The influence of surface energy on the self-cleaning of insect adhesive devices.

The ability of insects to adhere to surfaces is facilitated by the use of adhesive organs found on the terminal leg segments. These adhesive pads are inherently 'tacky' and are expected to be subject to contamination by particulates, leading to loss of function. Here, we investigated the self-cleaning of ants and beetles by comparing the abilities of both hairy and smooth pad forms to self-clean on both high and low energy surfaces after being fouled with microspheres of two sizes and surface energies. We focused on the time taken to regain adhesive potential in unrestrained Hymenopterans (Polyrhachis dives and Myrmica scabrinodis) and Coccinellids (Harmonia axyridis and Adalia bipunctata) fouled with microspheres. We found that the reattainment of adhesion is influenced by particle type and size in Hymenopterans, with an interaction between the surface energy of the contaminating particle and substrate. In Coccinellids, reattainment of adhesion was only influenced by particle size and substrate properties. The adhesive organs of Coccinellids appear to possess superior self-cleaning abilities compared with those of Hymenopterans, although Hymenopterans exhibit better adhesion to both surface types.

Intraoperative pressure measurement in radial artery harvest. A tool with additional value?

OBJECTIVES: The radial artery is widely used as a graft in coronary artery bypass surgery (CABG). Due to its location and function it should be screened prior to harvesting to avoid ischaemic complications of the hand. In acute situations the Allen test is often the only preoperative screening method available. As has been noted earlier, a negative Allen test does not mean a non-harvestable radial artery. We endeavoured to find out whether intraoperative pressure measurement could be used as a complement while screening the radial artery. DESIGN: Ninety patients planned for elective CABG with radial artery as a conduit were examined preoperatively with the Allen test, handheld Doppler and pletysmography of the second and fourth digits. Radial artery pressure was measured intraoperatively. Symptom scale was recorded pre- and postoperatively. RESULTS: There were ten patients with a positive Allen test. The intraoperative index of radial artery pressures was 0.868 in the Allen positive group and 0.885 in the Allen negative group with no statistically significant difference (P value .68). Tolerance of exercise and cold was significantly impaired postoperatively, P values .002 and .001 respectively. No ischaemic complications occurred. CONCLUSIONS: Intraoperative pressure measurement can be used when screening radial arteries are to be harvested and no metric preoperative screening methods are available.

Outcome of surgery for oesophageal carcinoma in a low volume centre, with and without preoperative chemoradiotherapy.

AIMS: To critically assess the outcome of surgery for oesophageal carcinoma, with or without neoadjuvant chemoradiotherapy. METHODS: Since April 1998 until August 2002 resectable oesophageal cancer patients referred to us have received multimodal treatment, consisting of two courses of fluorouracil, cisplatin and hydroxyurea and 2 x 20 Gy of radiotherapy followed by surgery. The outcome of this treatment was compared to the outcome of a historical group of oesophageal cancer patients, treated with surgery alone in the time period 1994 to 1998. The patients represent a consecutive series of 20 resectable oesophageal carcinomas, referred to us since 1994. Four patients (20%) were treated for squamocellular carcinoma, 16 (80%) patients for adenocarcinoma. RESULTS: Treatment related toxicity was low and there was no death attributable to the chemoradiotherapy. Postoperative hospital mortality (< 30 days) and morbidity rates were 10% and 50%, respectively. A complete pathological response (T0) occurred in two of the nine patients in the multimodal group (22%). Overall median survival was 11 months. Median survival among patients in the multimodal group was 14 months, as compared with 7 months in the group treated with surgery alone (P = 0.041). CONCLUSIONS: Despite low volume, outcome of surgery for oesophageal carcinoma was acceptable.

Phase transition of n-alkane layers adsorbed on mica.

Thin (thickness h approximately 3 nm) films of n-octadecane and n-hexadecane adsorbed on mica surfaces from vapor close to their bulk melting points (T(m)) have been studied in a surface force apparatus. Using data on the growth rate of capillary condensates between the mica surfaces in contact and measurements of h, we have identified a transition in the structure of the adsorbed films a few degrees above T(m). As T decreases the alkane layers appear to undergo a transition to a more ordered structure, akin to the postulated "surface freezing" of long-chain liquid n-alkanes.