Chemical detection with a single-walled carbon nanotube capacitor

We show that the capacitance of single-walled carbon nanotubes (SWNTs) is highly sensitive to a broad class of chemical vapors and that this transduction mechanism can form the basis for a fast, low-power sorption-based chemical sensor. In the presence of a dilute chemical vapor, molecular adsorbates are polarized by the fringing electric fields radiating from the surface of a SWNT electrode, which causes an increase in its capacitance. We use this effect to construct a high-performance chemical sensor by thinly coating the SWNTs with chemoselective materials that provide a large, class-specific gain to the capacitance response. Such SWNT chemicapacitors are fast, highly sensitive, and completely reversible.     

Slow fertilization of stickleback eggs: the result of sexual conflict?

Background  

The fertilization success in sperm competition in externally fertilizing fish depends on number and quality of sperm. The time delay between sequential ejaculations may further influence the outcome of sperm competition. Such a time interval can load the raffle over fertilization if fertilization takes place very fast. Short fertilization times are generally assumed for externally fertilizing fish such as the three-spined stickleback (Gasterosteus aculeatus). In this pair-spawning fish, territorial males often try to steal fertilizations in nests of neighbouring males. This sneaking behaviour causes sperm competition. Sneakers will only get a share of paternity when eggs are not fertilized immediately after sperm release. Contrary to males, females may be interested in multiple paternity of their clutch of eggs. There thus may be a sexual conflict over the speed of fertilization.     

Endotracheal intubation in horses: a study of two cuff inflation pressures, correlation with liquid aspiration, and tracheal wall damage

Nine adult horses were anesthetized for a nonsurvival abdominal adhesion study. Horses were randomly assigned into two groups to receive endotracheal tube cuff pressures of either 80 cm H₂O (Group P80) or 120 cm H₂O (Group P120). After intubation (Bivona 30 mm ID), anesthesia was maintained with isoflurane. Horses were ventilated 10 times per minute with a suitable inspiratory pressure to maintain Pe ′CO₂ in the 35–40 mm Hg (4.7–6.0 kPa) range. Cuff pressure was continuously monitored with a pressure transducer (TruWave, Baxter) calibrated to the atmospheric pressure and maintained at a constant pressure. Twenty‐five millilitres of methylene blue dye in saline were instilled proximal to the cuff over 5 minutes. The horses were euthanized 123 ± 23 minutes later (mean ± SD). Immediately, the trachea was opened distal to the tip of the endotracheal tube, and the mucosa was observed for evidence of dye leaking past the cuff. The cervical trachea was resected and the lumen exposed by a ventral longitudinal incision. Biopsies (1–2 rings) were obtained at mid‐cuff level and distal to the tip of the endotracheal tube, and placed in formalin for later histologic examinations (H&E stain). Methylene blue stain was not observed distal to the endotracheal tube cuff in any horse. Visual examination of the tracheal mucosa revealed hyperemic or hemorrhagic lesions at the level of cuff contact both ventrally and dorsally. Histologic changes included epithelium damage, submucosal neutrophil infiltrates, and acute submucosal hemorrhages. P80 horses had none or focal to multifocal lesions on the ventral and dorsal aspects of the rings. P120 horses had multifocal to diffuse lesions on all aspects (dorsal, ventral, and lateral). We concluded that the endotracheal tube cuff produced a seal sufficient to prevent leakage at both pressures. Tracheal damages on gross and microscopic examinations were more severe and occurred more frequently at the higher cuff pressure.     

Seasonal Changes in Testicular Cell Morphology in Domestic Male Cats (Felis catus)

The aim of this study was to asses the variation in the morphology of the seminal epithelium in relation to natural photoperiod in male cats. Tom cats (n = 240) were castrated every other week throughout the year. Each testis was fixed in Bouin's solution and cut into sections. The percentage of tubules with round spermatids (RS), elongated spermatids (ES), tailed spermatids (TS), mature spermatids (MS) and the number of Sertoli cells (SC) and Leydig cells (LC) were recorded in each sample. Testicles from males during short days (SHD) had a higher percentage of tubules with RS and ES compared to testicles from males during long days (LHD, 31.3 ± 0.6 vs 2.1 ± 0.6%, p < 0.001; 30.9 ± 0.7 vs 11.0 ± 0.7%, p < 0.001). Conversely, testicles from males during SHD had a lower percentage of tubules with TS and MS compared to testicles from males during LHD (24.5 ± 0.8 vs 29.7 ± 0.8%, p < 0.01; 13.1 ± 1.2 vs 57.0 ± 1.2%, p < 0.01). Furthermore, testicles from males during SHD had a higher number of SC and lower number of LC compared to testicles from males during LHD (11.4 ± 0.1 vs 8.0 ± 0.1%, p < 0.01; 19.2 ± 1.0 vs 38.0 ± 1.0%, p < 0.01). In conclusion, there are seasonal changes in testis cell morphology in the tom which may be related to seasonal sperm production.