Navigating chemical reaction space with a steering wheel

Autonomous reaction network exploration algorithms offer a systematic approach to explore mechanisms of complex chemical processes. However, the resulting reaction networks are so vast that an exploration of all potentially accessible intermediates is computationally too demanding. This renders brute-force explorations unfeasible, while explorations with completely pre-defined intermediates or hard-wired chemical constraints, such as element-specific coordination numbers, are not flexible enough for complex chemical systems. Here, we introduce a Steering Wheel to guide an otherwise unbiased automated exploration. The Steering Wheel algorithm is intuitive, generally applicable, and enables one to focus on specific regions of an emerging network. It also allows for guiding automated data generation in the context of mechanism exploration, catalyst design, and other chemical optimization challenges. The algorithm is demonstrated for reaction mechanism elucidation of transition metal catalysts. We highlight how to explore catalytic cycles in a systematic and reproducible way. The exploration objectives are fully adjustable, allowing one to harness the Steering Wheel for both structure-specific (accurate) calculations as well as for broad high-throughput screening of possible reaction intermediates.Comment: 40 pages, 10 figures, 1 tabl

Respiratory symptoms and cross-shift lung function in relation to cotton dust and endotoxin exposure in textile workers in Nepal: a cross-sectional study

Objectives: Inhalation of a cotton-based particulates has previously been associated with respiratory symptoms and impaired lung function. This study investigates the respiratory health of Nepalese textile workers in relation to dust and endotoxin exposure. Methods: A total of 938 individuals from four sectors (garment, carpet, weaving and recycling) of the textile industry in Kathmandu, Nepal completed a health questionnaire and performed spirometry. A subset (n=384) performed cross-shift spirometry. Personal exposure to inhalable dust and airborne endotoxin was measured during a full shift for 114 workers. Results: The overall prevalence of persistent cough, persistent phlegm, wheeze ever, breathlessness ever and chest tightness ever was 8.5%, 12.5%, 3.2%, 6.5% and 12.3%, respectively. Symptoms were most common among recyclers and least common among garment workers. Exposure to inhalable dust significantly predicted persistent cough and chest tightness. Exposure to endotoxin did not have any independent predictive effect. Significant cross-shift reduction in forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were found (p<0.001 for both) being largest for FEV1 in the recyclers (−143 mL), and least in the garment workers (−38 mL; p=0.012). Exposure to inhalable dust predicted a cross-shift reduction in FEV1. Conclusions: This study is the first to investigate the respiratory health of Nepalese cotton workers. The measured association between inhalable dust exposure and reporting of respiratory symptoms and across-shift decrement in FEV1 and FVC indicates that improved dust control measures should be instituted, particularly in the recycling and carpet sectors. The possible role of other biologically active agents of cotton dust beyond endotoxin should be further explored

Acetylene-ammonia-18-crown-6 (1/2/1)

The title compound, C2H2·C12H24O6·2NH3, was formed by co-crystallization of 18-crown-6 and acetylene in liquid ammonia. The 18-crown-6 molecule has threefold rotoinversion symmetry. The acteylene molecule lies on the threefold axis and the whole molecule is generated by an inversion center. The two ammonia molecules are also located on the threefold axis and are related by inversion symmetry. In the crystal, the ammonia molecules are located below and above the crown ether plane and are connected by intermolecular N-H...O hydrogen bonds. The acetylene molecules are additionally linked by weak C-H...N interactions into chains that propagate in the direction of the crystallographic c axis. The 18-crown-6 molecule [occupancy ratio 0.830 (4):0.170 (4)] is disordered and was refined using a split model

Shifting to Gig Labor: Perceptions of Sustainability

Digitalization is a global megatrend. Digital labour platforms allow companies to outsource work through an open call to a crowd of people and are the forefront of the “gig economy”, characterized by one-off tasks, without further commitments for the involved partners. Sustainability is another megatrend and controversial from the gig economy perspective. Non-standard gig arrangements bring higher time flexibility for the workers, allowing more individuals to integrate with the labour market. However, these digital employment relationships are associated with relatively weak labour market institutions and regulations, resulting in precarious jobs.Using data collected by semi-structured interviews, this paper explores the experience of Swiss workers who switched from a “standard-contract” employment position to occasional gig employment. This study finds evidence that the voluntary change towards a gig job may be associated with an improvement in perceived social sustainability, but a degradation of economic and environmental sustainability.The conclusion may be specific to the high development context where the study took place, Switzerland. However, if that is the case, a stronger policy message emerges - even in newer forms of employment, protective legal frameworks ensuring a basic safety net for individuals continue to be key for more sustainable labour arrangements

Exponential Decay Lifetimes of Excitons in Individual Single-Walled Carbon Nanotubes

The dynamics of excitons in individual semiconducting single-walled carbon nanotubes was studied using time-resolved photoluminescence (PL) spectroscopy. The PL decay from tubes of the same (n,m) type was found to be monoexponential, however, with lifetimes varying between less than 20 and 200 ps from tube to tube. Competition of nonradiative decay of excitons is facilitated by a thermally activated process, most likely a transition to a low-lying optically inactive trap state that is promoted by a low-frequency phonon mode

Does the ‘Scottish effect’ apply to all ethnic groups? All-cancer, lung, colorectal, breast and prostate cancer in the Scottish Health and Ethnicity Linkage Cohort Study

Copyright 2012 Elsevier B.V., All rights reserved.Peer reviewedPublisher PD

Using a new, low-cost air quality sensor to quantify second-hand smoke (SHS) levels in homes

Peer reviewedPreprintPreprintPreprintPostprin

Impact of clinical pathways in surgery

Background: One strategy to reduce the consumption of resources associated to specific procedures is to utilize clinical pathways, in which surgical care is standardized and preset by determination of perioperative in-hospital processes. The aim of this prospective study was to establish the impact of clinical pathways on costs, complication rates, and nursing activities. Method: Data was prospectively collected for 171 consecutive patients undergoing laparoscopic cholecystectomy (n = 50), open herniorrhaphy (n = 56), and laparoscopic Roux-en-Y gastric bypass (n = 65). Results: Clinical pathways reduced the postoperative hospital stay by 28% from a mean of 6.1 to 4.4days (p < 0.001), while the 30-day readmission rate remained unchanged (0.5% vs. 0.45%). Total mean costs per case were reduced by 25% from € 6,390 to € 4,800 (p < 0.001). Costs for diagnostic tests were reduced by 33% (p < 0.001). Nursing hours decreased, reducing nursing costs by 24% from € 1,810 to € 1,374 (p < 0.001). A trend was noted for lower postoperative complication rates in the clinical pathway group (7% vs. 14%, p = 0.07). Conclusions: This study demonstrates clinically and economically relevant benefits for the utilization of clinical pathways with a reduction in use of all resource types, without any negative impact on the rate of complications or re-hospitalizatio