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Geoengineering is the deliberate large-scale manipulation of environmental processes that affects the Earth's climate, in an attempt to counteract the effects of climate change. Injecting sulfate aerosol precursors and designed nanoparticles into the stratosphere to (i.e., solar radiation management [SRM]), has been suggested as one approach to geoengineering. Although much is being done to unravel the scientific and technical challenges around geoengineering, there have been few efforts to characterize the potential human health impacts of geoengineering, particularly with regards to SRM approaches involving stratospheric aerosols. This paper explores this information gap. Using available evidence, we describe the potential direct occupational and public health impacts of exposures to aerosols likely to be used for SRM, including environmental sulfates, black carbon, metallic aluminum, and aluminum oxide aerosols. We speculate on possible health impacts of exposure to one promising SRM material, barium titanate, using knowledge of similar nanomaterials. We also explore current regulatory efforts to minimize exposure to these toxicants. Our analysis suggests that adverse public health impacts may reasonably be expected from SRM via deployment of stratospheric aerosols. Little is known about the toxicity of some likely candidate aerosols, and there is no consensus regarding acceptable levels for public exposure to these materials. There is also little infrastructure in place to evaluate potential public health impacts in the event that stratospheric aerosols are deployed for solar radiation management. We offer several recommendations intended to help characterize the potential occupation and public health impacts of SRM, and suggest that a comprehensive risk assessment effort is needed before this approach to geoengineering receives further consideration.

Actions to reduce greenhouse gas (GHG) emissions often reduce co-emitted air pollutants, bringing co-benefits for air quality and human health. Past studies1-6 typically evaluated near-term and local co-benefits, neglecting the long-range transport of air pollutants7-9, long-term demographic changes, and the influence of climate change on air quality10-12. Here we simulate the co-benefits of global GHG reductions on air quality and human health using a global atmospheric model and consistent future scenarios, via two mechanisms: a) reducing co-emitted air pollutants, and b) slowing climate change and its effect on air quality. We use new relationships between chronic mortality and exposure to fine particulate matter13 and ozone14, global modeling methods15, and new future scenarios16. Relative to a reference scenario, global GHG mitigation avoids 0.5±0.2, 1.3±0.5, and 2.2±0.8 million premature deaths in 2030, 2050, and 2100. Global average marginal co-benefits of avoided mortality are $50-380 (ton CO2)-1, which exceed previous estimates, exceed marginal abatement costs in 2030 and 2050, and are within the low range of costs in 2100. East Asian co-benefits are 10-70 times the marginal cost in 2030. Air quality and health co-benefits, especially as they are mainly local and near-term, provide strong additional motivation for transitioning to a low-carbon future.

The cell membrane of Salinibacter ruber contains xanthorhodopsin, a light-driven transmembrane proton pump with two chromophores: a retinal and the carotenoid, salinixanthin. Action spectra for transport had indicated that light absorbed by either is utilized for function. If the carotenoid is an antenna in this protein, its excited state energy has to be transferred to the retinal and should be detected in the retinal fluorescence. From fluorescence studies, we show that energy transfer occurs from the excited singlet S(2) state of salinixanthin to the S(1) state of the retinal. Comparison of the absorption spectrum with the excitation spectrum for retinal emission yields 45 +/- 5% efficiency for the energy transfer. Such high efficiency would require close proximity and favorable geometry for the two polyene chains, but from the heptahelical crystallographic structure of the homologous retinal protein, bacteriorhodopsin, it is not clear where the carotenoid can be located near the retinal. The fluorescence excitation anisotropy spectrum reveals that the angle between their transition dipole moments is 56 +/- 3 degrees . The protein accommodates the carotenoid as a second chromophore in a distinct binding site to harvest light with both extended wavelength and polarization ranges. The results establish xanthorhodopsin as the simplest biological excited-state donor-acceptor system for collecting light.

L'exposition à la pollution de l'air domestique est un risque majeur pour la santé, mais les interventions validées restent insaisissables. L'étude randomisée sur la pollution de l'air et la santé au Ghana (GRAPHS) est un essai randomisé en grappes qui évalue l'efficacité des combustibles propres (gaz de pétrole liquéfié ou GPL) et des poêles à biomasse efficaces dans la région de Brong-Ahafo au centre du Ghana. Nous recrutons des femmes enceintes pour le GPL, une cuisinière efficace et des bras de contrôle et suivons le poids à la naissance et l'incidence de la pneumonie sévère évaluée par le médecin au cours de la première année de vie. Une femme est admissible à participer si elle est au premier ou au deuxième trimestre de la grossesse et porte un fœtus vivant, si elle est la cuisinière principale et si elle ne fume pas. Nous émettons l'hypothèse que les bébés nés de mères d'intervention pèseront plus et auront moins de cas de pneumonie sévère évalués par un médecin au cours de la première année de vie. De plus, un vaste effort personnel de surveillance de l'exposition à la pollution de l'air ouvre la voie à des analyses exposition-réponse, que nous présenterons aux côtés des analyses en intention de traiter. Un financement important a été fourni par l'Institut national des sciences de la santé environnementale, le Thrasher Research Fund et la Global Alliance for Clean Cookstoves. L'exposition à la pollution de l'air des ménages est un risque majeur pour la santé qui nécessite des interventions bien testées. LES GRAPHIQUES fourniront de nouvelles preuves importantes sur l'efficacité des poêles à biomasse efficaces et du GPL, et aideront ainsi à éclairer les politiques de santé et d'énergie dans les pays en développement. L'essai a été enregistré auprès de clinicaltrials.gov le 13 avril 2011 sous l'identifiant NCT01335490 . La exposición a la contaminación del aire en los hogares es un riesgo importante para la salud, pero las intervenciones validadas siguen siendo difíciles de alcanzar. El Ghana Randomized Air Pollution and Health Study (GRAPHS) es un ensayo aleatorizado por grupos que evalúa la eficacia de los combustibles limpios (gas licuado de petróleo o GLP) y las estufas de biomasa eficientes en la región de Brong-Ahafo, en el centro de Ghana. Reclutamos a mujeres embarazadas en GLP, estufas eficientes y brazos de control y rastreamos el peso al nacer y la incidencia de neumonía grave evaluada por el médico en el primer año de vida. Una mujer es elegible para participar si está en el primer o segundo trimestre del embarazo y lleva un feto único vivo, si es la cocinera principal y si no fuma. Presumimos que los bebés nacidos de madres de intervención pesarán más y tendrán menos casos de neumonía grave evaluada por el médico en el primer año de vida. Además, un extenso esfuerzo personal de monitoreo de la exposición a la contaminación del aire abre el camino para los análisis de exposición-respuesta, que presentaremos junto con los análisis de intención de tratar. El Instituto Nacional de Ciencias de la Salud Ambiental, el Fondo de Investigación Thrasher y la Alianza Mundial para Estufas Limpias proporcionaron fondos importantes. La exposición a la contaminación del aire en el hogar es un riesgo importante para la salud que requiere intervenciones bien probadas. LOS GRÁFICOS proporcionarán nuevas pruebas importantes sobre la eficacia tanto de las estufas de biomasa eficientes como del GLP y, por lo tanto, ayudarán a informar las políticas de salud y energía en los países en desarrollo. El ensayo se registró en clinicaltrials.gov el 13 de abril de 2011 con el identificador NCT01335490 . Household air pollution exposure is a major health risk, but validated interventions remain elusive.The Ghana Randomized Air Pollution and Health Study (GRAPHS) is a cluster-randomized trial that evaluates the efficacy of clean fuels (liquefied petroleum gas, or LPG) and efficient biomass cookstoves in the Brong-Ahafo region of central Ghana. We recruit pregnant women into LPG, efficient cookstove, and control arms and track birth weight and physician-assessed severe pneumonia incidence in the first year of life. A woman is eligible to participate if she is in the first or second trimester of pregnancy and carrying a live singleton fetus, if she is the primary cook, and if she does not smoke. We hypothesize that babies born to intervention mothers will weigh more and will have fewer cases of physician-assessed severe pneumonia in the first year of life. Additionally, an extensive personal air pollution exposure monitoring effort opens the way for exposure-response analyses, which we will present alongside intention-to-treat analyses. Major funding was provided by the National Institute of Environmental Health Sciences, The Thrasher Research Fund, and the Global Alliance for Clean Cookstoves.Household air pollution exposure is a major health risk that requires well-tested interventions. GRAPHS will provide important new evidence on the efficacy of both efficient biomass cookstoves and LPG, and will thus help inform health and energy policies in developing countries.The trial was registered with clinicaltrials.gov on 13 April 2011 with the identifier NCT01335490 . يمثل التعرض لتلوث الهواء المنزلي خطرًا صحيًا كبيرًا، لكن التدخلات التي تم التحقق منها لا تزال بعيدة المنال. دراسة تلوث الهواء والصحة العشوائية في غانا (الرسوم البيانية) هي تجربة عشوائية عنقودية تقيم فعالية الوقود النظيف (غاز البترول المسال) ومواقد الطهي ذات الكتلة الحيوية الفعالة في منطقة برونغ أهافو في وسط غانا. نقوم بتجنيد النساء الحوامل في غاز البترول المسال، وموقد الطهي الفعال، والتحكم في الأذرع وتتبع الوزن عند الولادة وحدوث الالتهاب الرئوي الحاد الذي يقدره الطبيب في السنة الأولى من العمر. يحق للمرأة المشاركة إذا كانت في الثلث الأول أو الثاني من الحمل وتحمل جنينًا فرديًا حيًا، وإذا كانت هي الطاهية الرئيسية، وإذا كانت لا تدخن. نحن نفترض أن الأطفال المولودين لأمهات التدخل سيكون وزنهم أكثر وسيصابون بعدد أقل من حالات الالتهاب الرئوي الحاد التي يقيمها الطبيب في السنة الأولى من الحياة. بالإضافة إلى ذلك، فإن جهد مراقبة التعرض الشخصي المكثف لتلوث الهواء يفتح الطريق أمام تحليلات التعرض والاستجابة، والتي سنقدمها جنبًا إلى جنب مع تحليلات نية العلاج. تم توفير تمويل كبير من قبل المعهد الوطني لعلوم الصحة البيئية، وصندوق ثراشر للبحوث، والتحالف العالمي لمواقد الطهي النظيفة. يعد التعرض لتلوث الهواء المنزلي خطرًا صحيًا كبيرًا يتطلب تدخلات تم اختبارها جيدًا. ستوفر الرسوم البيانية أدلة جديدة مهمة على فعالية كل من مواقد الطهي ذات الكتلة الحيوية الفعالة وغاز البترول المسال، وبالتالي ستساعد في إثراء سياسات الصحة والطاقة في البلدان النامية. تم تسجيل التجربة لدى clinicaltrials.gov في 13 أبريل 2011 بالمعرف NCT01335490 .

Energy transfer between photons and molecules and between neighboring molecules is ubiquitous in living nature, most prominently in photosynthesis. While energy transfer is efficiently utilized by living systems, its adoption to connect individual components in man-made plasmonic nanocircuits has been challenged by low transfer efficiencies that motivate the development of entirely new concepts for energy transfer. We introduce herein optoplasmonic superlenses that combine the capability of optical microcavities to insulate molecule-photon systems from decohering environmental effects with the superior light nanoconcentration properties of nanoantennas. The proposed structures provide significant enhancement of the emitter radiative rate and efficient long-range transfer of emitted photons followed by subsequent refocusing into nanoscale volumes accessible to near- and far-field detection. Optoplasmonic superlenses are versatile building blocks for optoplasmonic nanocircuits and can be used to construct “dark” single-molecule sensors, resonant amplifiers, nanoconcentrators, frequency multiplexers, demultiplexers, energy converters, and dynamical switches.

A majority of black carbon (BC) emitted to the atmosphere in the Indo-Gangetic Plain (IGP) region is from burning biomass fuel used in traditional, open-design cookstoves. However, BC and particulate matter (PM) household emissions are not well characterized. Household emission information is needed to develop emission profiles to validate regional climate change models and serve as a baseline for assessing the impact of adopting improved stove technology. This paper presents field-based household PM and BC exfiltration (amount exiting) estimates from village homes in rural Nepal that utilize traditional, open-design cookstoves. Use of these stoves resulted in a 26% mean PM exfiltration, ranging from 6% to 58%. This is a significant departure from an 80% estimate cited in previous reports. Furthermore, having a window/door resulted in an 11% increase in exfiltration when an opening was present, while fuel type had a marginally significant impact on emission. Air-exchange rates (AER) were determined with average (95% CI) AER of 12 (10-14) per hour, consistent with previous studies. In addition, BC to PM2.5 mass-ratio composition during cooking was ascertained, with an average (95% CI) of 31% (24-39), agreeing with previous biomass fuel emission composition literature.

Lignin is a heterogeneous aromatic biopolymer that accounts for nearly 30% of the organic carbon on Earth and is one of the few renewable sources of aromatic chemicals. As the most recalcitrant of the three components of lignocellulosic biomass (cellulose, hemicellulose and lignin), lignin has been treated as a waste product in the pulp and paper industry, where it is burned to supply energy and recover pulping chemicals in the operation of paper mills. Extraction of higher value from lignin is increasingly recognized as being crucial to the economic viability of integrated biorefineries. Depolymerization is an important starting point for many lignin valorization strategies, because it could generate valuable aromatic chemicals and/or provide a source of low-molecular-mass feedstocks suitable for downstream processing. Commercial precedents show that certain types of lignin (lignosulphonates) may be converted into vanillin and other marketable products, but new technologies are needed to enhance the lignin value chain. The complex, irregular structure of lignin complicates chemical conversion efforts, and known depolymerization methods typically afford ill-defined products in low yields (that is, less than 10-20wt%). Here we describe a method for the depolymerization of oxidized lignin under mild conditions in aqueous formic acid that results in more than 60wt% yield of low-molecular-mass aromatics. We present the discovery of this facile C-O cleavage method, its application to aspen lignin depolymerization, and mechanistic insights into the reaction. The broader implications of these results for lignin conversion and biomass refining are also considered.