Formation and Interaction of Membrane Tubes

We show that the formation of membrane tubes (or membrane tethers), which is a crucial step in many biological processes, is highly non-trivial and involves first order shape transitions. The force exerted by an emerging tube is a non-monotonic function of its length. We point out that tubes attract each other, which eventually leads to their coalescence. We also show that detached tubes behave like semiflexible filaments with a rather short persistence length. We suggest that these properties play an important role in the formation and structure of tubular organelles.Comment: 4 pages, 3 figure

Do the Potential Benefits of Metal-on-Metal Hip Resurfacing Justify the Increased Cost and Risk of Complications?

Metal-on-metal hip resurfacing arthroplasty (MoM HRA) may offer potential advantages over total hip arthroplasty (THA) for certain patients with advanced osteoarthritis of the hip. However, the cost effectiveness of MoM HRA compared with THA is unclear. The purpose of this study was to compare the clinical effectiveness and cost-effectiveness of MoM HRA to THA. A Markov decision model was constructed to compare the quality-adjusted life-years (QALYs) and costs associated with HRA versus THA from the healthcare system perspective over a 30-year time horizon. We performed sensitivity analyses to evaluate the impact of patient characteristics, clinical outcome probabilities, quality of life and costs on the discounted incremental costs, incremental clinical effectiveness, and the incremental cost-effectiveness ratio (ICER) of HRA compared to THA. MoM HRA was associated with modest improvements in QALYs at a small incremental cost, and had an ICER less than $50,000 per QALY gained for men younger than 65 and for women younger than 55. MoM HRA and THA failure rates, device costs, and the difference in quality of life after conversion from HRA to THA compared to primary THA had the largest impact on costs and quality of life. MoM HRA could be clinically advantageous and cost-effective in younger men and women. Further research on the comparative effectiveness of MoM HRA versus THA should include assessments of the quality of life and resource use in addition to the clinical outcomes associated with both procedures. Level I, economic and decision analysis. See Guidelines for Authors for a complete description of levels of evidence

Peripheral halo-functionalization in [Cu(N^N)(P^P)]+ emitters: influence on the performances of light-emitting electrochemical cells

A series of heteroleptic [Cu(N^N)(P^P)][PF6] complexes is described in which P^P = bis(2-(diphenylphosphino)phenyl)ether (POP) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos) and N^N = 4,4′-diphenyl-6,6′-dimethyl-2,2′-bipyridine substituted in the 4-position of the phenyl groups with atom X (N^N = 1 has X = F, 2 has X = Cl, 3 has X = Br, 4 has X = I; the benchmark N^N ligand with X = H is 5). These complexes have been characterized by multinuclear NMR spectroscopy, mass spectrometry, elemental analyses and cyclic voltammetry; representative single crystal structures are also reported. The solution absorption spectra are characterized by high energy bands (arising from ligand-centred transitions) which are red-shifted on going from X = H to X = I, and a broad metal-to-ligand charge transfer band with λmax in the range 387–395 nm. The ten complexes are yellow emitters in solution and yellow or yellow-orange emitters in the solid-state. For a given N^N ligand, the solution photoluminescence (PL) spectra show no significant change on going from [Cu(N^N)(POP)]+ to [Cu(N^N)(xantphos)]+; introducing the iodo-functionality into the N^N domain leads to a red-shift in λmaxem compared to the complexes with the benchmark N^N ligand 5. In the solid state, [Cu(1)(POP)][PF6] and [Cu(1)(xantphos)][PF6] (fluoro-substituent) exhibit the highest PL quantum yields (74 and 25%, respectively) with values of τ1/2 = 11.1 and 5.8 μs, respectively. Light-emitting electrochemical cells (LECs) with [Cu(N^N)(P^P)][PF6] complexes in the emissive layer have been tested. Using a block-wave pulsed current driving mode, the best performing device employed [Cu(1)(xantphos)]+ and this showed a maximum luminance (Lummax) of 129 cd m−2 and a device lifetime (t1/2) of 54 h; however, the turn-on time (time to reach Lummax) was 4.1 h. Trends in performance data reveal that the introduction of fluoro-groups is beneficial, but that the incorporation of heavier halo-substituents leads to poor devices, probably due to a detrimental effect on charge transport; LECs with the iodo-functionalized N^N ligand 4 failed to show any electroluminescence after 50 h

Copper(I) dye-sensitized solar cells with [Co(bpy)3]2+/3+ electrolyte

The hierarchical assembly of DSCs containing a new heteroleptic copper(I) complex with a phosphonic acid anchoring ligand is described; it is shown that conventional I−/I3− electrolytes may be replaced by [Co(bpy)3]2+/3+ with no loss in performance

What difference does a thiophene make? Evaluation of a 4,4′-bis(thiophene) functionalised 2,2′-bipyridyl copper(I) complex in a dye-sensitized solar cell

AbstractThe synthesis of a 4,4′-bis(2-thienyl-5-carboxylic acid) functionalised 2,2′-bipyridine ligand and corresponding copper(I) complex is described and its application in a dye-sensitized solar cell (DSSC) is studied. The positioning of the thiophene groups appears favourable from DFT analysis and a best efficiency of 1.41% was obtained with this dye, for a 0.3 cm2 cell area DSSC. Two absorbance bands are observed in the electronic absorption spectrum of the copper(I) complex at 316 nm and 506 nm, with ε values of 50,000 M−1 cm−1 and 9030 M−1 cm−1, respectively. Cyclic voltammetry and electrochemical impedance spectroscopy are also used to provide a detailed analysis of the dye and assess its functionality in a DSSC

The record-breaking rotational braking of the He strong CP star HD 37776

We study the long-term light and spectral variations in the He-strong magnetic chemically peculiar star HD 37776 (V901 Ori) to search for changes of its 1.5387 d period in 1976-2007. We analyze all published photometric observations and spectrophotometry in the HeI 4026 A line. The data were supplmented with 506 new (U)VB observations obtained during the last 2 observing seasons, 66 estimates of HeI equivalent widths on 23 CFHT spectrograms and 35 of the 6-m Zeeman spectrograms. All the 1895 particular observations heve been processed simultaneously. We confirm the previously suspected increase of the period in HD 37776 which is a record-breaking among CP stars. The mean rate of the period increase during the last 31 years is 0.541+-0.020 s per year. We interpret this ongoing period increase as the slowing down of the star's surface rotation due to momentum loss through events and processes in its magnetosphere.Comment: 3 pages, 1 figure, Proceedings of the "CP#AP Workshop", Vienna, 10.-14.Sept.2007, eds.J.Ziznovsky, J.Zverko, E.Paunzen, M.Netopil, will be published in Contrib. Astron. Obs. Skalnate Ples