Perfluoroalkylene oxide derivatives as potential elastomer precursors

The synthesis of octadecafluoro-3,9-dloxa-1,11- bis(3-methoxycarbonyl phenyl) undecane from hexafluoroglutaryl fluoride, via the intermediate octadecafluoro- 1,11-diido-3,9-dioxaundecane has been examined. Each stage of this sequence proceeds in poor yield, and no substantial improvement could be obtained by variation of conditions. The physical properties of the product lead to handling difficulties, and an attempt to derive a polymer from the system failed. A synthesis of difluoromalonyl chloride from perfluorocyolohexa-1,4-diene is described. Difluoromalonyl fluoride could not be obtained pure, either by fluorination of the chloride, or by direct oxidation of the diene. The addition reaction of hexafluoropropene epoxide with hexafluoroglutaryl fluoride, catalysed by caesium fluoride, provides a route to a mixture of fluorinated bifunctional ethers. By appropriate choice of reaction conditions, the isomeric distribution in the products maybe restricted; a mechanism Is suggested to account for the observed product distribution. Separation and purification of the reaction products provided a series of ether-containing bifunctlonal compounds, which on reduction yielded a corresponding series of ether diols. Polycondensation of the diols obtained as above with isophthal .oyl chloride gave a series of polyesters, which were compared with analogous polyesters derived from other systems. The thermal stability of polyesters having an ether link situated β to the eater group Is significantly lower than that of polyesters lacking this feature, but no simple relation was found between structure and the activation energy for degradation. The glass transition temperatures of non-ether containing polyesters correlate moderately well with predicted values. A knowledge of the glass temperatures of ether containing polyesters allows the calculation of the glass temperature of the hypothetical high molecular weight homopolymer of hexafluoropropene epoxide; a value of ca.-57ºC was obtained

Light emission through a corrugated metal film: The role of cross-coupled surface plasmon polaritons

S. Wedge, Ian R. Hooper, I. Sage, and William L. Barnes, Physical Review B, Vol. 69, article 245418 (2004). "Copyright © 2004 by the American Physical Society."We examine the phenomenon of light emission through a thin metal film that takes place via surface plasmon polaritons. Surface plasmon polariton cross coupling has recently been invoked to explain sharp features observed in the angle dependent emission spectra obtained from surface-emitting (through cathode) organic light-emitting diode structures. We investigated whether such a cross-coupling process is needed to explain such observations. We undertook measurements on samples for a variety of metal film thicknesses. Our results are consistent with the mechanism of surface plasmon polariton cross coupling but also show that the processes underlying the emission from such structures can be rather subtle

Where Is Law & Literature Headed? Roundtable Discussion

This is a roundtable that will discuss the question Where is Law and Literature Headed

Atmospheric CO2 decline and the timing of CAM plant evolution

Background and Aims: CAM photosynthesis is hypothesized to have evolved in atmospheres of low CO2 concentration in recent geological time because of its ability to concentrate CO2 around Rubisco and boost water use efficiency relative to C3 photosynthesis. We assess this hypothesis by compiling estimates of when CAM clades arose using phylogenetic chronograms for 73 CAM clades. We further consider evidence of how atmospheric CO2 affects CAM relative to C3 photosynthesis. Results: Where CAM origins can be inferred, strong CAM is estimated to have appeared in the past 30 million years in 46 of 48 examined clades, after atmospheric CO2 had declined from high (near 800 ppm) to lower (<450 ppm) values. In turn, 21 of 25 clades containing CAM species (but where CAM origins are less certain) also arose in the past 30 million years. In these clades, CAM is probably younger than the clade origin. We found evidence for repeated weak CAM evolution during the higher CO2 conditions before 30 million years ago, and possible strong CAM origins in the Crassulaceae during the Cretaceous period prior to atmospheric CO2 decline. Most CAM-specific clades arose in the past 15 million years, in a similar pattern observed for origins of C4 clades. Conclusions: The evidence indicates strong CAM repeatedly evolved in reduced CO2 conditions of the past 30 million years. Weaker CAM can pre-date low CO2 and, in the Crassulaceae, strong CAM may also have arisen in water-limited microsites under relatively high CO2. Experimental evidence from extant CAM species demonstrates that elevated CO2 reduces the importance of nocturnal CO2 fixation by increasing the contribution of C3 photosynthesis to daily carbon gain. Thus, the advantage of strong CAM would be reduced in high CO2, such that its evolution appears less likely and restricted to more extreme environments than possible in low CO2

Metaphor, transformation and transdisciplinarity

Metaphor, along with narrative and other linguistic devices such as myth, fable, parable, and allegory, enables us to make sense of the world around us and shape how we think and act individually and collectively in relation to society and the natural world. The chapter considers the properties of metaphors and how they can promote or curtail action towards transformative change in the direction of sustainability. The notion of transformation itself is examined and is taken to represent profound changes in the ways we understand economy, society, and the place of technology. Indeed, it calls for a recalibration of the popular imagination – and this is where metaphor, myth, and fable have such a vital role to play. As an introduction to the book, the chapter explains the structure of the volume comprising four parts each of which explore different dimensions of metaphor from the ways it shapes our relationship with science and technology to the rich terrain of psychoanalysis, creativity, and artistic practice. Each of the subsequent 13 chapters are briefly described and demonstrate the spirit of transdisciplinary collaboration which informs their quite different analyses, but which share a commitment to sustainability representing an authentic societal and environmental flourishing

The influence of syntactic knowledge on reading comprehension varies as a function of oral vocabulary in Spanish-speaking children

Background: Reading comprehension is a complex process influenced by many factors. However, the abilities that are known to influence reading comprehension may not contribute equally for children with different levels of oral language. Aims: Here we examined the relationship of two factors known to influence reading comprehension (morphology and syntax) in a group of children who varied in their levels of oral vocabulary. Method: Two hundred seventy-three typically developing Spanish-speaking fourth graders were assessed on non-verbal intelligence, word and pseudoword reading, oral vocabulary, morphological awareness and syntax, along with reading comprehension ability. Standardised oral language scores within this group ranged from the first to the 99th percentile. Mediated multiple regression with moderation was used to assess (1) whether the influence of oral vocabulary on reading comprehension was mediated by decoding, morphology or syntax and (2) whether the effects of syntax on reading comprehension varied as a function of oral vocabulary levels. Results: There was a direct positive relationship between vocabulary and reading comprehension, and this was mediated by word reading and syntax, but not by pseudoword reading or morphology. Furthermore, the relation between syntax and reading comprehension was moderated by oral vocabulary such that the strength of this relationship diminished as oral vocabulary levels increased. Conclusions: These findings suggest that longitudinal research is necessary to explore the possibility that a syntax intervention might be beneficial for readers with low oral vocabulary.FEDER 2014-2020Consejería de Economía, Conocimiento, Empresas y Universidad US-126479

The effects of morphological and syntactic knowledge on reading comprehension in Spanish speaking children

Reading comprehension is a complex task requiring many underlying skills. Syntactic awareness and morphological awareness are two such skills that have been shown to be related to reading comprehension. However, the majority of studies have been carried out in English, and very few have explored these skills in monolingual Spanish speaking children. Here we explored to what extent syntactic awareness and morphological awareness contributed to text comprehension in Spanish. 501 typically developing Spanish speaking 4th graders were assessed on non-verbal intelligence, word and nonword reading, oral vocabulary, morphological and syntactic knowledge, along with reading comprehension ability. After excluding children with poor decoding or low non-verbal intelligence, 234 children were retained for analysis. Multiple linear regression modelling was used to assess the unique contribution of each variable to reading comprehension. As per findings reported in English, syntactic knowledge was a significant predictor of comprehension after controlling for age, gender, non-verbal IQ, word reading and oral vocabulary, as well as morphological knowledge. In contrast, and contrary to results normally reported for English speaking children, morphological knowledge did not explain any variance in reading comprehension beyond that explained by the control variables. These results highlight the important contribution of syntactic knowledge to text comprehension in Spanish speaking children, as well as the importance of undertaking research in languages other than English.Ministerio de Economía y Competitividad PSI2015-65656-

Pulmonary hypERtension and measurement of exerciSe caPacIty REmotely: evaluation of the 1-minute sit to stand test (PERSPIRE): a cohort study

Background: Multi-parameter risk assessment is recommended to aid treatment decisions in patients with pulmonary arterial hypertension. The 1-minute sit-to-stand test has been validated for use in other respiratory illnesses. The aim of this study was to evaluate its safety in the hospital setting and potential utility in remote assessment in patients with pulmonary hypertension. Methods: In a prospective cohort study design patients performed the 1-minute sit-to-stand and Incremental Shuttle Walk tests on the same day. The primary aim of the study was to assess safety signals and correlations with other metrics used in risk assessment. Results: Sixty patients with pulmonary arterial hypertension and 15 with chronic thromboembolic pulmonary hypertension were enrolled. No adverse events were recorded. Post-test change in physiological parameters was lower for the 1-minute sit-to-stand than for the Incremental Shuttle Walk test in heart rate (+9.4(8.0)bpm versus +38.3(25.9)bpm (p<0.001)), oxygen saturation (−3.8(4.0)% versus −8.9(7.3)%, (p<0.01)) and systolic blood pressure (+10.1(10.5)mmHg versus +17.7(19)mmHg, p<0.001). There were significant correlations between the 1-minute-sit-to-stand and Incremental Shuttle Walking test (r= 0.702, p< 0.01), WHO FC (−0.449, p<0.01), emPHAsis-10 (−0.436, p<0.001) and NT-proBNP (−0.270, p=0.022). Ninety-seven percent of patients were willing to perform the test at home. Conclusion: This study has demonstrated the safety, sub-maximal characteristics of the 1-minute sit-to-stand test in pulmonary arterial hypertension chronic thromboembolic pulmonary hypertension in the hospital setting, its positive correlation with the Incremental Shuttle Walk test and potential role in remote risk assessment. Further evaluation of this exercise test is now warranted

Weak-anchoring effects in a thin pinned ridge of nematic liquid crystal

A theoretical investigation of weak-anchoring effects in a thin two-dimensional pinned static ridge of nematic liquid crystal resting on a flat solid substrate in an atmosphere of passive gas is performed. Specifically, we solve a reduced version of the general system of governing equations recently derived by Cousins et al. [Proc. Roy. Soc. A}, 478(2259):20210849, 2022] valid for a symmetric thin ridge under the one-constant approximation of the Frank--Oseen bulk elastic energy with pinned contact lines to determine the shape of the ridge and the behaviour of the director within it. Numerical investigations covering a wide range of parameter values indicate that the energetically-preferred solutions can be classified in terms of the Jenkins--Barratt--Barbero--Barberi critical thickness into five qualitatively different types of solution. In particular, the theoretical results suggest that anchoring breaking occurs close to the contact lines. The theoretical predictions are supported by the results of physical experiments for a ridge of the nematic 4'-pentyl-4-biphenylcarbonitrile (5CB). In particular, these experiments show that the homeotropic anchoring at the gas--nematic interface is broken close to the contact lines by the stronger rubbed planar anchoring at the nematic--substrate interface. A comparison between the experimental values of and the theoretical predictions for the effective refractive index of the ridge gives a first estimate of the anchoring strength of an interface between air and 5CB to be $(9.80\pm1.12)\times10^{-6}\,{\rm N m}^{-1}$ at a temperature of $(22\pm1.5)^\circ$C