Despite the prevalence of lithium ion batteries in modern technology, the search for alternative electrochemical systems to complement the global battery portfolio is an ongoing effort. The search has resulted in numerous candidates, among which mildly acidic aqueous zinc ion batteries have recently garnered significant academic interest, mostly due to their inherent safety. As the anode is often fixed as zinc metal in these systems, most studies address the absence of a suitable cathode for reaction with zinc ions. This has led to aggressive research into viable intercalation cathodes, some of which have shown impressive results. However, many investigations often overlook the implications of the zinc metal anode, when in fact the anode is key to determining the energy density of the entire cell. In this regard, we aim to shed light on the importance of the zinc metal anode. This perspective offers a brief discussion of zinc electrochemistry in mildly acidic aqueous environments, along with an overview of recent efforts to improve the performance of zinc metal to extract key lessons for future research initiatives. Furthermore, we discuss the energy density ramifications of the zinc anode with respect to its weight and reversibility through simple calculations for numerous influential reports in the field. Finally, we offer some perspectives on the importance of optimizing zinc anodes as well as a future direction for developing high-performance aqueous zinc ion batteries. Fig. 7 (a) A schematic illustration of the "electro-healing" strategy. (b) Galvanostatic voltage profiles of Zn symmetric cells with (magenta) and without (dark green) a healing step at different current densities (top: 7.5 mA cm À2 , bottom: 10 mA cm À2 ). Reprinted with permission from ref. 58.
There is an intriguing, current controversy on the involvement of iron(III)-hydroperoxo species as a "second electrophilic oxidant" in oxygenation reactions by heme and non-heme iron enzymes and their model compounds. In the present work, we have performed reactivity studies of the iron-hydroperoxo species in nucleophilic and electrophilic reactions, with in situ-generated mononuclear non-heme iron(III)-hydroperoxo complexes that have been well characterized with various spectroscopic techniques. The intermediates did not show any reactivities in the nucleophilic (e.g., aldehyde deformylation) and electrophilic (e.g., oxidation of sulfide and olefin) reactions. These results demonstrate that non-heme iron(III)-hydroperoxo species are sluggish oxidants and that the oxidizing power of the intermediates cannot compete with that of high-valent iron(IV)-oxo complexes. We have also reported reactivities of mononuclear non-heme iron(III)-peroxo and iron(IV)-oxo complexes in the aldehyde deformylation and the oxidation of sulfides, respectively.
Axial ligand substitution of a mononuclear nonheme oxoiron(IV) complex, [FeIV(O)(TMC)(NCCH3)]2+ (1) (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), leads to the formation of new FeIV=O species with relatively intense electronic absorption features in the near-UV region. The presence of these near-UV features allowed us to make the first observation of Fe=O vibrations of S = 1 mononuclear nonheme oxoiron(IV) complexes by resonance Raman spectroscopy. We have also demonstrated that the reactivity of nonheme oxoiron(IV) intermediates is markedly influenced by the axial ligands.
Purpose-Little is known about the speech and language abilities of children with cerebral palsy (CP) and there is currently no system for classifying speech and language profiles. Such a system would have epidemiological value and would have the potential to advance the development of interventions that improve outcomes. In this study, we propose and test a preliminary speech and language classification system by quantifying how well speech and language data differentiate among children classified into different hypothesized profile groups.Method-Speech and language assessment data were collected in a laboratory setting from 34 children with CP (18 males; 16 females) who were a mean age of 54 months (SD 1.8 months). Measures of interest were vowel area, speech rate, language comprehension scores, and speech intelligibility ratings.Results-Canonical discriminant function analysis showed that three functions accounted for 100% of the variance among profile groups, with speech variables accounting for 93% of the variance. Classification agreement varied from 74% to 97% using four different classification paradigms.Conclusions-Results provide preliminary support for the classification of speech and language abilities of children with CP into four initial profile groups. Further research is necessary to validate the full classification system. Keywords cerebral palsy; dysarthria; speech acoustics; speech and language profiles; classification Cerebral palsy (CP) is the most common cause of severe motor disability in children (Lepage, Noreau, Bernard, & Fougeyrollas, 1998), and it can have a profound impact on all aspects of life (Kennes, Rosenbaum, Hanna, Walter et al., 2002;Liptak, O'Donell, Conaway, Chumlea et al., 2001). For the past 40 years, the prevalence of CP has been relatively stable (or perhaps increasing slightly (Paneth, Hong, & Korzeniewski, 2006)). International estimates suggest that CP affects between 1.2 and 3.0 per 1000 children in developed countries (Odding, Roebroeck, & Stam, 2006;Paneth et al., 2006). However, in the United States, the most recent study suggests that CP may affect up to 3.6 per 1000 children (Yeargin-Allsopp, Braun, Doernbery, Benedict et al., 2008).CP is an umbrella term for which a number of different definitions have been proposed over the years. The most recent consensus definition specifies that CP: a.) is characterized by movement and posture disturbance; b.) is non-progressive in nature; c.) has its onset within NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript the pre-natal or neonatal period; d.) is caused by some type of damage to the central nervous system; and e.) is often accompanied by co-occurring problems with sensation, perception, cognition, communication, and behavior (Rosenbaum, Paneth, Leviton, Goldstein et al., 2007). Although experts have recognized the latter-most part of this definition for many years, problems with sensation, cognition, communication, and behavior have not been formally acknowledged as ...
Purpose Speech acoustic characteristics of children with cerebral palsy (CP) were examined with a multiple speech subsystem approach; speech intelligibility was evaluated using a prediction model in which acoustic measures were selected to represent three speech subsystems. Method Nine acoustic variables reflecting different subsystems, and speech intelligibility, were measured in 22 children with CP. These children included 13 with a clinical diagnosis of dysarthria (SMI), and nine judged to be free of dysarthria (NSMI). Data from children with CP were compared to data from age-matched typically developing children (TD). Results Multiple acoustic variables reflecting the articulatory subsystem were different in the SMI group, compared to the NSMI and TD groups. A significant speech intelligibility prediction model was obtained with all variables entered into the model (Adjusted R-squared = .801). The articulatory subsystem showed the most substantial independent contribution (58%) to speech intelligibility. Incremental R-squared analyses revealed that any single variable explained less than 9% of speech intelligibility variability. Conclusions Children in the SMI group have articulatory subsystem problems as indexed by acoustic measures. As in the adult literature, the articulatory subsystem makes the primary contribution to speech intelligibility variance in dysarthria, with minimal or no contribution from other systems.
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