1,650 research outputs found
The quest for extreme water repellency: Superhydrophobicity made easy
In his seminal work On Floating Bodies I Archimedes of Syracuse provided an explanation of the action of solid bodies on water. Although his thesis immediately benefitted King Heiro IIĀ² and has continued to serve mankind well, it ignores the effect of the interfacial interactions between the solid, water and air (surface tension). These interactions are negligible, or at least are considered negligible, compared to forces arising from the effect of gravity on large bodies. However, as the mass of the body decreases, the surface interactions become increasingly important leading to some unusual and potentially useful phenomena. The understanding and application of these effects is currently driving much fundamental research by physicists, chemical engineers, material scientists, and chemists into surfaces that display extreme properties, in particular extreme water repellency, or superhydrophobicitv. It is only comparatively recently that detailed mathematical expressions for the interaction between a liquid, solid and gas at these extremes have been developed, making progress that parallels that for the fabrication of these surfaces
On the importance of ĻāĻ stacking and cationāanion interactions in the construction of non-centrosymmetric networks of bromide salts of imidazolium cations bearing arene and polyfluoroarene rings
The salt 1-(2,3,5,6-tetrafluoropyridyl)-3-benzylimidazolium bromide crystallizes in the non-centrosymmetric space group Pna2ā. The structure arises from ĻāĻ stacking between the benzyl and tetrafluoropyridyl groups of the cations and cationābromide interactions. It is the latter that gives rise to the non-centrosymmetry
Experimental evidence for radiative attachment in astrochemistry from electron attachment to NCCCCN
Electron attachment to NCCCCN, dicyanoacetylene (2-butynedinitrile), has been observed. Metastable parent anions, NCCCCN_ā, with microsecond or longer lifetimes are formed close to 0 eV electron energy with a cross section of ā„0.25 2. The stability of NCCCCN suggests that radiative attachment to NCCCCN and similar _ā Ā°A linear carbon chain molecules may be an important mechanism for the formation of negatively charged molecular ions in astrophysical environments. CCCN_ and CN_ fragment anions are formed at ā¼3 and ā¼6 eV
Infinite stacking of alternating polyfluoroaryl rings and bromide anions
The crystal structure of 1-(4-bromo-2,3,5,6-tetrafluorophenyl)-3-benzylimidazolium bromide comprises columns of parallel bromotetrafluorophenyl rings with an interplanar distance of 6.936(6) Ć
separated by bromide anions
Access to psychological support for young people following stoma surgery: Exploring patientsā and cliniciansā perspectives
Psychological problems are common among people with inflammatory bowel disease (IBD) following stoma surgery. However, the ways in which stoma-related psychological needs are identified and addressed in healthcare settings remain unexplored. In this study, we investigated the perspectives of young people with a stoma and healthcare professionals about access to psychological support. Semi-structured interviews were conducted with young people with an IBD stoma (18-29 years) (n=13) and healthcare professionals (n=15), including colorectal surgeons, gastroenterologists, specialist nurses in IBD and stoma care, and general practitioners in England. Data collection and analysis were informed by constructivist grounded theory. Three analytic categories were developed: āinitiating support-seekingā, āaffirming psychological needsā, and āmobilizing psychological supportā, which capture young peoplesā trajectory to accessing psychological support. Based on the findings, we highlight the need for both patients and healthcare professionals to assign greater priority to the identification of psychological symptoms post-stoma surgery. More effective care pathways, which include responsive psychological services, would enhance access to psychological support for young people with a stoma
A classification of local Weyl invariants in D=8
Following a purely algebraic procedure, we provide an exhaustive
classification of local Weyl-invariant scalar densities in dimension D=8.Comment: LaTeX, 19 pages, typos corrected, one reference adde
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