Operational lifetime is a critical performance parameter of organic electronic devices and can be cut short by multiple degradation mechanisms. One supposed cause is metal migration between the electrodes, which, however, is difficult to study independently of other failure modes. We present a setup, which excludes such competing processes and demonstrates that silver (Ag) electrochemical migration through organic optoelectronic materials occurs predominantly by cation transport. Metal dendrites form at the cathode, eventually causing short circuits between the electrodes. Lifetime studies with organic light-emitting diodes containing Ag electrodes suggest that results obtained with our setup can provide relevant information about degradation in real devices.

The large volume production of flexible electronics by solution based roll-to-roll (R2R) manufacturing technologies is a promising upscaling strategy for the organic electronics industry. Typical optoelectronic devices like organic light emitting diodes (OLEDs) consist of a complex stack of functional layers. Solution deposition of these structures eliminates the need for expensive vacuum processing. This contribution presents approaches for solution based R2R production methods of functional OLED layers on flexible polymer substrates. The development of a R2R line with two slot-die coating stations is discussed which can deposit two uniform layers consecutively in a single run (“tandem coating”) at web speeds up to 30 m/min. Furthermore, it offers the unique feature that there is no contact between the rollers and the top side of the substrate where the functional coating is deposited. Thereby, an important source of particle contamination and other damage to the device is eliminated. In addition to continuous deposition, stripe and intermittent coating techniques have been developed, allowing the production of patterned layers. Finally, examples will be shown of OLEDs where two functional materials are deposited by R2R processing from solution.

Major soluble chemical impurities have been measured along a 130 m firn core from the Amundsen–Scott Station in order to assess Southern Hemisphere environmental variability over the last millennium. Particular attention is given to the possible impact of the Little Ice Age, a well-known climatic disturbance which occurred in the Northern Hemisphere between about A.D. 1500 and 1900.

Na+, K+, NH4+, Cl+, SO42− and NO3− concentrations were carefully determined in forty-two 40 cm firn sections. Stringent precautions were taken to ensure the analytical reliability of the data set obtained. The average concentrations are (in ng g−1): 11.0 ± 2.5, 0.7 ± 0.4, 0.5 ± 0.2, 31 ± 5.6, 58 ± 11.6 and 103 ± 11.6 respectively (the scatter represents the standard deviation).

No definite trend is detected which could be linked to the Little Ice Age disturbance.

Acid fallout from volcanic eruptions is well documented in the Greenland and Antarctic ice sheets (Hammer and others, 1980; Hammer, 1984; Legrand and Delmas, 1987). However, to date, no volcanic ash (tephra) layers have been positively identified in association with any of the high electrical conductivity layers that mark the volcanic acid deposition. In this paper we report the results of a study of the chemical composition of insoluble microparticles filtered from five intervals of a core from the South Pole. These five intervals were identified by Kirchner (1988) as being due to volcanic fallout, on the basis of electrical conductivity and sulfuric acid measurements.

The major element composition of tiny (<5 µm) glass shards found in these layers was determined and compared with analyses of volcanic ash from known eruptions or from volcanic sources suspected of having produced the fallout. Glass shards from volcanic eruptions of both local (Antarctic and sub-Antarctic) and of global (Indonesian/South American) importance have been identified in this study.

To explain why English compounds generally avoid internal inflectional suffixation (e.g., key-chain rather than keys-chain), linguists have often invoked the Level Ordering Hypothesis, that is, that particular types of morphology, in this case inflectional suffixation, are derivationally ordered after compounding. However, a broad range of counter-examples and conceptual objections to Level Ordering have emerged. We propose an alternative account, based on the observation that certain English inflectional suffixes are more perceptible than others (-ing > -s > -ed), and that these suffixes are less crucial to lexical access and recovery of meaning than corresponding root-final segments. This proposal was tested in perception and production experiments. In the perception experiment, compounds with a nonsense word as modifier (e.g., dacks van, dacked van) were auditorily presented to native English speakers, who were asked to spell what they heard. The participants omitted significantly more -ed than -s or -ing. In the production experiment, native English speakers read these compounds. The speakers dropped significantly more -ed than -s or -ing. Furthermore, they dropped more of these sounds when they were spelled as affixes than as part of the root (e.g., dacked van vs. dact van). These results suggest that English speakers’ avoidance or inclusion of inflection in compounds is based not on Level Ordering but on perceptibility, as well as the status of the consonant as an affix. We further present a formal analysis capturing these factors in terms of Steriade’s Licensing-by-Cue proposal.

A fundamental observation of phonological theory is that, out of the rich sound signal of speech, a small subset of phonetic properties is contrastive in any given language. Standardly, this observation is captured by excluding the non-distinctive phonetic properties from some levels of representation, yielding an abstract categorical representation of the contrasts among the speech sounds. Universally non-contrastive features have generally been assumed to be unspecified throughout the phonological component; thus, for example, Keating (1984) and Lombardi (1991) have argued against inclusion of particular laryngeal features in phonological representation on the grounds that they are never contrastive. Language-particular non-contrastive features have generally been assumed to be unspecified only in underlying representation and early stages of the derivation (e.g. Kiparsky 1982, Archangeli 1984, 1988, Archangeli & Pulleyblank 1986, 1994, Steriade 1987, Clements 1988). Moreover, since the discovery of extensive language-particular gradient alternations, it has standardly been assumed that a subsequent phonetic component is needed, to fill in gradient and universally non-contrastive properties (e.g. Pierrehumbert 1980, Keating 1990; but see Pierrehumbert 1994 for an attack on this view of the phonetics–phonology interface). This model is schematised in Fig. 1.

It is generally acknowledged, by both its proponents and detractors, that Optimality Theory has provoked a reexamination, in recent years, of the role of functional considerations, and their typological reflexes, in phonological theory. April McMahon's Change, chance, and optimality attempts an in-depth examination of this issue, particularly from the perspective of the relation between synchrony and diachrony in linguistic theory. The issue, and OT's general stance towards it, are summarised by Prince & Smolensky (1993: 198):

One might feel compelled to view a grammar as a more-or-less arbitrary assortment of formal rules, where the principles that the rules subserve (the ‘laws’) are placed entirely outside the grammar, beyond the purview of formal or theoretical analysis, inert but admired. It is not unheard of to conduct phonology in this fashion. We urge a reassessment of this essentially formalist position. If phonology is separated from the principles of well-formedness (the ‘laws’) that drive it, the resulting loss of constraint and theoretical depth will mark as major defeat for the enterprise. The danger, therefore, lies in the other direction: clinging to a conception of Universal Grammar as little more than a loose organizing framework for grammars. A much stronger stance, in accord with the thrust of recent work, is available. When the scalar and the gradient are recognized and brought within the purview of theory, Universal Grammar can supply the very substance from which grammars are built: a set of highly general constraints which, through ranking, interact to produce the elaborate particularity of individual languages.