Fungal invasion-induced accumulation of salicylic acid promotes anthocyanin biosynthesis through MdNPR1-MdTGA2.2 module in apple fruits.

In the field, necrosis area induced by pathogens is usually surrounded by a red circle in apple fruits. However, the underlying molecular mechanism of this phenomenon remains unclear. In this study, we demonstrated that accumulated salicylic acid (SA) induced by fungal infection promoted anthocyanin biosynthesis through MdNPR1-MdTGA2.2 module in apple (Malus domestica). Inoculating apple fruits with Valsa mali or Botryosphaeria dothidea induced a red circle surrounding the necrosis area, which mimicked the phenotype observed in the field. The red circle accumulated a high level of anthocyanins, which was positively correlated with SA accumulation stimulated by fungal invasion. Further analysis showed that SA promoted anthocyanin biosynthesis in a dose-dependent manner in both apple calli and fruits. We next demonstrated that MdNPR1, a master regulator of SA signaling, positively regulated anthocyanin biosynthesis in both apple and Arabidopsis. Moreover, MdNPR1 functioned as a co-activator to interact with and enhance the transactivation activity of MdTGA2.2, which could directly bind to the promoters of anthocyanin biosynthetic and regulatory genes to promote their transcription. Suppressing expression of either MdNPR1 or MdTGA2.2 inhibited coloration of apple fruits, while overexpressing either of them significantly promoted fruit coloration. Finally, we revealed that silencing either MdNPR1 or MdTGA2.2 in apple fruits repressed SA-induced fruit coloration. Therefore, our data determined that fungal-induced SA promoted anthocyanin biosynthesis through MdNPR1-MdTGA2.2 module, resulting in a red circle surrounding the necrosis area in apple fruits.

Identification of Hsp20 gene family in Malus domestica and functional characterization of Hsp20 class I gene MdHsp18.2b.

Heat shock protein 20 (Hsp20) is a small molecule heat shock protein that plays an important role in plant growth, development, and stress resistance. Little is known about the function of Hsp20 family genes in apple (Malus domestica). Here, we performed a genome-wide analysis of the apple Hsp20 gene family, and a total of 49 Hsp20s genes were identified from the apple genome. Phylogenetic analysis revealed that the 49 genes were divided into 11 subfamilies, and MdHsp18.2b, a member located in the CI branch, was selected as a representative member for functional characterization. Treatment with NaCl and Botryosphaeria dothidea (B. dothidea), the causal agent of apple ring rot disease, significantly induced MdHsp18.2b transcription level. Further analysis revealed that overexpressing MdHsp18.2b reduced the resistance to salt stress but enhanced the resistance to B. dothidea infection in apple calli. Moreover, MdHsp18.2b positively regulated anthocyanin accumulation in apple calli. Physiology assays revealed that MdHsp18.2b promoted H2O2 production, even in the absence of stress factors, which might contribute to its functions in response to NaCl and B. dothidea infection. Hsps usually function as homo- or heterooligomers, and we found that MdHsp18.2b could form a heterodimer with MdHsp17.9a and MdHsp17.5, two members from the same branch with MdHsp18.2b in the phylogenetic tree. Therefore, we identified 49 Hsp20s genes from the apple genome and found that MdHsp18.2b was involved in regulating plant resistance to salt stress and B. dothidea infection, as well as in regulating anthocyanin accumulation in apple calli.

Functions of Phytochrome Interacting Factors (PIFs) in Adapting Plants to Biotic and Abiotic Stresses.

Plants possess the remarkable ability to sense detrimental environmental stimuli and launch sophisticated signal cascades that culminate in tailored responses to facilitate their survival, and transcription factors (TFs) are closely involved in these processes. Phytochrome interacting factors (PIFs) are among these TFs and belong to the basic helix-loop-helix family. PIFs are initially identified and have now been well established as core regulators of phytochrome-associated pathways in response to the light signal in plants. However, a growing body of evidence has unraveled that PIFs also play a crucial role in adapting plants to various biological and environmental pressures. In this review, we summarize and highlight that PIFs function as a signal hub that integrates multiple environmental cues, including abiotic (i.e., drought, temperature, and salinity) and biotic stresses to optimize plant growth and development. PIFs not only function as transcription factors to reprogram the expression of related genes, but also interact with various factors to adapt plants to harsh environments. This review will contribute to understanding the multifaceted functions of PIFs in response to different stress conditions, which will shed light on efforts to further dissect the novel functions of PIFs, especially in adaption to detrimental environments for a better survival of plants.

Inhibitory Effect of Tea Saponin on Major Apple-Disease-Inducing Fungi.

Plant secondary metabolites are well known for their biological functions in defending against pathogenic microorganisms. Tea saponin (TS), one type of secondary metabolite of the tea plant (Camellia sinensis), has been shown to be a valuable botanical pesticide. However, its antifungal activity in controlling the fungi Valsa mali, Botryosphaeria dothidea, and Alternaria alternata, which induce major diseases in apple (Malus domestica), has not been determined. In this study, we first determined that TS has higher inhibitory activity than catechins against the three types of fungi. We further utilized in vitro and in vivo assays to confirm that TS showed high antifungal activity against the three types of fungi, especially for V. mali and B. dothidea. In the in vivo assay, application of a 0.5% TS solution was able to restrain the fungus-induced necrotic area in detached apple leaves efficiently. Moreover, a greenhouse infection assay also confirmed that TS treatment significantly inhibited V. mali infection in leaves of apple seedlings. In addition, TS treatment activated plant immune responses by decreasing accumulation of reactive oxygen species and promoting the activity of pathogenesis-related proteins, including chitinase and ß-1,3-glucanase. This indicated that TS might serve as a plant defense inducer to activate innate immunity to fight against fungal pathogen invasion. Therefore, our data indicated that TS might restrain fungal infection in two ways, by directly inhibiting the growth of fungi and by activating plant innate defense responses as a plant defense inducer.

Broadband photomultiplication organic photodetectors.

Broadband photomultiplication organic photodetectors (PMOPDs) can be achieved with a double-layered active layer prepared from IEICO-4F : PBDB-T blend solutions with different weight ratios (1 : 1 or 3 : 100, wt/wt). The response range of the double-layered PMOPDs covers from 310 nm to 930 nm, determined by the photon harvesting range of the IEICO-4F : PBDB-T (1 : 1, wt/wt) layer. The IEICO-4F : PBDB-T (3 : 100, wt/wt) layer was used as a PM layer in the double-layered PMOPDs, achieving external quantum efficiency (EQE) more than 100% based on the work mechanism of trap-assisted hole tunneling injection. The trapped electrons in PBDB-T/IEICO-4F/PBDB-T near the Al electrode will makeinterfacial-band-bending to narrow the injection barrier, resulting in hole-tunneling-injection from the external circuit. The polymer PBDB-T can provide an efficient charge transport channel for the injected hole from the external circuit. The specific detectivity (D*) and responsivity (R) of the double-layered PMOPDs are 1.05 ± 0.03 × 1012 Jones and 0.94 ± 0.03 A W-1 at 810 nm under a -10 V bias, respectively.

The ankyrin repeat-containing protein MdANK2B regulates salt tolerance and ABA sensitivity in Malus domestica.

KEY MESSAGE: The ankyrin repeat-containing protein MdANK2B was identified to contribute to increasing resistance to salt stress and decreasing sensitivity to ABA in Malus domestica. Ankyrin (ANK) repeat-containing proteins occur widely in prokaryotes, eukaryotes, and even in some viruses and play a critical role in plant growth and development, as well as the response to biotic and abiotic stress. However, the function of ANK repeat-containing proteins in apple (Malus domestica) has not yet been investigated. Here, we identified apple MdANK2B based on homology analysis with the Arabidopsis ANK repeat-containing proteins AtAKR2A and AtAKR2B. MdANK2B was found to be localized in the cytoplasm, and its encoding gene was highly expressed in both apple leaves and fruits. In addition, MdANK2B gene expression was highly induced by salt stresses and abscisic acid (ABA). Overexpression of MdANK2B increased resistance to salt stress and decreased sensitivity to ABA in both transgenic apple calli and seedlings. In addition, overexpression of MdANK2B reduced the accumulation of reactive oxygen species (ROS) by enhancing the activity of antioxidant enzymes in response to salt stress. Our data revealed the role of MdANK2B in response to salt stress and ABA treatment in apple, which widens the known functions of ANK repeat-containing proteins in response to abiotic stress.

Evaluation of liver parenchyma stiffness in patients with liver tumours: optimal strategy for shear wave elastography.

OBJECTIVES: To determine the methodology of non-invasive test for evaluation of liver stiffness (LS) with tumours using two-dimensional (2D) shear wave elastography (SWE). METHODS: One hundred and twenty-seven patients with liver tumours underwent 2D-SWE before surgery to measure liver and spleen stiffness (SS). Two-dimensional SWE values were obtained in the liver at 0-1 cm, 1-2 cm and >2 cm from the tumour edge (PLS-1, PLS-2 and RLS, respectively). The influence of tumour-associated factors was evaluated. The area under the receiver operating characteristic curve (AUC) for each value was analysed to diagnose cirrhosis. RESULTS: PLS-1 was higher than PLS-2, which was even higher than RLS (p < 0.001). The AUCs of PLS-1, PLS-2, RLS and SS for diagnosing cirrhosis were 0.760, 0.833, 0.940 and 0.676, with the specificity of 75.7%, 67.6%, 90.3% and 77.4%, respectively. Tumour sizes, locations or types showed no apparent influence on 2D-SWE values except for RLS, which was higher in patients with primary hepatic carcinomas (p < 0.05). CONCLUSIONS: LS with tumours is best measured at >2 cm away from the tumour edge. SS measurement could be used as an alternative to LS measurement in the event of no available liver for detection. KEY POINTS: • Tumour-associated factors impact background liver stiffness assessment. • Background liver stiffness is best measured at >2 cm from tumour edge. • Spleen stiffness can be an alternative to assess background liver stiffness.

Significance of oral cancer-associated fibroblasts in angiogenesis, lymphangiogenesis, and tumor invasion in oral squamous cell carcinoma.

BACKGROUND: Cancer-associated fibroblasts (CAFs) are recognized as a pivotal promoter in cancer initiation and development. However, the role of CAFs in the progression and metastasis of oral squamous cell carcinoma (OSCC) has not been fully elucidated. MATERIALS AND METHODS: Lymphatic vessel density (LVD) and microvessel density (MVD) and the expression of α-smooth muscle actin (α-SMA) and matrix metalloproteinase-9 (MMP-9) were evaluated by immunohistochemistry in 86 cases of OSCC. The correlations between α-SMA expression and MMP-9 expression, LVD, MVD, and other clinicopathological parameters were analyzed. In vitro invasion assay was performed to assess the effect of CAFs on the invasion of OSCC cells. We also investigated the effect of CAFs on the angiogenesis and lymphangiogenesis by inoculating CAFs with OSCC cells into nude mice subcutaneously. RESULTS: Positive expression of α-SMA protein was detected in 69.8% of the tumors. Increased α-SMA expression was correlated strongly with enhanced tumor invasion, higher tumor grade, increased risk of recurrence, lymph node involvement, and higher peritumoral lymphatic vessel density and microvessel density (P < 0.05). CAFs induced more cancer cells to invade relative to normal fibroblasts (NFs) (P < 0.05). Compared with co-injection of OSCC cells and NFs or injection of tumor cells alone, co-injection of OSCC cells and CAFs resulted in earlier tumor formation and bigger tumor volume accompanied with increased angiogenesis and lymphangiogenesis (P < 0.05). CONCLUSION: CAFs may play critical roles in OSCC progression as an inducer of tumor invasion, angiogenesis, and lymphangiogenesis. Therapeutic strategies targeting CAFs against OSCC is promising and need further exploration.

Plant disease resistance outputs regulated by AP2/ERF transcription factor family.

Plants have evolved a complex and elaborate signaling network to respond appropriately to the pathogen invasion by regulating expression of defensive genes through certain transcription factors. The APETALA2/ethylene response factor (AP2/ERF) family members have been determined as key regulators in growth, development, and stress responses in plants. Moreover, a growing body of evidence has demonstrated the critical roles of AP2/ERFs in plant disease resistance. In this review, we describe recent advances for the function of AP2/ERFs in defense responses against microbial pathogens. We summarize that AP2/ERFs are involved in plant disease resistance by acting downstream of mitogen activated protein kinase (MAPK) cascades, and regulating expression of genes associated with hormonal signaling pathways, biosynthesis of secondary metabolites, and formation of physical barriers in an MAPK-dependent or -independent manner. The present review provides a multidimensional perspective on the functions of AP2/ERFs in plant disease resistance, which will facilitate the understanding and future investigation on the roles of AP2/ERFs in plant immunity.

[Clinical value of CT-guided (125)I brachytherapy for retroperitoneal metastatic lymph node from PHC].

OBJECTIVE: To discuss the clinical value of CT-guided (125)I brachytherapy with retroperitoneal metastatic lymph nodes from primary hepatic carcinoma(PHC). METHODS: Twenty patients with retroperitoneal metastatic lymph node recurrence from PHC were percutaneously treated by (125)I brachytherapy with computed tomographic (CT) guidance. The number, radioactive dose, placed position of radioactive seeds and puncture path were determined by computerized treatment planning system (TPS). The radioactive seeds were implanted when the needles were in right position by CT scan. Radiotherapy verification and quality assessment were performed after treatment by CT scan. Follow-up contrast material-enhanced CT were reviewed. RESULTS: The local control rate of 3, 6, 10, 15 months was 70.0%, 56.3%, 44.4%, 25.0% respectively. There were no severe complications such as massive bleeding and radiation injury of normal tissues. CONCLUSION: CT-guided (125)I brachytherapy are effective and may be safely applied to retroperitoneal metastatic lymph nodes from PHC.

Irradiation stent with 125 I plus TACE versus sorafenib plus TACE for hepatocellular carcinoma with major portal vein tumor thrombosis: a multicenter randomized trial.

BACKGROUND AND AIM: Treatment strategy for hepatocellular carcinoma (HCC) and Vp4 [main trunk] portal vein tumor thrombosis (PVTT) remains limited due to posttreatment liver failure. We aimed to assess the efficacy of irradiation stent placement with 125 I plus transcatheter arterial chemoembolization (TACE) (ISP-TACE) compared to sorafenib plus TACE (Sora-TACE) in these patients. METHODS: In this multicenter randomized controlled trial, participants with HCC and Vp4 PVTT without extrahepatic metastases were enrolled from November 2018 to July 2021 at 16 medical centers. The primary endpoint was overall survival (OS). The secondary endpoints were hepatic function, time to symptomatic progression, patency of portal vein, disease control rate, and treatment safety. RESULTS: Of 105 randomized participants, 51 were assigned to the ISP-TACE group, and 54 were assigned to the Sora-TACE group. The median OS was 9.9 months versus 6.3 months (95% CI: 0.27-0.82; P =0.01). Incidence of acute hepatic decompensation was 16% (8 of 51) versus 33% (18 of 54) ( P =0.036). The time to symptomatic progression was 6.6 months versus 4.2 months (95% CI: 0.38-0.93; P =0.037). The median stent patency was 7.2 months (interquartile range, 4.7-9.3) in the ISP-TACE group. The disease control rate was 86% (44 of 51) versus 67% (36 of 54) ( P =0.018). Incidences of adverse events at least grade 3 were comparable between the safety populations of the two groups: 16 of 49 (33%) versus 18 of 50 (36%) ( P =0.73). CONCLUSION: Irradiation stent placement plus TACE showed superior results compared with sorafenib plus TACE in prolonging OS in patients with HCC and Vp4 PVTT.

Nitrate-inducible MdBT2 acts as a restriction factor to limit apple necrotic mosaic virus genome replication in Malus domestica.

Apple necrotic mosaic virus (ApNMV) is highly associated with the occurrence of apple mosaic disease in China. However, ApNMV-host interactions and defence mechanisms of host plants against this virus are poorly studied. Here, we report that nitrate treatment restrains ApNMV genomic RNA accumulation by destabilizing viral replication protein 1a through the MdBT2-mediated ubiquitin-proteasome pathway. MdBT2, a nitrate-responsive BTB/TAZ domain-containing protein, was identified in a yeast two-hybrid screen of an apple cDNA library using viral protein 1a as bait, and 1a was further confirmed to interact with MdBT2 both in vivo and in vitro. It was further verified that MdBT2 promoted the ubiquitination and degradation of viral protein 1a through the ubiquitin-proteasome pathway in an MdCUL3A-independent manner. Viral genomic RNA accumulation was reduced in MdBT2-overexpressing transgenic apple leaves but enhanced in MdBT2-antisense leaves compared to the wild type. Moreover, MdBT2 was found to interfere with the interaction between viral replication proteins 1a and 2apol by competitively interacting with 1a. Taken together, our results demonstrate that nitrate-inducible MdBT2 functions as a limiting factor in ApNMV viral RNA accumulation by promoting the ubiquitination and degradation of viral protein 1a and interfering with interactions between viral replication proteins.

Apple receptor-like kinase FERONIA regulates salt tolerance and ABA sensitivity in Malus domestica.

FERONIA (FER) is a membrane-localized receptor-like kinase that plays pivotal roles in male and female gametophyte recognition, hormone signaling crosstalk, and biotic and abiotic responses. Most reports focus on the functions of FER in model plant Arabidopsis thaliana. However, the functions of FER homologs have not been deeply investigated in apple (Malus domestica), an important economic fruit crop distributed worldwide, especially in China. In this study, we identified an apple homolog of Arabidopsis FER, named MdFER (MDP0000390677). The two proteins encoded by AtFER and MdFER share similar domains: an extracellular malectin-like domain, a transmembrane domain, and an intracellular kinase domain. MdFER was further proven to localize to the plasma membrane in the epidermal cells of Nicotiana benthamiana. MdFER was widely expressed in different apple tissues, but the highest expression was found in roots. In addition, expression of MdFER was significantly induced by treatment with abscisic acid (ABA) and salt (NaCl). Overexpressing MdFER dramatically improved the resistance to salt stress and reduced the sensitivity to ABA in apple callus, while suppressing MdFER expression showed contrary effects. Furthermore, ectopic expression of MdFER in Arabidopsis significantly increased the salt tolerance and reduced the sensitivity to ABA. In addition, under salt stress and ABA treatment, Arabidopsis with highly expressed MdFER accumulated less reactive oxygen species (ROS), and the enzymatic activity of two ROS scavengers, superoxide dismutase and catalase, was higher compared with that of wild type (WT). Our work proves that MdFER positively regulates salt tolerance and negatively regulates ABA sensitivity in apple, which enriched the functions of FER in different plant species.

Pulmonary mucosa-associated lymphoid tissue lymphoma: computed tomography and ¹8F fluorodeoxyglucose-positron emission tomography/computed tomography imaging findings and follow-up.

PURPOSE: The aim of the study was to present the computed tomography (CT) and fluorine 18 (F) fluorodeoxyglucose-positron emission tomography (FDG-PET)/CT imaging findings of pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma and evaluate their roles in the follow-up of this tumor. METHODS: Computed tomography and FDG-PET/CT imaging findings of 18 cases of pathologically proven pulmonary MALT lymphoma were reviewed retrospectively. RESULTS: Multiple and solitary lesions were detected in 15 and 3 patients, respectively. Of those patients with multiple pulmonary lesions, 12 were bilateral, and 3 were unilateral. A total of 51 pulmonary lesions were identified in 18 patients, which included lesions with consolidation (31/51), mass and nodule (12/51), and ground-glass attenuation (8/51). F fluorodeoxyglucose-PET/CT imaging (n = 8) revealed increased FDG uptake in all lesions in 8 cases. At follow-up, 3 patients experienced complete remission, 10 had partial remission, and 2 remained stable. CONCLUSIONS: Computed tomography and FDG-PET/CT images of the pulmonary MALT lymphoma usually reveal multiple, bilateral consolidations, masses, or nodules with air bronchogram and increased FDG uptake. Computed tomography and FDG-PET/CT imaging play important roles in the diagnosis and follow-up of patients with pulmonary MALT lymphoma.

[Comparison of safety and efficacy for transcatheter arterial chemoembolization alone and plus radiofrequency ablation in the treatment of single branch portal vein tumor thrombus of hepatocellular carcinoma and their prognosis factors].

OBJECTIVE: To compare the transcatheter arterial chemoembolization (TACE) alone or plus radiofrequency ablation (RFA) in the treatment of single branch portal vein tumor thrombus(PVTT)in patients with hepatocellular carcinoma (HCC) so as to evaluate the safety, control rate, prognostic factors and overall survival. METHODS: From January 2004 to December 2007, 50 HCC patients (< 5 cm in diameter and 3 parenchymal lesions) with concurrent PVTT were enrolled and treated by TACE alone or TACE plus RFA randomly (TACE, n = 25; TACE-RFA, n = 25). In TACE group, the intra-hepatic lesions received TACE sequentially with RFA; in TACE-RFA group, PVTT and intra-hepatic lesions were treated with TACE sequentially with RFA separately. Strict follow-up was conducted by computed tomography and alpha-fetoprotein (AFP) assay. The survival time was analyzed by the Kaplan-Meier method and Cox regression analysis was performed to evaluate the prognostic factors. RESULTS: Of all 50 HCC patients with single branch PVTT with TACE or RFA, 47 patients (TACE, n = 24; TACE-RFA, n = 23) received all the scheduled procedures and completed the follow-up. Two patients (8.3%) in TACE group had liver dysfunction versus none in TACE-RFA group, 2 patients (8.7%) developed bile duct injury in TACE-RFA group related with the RFA procedure. The OR (overall response) for PVTT was 54.2% (complete response (CR) 8.3%, partial response (PR) 45.8%) in TACE group while 87.0% (CR 60.9%, PR 26.1%) in TACE-RFA group during the follow-up. From the definite diagnosis of HCC, the median survival was 8 months. And the 1-, 2- & 3-year survival rates were 33.3%, 12.5%, 8.3% in TACE group. And 26 months, 65.2%, 47.8%, 30.4% in TACE-RFA group respectively. The difference between two groups was significant. From the definite diagnosis of PVTT, the respective data were 7 months, 12.5% and 4.2%, 0 in TACE group versus 22 months, 52.2%, 34.8%, and 8.7% in TACE-RFA group with a significant P value. In multivariate analysis, only therapy (TACE or TACE-RFA) showed a protective value (hazard rate 0.430 vs 0.345, P < 0.05). Survival was not correlated with age, intra-hepatic tumor status, liver functions and AFP level for all patients. CONCLUSION: RFA is both safe and efficacious to prolong survival in the treatment of single branch PVTT plus TACE in selected HCC patients. It may provide rationales for further studies of evaluating the outcome of RFA plus other therapies in the treatment of HCC with single branch PVTT.

[Luminescence characteristics of PVK doped with Eu-complex Eu(UVA)3Phen].

The present work investigates the photoluminescence (PL) and electroluminescence (EL) characteristics of Eu-complex Eu (UVA)3Phen doped PVK with different doping concentrations. The results indicate that there exists Forster energy transfer from PVK to Eu(UVA)3 phen in the mixed system. It can get good color purity by optimizing the doping concentration of host and guest materials. And the authors can obtain the best doping concentration to be 4% in EL device.

[Effects of hole-injection layers on the performance of blue organic light-emitting diodes].

The present work investigates the effects of different buffer layers on the performance of blue organic light-emitting diodes (OLEDs), and compares them with the device with no buffer layer. Two kinds of blue OLEDs with 4,4'-bis(2,2'-diphenyl vinyl)-1,1'-biphenyl (DPVBi) as the emitting layer, N, N'-bis-(1-naphthyl)-N, N'-1-diphenyl-1,1 '-biphenyl-4, 4'-diamine (NPB) as the hole transporting layer, and copper phthalocyanine (CuPc) and poly(3,4-ethylenedioxythiophene) : poly (styrenesulphonate) PEDOT : PSS as the hole injection layer respectively were fabricated with the structures of ITO/CuPc/NPB/DPVBi/BCP/Alq3 /Al and ITO/PEDOT : PSS/NPB/DPVBi/BCP/Alq3/Al. Moreover, the effects of different preparation technology of CuPc on the performance of OLEDs were also investigated. It was found that the performance of the devices with a hole injection layer is better than that of the device without any hole-injection layer. Although the luminance and efficiency of the water-soluble CuPc based device are worse than that of the device with thermally evaporated CuPc, but better than that of the device with water-soluble PEDOT : PSS. So the water-soluble CuPc is a good hole injection material because it is easier to fabricate the film than traditional CuPc.

[Effect of mixed interface on the performance of solution-processed phosphorescent OLEDs].

In the present work, in order to improve electron injection and transport at the interface of the hole blocking layer (HBL) and the electron transport layer (ETL) in the hole-domain solution processed phosphorescent organic light emitting devices (PhOLEDs), the mixed interface layer (MIL) was fabricated by partially co-doping hole blocking material 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and electron transport material tris(8-quinolinolato) aluminum (Alq3) between HBL/ ETL. The MIL thickness was kept at 10nm, while the doping ratio of these two materials varied. Under a given electric field, the devices with the MIL at any mixed ratios all show much higher luminance and current density than those with a typical interface. For example, the luminance power and current density at 10 V for a typical device are 1.03 microW and 5.13 mA x cm(-2), while in case of mixed interface are 3.64 microW and 18.1 mA x cm(-2), respectively. From data results and theoretical analysis, the possible derivation of these improvements is considered to be the reduced electron accumulation at the interface resulting from the reduced electron injection energy barrier and lowered transport mobility by BCP material, which leads to an increase in electron amount in the emission layer and therefore the higher luminance and current density.

[Study on the movement of the carrier recombination region in organic light-emitting diodes (OLEDs) based on DPVBi/Alq3].

Series of organic light emitting devices with basic structure of ITO/PCBM: PVK(x Wt%, approximately 40 nm)/DPVBi(30 nm)/Alq3 (30 nm)/Al were fabricated in order to investigate the carrier recombination region movement in these devices. The carrier injection-dependent, the carrier transport-dependent and the voltage-dependent carrier recombination region movements were investigated respectively by modifying cathode with lithium fluoride, by changing the doping concentration of PCBM and by changing the voltage on the devices. The physical mechanism behind the voltage-dependent carrier recombination region movement was discussed.

[Luminescence characteristics of PVK doped with Ir(Fppy)3].

In the present work, the photoluminescence (PL) and electroluminescence (EL) characteristics of Tris[2-(2,4-difluorophenyl)pyridine]iridium(III) (Ir(Fppy)3) doped poly(n-vinylcarbazole) (PVK) with different doping concentrations were investigated. And a blue phosphorescent organic light-emitting diode (OLED) with the structures of ITO/PEDOT : PSS/PVK : Ir(Fppy)3/BCP/Alq3/LiF/Al was fabricated. The experimental results show that the luminescence performances of devices are different as the doping concentration of Ir(Fppy)3 is different. When the doping concentration of Ir(Fppy)3 is lower, the luminescence of PVK can be found in EL spectra. When the doping concentration is too high, concentration quenching may occur. As the doping concentration is suitable, the luminescence of PVK can not be found, only the luminescence of Ir(Fppy)3 can be found in EL spectra. It is concluded that the device with doping concentration of 4% has the best photoelectric performance according to its current density-voltage-luminance curve.