Device optimization Based on Electrical and Optical Simulation of Tris(8-hydroxyquinoline) Aluminium Based Microacavity Organic Light Emitting Diode (MOLED)

OLED has emerged as a potential candidate for applications in display devices due to its prominent advantages in size, brightness and wide viewing angle. Following our previous work, where optical analysis of the OLED has been documented1 we present in this work detailed examination optical and electrical analysis of the performance of an OLEDs based on two organic layers: N,N'-di(naphthalene-1-yl)-N,N'-diphenylbenzidine (NPB) as the hole transport layer and tris (8-hydroxyquinoline) aluminium (Alq3) as the emitting layer, and two metallic mirrors. Our optical model fully takes into account dispersion in glass substrate, organic layers as well as the dispersion in metal contacts/mirrors. Influence of the incoherent transparent glass substrate is also accounted for. Two metal contacts Ag and Cu have been considered for anode and cathode respectively. For the hole transport layer NPB was used. The OLED structure is examined as a function of: thickness of the organic layers, and position of the hole transport layer/Alq3 interface. In order to obtain better agreement with EL experimental data, electrical models was developed in conjunction with the existing optical model to facilitate accurate optimisation of the OLED structure. The electrical model developed considers the metal contact as Schottky contact, the carrier mobility is taken to be field dependent with the Poole-Frenkel-like form and Langevin recombination model is used. The carrier transport was simulated using one-dimensional time-independent drift-diffusion model using device simulation software ATLAS.2 Finally, the optimised devices were fabricated and characterised and experimental and calculated optical emission spectra were compared together with results obtained from electrical transport model

Electrical and Optical Simulation of Tris(8-hydroxyquinoline) Aluminium-Based Microcavity Organic Light Emitting Diode (MOLED)

A detailed examination of the emitted radiation spectrum from tris(8-hydroxyquinoline) aluminum (Alq) based OLEDs on optical and electrical models have been presented. The OLED structure is examined as a function of choice of anode material and position of the NPB/Alq interface. The simulation results have been compared to those obtained from experiments, showing good agreement in both electrical and optical characteristics. The enhancement in light emission by aligning antinode of the stand wave pattern with effective carrier recombination region has been observed

Differences in human plasma protein interactions between various polymersomes and stealth liposomes as observed by fluorescence correlation spectroscopy

A significant factor hindering the clinical translation of polymersomes as vesicular nanocarriers is the limited availability of comparative studies detailing their interaction with blood plasma proteins compared to liposomes. Here, polymersomes are self-assembled via film rehydration, solvent exchange, and polymerization-induced self-assembly using five different block copolymers. The hydrophilic blocks are composed of anti-fouling polymers, poly(ethylene glycol) (PEG) or poly(2-methyl-2-oxazoline) (PMOXA), and all the data is benchmarked to PEGylated “stealth” liposomes. High colloidal stability in human plasma (HP) is confirmed for all but two tested nanovesicles. In situ fluorescence correlation spectroscopy measurements are then performed after incubating unlabeled nanovesicles with fluorescently labeled HP or the specific labeled plasma proteins, human serum albumin, and clusterin (apolipoprotein J). The binding of HP to PMOXA-polymersomes could explain their relatively short circulation times found previously. In contrast, PEGylated liposomes also interact with HP but accumulate high levels of clusterin, providing them with their known prolonged circulation time. The absence of significant protein binding for most PEG-polymersomes indicates mechanistic differences in protein interactions and associated downstream effects, such as cell uptake and circulation time, compared to PEGylated liposomes. These are key observations for bringing polymersomes closer to clinical translation and highlighting the importance of such comparative studies

A Pair of Disjoint 3-GDDs of type g^t u^1

Pairwise disjoint 3-GDDs can be used to construct some optimal constant-weight codes. We study the existence of a pair of disjoint 3-GDDs of type $g^t u^1$ and establish that its necessary conditions are also sufficient.Comment: Designs, Codes and Cryptography (to appear

Low-cost CMOS Neurological Sensor Array

Current methods used to study neural communication have not been able to achieve both good spatial and temporal resolution of recordings. There are two ways to record synaptic potentials from nerve endings: recordings using single or dual intracellular or extra cellular metal electrodes give good temporal resolution but poor spatial resolution, and recording activity with fluorescent dyes gives good spatial resolution but poor temporal resolution. Such medical research activity in the area of neurological signal detection has thus identified a requirement for the design of a CMOS circuit that contains an array of independent sensors. As both spatial and temporal distribution of acquired data is required in this application, the circuit must be capable of continuous measurement of synaptic potentials from an array of points on a tissue sample, with a 10 µm separation between sensor points.The major requirement for the circuit is that it is capable of sensing synaptic potentials of the order of several mV, with a resolution of 0.05 mV. For data recording purposes, the circuit must amplify these synaptic potentials and digitise them together with their locations in the sensor array. Finally, the circuit must be biologically inert, to avoid specimen deterioration.This paper presents the design of a prototype single-chip circuit, which provides a 6 x 3 array of independent synaptic potential sensors. The signal from each of the sensors is amplified and time-multiplexed into an on-chip A/D converter. The circuit provides an 8-bit synaptic potential value, together with an 8-bit field containing array location and trigger signals suitable for external data acquisition instrumentation.Our test circuit is implemented in a low-cost 0.5 um, 5 V CMOS process. The fabricated die is mounted in a standard 40 pin DIP ceramic package, with no lid to allow direct contact of the die surface with the tissue sample. The only post-processing step required for these packages is to encapsulate the exposed bond wires to ensure that the device is biologically inert. No further processing of the silicon die is required. Both the circuit design and the chip performance will be presented in the seminar

Cavity Design and Optimization for Organic Microcavity OLEDs

We report on detailed simulations of the emission from microcavity OLEDs consisting of widely used organic materials, n,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine (NPB) as a hole transport layer and tris (8-hydroxyquinoline) (Alq3) as emitting and electron transporting layer. The thick silver film was considered as a top mirror, while silver or copper films on quartz substrate were considered as bottom mirrors. The electroluminescence emission spectra, electric field distribution inside the device, carrier density and recombination rate were calculated as a function of the position of the emission layer, i.e. interface between NPB and Alq3. In order to achieve optimum emission from a microcavity OLED, it is necessary to align the position of the recombination region with the antinode of the standing wave inside the cavity. Once the optimum structure has been determined, the microcavity OLED devices were fabricated and characterized. The experimental results have been compared to the simulations and the influence of the emission region width and position on the performance of microcavity OLEDs was discussed

Group-works: exploring multiplex networks, leadership and group performance

The purpose of this paper is to explore the effect of “multiplex” (multiple overlapping) networks and leadership on group performance in a higher education setting. Using a combination of social network analysis and interviews, the authors employ a case study approach to map the connections between academic group members. This paper analyses the relationship between this mapping and academic performance. The authors identified two dimensions which influence group effectiveness: multiplex networks and distributed-coordinated leadership. Where networks are built across tasks, inter-relationships develop that lead to greater group performance. Where group members create a dense hive of interconnectivity and are active across all group tasks, and also informally, this increases the opportunity for knowledge sharing. When this is similarly experienced by a majority of group members, there is positive reinforcement, resulting in greater group effectiveness. This paper highlights the importance of the richness of formal ties in knowledge intensive settings. This paper is the first to differentiate between formal connections between colleagues related to different tasks within their role. This suggests that dense configurations of informal ties are insufficient; they must be coupled with strong ties around formal activity and demonstrative leadership

Potentiation of the anticancer effect of valproic acid, an antiepileptic agent with histone deacetylase inhibitory activity, by the kinase inhibitor Staurosporine or its clinically relevant analogue UCN-01

Histone deacetylase inhibitors (HDACIs) are novel anticancer agents with potent cytotoxicity against a wide range of malignancies. We have previously demonstrated that either Calphostin C (CC) (a protein kinase C (PKC) inhibitor) or Parthenolide (an NF-κB inhibitor) abrogates HDACI-induced transcriptional activation of NF-κB and p21, which is associated with profound potentiation of HDACI-mediated induction of apoptosis. Valproic acid (VA), a commonly used antiepileptic agent, has recently been shown to be an HDACI. This study was aimed to evaluate the anticancer property of VA in thoracic cancer cells and the development of clinically relevant strategies to enhance VA-mediated induction of apoptosis using kinase inhibitors Staurosporine (STP) or its analogue UCN-01. Treating cultured thoracic cancer cells with VA (0.62–10.0 mM) resulted in significant cell line- and dose-dependent growth inhibition (IC50 values: 4.1–6.0 mM) and cell cycle arrest at G1/S checkpoint with profound accumulation of cells at G0/G1 phase but little induction of apoptosis. Valproic acid, being an HDACI, caused significant dose-dependent accumulation of hyperacetylated histones, following 24 h of treatment. Valproic acid-mediated 5–20-fold upregulation of transcriptional activity of NF-κB was substantially (50–90%) suppressed by cotreatment with CC, STP or UCN-01. Whereas minimal death (<20%) was observed in cells treated with either VA (1.0 or 5.0 mM) alone or kinase inhibitors alone, 60–90% of cells underwent apoptosis following exposure to combinations of VA+kinase inhibitors. Kinase inhibitor-mediated suppression of NF-κB transcriptional activity played an important role in sensitising cancer cells to VA as direct inhibition of NF-κB by Parthenolide drastically synergised with VA to induce apoptosis (VA+Parthenolide: 60–90% compared to <20% following single-drug treatments). In conclusion, VA, a well-known antiepileptic drug, has mild growth-inhibitory activity on cultured cancer cells. The weak VA-mediated induction of apoptosis of thoracic cancer cells can be profoundly enhanced either by Parthenolide, a pharmacologic inhibitor of NF-κB, or by UCN-01 a kinase inhibitor that has already undergone phase I clinical development. Combinations of VA with either a PKC inhibitor or an NF-κB inhibitor are promising novel molecularly targeted therapeutics for thoracic cancers