Failure Mechanisms of Stretchable Perovskite Light-Emitting Devices under Monotonic and Cyclic Deformations

This paper presents the results of experimental and analytical studies of the failure mechanisms of stretchable perovskite light-emitting devices (PeLEDs). The multilayered PeLED structures consist of an anodic layer of poly(3,4-ethylenedioxythiophene):polystyrene-sulfonate (PEDOT:PSS), an emissive layer of methylammonium lead bromide (MAPbBr₃), and a eutectic gallium–indium (EGaIn) cathodic layer, which are deposited onto treated polydimethylsiloxane substrates. The intrinsically nonstretchable MAPbBr₃ and PEDOT:PSS are modified with poly(ethylene oxide). The failure mechanisms of the layered stretchable PeLED structures are then investigated under monotonic and cyclic deformations. The optical and scanning electron microscopy images show the deflection and propagation of cracks and wrinkles under applied strains. Cracking of perovskite crystal and debonding of films are also observed with increased cyclic deformation. The effects of the failure mechanisms on the optoelectronic properties of the devices are then studied. The in situ measured transmittance of the PEDOT:PSS (≈75%) reduces with increasing uniaxial strain, and then is increased close to its initial value when the strain is released. The turn-on voltage of the device increases with increasing number of cycles between 50 and 1000 cycles at 20% strain level. The fatigue lifetimes of the PeLED structures are used to explain the design of stretchable perovskite devices.     

Current Situation and Prospect of Nanometrology and its Standardization in Indonesia

As one of the emerging technologies in Indonesia, nanotechnology requires comprehensive studies of supporting infrastructures as well as the regulation that will underpin the quality of nanoproducts or nanoservices. Nanometrology is one of the most important supporting infrastructures for development of nanotechnology. This article reviews the importance of nanometrology and its standardization within the context of nanotechnology development in Indonesia. Current situation of nanotechnology development, relevant standards availability, necessity for new standards, nanometrology development and future goals have been explained. This article contributes novel insights about nanotechnology and nanometrology developments and may help the regulation body to make the policy.     

Determination of free reduced and total glutathione in wheat flours by an isotope dilution assay

Summary An isotope dilution assay (IDA) for free reduced glutathione (GSH) and total glutathione (GSH, oxidised glutathione and protein-bound glutathione) was developed and its accuracy and sensitivity were established. The new method for GSH required extraction of flour samples with a buffer at pH 4.5 containingN-ethyl maleimide (NEMI) and¹⁴C-labelled S-(N-ethylsuccinimido) glutathione ([¹⁴C]GS-NEMI), purification of the labelled and unlabelled GS-NEMI by three Chromatographic steps and assay of the specific radioactivity of the GS-NEMI isolated. Total glutathione was assayed after reduction with dithioerythritpl. Applications of the IDA indicated that the levels of GSH (16–41 nmol/g) and total glutathione (170–185 nmol/g) were relatively low in flours with low ash contents, but increased with increasing extraction grade. The level of GSH was higher in a flour obtained from kernels that were ground in the absence of gaseous oxygen. Storage of flours reduced the GSH concentration. IDA of fractions obtained from flour showed that the extraction residue, mainly consisting of starch and glutelins, contained most of the bound glutathione.

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Bestimmung von freiem reduziertem und vom gesamten Glutathion in Weizenmehlen durch Isotopenverdünnungsanalyse

Zusammenfassung Eine Isotopenverdünnungsanalyse (IVA) wurde für das freie reduzierte (GSH) und das gesamte Glutathion (GSH, GSSG proteingebundenes Glutathion) entwickelt und auf seine Genauigkeit und Empfindlichkeit überprüft. Die neue Methode für GSH erfordert die Extraktion der Mehlprobe mit einem Puffer bei pH 4,5, der N-Ethylmaleinsäureimid (NEMI) und [¹⁴C]-GS-NEMI enthält, Reinigung des markierten und unmarkierten GS-NEMI durch drei chromatographische Schritte sowie die Bestimmung der spezifischen Radioaktivität von dem isolierten GS-NEMI. Das gesamte Glutathion wird nach Reduktion mit Dithioerythrit bestimmt. Anwendungen der IVA zeigten, daß die Konzentrationen von GSH (16 bis 41 nmol) und von gesamtem Glutathion (170 bis 185 nmol/g) relativ gering waren in Mehlen mit niedrigen Aschegehalten, aber daß sie mit steigendem Ausmahlungsgrad zunahmen. Die GSH-Konzentration war in einem Mehl höher, das aus Körnern stammte, die in Abwesenheit von Sauerstoff gemahlen worden waren. Die Lagerung von Mehlen erniedrigte den GSH-Gehalt. Die IVA von Mehlfraktionen zeigte, daß der Extraktionsrückstand, der hauptsächlich aus Stärke und Glutelinen bestand, das meiste gebundene Glutathion enthielt.

     

New efficient exponentially weighted moving average variability charts based on auxiliary information

Control chart is a well-known tool for monitoring the performance of an ongoing process. The variability of a process is an important parameter that may deteriorate the process performance if it is not taken care on time. In this study, we have proposed some new auxiliary information-based exponentially weighted moving average (EWMA) charts for improved monitoring of process variability. We employed auxiliary information in some useful forms including ratio, regression, power ratio, ratio exponential, ratio regression, power ratio regression, and ratio exponential regression estimators. The performance of the newly developed charts is evaluated and compared with some existing charts (viz., the NEWMA, the Improved R, the Synthetic R, and the classical R charts), using some useful measures such as average run length (ARL), extra quadratic loss, and relative ARL. The comparative analysis revealed that the proposed charts outperform their counterparts, especially when there is a strong relationship between the study and the auxiliary variables. Finally, an illustrative example is provided for the monitoring of air quality data.     

Characterization of Ba0.55Sr0.45TiO3 films as light and temperature sensors and its implementation on automatic drying system model

The growth of Ba_0.55Sr_0.45TiO₃ films on p-type silicon substrate with depletion and enhancement treatments have been conducted in this research. The aims were to examine film sensitivity as light sensor and value range, resolution, acuracy level, and their hysteresis as temperature sensor. The films were annealed at 800, 850, and 900 °C for 15 hours. In this work, enhancement BST of 850 °C was the best quality film and utilized as light and temperature sensors. Its implementation has been successfully conducted on ATMega8535 microcontroller-based automatic drying system model by exploiting the working principle of the BST films as automatic switch.     

Hydraulics conveyances of mud slurry by a spiral pipe

Indonesia particularly East Java has been suffering from eruption of gas and mud slurry, caused by oil and gas exploration. Everyone calls this disaster as Sidoarjo mud or Lapindo mud. Mud slurry is essentially a mixture of a carrying fluid and solid particles held in suspension. When the mud slurry flow speed is not sufficiently high the particles will not be maintained in suspension. In spiral pipe twisted with a constant pitch in relation to the axis a swirling flow occurs when fluids flow in the pipe. The aim of this study is to examine characteristics of the hydraulic transport of mud slurry flowing in the spiral pipe with three-shape groove pipe walls. The shear stress and the shear strain are calculated by measuring the pressure drop and the volumetric flow rate in circular pipe, respectively. The power law exponent were about 0.93–1.0 for mud slurry solution of 45%, 30% and 20% of weight concentrations. The diameter of particles was 0.95 mm and the density was 2.19 × 10³ (kg/m³). The apparent viscosity of mud slurry solution is not constant to the shear strain but the relationship is approximated by model of power law. The friction factor of mud slurries in a spiral pipe with ratio pitch per diameter 6.7 is lower than circular pipe and spiral pipe with P/Di= 3.9 and 4.3. It was shown that the spiral pipe caused drag reduction in flowing of mud slurries. The drag reduction ratio of spiral pipe was about 28% for Cw=30% at Re’=32 × 10³. This paper was presented at the 7th JSME-KSME Thermal and Fluids Engineering Conference, Sapporo, Japan, October 2008. Yanuar received his B.S. degree in Mechanical Engineering from Indonesia University, Indonesia, in 1986. He then received his Master of Eng. and Doctor of Eng. in Mechanical Engineering from University of Tokyo Metropolitan, Japan, in 1995 and 1998, respectively. Professor at Mechanical Engineering at University of Indonesia in Jakarta, Indonesia.     

Oxidation of Cr2AlC (0001): Insights from Ab Initio Calculations

We performed an investigation of the initial stage of oxidation onto a relevant Cr₂AlC (0001) surface by ab initio calculations. For the most energetically stable Al-terminated Cr₂AlC (0001) surface, a detailed model describing the oxygen-surface interaction is developed by exploring the adsorption energetics. Based on the evaluation of the energetics and the structural properties of the atomistic models generated, the results point to an initial stage of the Cr₂AlC (0001) surface oxidation with some similarities with those observed in the Al (111) layer. Our findings on the bonding mechanism of single O adsorption atoms of the surface may lead to further alloying strategies to enhance oxidation resistance in a wide range of refractory-metal-based MAX phases.