New insights into the photochemistry of carotenoid spheroidenone in light-harvesting complex 2 from the purple bacterium Rhodobacter sphaeroides

Light-harvesting complex 2 (LH2) from the semi-aerobically grown purple phototrophic bacterium Rhodobacter sphaeroides was studied using optical (static and time-resolved) and resonance Raman spectroscopies. This antenna complex comprises bacteriochlorophyll (BChl) a and the carotenoid spheroidenone, a ketolated derivative of spheroidene. The results indicate that the spheroidenone-LH2 complex contains two spectral forms of the carotenoid: (1) a minor, ‘‘blue’’ form with an S2 (11 Bu ?) spectral origin band at 522 nm, shifted from the position in organic media simply by the high polarizability of the binding site, and (2) the major, ‘‘red’’ form with the origin band at 562 nm that is associated with a pool of pigments that more strongly interact with protein residues, most likely via hydrogen bonding. Application of targeted modeling of excited-state decay pathways after carotenoid excitation suggests that the high (92%) carotenoid-to-BChl energy transfer efficiency in this LH2 system, relative to LH2 complexes binding carotenoids with comparable double-bond conjugation lengths, derives mainly from resonance energy transfer from spheroidenone S2 (11 Bu ?) state to BChl a via the Qx state of the latter, accounting for 60% of the total transfer. The elevated S2 (11 Bu ?) ? Qx transfer efficiency is apparently associated with substantially decreased energy gap (increased spectral overlap) between the virtual S2 (11 Bu ?) ? S0 (11 Ag -) carotenoid emission and Qx absorption of BChl a. This reduced energetic gap is the ultimate consequence of strong carotenoid–protein interactions, including the inferred hydrogen bondin

The nature of singlet exciton fission in carotenoid aggregates.

Singlet exciton fission allows the fast and efficient generation of two spin triplet states from one photoexcited singlet. It has the potential to improve organic photovoltaics, enabling efficient coupling to the blue to ultraviolet region of the solar spectrum to capture the energy generally lost as waste heat. However, many questions remain about the underlying fission mechanism. The relation between intermolecular geometry and singlet fission rate and yield is poorly understood and remains one of the most significant barriers to the design of new singlet fission sensitizers. Here we explore the structure-property relationship and examine the mechanism of singlet fission in aggregates of astaxanthin, a small polyene. We isolate five distinct supramolecular structures of astaxanthin generated through self-assembly in solution. Each is capable of undergoing intermolecular singlet fission, with rates of triplet generation and annihilation that can be correlated with intermolecular coupling strength. In contrast with the conventional model of singlet fission in linear molecules, we demonstrate that no intermediate states are involved in the triplet formation: instead, singlet fission occurs directly from the initial 1B(u) photoexcited state on ultrafast time scales. This result demands a re-evaluation of current theories of polyene photophysics and highlights the robustness of carotenoid singlet fission.This work was supported by the EPSRC (UK) (EP/G060738/ 1), the European Community (LASERLAB-EUROPE, grant agreement no. 284464, EC’s Seventh Framework Programme; and Marie-Curie ITN-SUPERIOR, PITN-GA-2009-238177), and the Winton Programme for the Physics of Sustainability. G.C. acknowledges support by the European Research Council Advanced Grant STRATUS (ERC-2011-AdG No. 291198). J.C. acknowledges support by the Royal Society Dorothy Hodgkin Fellowship and The University of Sheffield’s Vice- Chancellor’s Fellowship scheme.This is the final published version. It was first made available by ACS at http://pubs.acs.org/doi/abs/10.1021/jacs.5b01130

A Review of the Evidence Germane to the Putative Protective Role of the Macular Carotenoids for Age-Related Macular Degeneration

There is a consensus that age-related macular degeneration (AMD) is the result of (photo)- oxidative-induced retinal injury and its inflammatory sequelae, the latter being influenced by genetic background. The dietary carotenoids, lutein (L), zeaxanthin (Z), and meso-zeaxanthin (meso-Z), accumulate at the macula, where they are collectively known as macular pigment (MP). The anatomic (central retinal), biochemical (anti-oxidant) and optical (short-wavelength- filtering) properties of this pigment have generated interest in the biologically plausible rationale that MP may confer protection against AMD. Level 1 evidence has shown that dietary supplementation with broad-spectrum anti-oxidants results in risk reduction for AMD progression. Studies have demonstrated that MP rises in response to supplementation with the macular carotenoids, although level 1 evidence that such supplementation results in risk reduction of AMD and/or its progression is still lacking. Although appropriately weighted attention should be accorded to higher levels of evidence, the totality of available data should be appraised in an attempt to inform professional practice. In this context, the literature demonstrates that supplementation with the macular carotenoids is probably the best means of fortifying the anti-oxidant defenses of the macula, thus putatively reducing the risk of AMD and/or its progression

Ultrafast transient absorption spectroscopy: principles and application to photosynthetic systems

The photophysical and photochemical reactions, after light absorption by a photosynthetic pigment–protein complex, are among the fastest events in biology, taking place on timescales ranging from tens of femtoseconds to a few nanoseconds. The advent of ultrafast laser systems that produce pulses with femtosecond duration opened up a new area of research and enabled investigation of these photophysical and photochemical reactions in real time. Here, we provide a basic description of the ultrafast transient absorption technique, the laser and wavelength-conversion equipment, the transient absorption setup, and the collection of transient absorption data. Recent applications of ultrafast transient absorption spectroscopy on systems with increasing degree of complexity, from biomimetic light-harvesting systems to natural light-harvesting antennas, are presented. In particular, we will discuss, in this educational review, how a molecular understanding of the light-harvesting and photoprotective functions of carotenoids in photosynthesis is accomplished through the application of ultrafast transient absorption spectroscopy

Dissemination and Implementation of the Swedish National Guidelines for Treatment of Substance use : A five year evaluation

This thesis contains four empirical studies. The data derives from an evaluation project named Knowledge to Practice (KtP) that aimed to disseminate and implement the Swedish National Guidelines for Alcohol and Substance Abuse in Substance Use Disorder-treatment from 2010–2014. The aim of this thesis was to identify key determinants affecting implementation. The data collection consisted of: - Web surveys that were distributed annually from 2010–2014 to a panel of 3,852 respondents working in substance abuse treatment in social services and health care - Web surveys distributed to approximately 10,000 participants in the national core curriculum course. Surveys were distributed before the start of the course and immediately after the course ended. A follow-up web survey was distributed one year later - Semi-structured surveys for all regions’ user organizations to answer in focus groups - Interviews with process managers in every region The aim of Study I was to describe KtP's efforts and the situation in 2012. Web surveys were distributed to a panel of 3,852 respondents and 10,000 participants from core curriculum courses. Process managers from all 21 regions were interviewed. Study II used an instrument named Organizational Readiness for Change (ORC).The aim was to: (a) identify clusters of employees with different ORC profiles and (b) investigate whether belonging to a specific profile predicted the use of therapy methods, assessment instruments and cross-sectional collaboration. The ORC instrument was part of an annual web survey to a panel of 3,852 respondents.The aim of Study III was to evaluate, via a four-year follow-up study, whether user organizations continued existing after national support concluded and if their influence within social services and health care was implemented over time. The aim of Study III was to evaluate, via a four-year follow-up study, whether user organizations continued existing after national support concluded and if their influence within social services and health care was implemented over time. The aim of Study IV was to evaluate the extent of the dissemination and implementation work organised by KtP and whether there was increased use of treatment methods, assessment instruments and changes in cross-sectional collaboration between authorities. Factors associated with success were studied on three organizational levels: regional, municipal and individual. Results show that setting and person-related determinants, as measured by the ORC instrument, predicted implementation of assessment instruments and treatment methods. Profiles with high scores on institutional resources, staff attributes and organizational climate and low scores on motivational readiness were associated with more successful implementation. Respondent-level specialist competence and the ORC factors of staff attributes and institutional resources were related to the use of treatment methods. The ORC factor of organizational climate was related to the increase of cross-sectionalcollaboration at a respondent level. Years of employment working with substance users predicted increased use of assessment instruments and in contrast, the ORC factor institutional resources available were negatively related to instrument use. No predictors were found at the region/municipality level. The majority of respondents were positive to the national guidelines and found them useful in their daily work. They also reported positive attitudes to the KtP project. In 2011, two-thirds of the process managers from Sweden's 21 counties assessed that KtP's most important results were access to education and method support. The one-year follow-up web survey distributed to the participants in core curriculum courses showed that memory retention of the course content was fair. Eighty per cent of the respondents gave the correct answer to seven out of nine questions. User organizations still existed in most regions and they reported increased influence in the field of substance use treatment, both in social services and within health care services

Upplevelser av inkludering - med fokus på förskolebarn i behov av särskilt stöd och deras inkludering ur föräldrars och pedagogers perspektiv

Syftet med den här studien är att belysa hur föräldrar och pedagoger upplever att förskolebarn i behov av särskilt stöd inkluderas i förskolan. Frågeställningarna utgår ifrån hur föräldrar och pedagoger upplever att barn i behov av särskilt stöd inkluderas i förskolans verksamhet; förhållningssätt till och bemötande av barn i behov av särskilt stöd i förskolan samt pedagogernas arbetssätt med att inkludera barn i behov av särskilt stöd. I studien har jag använt de teoretiska begreppen inkludering och delaktighet, samt tre olika perspektiv på specialpedagogik; kompensatoriskt och kritiskt perspektiv, samt dilemmaperspektivet. Den tidigare forskningen berör inkludering, delaktighet och föräldrars och pedagogers upplevelser. En kvalitativ metod har använts för insamling av empiri. Det insamlade materialet består av tre intervjuer med föräldrar till förskolebarn i behov av särskilt stöd och åtta intervjuer med pedagoger på två förskolor. En av slutsatserna i studien är att såväl föräldrar som pedagoger upplever att barnen är inkluderade i förskolans verksamhet. Analysen visar att upplevelserna pekar på att tre av fyra faktorer är uppfyllda för att barn ska anses vara inkluderade enligt Farrells definition av inkludering. Dessa faktorer är närvaro, aktivt deltagande samt lärande och utveckling. Jag noterade att den fjärde faktorn, acceptans, endast framhölls av ett fåtal pedagoger, medan alla föräldrarna betonade vikten av det. Studien visar också att pedagogerna arbetar parallellt enligt såväl ett kompensatoriskt synsätt som ett dilemmaperspektiv. Dels kompenseras barnet genom att det enskilt får arbeta med ansvarpedagog, dels arrangeras gruppsammansättningar för att få fram barnens styrkor och främja deras möjlighet till samspel

The photophysics and functions of some naturally occurring carotenoids

Carotenoids are one of the most widespread and important group of pigments in Nature and they can act as light-harvesting agents, photoprotectors and antioxidants. Mechanisms of their multiple functions are not fully understood mainly because their complicated photophysics involving ?dark? excited states. The central theme of this thesis is characterization of the lowest dark S1 state of carotenoids in solution or bound to proteins by means of time-resolved pump and probe spectroscopy. In solution, the relaxation pattern of carotenoids was studied, with the vibrational relaxation in the S1 state as a main focus. In a more extended study of the relaxation pathways in the carotenoid zeaxanthin, the excitation wavelength dependence was also elucidated. The observed results showed a different relaxation pattern after excitation with higher energy and direct generation of the zeaxanthin triplet and radical. Due to the fact that a protein environment may affect the spectroscopic properties of a carotenoid molecule, the spectroscopic properties of two carotenoid-protein complexes were studied in this thesis. First, the interaction between a photosynthetic protein and a carotenoid was explored. The results showed that the efficiency of the energy transfer between carotenoids and bacteriochlorophyll within a light-harvesting complex from purple bacteria was decreased when the number of conjugated double bonds of the carotenoids was increased. Second, the interaction between a protein found in the human eye and the xanthophylls, zeaxanthin and lutein, was studied. By a comparison of the spectroscopic properties of the xanthophylls in solution, a specific binding between the xanthophylls and the protein was found. Finally, a way of controlling the formation of the aggregated forms of zeaxanthin was explored. Further, the time-resolved measurements showed different spectroscopic properties, for example longer S1 lifetime, in the aggregates compared to monomeric zeaxanthin

Children's movement in the preschool yard : A study of how children's physical activity is affected during outdoor activities

Studiens syfte är att undersöka vad i utemiljön som kan skapa möjligheter eller hinder för barns rörelse och fysiska aktivitet i förskolan. Arbetet utgår från kvalitativ metod och baseras på intervjuer med fyra förskollärare från fyra olika förskolor där utemiljön skiljer sig åt. Det insamlade materialet har sedan analyseras med hjälp av den sociokulturella teorin med fokus på Vygotskijs tankar kring rummet, artefakter och samspel. Resultatet av studien visar att det finns olika faktorer i utemiljön som påverkar förutsättningarna för barns rörelse. Dessa faktorer kopplas till miljöns utformning, tillgängliga artefakter, regler under utevistelsen samt samspelet mellan pedagogen och barnet. Det framkommer även i resultatet att pedagogen har en stor roll i att kunna förändra förutsättningarna för barns fysiska aktivitet. Slutligen visar studien hur de tre teoretiska begreppen kan komma samman till en helhet i vissa fysiska aktiviteter.