A Fluctuation Equation of State for Prediction of High-Pressure Densities of Ionic Liquids

International audienceDuring this work, we demonstrate, for the first time, that the volumetric properties of pure ionic liquids could be truly predicted as a function of temperature from 219 K to 473 K and pressure up to 300 MPa. This has been achieved by using only density and isothermal compressibility data at atmospheric pressure through the Fluctuation Theory-based Tait-like Equation of State (FT-EoS). The experimental density data of 80 different ionic liquids, described in the literature by several research groups as a function of temperature and pressure, was then used to provide comparisons. Excellent predictive capability of FT-EoS was observed with an overall relative absolute average deviation close to 0.14% for the 15,298 data points examined during this work

Marcapasso de Dupla-Câmara e Desfibrilador Mono-Câmara

A convivência entre marcapassos e desfibriladores está em vias de desaparecimento, mas ainda se impoe em alguns casos particulares. Este trabalho faz o balanço entre as compatibilidades e as incompatibilidades dos modelos recentes. O presente relato de caso refere-se a um paciente no qual o desfibrilador foi escolhido e posicionado atrás do grande peitoral esquerdo, de modo a separá-lo de um marcapasso de dupla-câmara implantado anteriormente. A programaçao de ambos, que eram da mesma marca, pôde ser efetuada pelo mesmo programador, mediante subterfúgios. Nenhuma interferência sobreveio entre os dois aparelhos, sendo necessário apenas corrigir algumas incompatibilidades na programaçao do marcapasso, passíveis de comprometer o funcionamento do desfibrilador

Marcapasso de Dupla-Câmara e Desfibrilador Mono-Câmara

A convivência entre marcapassos e desfibriladores está em vias de desaparecimento, mas ainda se impoe em alguns casos particulares. Este trabalho faz o balanço entre as compatibilidades e as incompatibilidades dos modelos recentes. O presente relato de caso refere-se a um paciente no qual o desfibrilador foi escolhido e posicionado atrás do grande peitoral esquerdo, de modo a separá-lo de um marcapasso de dupla-câmara implantado anteriormente. A programaçao de ambos, que eram da mesma marca, pôde ser efetuada pelo mesmo programador, mediante subterfúgios. Nenhuma interferência sobreveio entre os dois aparelhos, sendo necessário apenas corrigir algumas incompatibilidades na programaçao do marcapasso, passíveis de comprometer o funcionamento do desfibrilador

N,N′-Disubstituted Indigos as Readily Available Red-Light Photoswitches with Tunable Thermal Half-Lives

Some rare indigo derivatives have been known for a long time to be photochromic upon irradiation with red light, which should be advantageous for many applications. However, the absence of strategies to tune their thermal half-lives by modular molecular design as well as the lack of proper synthetic methods to prepare a variety of such molecules from the parent indigo dye have so far precluded their use. In this work, several synthetic protocols for N-functionalization have been developed, and a variety of N-alkyl and N-aryl indigo derivatives have been prepared. By installation of electron-withdrawing substituents on the N-aryl moieties, the thermal stability of the Z-isomers could be enhanced while maintaining the advantageous photoswitching properties upon irradiation with red light (660 nm LED). Both experimental data and computational results suggest that the ability to tune thermal stability without affecting the dyes' absorption maxima originates from the twisted geometry of the N-aryl groups. The new indigo photoswitches reported are expected to have a large impact on the development of optical methods and applications in both life and material sciences

Charge transfer from the carotenoid can quench chlorophyll excitation in antenna complexes of plants

The photosynthetic apparatus of higher plants can dissipate excess excitation energy during high light exposure, by deactivating excited chlorophylls through a mechanism called nonphotochemical quenching (NPQ). However, the precise molecular details of quenching and the mechanism regulating the quenching level are still not completely understood. Focusing on the major light-harvesting complex LHCII of Photosystem II, we show that a charge transfer state involving Lutein can efficiently quench chlorophyll excitation, and reduce the excitation lifetime of LHCII to the levels measured in the deeply quenched LHCII aggregates. Through a combination of molecular dynamics simulations, multiscale quantum chemical calculations, and kinetic modeling, we demonstrate that the quenching level can be finely tuned by the protein, by regulating the energy of the charge transfer state. Our results suggest that a limited conformational rearrangement of the protein scaffold could act as a molecular switch to activate or deactivate the quenching mechanism.FWN – Publicaties zonder aanstelling Universiteit Leide

Challenges relating to comparison of flavonoid glycosides dissolution profiles from Sutherlandia frutescens products

Unlike the case of conventional drug formulations, dissolution tests have hitherto not been required for herbal medicinal products commercially available in South Africa. This study investigated dissolution of the South African Sutherlandia frutescens using selected flavonoid glycosides as marker compounds. Dissolution of markers was assessed in three dissolution media at pH 1.2, 4.5 and 6.8, and samples were analysed using a validated HPLC method. The dissolution profile of each marker varied for the different materials investigated. All three media utilised showed differences in flavonoid glycoside dissolution between the S. frutescens products evaluated, with f2 values <50 for comparison of flavonoid dissolution from any two of the materials. Dissolution of S. frutescens materials could thus be characterised using the markers in all the media tested. This tool may be employed in the future for comparison of orally administered S. frutescens products, provided between batch variability is evaluated and found less than between-sample variability.IS

The first penicillate millipedes from the vicinity of Manaus, Central Amazonia, Brazil (Diplopoda: Polyxenida)

Two new and an undetermined/unnamed species in the penicillate diplopod genera Lophoturus BROLEMANN, 1931 and Macroxenodes SILVESTRI, 1948 are described from the vicinity of Manaus, Central Amazonia, Brazil: L. adisi n.sp., M. amazonicus n.sp., and M. sp.. L. adisi n.sp. is characteristic in having the molar plate with a swollen dorsal molar plate shoulder of the mandible, while M. amazonicus n.sp. in having three thick bacilliform dorsal sensilla separated from a second group of posterior ventral sensilla on antennal segment VI, the gnathochilarium wìth 21 to 23 palpal sensilla and the femoral and tibial setae with a noval base furnished with 3 or 4 long spines. Also, L.adisi n.sp., which is the dominant species at the locality, has been investigated as to its postembryonic stadia and rnandibular structure. On the other hand, M. sp. is characteristic in having more numerous sensilla located in one or two rows in the dorso-distal part of antennal segment VI, in the tergal trichomes grouped in two separated oval areas, and in 22 or 23 palpal sensilla. Plesioproctus CONDÉ, 1964 is shown to be a junior synonym of Ancistroxenus SCHUBART, 1947, n. syn. The synonymy results from a revision of type material of the Brazilian Ancistroxenus tupiensis SCHUBART, 1947. Plesioproctus comans (LOOMIS 1934), from Trinidad, is formally transferred to Ancistroxenus, resulting in A. comans (LOOMIS 1934), n. comb., a species which is also a subjective senior synonym of Ancistroxenus tupiensis SCHUBART, 1947, n. syn.. A. comans has been recorded from the study region for the first time, and its postembryonic stadia are fully redescribed. A key to the genera of the family Lophoproctidae is given

Making Sense of Family Deaths in Urban Senegal: Diversities, Contexts, and Comparisons

Despite calls for cross-cultural research, Minority world perspectives still dominate death and bereavement studies, emphasizing individualized emotions and neglecting contextual diversities. In research concerned with contemporary African societies, on the other hand, death and loss are generally subsumed within concerns about AIDS or poverty, with little attention paid to the emotional and personal significance of a death. Here, we draw on interactionist sociology to present major themes from a qualitative study of family deaths in urban Senegal, theoretically framed through the duality of meanings-in-context. Such themes included family and community as support and motivation; religious beliefs and practices as frameworks for solace and (regulatory) meaning; and material circumstances as these are intrinsically bound up with emotions. Although we identify the experience of (embodied, emotional) pain as a common response across Minority and Majority worlds, we also explore significant divergencies, varying according to localized contexts and broader power dynamics

Noncommutative Switching of Double Spiropyrans

The spiropyran family of photochromes are key components in molecular-based responsive materials and devices, e.g., as multiphotochromes, covalently coupled dyads, triads, etc. This attention is in no small part due to the change in properties that accompany the switch between spiropyran and merocyanine forms. Although the spiropyran is a single structural isomer, the merocyanine form represents a family of isomers (TTT, TTC, CCT, etc.) and protonation states. Combining two spiropyrans into one compound increases the number of possible structures dramatically and the interaction between the units determines, which are impeded due to intramolecular quenching of excited states. Here, we show that the coupling of two spiropyran photochromes through their phenol units yields favorable interactions (crosstalk) between the components that provides access to species inaccessible with the component monospiropyran alone. Specifically, the ring opening of one spiropyran unit, which is thermally stable at-30 °C, prevents ring opening of the second spiropyran unit. Furthermore, whereas protonated E-and Z-monomerocyanines were previously shown to undergo thermal-and photo-equilibration, the corresponding protonated E-and Z-bimerocyanines are thermally stable and show one-way photoisomerization from the Z,Z-to an emissive E,E-bimerocyanine form. Subsequent deprotonation at room temperature resets the system to the bispiro ring-closed form, but deprotonation at-30 °C yields the otherwise inaccessible bimerocyanine form. This form is photochemically inert but undergoes a two-step thermal relaxation via the merocyanine-spiropyran form, showing that the connection at the phenol units provides sufficient intramolecular interaction to fine-tune the complex isomerization pathways of spiropyrans and demonstrating noncommutability in photo-and pH-regulated multistep isomerization pathways