Switchable synchronisation of pirouetting motions in a redox-active [3]rotaxane

In this study, the crown/ammonium [3]rotaxane R2 is reported which allows a switchable synchronisation of wheel pirouetting motions. The rotaxane is composed of a dumbbell-shaped axle molecule with two mechanically interlocked macrocycles which are decorated with a redox-active tetrathiafulvalene (TTF) unit. Electrochemical, spectroscopic, and electron paramagnetic resonance experiments reveal that rotaxane R2 can be reversibly switched between four stable oxidation states (R2, R2˙+, R22(˙+), and R24+). The oxidations enable non-covalent, cofacial interactions between the TTF units in each state—including a stabilised mixed-valence (TTF2)˙+ and a radical-cation (TTF˙+)2 dimer interaction—which dictate a syn (R2, R2˙+, and R22(˙+)) or anti (R24+) ground state co-conformation of the wheels in the rotaxane. Furthermore, the strength of these wheel–wheel interactions varies with the oxidation state, and thus electrochemical switching allows a controllable synchronisation of the wheels’ pirouetting motions. DFT calculations explore the potential energy surface of the counter-rotation of the two interacting wheels in all oxidation states. The controlled coupling of pirouetting motions in rotaxanes can lead to novel molecular gearing systems which transmit rotational motion by switchable non-covalent interactions

Comparison of structure, regeneration and dead wood in virgin forest remnant and managed forest on Grmecˇ Mountain in Western Bosnia

This paper compares the forest structure, regeneration and distribution of dead wood in a virgin forest remnant and a close-to-nature managed beech–conifer mixture situated on Grmecˇ Mountain inWestern Bosnia. The investigations were carried out in a 1 ha permanent sample plot and 35 circular plots (20m radius) in the virgin forest and in 17 circular plots (25m radius) in managed forests. The number of trees in the managed forest was significantly ( p ¼ 0.05) higher than that in virgin forest and the distribution of the number of trees per diameter classes had a decreasing trend, but with a different shape in the virgin forest compared to the managed stands. In the lower diameter classes, the stock volume recorded in virgin forest was half of that in the managed forest, whilst for higher diameter classes the cumulated volume of the growing stock was almost double in virgin forest. The young crops had a significantly lower presence in the virgin forest and a larger volume of dead wood was identified in the virgin forest than in managed stands. The study results are important in assessing the consequences of close-to-nature management on the forest structure and regeneration when compared to the condition in virgin forests

The 2017 European Society of Coloproctology (ESCP) international snapshot audit of left colon, sigmoid and rectal resections – study protocol

Background: Left hemicolectomy, sigmoid, and rectal resections are commonly performed colorectal operations. There is significant variability in the techniques utilised to undertake these operationsat patient, surgeon and unit level. Aim: To explore differences in patients, techniques and outcomes across an international cohort to identify areas of practice variability resulting in apparent differences in outcome warranting further study. Endpoints: A three-stage data collection strategy collecting patient demographics, operative details and outcome markers. Several outcomes measures will be used including mortality, surgical morbidity (including anastomotic leak) and length of hospital stay. Methods: A two-month prospective audit to be performed across Europe in early 2017, co-ordinated by the European Society of Coloproctology. The main audit will be preceded by a one-week, five centre pilot. Sites will be asked to pre-register for the audit and obtain appropriate regional or national approvals. During the study period all eligible operations will be recorded contemporaneously and followed-up through to 30 days. The audit will be performed using a standardised pre-determined protocol and a secure online database. In the first ESCP conducted audit in 2015, 38 countries registered 3208 patients undergoing right hemi-colectomy, while in the second audit 2441 patients undergoing stoma closure were recruited from 48 countries. It is expected that equivalent numbers will be obtained in this audit. The report of this audit will be prepared in accordance with guidelines set by the STROBE (strengthening the reporting of observational studies in epidemiology) statement for observational studies. Discussion: This multicentre, pan-European audit will be delivered by colorectal surgeons and trainees in an organised and homogenous manner. The data obtained about areas of variability in provision or practice, and how this may impact upon outcomes, will serve to improve overall patient care as well as being hypothesis generating and inform areas needing future prospective study