Enacting Two-Electron Transfer from a Double-Triplet State of Intramolecular Singlet Fission.

A simulation-led strategy enacts two-electron transfer between an intramolecular singlet fission chromophore (tetracyanomethylene quinoidal bithiopehene with ß,ß'-solubilizing groups) and multielectron acceptor (anthraquinone). The thermodynamic plausibility of multielectron transfer from a double-triplet state and the absorption spectra of electron transfer (ET) products were predicted using quantum chemical simulations. These predictions are consistent with experimental observations of reduced lifetimes in time-resolved fluorescence spectroscopy, changes in transmission profile, and appearance of new absorption bands in transient absorption spectroscopy, all of which support multi-ET in the QOT2/AQ mixture. The analysis suggests 2ET is favored over 1ET by a 2.5:1 ratio.

Comparative Quantification of Trail-Following Behavior in Pest Ants.

A comparison of trail-following movement parameters of six major urban pest ants, Nylanderia fulva (Forel) (Hymenoptera: Formicidae), Pheidole megacephala, Linepithema humile (Mayr), Solenopsis invicta Buren, Paratrechina longicornis (Forel), and Technomyrmex albipes (Smith) demonstrated several differences in velocity of movement, amplitude of the deviations from a marked trail, percent fidelity to the trail, number of curves per unit of trail, and trail-following accuracy. Paratrechina longicornis and N. fulva had the largest deviations from the marked trails and moved three times faster (25-30 mm/s) along the trail than the slowest ant, S. invicta (< 10 mm/s), with other ants following between these extremes. Species differences in relation to going toward or returning from food were observed in a few cases, especially with Pa. longicornis for which velocity, amplitude, and trail fidelity differed between the foraging and return trails. Quantification of ant trail-following movement parameters can be useful in understanding the mechanics of ant movement and may be important in testing specific strategies and products that disrupt trail-following behavior.

[Aortic root homograft in the surgical treatment of aortic valve disease with dilated ascending aorta]. / Homoinjerto de raíz aórtica para el tratamiento quirúrgico de las afecciones de la válvula aórtica con aorta ascendente dilatada.

INTRODUCTION AND OBJECTIVES: Patients with aortic valve disease and a dilated ascending aorta are usually treated with a composite graft comprising a valve and conduit. We review here the results of treatment with an aortic root homograft as a valid alternative. PATIENTS AND METHOD: Twenty-two consecutive patients with a mean age of 64.8 (8.8) years were studied. Mean ascending aorta dilation was 54.55 mm, aortic valve insufficiency was present in 16 patients, and a combined lesion was present in 6. In all cases a cryopreserved aortic root homograft was used to replace the aortic valve and ascending aorta. In 9 cases a Dacron conduit was used beyond the sinotubular junction to restore continuity between the homograft and the native aorta. RESULTS: All patients survived surgery. One patient had postoperative systemic inflammatory response syndrome and one patient was re-explored for excessive bleeding. Mean duration of follow-up was 12.1 months (range 2-36 months). No patient was given anticoagulants, and one had an early transient cerebrovascular accident followed by complete recovery. At one month postsurgery the left ventricular systolic (P<.001) and diastolic (P<.009) diameters had decreased significantly on echocardiography, and these decreases persisted throughout follow-up. The caliber of the ascending aorta was normal in all patients (< or =30 mm) except one. CONCLUSIONS: Aortic root homografts are a valid alternative in the treatment of aortic valve disease with ascending aorta dilation. The main advantages of this therapy are that permanent anticoagulation is not needed, and that left ventricular dimensions recover rapidly.