K2 SiF6 : Mn4+ with a protective coating (C-KSFM) is only 33.2%. As a proof of general applicability, this strategy was also conducted to K2 TiF6 : Mn4+ phosphor, which is less moisture-stable than K2 SiF6 : Mn4+ . The luminescence intensity of the degraded K2 TiF6 : Mn4+ (D-KTFM) phosphor can be restored to 162.6% of original level of the K2 TiF6 : Mn4+ synthesized through a cation exchange approach without any treatment (O-KTFM). The emission intensity of the restored K2 TiF6 : Mn4+ (R-KTFM) phosphor retains 62.8% of its initial emission intensity after soaking in deionized water for 300 min. Finally, the R-KSFM phosphors were packaged into white light-emitting diodes with blue InGaN chips and Y3 Al5 O12 : Ce3+ yellow phosphors. The WLEDs display excellent color rendition with higher color rendering index, lower color temperature (WLED-II: Ra =83.6, R9 =57.3, 3743 K, ηl =199.68 lm/W; WLED-III: Ra =90.4, R9 =94.2, 2892 K, ηl =183.3 1 m/W). The above results show that the reverse strategy can be applied in those phosphor materials with poor moisture resistance to restore luminescence properties and improve moisture resistance without excessively care about the deterioration during the production, storage and transportation.

10.
Kidney Int Rep ; 5(9): 1416-1421, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32838083

RESUMO

BACKGROUND: There is a paucity of information regarding severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in patients undergoing maintenance hemodialysis. We aimed to estimate the cumulative attack rate of SARS-CoV-2 in hemodialysis patients in China using a serological test. METHODS: We enrolled all hemodialysis patients from 8 hemodialysis facilities in Honghu and Jingzhou of Hubei province and Guangzhou and Foshan of Guangdong province in China. We screened these patients for SARS-CoV-2 infection by both a reverse-transcriptase polymerase chain reaction (RT-PCR) test for viral RNA and a serological test for IgG and IgM antibodies. Data on demographics and clinical characteristics were collected via case report forms. We also enrolled the health care workers from the participating hospitals and compared the seropositive rate between hemodialysis patients and health care workers in the same region. RESULTS: Among 1542 hemodialysis patients, 5 (0.32%) and 51 (3.3%) were tested positive by the RT-PCR test and the serological test, respectively. The seropositive rate in Hubei (3.6%) was higher than that in Guangdong (2.8%), although the difference was not statistically significant (P = 0.5). Most of the seropositive patients were asymptomatic. Independent risk factors for SARS-CoV-2 infection were being older than 65 years, having manifestation of lung infection in imaging examinations, and having a lower level of serum albumin. In comparison, the seropositive rate in 3205 health care workers was 1.2%,which was significantly lower than that observed in the hemodialysis patients (P < .001). CONCLUSION: The cumulative rate of SARS-CoV-2 infection in hemodialysis patients in China was high at 3.3%. Serological test detected 10 times more cases of SARS-CoV-2 infection than the RT-PCR test and should be the preferred tool for estimating the prevalence of coronavirus disease 2019 (COVID-19).

12.
Nat Med ; 26(8): 1193-1195, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32504052

RESUMO

Detection of asymptomatic or subclinical novel human coronavirus SARS-CoV-2 infection is critical for understanding the overall prevalence and infection potential of COVID-19. To estimate the cumulative prevalence of SARS-CoV-2 infection in China, we evaluated the host serologic response, measured by the levels of immunoglobulins M and G in 17,368 individuals, in the city of Wuhan, the epicenter of the COVID-19 pandemic in China, and geographic regions in the country, during the period from 9 March 2020 to 10 April 2020. In our cohorts, the seropositivity in Wuhan varied between 3.2% and 3.8% in different subcohorts. Seroposivity progressively decreased in other cities as the distance to the epicenter increased. Patients who visited a hospital for maintenance hemodialysis and healthcare workers also had a higher seroprevalence of 3.3% (51 of 1,542, 2.5-4.3%, 95% confidence interval (CI)) and 1.8% (81 of 4,384, 1.5-2.3%, 95% CI), respectively. More studies are needed to determine whether these results are generalizable to other populations and geographic locations, as well as to determine at what rate seroprevalence is increasing with the progress of the COVID-19 pandemic. Serologic surveillance has the potential to provide a more faithful cumulative viral attack rate for the first season of this novel SARS-CoV-2 infection.


Assuntos
Anticorpos Antivirais/sangue , Infecções por Coronavirus/sangue , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Pneumonia Viral/sangue , Anticorpos Antivirais/imunologia , Betacoronavirus/patogenicidade , COVID-19 , China/epidemiologia , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/virologia , Feminino , Pessoal de Saúde , Humanos , Imunoglobulina G/imunologia , Imunoglobulina M/imunologia , Masculino , Pessoa de Meia-Idade , Pandemias , Pneumonia Viral/epidemiologia , Pneumonia Viral/virologia , SARS-CoV-2 , Estudos Soroepidemiológicos
13.
Med Sci Monit ; 26: e924372, 2020 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-32592386

RESUMO

BACKGROUND Diabetic nephropathy (DN) is one of the chronic microvascular complications of diabetes. This study focused on the protective effects of pyrroloquinoline quinone (PQQ) on oxidative stress (OS) in DN. MATERIAL AND METHODS Thirty Sprague Dawley rats were randomly selected for this study; 10 rats were randomly selected as the control group. The other 20 rats were established for the DN model. After establishment of the successful model, the DN model rats were randomly divided into a DN group and a PQQ group. The PQQ group was fed with a PQQ diet. Blood urea nitrogen (BUN), serum creatinine (SCr), and blood glucose levels were measured in each group, and OS-related protein expression and AMPK pathway were detected by western blot and quantitative real-time polymerase chain reaction (qRT-PCR). At the same time, we constructed a DN model by culturing NRK-52E cells with high glucose to detect the molecular mechanisms. RESULTS The kidney function of the DN group was significantly decreased, SCr and BUN levels were significantly increased, and the renal structure under the microscope was disordered, and interstitial edema was obvious. The expression of SOD1, SOD2, GPX1, and GPX3 were significantly decreased, and the level of reactive oxygen species (ROS) was significantly increased. PQQ treatment can effectively alleviate renal function, improve structural damage, and inhibit OS. In vivo, PQQ can effectively inhibit high glucose-induced OS damage and activate the AMPK/FOXO3a signaling pathway. CONCLUSIONS PQQ improves renal structural damage and functional damage, and protects kidney cells in DN by inhibiting OS, which may be related to activating the AMPK/FOXO3a pathway.


Assuntos
Diabetes Mellitus Experimental/metabolismo , Nefropatias Diabéticas/genética , Sequestradores de Radicais Livres/farmacologia , Rim/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Cofator PQQ/farmacologia , Adenilato Quinase/efeitos dos fármacos , Adenilato Quinase/metabolismo , Animais , Glicemia/metabolismo , Nitrogênio da Ureia Sanguínea , Linhagem Celular , Creatinina/metabolismo , Diabetes Mellitus Experimental/complicações , Nefropatias Diabéticas/etiologia , Nefropatias Diabéticas/metabolismo , Nefropatias Diabéticas/patologia , Proteína Forkhead Box O3/efeitos dos fármacos , Proteína Forkhead Box O3/metabolismo , Glutationa Peroxidase/efeitos dos fármacos , Glutationa Peroxidase/genética , Rim/metabolismo , Rim/patologia , Distribuição Aleatória , Ratos , Espécies Reativas de Oxigênio/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Transdução de Sinais , Superóxido Dismutase/efeitos dos fármacos , Superóxido Dismutase/genética , Superóxido Dismutase-1/efeitos dos fármacos , Superóxido Dismutase-1/genética , Glutationa Peroxidase GPX1
14.
Dalton Trans ; 49(6): 1935-1946, 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-31971188

RESUMO

A novel Sr2MgB2O6 (SMBO) green-emitting phosphor co-doped with Ce3+-Tb3+ was synthesized at 950 °C via solid-state reactions, and the ultra-narrow-band green emission of Tb3+ was significantly enhanced almost 20 times via energy transfer from Ce3+ to Tb3+. It was found to have a broad excitation band (250 to 400 nm), and the full width at half-maximum (FWHM) of the dominant green emission band around 544 nm was only about 10 nm. The electronic band gap of the SMBO matrix was calculated by density functional theory (DFT) to be 4.60 eV, and this was well verified by the diffuse reflection spectra results. Furthermore, the composition-optimized phosphor SMBO:0.05Ce3+,0.05Tb3+ exhibits excellent thermal quenching resistance (75.3% intensity at 423 K) and relatively high external quantum efficiency (EQE = 48.92%). Finally, two white light-emitting diode (WLED) packages were fabricated via combining a 365 nm n-UV chip, the optimal sample and commercial blue and red phosphors to assess the application potential of the phosphors. The test results indicate that the obtained WLEDs-1 fabricated with K2SiF6:Mn4+ has an outstanding color rendering index (Ra = 85.7) and Commission Internationale de L'Eclairage (CIE) coordinates (0.3242, 0.3334). Meanwhile, the color gamut can reach 87% of the National Television Standards Committee (NTSC) CIE 1931 color gamut. WLEDs-2 fabricated with red emitting CaAlSiN3:Eu2+ produced warm white light with color coordinates of (0.3792, 0.3810), a high color rendering index of 82.3, and a low correlated color temperature of 4065 K. These results reveal the broad prospects of this phosphor for LED-based applications.

15.
Inorg Chem ; 58(22): 15207-15215, 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31652053

RESUMO

To improve absorption efficiency (AE) and subsequently improve external quantum efficiency (EQE) remains one of the significant challenges for Mn4+-doped red-emitting fluoride phosphors. In this study, we propose to use Mn4+ as a part of matrix to enhance the AE of fluoride phosphors. Red-emission phosphors Cs2MnF6, Cs2MnF6:Sc3+, and Cs2MnF6:Si4+ were synthesized successfully by a coprecipitation method. The Rietveld refinement of X-ray diffraction reveals that this red phosphor exhibits a cubic structure in Fm3̅m space group. Owing to Mn4+ being a part of matrix, this kind of red phosphor possesses an extremely high AE, which can be promoted to 88%. The doping of Sc3+ and Si4+ ions into Cs2MnF6 can effectively increase the luminescence intensity to 253 and 232%, respectively, relative to that of Cs2MnF6. The relative emission intensity of Cs2MnF6:5%Si4+ red phosphor preserves about 115% when temperature rises to 175 °C. By employing Cs2MnF6:5%Si4+ as a red-emitting component, high-performance LED-1 with Ra = 86.2, R9 = 82.1 and CCT = 3297 K, and LED-2 with an ultrawide color gamut (NTSC value of 122.3% and rec. 2020 value of 91.3%) are obtained. This work may provide a new idea to explore a new type of fluoride phosphor with high EQE for high-performance white-light-emitting diodes.

16.
Dalton Trans ; 47(45): 16048-16056, 2018 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-30206588

RESUMO

The addition of a red-emitting phosphor to YAG:Ce3+-based white light-emitting diodes (WLEDs) greatly facilitates their applications in the field of high-color-rendering-index warm solid-state lighting. It is highly desirable to develop a red phosphor with satisfactory spectral features and low synthesis cost. In this study, a novel non-rare-earth and nonequivalent doping type of Cs2NbOF5:Mn4+ oxyfluoride red-emitting phosphor with high luminous efficiency was obtained via a facile room-temperature co-precipitation method, and its morphology and luminescent properties were investigated in detail. The Cs2NbOF5:Mn4+ phosphor with micro-rod-like morphology exhibited broad band absorption at blue light region (∼474 nm) and narrow bandwidth emissions at red region (∼633 nm). The color purity of the Cs2NbOF5:Mn4+ phosphor was calculated to be about 99%, and the internal quantum yield (QY) under 474 nm excitation was 63.4%. The concentration quenching of Mn4+ in Cs2NbOF5 matrix was mainly due to dipole-dipole interactions, and the activation energy of temperature quenching was calculated to be ∼0.2610 eV. The demonstration of a blue InGaN LED chip in combination with a blend of newly developed Cs2NbOF5:Mn4+ red phosphor and YAG:Ce3+ yellow phosphor greatly decreased the correlated color temperature (CCT) from 6255 to 3517 K while significantly improving the color rendering index (CRI) from 72.5 to 87.5. It deserves to be mentioned that the brand-new matrix to phosphor in the present study can be extended to various niobium/tantalum oxyfluoride series, which is very helpful for developing and designing new red phosphors.

17.
ACS Appl Mater Interfaces ; 10(23): 19783-19795, 2018 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-29781267

RESUMO

A new generation of red phosphors of complex fluoride matrices activated with Mn4+ has gained a broad interest in getting high color quality and low color temperature of solid-state white light-emitting diodes (WLEDs). However, besides their instability toward moisture, the extremely irregular and nonuniform morphologies of these phosphors have limited their practical industry applications. In the present study, a novel type of K3ScF6:Mn4+ red phosphor with highly regular, uniform, and high color purity was obtained successfully through a facile coprecipitation route under mild conditions. The crystal structure was identified with aids of the powder X-ray diffraction, Rietveld refinement, and density functional theory calculations. The prototype crystallizes in the space group Fm3 m with a cubic structure, and the lattice parameters are fitted well to be a = b = c = 8.4859(8) Å and V = 611.074(2) Å3. The Mn4+ ions occupy Sc3+ sites and locate at the centers of the distorted ScF6 octahedrons. A wide band gap of approximately 6.15 eV can provide sufficient space to accommodate impurity energy levels. Unlike most other Mn4+ ion-activated fluoride phosphors, the as-prepared K3ScF6:Mn4+ phosphors demonstrate highly uniform and regular morphologies with shapes transforming from cube to octahedron with increasing Mn4+ ion concentration. Under blue light excitation, the as-prepared K3ScF6:Mn4+ sample exhibits intense sharp-line red fluorescence (the strongest peak located at 631 nm) with high color purity. An excellent recovery in luminescence upon heating and cooling processes implies high stability of K3ScF6:Mn4+. Furthermore, a warm WLED fabricated with blue GaN chips merged with the mixture of K3ScF6:Mn4+ and the well-known commercial YAG:Ce3+ yellow phosphors exhibits wonderful color quality with lower correlated color temperature (3250 K) and higher color-rendering index ( Ra = 86.4). These results suggest that the K3ScF6:Mn4+ phosphor possesses stupendous potentiality for practical applications.

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