Photoactivated Artificial Molecular Motors

Accurate control of long-range motion at the molecular scale holds great potential for the development of ground-breaking applications in energy storage and bionanotechnology. The past decade has seen tremendous development in this area, with a focus on the directional operation away from thermal equilibrium, giving rise to tailored man-made molecular motors. As light is a highly tunable, controllable, clean, and renewable source of energy, photochemical processes are appealing to activate molecular motors. Nonetheless, the successful operation of molecular motors fueled by light is a highly challenging task, which requires a judicious coupling of thermal and photoinduced reactions. In this paper, we focus on the key aspects of light-driven artificial molecular motors with the aid of recent examples. A critical assessment of the criteria for the design, operation, and technological potential of such systems is provided, along with a perspective view on future advances in this exciting research area

Severe and polytraumatic injuries among recreational skiers and snowboarders: incidence, demographics and injury patterns in South Tyrol

Background Alpine skiing and snowboarding are popular winter sports. The practice of these sports is related to traumatic injuries, some of which are severe and/or life threatening. Objectives To identify the incidence, injury patterns and associated risk factors of severe and polytraumatic injuries in South Tyrol. Materials and methods During four consecutive winter seasons (2001-2005), data of every patient referred to our emergency department (Bolzano-Bozen) after a skiing or snowboarding accident were collected. One hundred and five patients with an Injury Severity Score of 16 or higher were identified (90 skiers, 15 snowboarders). Statistical descriptive analyses were carried out by producing frequency tables. Chi-square test was performed to verify possible association between injury severity and type of sport. Risk factors for severe injuries were evaluated using logistic regression with robust variance estimators. Results Traumatic brain injury was the most common injury observed (51 cases), followed by vertebral injury (45 cases); 63% of the patients reported two or more associated injuries. We observed significant associations between severe spine injuries and the following risk factors: snowboarders who reported more severe injuries than skiers [odds ratio = 5.89, 95% confidence interval (CI) = 1.31, 26.44], age classes of 40-50 years and over 60 years showed an OR of 8.10 (95% CI = 1.87, 35.06) and 5.16 (95% CI = 1.27, 21.01), respectively, with respect to age class (20-40 years). Conclusion Severe traumatic injuries occur among skiers and snowboarders, and preventive measures such as the use of helmets and educational programs, are necessary. European Journal of Emergency Medicine 19: 69-72 (C) 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Stereodynamics of E/Z isomerization in rotaxanes through mechanical shuttling and covalent bond rotation

We report on a set of rotaxanes with symmetrical axles equipped with a central amide group that installs E/Z stereoisomerism owing to the ring position along the axle. Isomerization by concomitant rotation about the amide bond and ring shuttling along the axle was thoroughly characterized in different solvents. The results trigger a discussion on core concepts, such as microscopic reversibility and transition state theory, and provide insights for designing molecules capable to transform and transmit motion between subcomponents

Factors affecting injury severity among recreational skiers and snowboarders: an epidemiology study

Different results have been reported for skiing and snowboarding injuries worldwide. Few studies consider the injury severity score (ISS) for the evaluation of differences among injured skiers–snowboarders. The aim of this study is to identify possible risk factors that affect the severity of skiing and snowboarding injuries in three winter seasons (2002–2005) in South Tyrol. For every injured skier or snowboarder referred to our emergency department in three consecutive seasons, the following data were collected: date of birth, gender, self-declared technical skills level, place of residence (local/non-local), as well as the date, time, and place of the accident. Type of injury and ISS were retrospectively assigned. Data concerning the snowfall in the last 24 h, average snow level, and outdoor air temperature values were obtained from four weather stations that were located inside the ski resorts. A multiple linear regression model was used to evaluate the association between ISS and potential determinants. In the analyzed seasons, 2,511 injured skiers and 843 injured snowboarders were evaluated at our emergency department. There was a significant change in the ISS value for subjects with different self-reported skills levels (P.001). Men and non-local residents experienced more severe injuries than women and local residents, respectively (P.013, P.001). The ISS was higher for people aged over 60 (P.001). Snowfalls brought about a decrease in accident severity (P = 0.009). The severity of the injuries increases with age. Prevention and information programs should be targeted to people who are at high risk of severe injury. A 24-h fresh snowfall seems to reduce the severity of injuries. Very little is known about snow conditions and winter sports injury. Further studies are needed to explore this field

Sledding injuries: is safety in this winter pastime overlooked? A three-year survey in South-Tyrol

which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background: Sledding is a popular traditional pastime in northern countries. However it is only rarely thought as a potentially dangerous activity even though serious injuries and deaths do occur. The purpose of this study was to calculate the incidence, the severity and the pattern of sleddingrelated injuries in our area, in order to set up possible preventive measures. Results: In three consecutive winter seasons (Dec.–Apr.,2002–2005). 356 patients (182 males, 174 females, mean age 26.9 years, range 2 to 81) were referred directly to our ED after a sledding injury. One patient (male, age 21 years) was transferred from a community hospital and died on the following day. Two patients (males, age 47 and 28 years) were declared dead on the scene. In the majority of the cases the accident was due to a fall and collision with the ground or a standing object. The number of injuries showed a progressive increase during the observed seasons and all deadly accidents were observed in the last season. Injuries were divided into three severity classes: minor (ISS ≤ 3), intermediate (ISS ≥ 4 < 15), severe (ISS ≥ 15). Minor and intermediate injuries were equally distributed between males and females, whereas all severe and deadly accidents occurre

Second-Generation Light-Fueled Supramolecular Pump

open7noFinancial support from the European Research Council (H2020 Advanced Grant 692981 to A.C.)We describe the modular design of a pseudorotaxane-based supramolecular pump and its photochemically driven autonomous nonequilibrium operation in a dissipative regime. These properties derive from careful engineering of the energy maxima and minima along the threading coordinate and their light-triggered modulation. Unlike its precursor, this second-generation system is amenable to functionalization for integration into more complex devices.openCanton, Martina; Groppi, Jessica; Casimiro, Lorenzo; Corra, Stefano; Baroncini, Massimo; Silvi, Serena; Credi, AlbertoCanton, Martina; Groppi, Jessica; Casimiro, Lorenzo; Corra, Stefano; Baroncini, Massimo; Silvi, Serena; Credi, Albert

Chemical On/Off Switching of Mechanically Planar Chirality and Chiral Anion Recognition in a [2]Rotaxane Molecular Shuttle

We exploit a reversible acid-base triggered molecular shuttling process to switch an appropriately designed rotaxane between prochiral and mechanically planar chiral forms. The mechanically planar enantiomers and their interconversion, arising from ring shuttling, have been characterized by NMR spectroscopy. We also show that the supramolecular interaction of the positively charged rotaxane with optically active anions causes an imbalance in the population of the two enantiomeric co-conformations. This result represents an unprecedented example of chiral molecular recognition and can disclose innovative approaches to enantioselective sensing and catalysis

Artificial supramolecular pumps powered by light

The development of artificial nanoscale motors that can use energy from a source to perform tasks requires systems capable of performing directionally controlled molecular movements and operating away from chemical equilibrium. Here we describe the design, synthesis and properties of pseudorotaxanes in which a photon input triggers the unidirectional motion of a macrocyclic ring with respect to a non-symmetric molecular axle. The photoinduced energy ratcheting at the basis of the pumping mechanism is validated by measuring the relevant thermodynamic and kinetic parameters. Owing to the photochemical behaviour of the azobenzene moiety embedded in the axle, the pump can repeat its operation cycle autonomously under continuous illumination. We use NMR spectroscopy to observe the dissipative non-equilibrium state generated in situ by light irradiation. We also show that fine changes in the axle structure lead to an improvement in the performance of the motor. Such results highlight the modularity and versatility of this minimalist pump design, which provides facile access to dynamic systems that operate under photoinduced non-equilibrium regimes

Precision molecular threading/dethreading

Abstract: The general principles guiding the design of molecular machines based on interlocked structures are well known. Nonetheless, the identification of suitable molecular components for a precise tuning of the energetic parameters that determine the mechanical link is still challenging. Indeed, what are the reasons of the \u201call-or-nothing\u201d effect, which turns a molecular \u201cspeed-bump\u201d into a stopper in pseudorotaxane-based architectures? Here we investigate the threading and dethreading processes for a representative class of molecular components, based on symmetric dibenzylammonium axles and dibenzo[24]crown-8 ether, with a joint experimental-computational strategy. From the analysis of quantitative data and an atomistic insight, we derive simple rules correlating the kinetic behaviour with the substitution pattern, and provide rational guidelines for the design of modules to be integrated in molecular switches and motors with sophisticated dynamic feature

Severe and polytraumatic injuries among recreational skiers and snowboarders: incidence, demographics and injury patterns in South Tyrol

Background Alpine skiing and snowboarding are popular winter sports. The practice of these sports is related to traumatic injuries, some of which are severe and/or life threatening. Objectives To identify the incidence, injury patterns and associated risk factors of severe and polytraumatic injuries in South Tyrol. Materials and methods During four consecutive winter seasons (2001-2005), data of every patient referred to our emergency department (Bolzano-Bozen) after a skiing or snowboarding accident were collected. One hundred and five patients with an Injury Severity Score of 16 or higher were identified (90 skiers, 15 snowboarders). Statistical descriptive analyses were carried out by producing frequency tables. Chi-square test was performed to verify possible association between injury severity and type of sport. Risk factors for severe injuries were evaluated using logistic regression with robust variance estimators. Results Traumatic brain injury was the most common injury observed (51 cases), followed by vertebral injury (45 cases); 63% of the patients reported two or more associated injuries. We observed significant associations between severe spine injuries and the following risk factors: snowboarders who reported more severe injuries than skiers [odds ratio = 5.89, 95% confidence interval (CI) = 1.31, 26.44], age classes of 40-50 years and over 60 years showed an OR of 8.10 (95% CI = 1.87, 35.06) and 5.16 (95% CI = 1.27, 21.01), respectively, with respect to age class (20-40 years). Conclusion Severe traumatic injuries occur among skiers and snowboarders, and preventive measures such as the use of helmets and educational programs, are necessar