Light Scattering by Cholesteric Skyrmions

We study the light scattering by localized quasi planar excitations of a Cholesteric Liquid Crystal known as spherulites. Due to the anisotropic optical properties of the medium and the peculiar shape of the excitations, we quantitatively evaluate the cross section of the axis-rotation of polarized light. Because of the complexity of the system under consideration, first we give a simplified, but analytical, description of the spherulite and we compare the Born approximation results in this setting with those obtained by resorting to a numerical exact solution. The effects of changing values of the driving external static electric (or magnetic) field is considered. Possible applications of the phenomenon are envisaged.Comment: 18 pages, 14 figure

An innovative, fast and facile soft-template approach for the fabrication of porous PDMS for oil-water separation

Oil wastewater and spilled oil caused serious environmental pollution and damage to public health in the last years. Therefore, considerable efforts are made to develop sorbent materials able to separate oil from water with high selectivity and sorption capacity. However most of them are low reusable, with low volume absorption capacity and poor mechanical properties. Moreover, the synthesis is time-consuming, complex and expensive limiting its practical application in case of emergency. Here we propose an innovative approach for the fabrication of porous PDMS starting from an inverse water-in-silicone procedure able to selectively collect oil from water in few seconds. The synthesis is dramatically faster than previous approaches, permitting the fabrication of the material in few minutes independently from the dimension of the sponges. The porous material evidenced a higher volume sorption capacity with respect to other materials already proposed for oil sorption from water and excellent mechanical and reusability properties.This innovative fast and simple approach can be successful in case of emergency, as oil spill accidents, permitting in situ fabrication of porous absorbents

An assessment of the effect of supersonic aircraft operations on the stratospheric ozone content

An assessment of the potential effect on stratospheric ozone of an advanced supersonic transport operations is presented. This assessment, which was undertaken because of NASA's desire for an up-to-date evaluation to guide programs for the development of supersonic technology and improved aircraft engine designs, uses the most recent chemical reaction rate data. From the results of the present assessment it would appear that realistic fleet sizes should not cause concern with regard to the depletion of the total ozone overburden. For example, the NOx emission of one type designed to cruise at 20 km altitude will cause the ozone overburden to increase by 0.03% to 0.12%, depending upon which vertical transport is used. These ozone changes can be compared with the predictions of a 1.74% ozone decrease (for 100 Large SST's flying at 20 km) made in 1974 by the FAA's Climatic Impact Assessment Program

When contrasting polarity, the Dutch use particles, Germans intonation

This study compares how Dutch and German, two closely related languages, signal a shift from a negative to a positive polarity in two contexts, when contrasting the polarity relative to a different topic situation (In my picture the man washes the car following after In my picture the man does not wash the car, henceforth polarity contrast) and when correcting the polarity of a proposition (The man washes the car following after The man does not wash the car, henceforth polarity correction). Production data show that in both contexts German speakers produced Verum focus (i.e., a high-falling pitch accent on the finite verb), while Dutch speakers mostly used the accented affirmative particle wel. This shows that even lexically and syntactically close languages behave differently when it comes to signalling certain pragmatic functions. Furthermore, we found that in polarity correction contexts, both affirmative particles and Verum focus were realized with stronger prosodic prominence. This difference was found in both languages and might be due to a secondary (syntagmatic) effect of the information structure of the utterance (absence or presence of a contrastive topic)

Intonational means to mark verum focus in German and French

German and French differ in a number of aspects. Regarding the prosody-pragmatics interface, German is said to have a direct focus-to-accent mapping, which is largely absent in French – owing to strong structural constraints. We used a semi-spontaneous dialogue setting to investigate the intonational marking of Verum Focus, a focus on the polarity of an utterance in the two languages (e.g. the child IS tearing the banknote as an opposite claim to the child is not tearing the banknote). When Verum Focus applies to auxiliaries, pragmatic aspects (i.e. highlighting the contrast) directly compete with structural constraints (e.g. avoiding an accent on phonologically weak elements such as monosyllabic function words). Intonational analyses showed that auxiliaries were predominantly accented in German, as expected. Interestingly, we found a high number of (as yet undocumented) focal accents on phrase-initial auxiliaries in French Verum Focus contexts. When French accent patterns were equally distributed across information structural contexts, relative prominence (in terms of peak height) between initial and final accents was shifted towards initial accents in Verum Focus compared to non-Verum Focus contexts. Our data hence suggest that French also may mark Verum Focus by focal accents but that this tendency is partly overridden by strong structural constraints

Characterization of gas phase aggregates of bis(2-ethylhexyl)sulfosuccinate (AOT) and divalent metal ions. Elimination of radical species in the decomposition pathways of even-electron [AOTMIICl2]– anions

Structure and properties of even-electron anionic species formed by bis(2-ethylhexyl)sulfosuccinate (AOT) and divalentmetal ions (MII) with stoichiometry [AOTMIICl2]– have been investigated by using electrospray ionization and different mass spectrometry techniques, such as high resolution, accurate mass measurements, collision-induced dissociation (CID) multiple-stage mass spectrometry.Owing to CID, eliminations of neutrals,mainly consisting in hydrochloric acid, 2-ethyl-1-hexene and 2-ethylhexanol, and an unexpected loss of an alkyl radical have been observed. The radical anions [C4HO6SMIICl]–• so produced have been characterized by MS3 experiments. Density functional theory calculations have been carried out for investigating structure and stability of the ionic species formed in the decomposition pathways

Instalações.

Selecionando locais para as instalações. Instalações: abrigos, apriscos, baias para reprodutores, setor de manejo, sala de ordenha, quarentenario e ambulatório. Istalações para crescimento e engorda. Cercas para caprinos: convencionais e móveis. Equipamento para as instalações: comedouros, comedouros para concentrados, fenis, comedouros de concentrados e feno, comedouros conjugados as cercas, saleiro, manejo de dejetos

Which drawing to deliver more information?

The paper explores the potential of methods and languages designed to facilitate the communication of appropriate information content for the different levels of detail required in the creation of an architectural design, levels with different purposes, but nevertheless co-ordinated. Within this thesis, the many different facets of drawing and the language of graphics are confirmed as agents of intellectual mediation, as a support for expression and also as dynamic cultural and evolving factors. In order to reply to the new demands of performance, due to the increasing fragmentation of responsibility for design, some adjustments in the workflow are needed, essential to support renewed practices; in fact, supporting this dynamic, the representation seems to have recovered a role of increased visibility and importance, regaining an effective recognition through a reconfirmation that remarks the delicate function of communication, interpretation and criticism. The added value of the BIM methodologies (Building Information Modeling), is not limited by the ability to handle graphical representations at different scales with a single 3D model, but it answers to some requests connected by the data complexity inherent with the design and construction, actively supporting the engineering process: this means to relate actors or the building process to each other in a new way, reforming the assets and the processing modes, requiring explicit coordination for activities and procedures. At this regard, we analyze new operational workflow through a brief description of some designs carried out through the collaboration between DISEG (Department of Structural, Geotechnical and Building Engineering) and the Building Service of the Politecnico di Torino, speaking about drawings and representations

Ion-mediated nucleation as an important global source of tropospheric aerosols

International audienceAerosol nucleation events have been observed at a variety of locations worldwide, and may have significant climatic and health implications. While ions have long been suggested as favorable nucleation embryos, their significance as a global source of particles has remained uncertain. Here, an ion-mediated nucleation (IMN) mechanism, which incorporates new thermodynamic data and physical algorithms, has been integrated into a global chemical transport model (GEOS-Chem) to study ion-mediated particle formation in the global troposphere. The simulated annual mean results have been compared to a comprehensive set of data relevant to particle nucleation around the globe. We show that predicted annual spatial patterns of particle formation agree reasonably well with land-, ship-, and aircraft-based observations. Our simulations show that, globally, IMN in the boundary layer is largely confined to two broad latitude belts: one in the northern hemisphere (~20° N?70° N), and one in the southern hemisphere (~30° S?90° S). In the middle latitude boundary layer over continents, the annual mean IMN rates are generally above 104 cm?3day?1, with some hot spots reaching 105 cm?3day?1. The zonally-averaged vertical distribution of IMN rates indicates that IMN is significant in the tropical upper troposphere, the entire middle latitude troposphere, and over Antarctica. Comparing the relative strengths of particle sources due to IMN and due to primary particle emissions demonstrates that IMN is significant on a global scale. Further research is needed to reduce modeling uncertainties and to understand the ultimate contribution of freshly nucleated particles to the abundance of cloud condensation nuclei