Application of molybdenum trioxide in polymer light-emitting diodes

The thesis investigates the application of molybdenum trioxide (MoO3-x) as hole injection layers (HILs) in polymeric light-emitting-diodes (PLEDs). Recent application of metal oxides into the PLED architecture has been motivated by the benefits of enhanced device performances, as well as, for the protection against the intrusion of oxygen and water into PLEDs. In this thesis, the performance of MoO3-x HILs in PLEDs is investigated by fabricating ITO/MoO3-x/TFB/F8BT/Ca/Al electroluminescent devices and characterising their efficiency and luminescence properties. Also the performance of the device is studied within the context of the physical properties of MoO3-x lms and electroluminescent polymers, experimentally determined by various techniques. Three different types of PLEDs are fabricated and characterised, each incorporating MoO3-x HILs with different electronic properties. Such difference in the lms are achieved by post-deposition annealing of MoO3-x lms in air and nitrogen. It is determined that annealing MoO3-x lms in air has the effect of increasing their hole concentration. This improves the performance of MoO3-x as hole injection layers in PLEDs. Upon annealing the as-deposited MoO3-x HILs in air, the maximum current efficiency of PLEDs increases from 1.27 cd/A to 1.44 cd/A. Also the maximum luminescence increases from 2723 cd/m2 to 5680 cd/m2. Kelvin probe and electroabsorption spectroscopy measurements show that annealing MoO3 x lms has the effect of decreasing their work function by 0.3 eV. Finally, using time-correlated single photon counting (TCSPC), the photoluminescence (PL) lifetime of F8BT and TFB single layers, and TFB/F8BT bilayers are determined, with and without the presence of a MoO3x contact. The PL lifetime of excitons in pure F8BT is measured to decrease from 1300 to 760 ps upon incorporation of a MoO3x contact. In contrast to F8BT, the PL lifetime of TFB is determined to be 500 40 ps, regardless of the presence of a neighbouring contact. The TFB/F8BT bilayers exhibit biexponential decay characteristics with two lifetime values; 800 50 ps and 5000 400 ps

Tuning Locality of Pair Coherence in Graphene-based Andreev Interferometers

We report on gate-tuned locality of superconductivity-induced phase-coherent magnetoconductance oscillations in a graphene-based Andreev interferometer, consisting of a T-shaped graphene bar in contact with a superconducting Al loop. The conductance oscillations arose from the flux change through the superconducting Al loop, with gate-dependent Fraunhofer-type modulation of the envelope. We confirm a transitional change in the character of the pair coherence, between local and nonlocal, in the same device as the effective length-to-width ratio of the device was modulated by tuning the pair-coherence length xi(T) in the graphene layer.open1133sciescopu

All-Printed, Stretchable Zn-Ag2O Rechargeable Battery via Hyperelastic Binder for Self-Powering Wearable Electronics

While several stretchable batteries utilizing either deterministic or random composite architectures have been described, none have been fabricated using inexpensive printing technologies. In this study, the authors printed a highly stretchable, zinc-silver oxide (Zn-Ag2O) battery by incorporating polystyrene-block-polyisoprene-block-polystyrene (SIS) as a hyperelastic binder for custom-made printable inks. The remarkable mechanical properties of the SIS binder lead to an all-printed, stretchable Zn-Ag2O rechargeable battery with a ≈2.5 mA h cm−2 reversible capacity density even after multiple iterations of 100% stretching. This battery offers the highest reversible capacity and discharge current density for intrinsically stretchable batteries reported to date. The electrochemical and mechanical properties are characterized under different strain conditions. The new stress-enduring printable inks pave ways for further developing stretchable electronics for the wide range of wearable applications

Hierarchical microchanneled scaffolds modulate multiple tissue-regenerative processes of immune-responses, angiogenesis, and stem cell homing

Recapitulating the in vivo microenvironments of damaged tissues through modulation of the physicochemical properties of scaffolds can boost endogenous regenerative capacity. A series of critical events in tissue healing including immune-responses, angiogenesis, and stem cell homing and differentiation orchestrate to relay the regeneration process. Herein, we report hierarchically structured (‘microchanneled’) 3D printed scaffolds (named ‘μCh’), in contrast to conventional 3D printed scaffolds, induce such cellular responses in a unique way that contributes to accelerated tissue repair and remodeling. The μCh reduced the extracellular trap formation of anchored neutrophils at the very beginning (24 h) of implantation while increasing the number of live cells. Among the macrophages covered the surface of μCh over 7 days a major population polarized toward alternativelly activated phase (M2) which contrasted with control scaffolds where classically activated phase (M1) being dominant. The mesenchymal stem cells (MSCs) recruited to the μCh were significantly more than those to the control, and the event was correlated with the increased level of stem cell homing cytokine, stromal derived factor 1 (SDF1) sequestered to the μCh. Furthermore, the neo-blood vessel formation was more pronounced in the μCh, which was in line with the piling up of angiogenic factor, vascular endothelial growth factor (VEGF) in the μCh. Further assays on the protein sequestration to the μCh revealed that a set of chemokines involved in early pro-inflammatory responses were less found whereas representative adhesive proteins engaged in the cell-matrix interactions were significantly more captured. Ultimately, the fibrous capsule formation on the μCh was reduced with respect to the control, when assessed for up to 21 days, indicating less severe foreign body reaction. The tissue healing and regenerative capacity of the μCh was then confirmed in a critically sized bone model, where those series of events observed are essential to relay bone regeneration. The results over 6 weeks showed that the μCh significantly enhanced the early bone matrix deposition and accelerated bone regeneration. While more in-depth studies remain as to elucidate the underlying mechanisms for each biological event, the molecular, cellular and tissue reactions to the μCh were coherently favorable for the regeneration process of tissues, supporting the engineered scaffolds as potential therapeutic 3D platforms

Resolution-enhanced X-ray fluorescence microscopy via deep residual networks

Multimodal hard X-ray scanning probe microscopy has been extensively used to study functional materials providing multiple contrast mechanisms. For instance, combining ptychography with X-ray fluorescence (XRF) microscopy reveals structural and chemical properties simultaneously. While ptychography can achieve diffraction-limited spatial resolution, the resolution of XRF is limited by the X-ray probe size. Here, we develop a machine learning (ML) model to overcome this problem by decoupling the impact of the X-ray probe from the XRF signal. The enhanced spatial resolution was observed for both simulated and experimental XRF data, showing superior performance over the state-of-the-art scanning XRF method with different nano-sized X-ray probes. Enhanced spatial resolutions were also observed for the accompanying XRF tomography reconstructions. Using this probe profile deconvolution with the proposed ML solution to enhance the spatial resolution of XRF microscopy will be broadly applicable across both functional materials and biological imaging with XRF and other related application areas

Improving the rheological and thermal properties of wheat dough by the addition of gamma-polyglutamic acid

[[abstract]]Abstract: The theological and thermal properties of wheat dough with the addition of gamma-polyglutamic acid (PGA) (0.5, 1.0, 5.0 g kg(-1), w/w) was evaluated by the measurements of farinography, rapid visco analysis and differential scanning calorimetry. Adding 5.0 g kg(-1) PGA in wheat dough increased the mixing stability and raised the pasting temperature from 75.8 to 84.4 degrees C, but decreased the peak viscosity and breakdown. The water holding capacity of wheat dough increased with the addition of 5.0 g kg(-1) of PGA. At 5.0 g kg(-1) level, PGA caused significant declines in the enthalpy, onset and peak temperatures of ice-melting transition of wheat dough. Scanning electron microscopy showed that wheat bread with the addition of 1.0 and 5.0 g kg(-1) PGA exhibited microstructures with smoother surfaces. During storage, PGA retarded the staling process of wheat bread. (c) 2007 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved

Effect of surfactant concentration variation on the thermoelectric properties of mesoporous ZnO

The electrical and thermal conductivities and the Seebeck coefficient of mesoporous ZnO thin films were investigated to determine the change of their thermoelectric properties by controlling surfactant concentration in the mesoporous ZnO films, because the thermoelectric properties of mesoporous ZnO films can be influenced by the porosity of the mesoporous structures, which is primarily determined by surfactant concentration in the films. Mesoporous ZnO thin films were successfully synthesized by using sol-gel and evaporation-induced self-assembly processes. Zinc acetate dihydrate and Brij-76 were used as the starting material and pore structure-forming template, respectively. The porosity of mesoporous ZnO thin films increased from 29% to 40% with increasing surfactant molar ratio. Porosity can be easily altered by controlling the molar ratio of surfactant/precursor. The electrical and thermal conductivity and Seebeck coefficients showed a close correlation with the porosity of the films, indicating that the thermoelectric properties of thin films can be changed by altering their porosity. Mesoporous ZnO thin films with the highest porosity had the best thermoelectric properties (the lowest thermal conductivity and the highest Seebeck coefficient) of the films examined. © 2013 Min-Hee Hong et al

Effective NSAID treatment indicates that hyperprostaglandinism is affecting the clinical severity of childhood hypophosphatasia

BACKGROUND: Hypophosphatasia (HP) is an inborn error of bone metabolism characterized by a genetic defect in the gene encoding the tissue-nonspecific alkaline phosphatase (TNSALP). There is a lack of knowledge as to how the variability and clinical severity of the HP phenotype (especially pain and walking impairment) are related to metabolic disturbances or impairments, subsequent to the molecular defect. METHODS: We analyzed the changes in clinical symptoms and the prostaglandin (PG) metabolism in response to treatment with non-steroidal anti-inflammatory drugs (NSAIDs) in six children affected by childhood HP. In addition, by exposing HP fibroblasts to pyridoxal phosphate and/or calcium pyrophosphate in vitro, we analyzed whether the alterations in PG levels are sequelae related to the metabolic defect. RESULTS: Childhood HP patients, who often complain about pain in the lower limbs without evident fractures, have systemic hyperprostaglandinism. Symptomatic anti-inflammatory treatment with NSAIDs significantly improved pain-associated physical impairment. Calcium pyrophosphate, but not pyridoxal phosphate, induced cyclooxygenase-2 (COX-2) gene expression and PG production in HP and normal fibroblasts in vitro. CONCLUSION: Clinical features of childhood HP related to pain in the lower legs may be, at least in part, sequelae related to elevated PG levels, secondary to the primary metabolic defect. Consequently, NSAID treatment does improve the clinical features of childhood HP

Rapid detection of BRCA1/2 recurrent mutations in Chinese breast and ovarian cancer patients with multiplex SNaPshot genotyping panels.

BRCA1/2 mutations are significant risk factors for hereditary breast and ovarian cancer (HBOC), its mutation frequency in HBOC of Chinese ethnicity is around 9%, in which nearly half are recurrent mutations. In Hong Kong and China, genetic testing and counseling are not as common as in the West. To reduce the barrier of testing, a multiplex SNaPshot genotyping panel that targeted 25 Chinese BRCA1/2 mutation hotspots was developed, and its feasibility was evaluated in a local cohort of 441 breast and 155 ovarian cancer patients. For those who tested negative, they were then subjected to full-gene testing with next-generation sequencing (NGS). BRCA mutation prevalence in this cohort was 8.05% and the yield of the recurrent panel was 3.52%, identifying over 40% of the mutation carriers. Moreover, from 79 Chinese breast cancer cases recruited overseas, 2 recurrent mutations and one novel BRCA2 mutation were detected by the panel and NGS respectively. The developed genotyping panel showed to be an easy-to-perform and more affordable testing tool that can provide important contributions to improve the healthcare of Chinese women with cancer as well as family members that harbor high risk mutations for HBOC