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With the acceleration of the scaling down of integrated circuits, it has become very challenging to fabricate a metal–insulator–metal (MIM) capacitor with a high capacitance density and low leakage current for nanoscale dynamic random access memory. Yttria-stabilized-zirconia (YSZ) thin films, one of the insulators in the constitution of MIM capacitors, have been reported to have various crystal structures from the monoclinic phase to the cubic phase according to different Y doping levels. The electrical characteristics depend on the crystal structure of the YSZ thin film. Here, we report the local crystallization of YSZ thin films via Joule heating and the leakage current induced during in situ transmission electron microscopy biasing tests. We studied the crystallization process and the increase in the leakage current using experimental and simulation results. It is important to understand the relationship between the crystallinity and electrical properties of YSZ thin films in MIM capacitors. [ABSTRACT FROM AUTHOR]

Abstract Understanding the degradation mechanism of organic light-emitting diodes (OLED) is essential to improve device performance and stability. OLED failure, if not process-related, arises mostly from chemical instability. However, the challenges of sampling from nanoscale organic layers and interfaces with enough analytical information has hampered identification of degradation products and mechanisms. Here, we present a high-resolution diagnostic method of OLED degradation using an Orbitrap mass spectrometer equipped with a gas cluster ion beam to gently desorb nanometre levels of materials, providing unambiguous molecular information with 7-nm depth resolution. We chemically depth profile and analyse blue phosphorescent and thermally-activated delayed fluorescent (TADF) OLED devices at different degradation levels. For OLED devices with short operational lifetimes, dominant chemical degradation mainly relate to oxygen loss of molecules that occur at the interface between emission and electron transport layers (EML/ETL) where exciton distribution is maximised, confirmed by emission zone measurements. We also show approximately one order of magnitude increase in lifetime of devices with slightly modified host materials, which present minimal EML/ETL interfacial degradation and show the method can provide insight for future material and device architecture development.

In most solution-processed organic devices, a poly(3,4-ethylenedioxythiophene) (PEDOT) polymerized with poly(4-styrenesulfonate) (PSS) film is inevitably affected by various conditions during the subsequent solution-coating processes. To investigate the effects of direct solvent exposure on the properties of PEDOT polymerized with PSS (PEDOT:PSS) films, photoemission spectroscopy-based analytical methods were used before and after solvent-coating processes. Our results clearly indicate that PEDOT:PSS films undergo a different transition mechanism depending on the solubility of the solvent in water. The water-miscible solvents induce the solvation of hydrophilic PSS chains. As a result, this process allows the solvent to diffuse into the PEDOT:PSS film, and a conformational change between PEDOT and PSS occurs. On the other hand, the water-immiscible organic solvents cause the partial adsorption of solvent molecules at the PE surface, which leads to changes in the surface properties, including work function. Based on our finding, we demonstrate that the energy-level alignments at the organic semiconductor/electrode interface for the PEDOT:PSS films can be controlled by simple solvent treatments. [ABSTRACT FROM AUTHOR]

Background and Objectives: This study aimed to describe the ischemic stroke subtypes and risk factors in young Korean adults, focusing mainly on traditional risk factors and management of ischemic stroke. Methods: The study patients were the first-ever acute cerebral ischemic infarction age 49 years or below admitted to the Kyung Hee University Medical Centre from September 2003 to June 2009, with ischaemic stroke patients ⩾50 years as control. The stroke subtypes was categorized according to Trial of Org 10172 in Acute Stroke Treatment classification. The traditional risk factors of ischemic stroke were examined. For those known to have hypertension and diabetes prior to onset of stroke, their adherence to treatment of hypertension and diabetes was also assessed. Results: Close to half of the patients ⩽49 years were due to premature atherosclerosis from small vessel occlusion and large artery atherosclerosis. The most common risk factor in declining order was hypertension, smoking, dyslipidemia and obesity. On logistic regression analysis, hypertension, dyslipidemia, and obesity were strongly associated with small vessel occlusion. In patients who were known to have hypertension and diabetes prior to the onset of stroke, the younger patients were less adherent to the treatment as primary prevention than the older stroke patients. Conclusion: This study suggests that premature atherosclerosis from small vessel occulusion is the most common cause of ischaemic stroke among young adults in Korea. Non-adherence to primary preventive treatment of hypertension and diabetes is common. [ABSTRACT FROM AUTHOR]

BBK32 is a fibronectin-binding protein from the Lyme disease-causing spirochete Borrelia burgdorferi. In this study, we show that BBK32 shares sequence similarity with fibronectin module-binding motifs previously identified in proteins from Streptococcus pyogenes and Staphylococcus aureus. Nuclear magnetic resonance spectroscopy and isothermal titration calorimetry are used to confirm the binding sites of BBK32 peptides within the N-terminal domain of fibronectin and to measure the affinities of the interactions. Comparison of chemical shift perturbations in fibronectin F1 modules on binding of peptides froln BBK32, FnBPA from S. aureus, and SfbI from S. pyogenes provides further evidence for a shared mechanism of binding. Despite the different locations of the bacterial attachment sites in BBK32 compared with SfbI from S. pyogenes and FnBPA from S. aureus, an antiparallel orientation is observed for binding of the N-terminal domain of fibronectin to each of the pathogens. Thus, these phylogenetically and morphologically distinct bacterial pathogens have similar mechanisms for binding to human fibronectin. [ABSTRACT FROM AUTHOR]

Fibronectin (Fn) binding by the Streptococcus pyogenes protein SfbI has been shown to trigger integrindependent internalization of this pathogen by human epithelial and endothelial cells. Here, using nuclear magnetic resonance spectroscopy and isothermal titration calorimetry in a dissection approach, the basis for the specificity and high affinity of the interaction between the N-terminal domain of Fn and SfbI is revealed. Each of the five Fn type 1 modules is directly involved in the interaction and is recognized by short consecutive motifs within the repeat region of SfbI. Crucially, these motifs must be combined in the correct order to form a high affinity ligand for the N-terminal domain of Fn. [ABSTRACT FROM AUTHOR]