Predicting stomatal responses to the environment from the optimization of photosynthetic gain and hydraulic cost.

PubMed

Sperry, John S; Venturas, Martin D; Anderegg, William R L; Mencuccini, Maurizio; Mackay, D Scott; Wang, Yujie; Love, David M

2017-06-01

Stomatal regulation presumably evolved to optimize CO 2 for H 2 O exchange in response to changing conditions. If the optimization criterion can be readily measured or calculated, then stomatal responses can be efficiently modelled without recourse to empirical models or underlying mechanism. Previous efforts have been challenged by the lack of a transparent index for the cost of losing water. Yet it is accepted that stomata control water loss to avoid excessive loss of hydraulic conductance from cavitation and soil drying. Proximity to hydraulic failure and desiccation can represent the cost of water loss. If at any given instant, the stomatal aperture adjusts to maximize the instantaneous difference between photosynthetic gain and hydraulic cost, then a model can predict the trajectory of stomatal responses to changes in environment across time. Results of this optimization model are consistent with the widely used Ball-Berry-Leuning empirical model (r 2  > 0.99) across a wide range of vapour pressure deficits and ambient CO 2 concentrations for wet soil. The advantage of the optimization approach is the absence of empirical coefficients, applicability to dry as well as wet soil and prediction of plant hydraulic status along with gas exchange. © 2016 John Wiley & Sons Ltd.

Moving on from rigid plant stoichiometry: Optimal canopy nitrogen allocation within a novel land surface model

NASA Astrophysics Data System (ADS)

Caldararu, S.; Kern, M.; Engel, J.; Zaehle, S.

2016-12-01

Despite recent advances in global vegetation models, we still lack the capacity to predict observed vegetation responses to experimental environmental changes such as elevated CO2, increased temperature or nutrient additions. In particular for elevated CO2 (FACE) experiments, studies have shown that this is related in part to the models' inability to represent plastic changes in nutrient use and biomass allocation. We present a newly developed vegetation model which aims to overcome these problems by including optimality processes to describe nitrogen (N) and carbon allocation within the plant. We represent nitrogen allocation to the canopy and within the canopy between photosynthetic components as an optimal processes which aims to maximize net primary production (NPP) of the plant. We also represent biomass investment into aboveground and belowground components (root nitrogen uptake , biological N fixation) as an optimal process that maximizes plant growth by considering plant carbon and nutrient demands as well as acquisition costs. The model can now represent plastic changes in canopy N content and chlorophyll and Rubisco concentrations as well as in belowground allocation both on seasonal and inter-annual time scales. Specifically, we show that under elevated CO2 conditions, the model predicts a lower optimal leaf N concentration, which, combined with a redistribution of leaf N between the Rubisco and chlorophyll components, leads to a continued NPP response under high CO2, where models with a fixed canopy stoichiometry would predicts a quick onset of N limitation. In general, our model aims to include physiologically-based plant processes and avoid arbitrarily imposed parameters and thresholds in order to improve our predictive capability of vegetation responses under changing environmental conditions.

Effect of carbon dioxide on the thermal degradation of lignocellulosic biomass.

PubMed

Kwon, Eilhann E; Jeon, Eui-Chan; Castaldi, Marco J; Jeon, Young Jae

2013-09-17

Using biomass as a renewable energy source via currently available thermochemical processes (i.e., pyrolysis and gasification) is environmentally advantageous owing to its intrinsic carbon neutrality. Developing methodologies to enhance the thermal efficiency of these proven technologies is therefore imperative. This study aimed to investigate the use of CO2 as a reaction medium to increase not only thermal efficiency but also environmental benefit. The influence of CO2 on thermochemical processes at a fundamental level was experimentally validated with the main constituents of biomass (i.e., cellulose and xylan) to avoid complexities arising from the heterogeneous matrix of biomass. For instance, gaseous products including H2, CH4, and CO were substantially enhanced in the presence of CO2 because CO2 expedited thermal cracking behavior (i.e., 200-1000%). This behavior was then universally observed in our case study with real biomass (i.e., corn stover) during pyrolysis and steam gasification. However, further study is urgently needed to optimize these experimental findings.

Temperature, Oxygen, and Salt-Sensing Neurons in C. elegans Are Carbon Dioxide Sensors that Control Avoidance Behavior

PubMed Central

Bretscher, Andrew Jonathan; Kodama-Namba, Eiji; Busch, Karl Emanuel; Murphy, Robin Joseph; Soltesz, Zoltan; Laurent, Patrick; de Bono, Mario

2011-01-01

Summary Homeostatic control of body fluid CO2 is essential in animals but is poorly understood. C. elegans relies on diffusion for gas exchange and avoids environments with elevated CO2. We show that C. elegans temperature, O2, and salt-sensing neurons are also CO2 sensors mediating CO2 avoidance. AFD thermosensors respond to increasing CO2 by a fall and then rise in Ca2+ and show a Ca2+ spike when CO2 decreases. BAG O2 sensors and ASE salt sensors are both activated by CO2 and remain tonically active while high CO2 persists. CO2-evoked Ca2+ responses in AFD and BAG neurons require cGMP-gated ion channels. Atypical soluble guanylate cyclases mediating O2 responses also contribute to BAG CO2 responses. AFD and BAG neurons together stimulate turning when CO2 rises and inhibit turning when CO2 falls. Our results show that C. elegans senses CO2 using functionally diverse sensory neurons acting homeostatically to minimize exposure to elevated CO2. PMID:21435556

Pharyngeal pumping inhibition and avoidance by acute exposure to high CO2 levels are both regulated by the BAG neurons via different molecular pathways

PubMed Central

Sharabi, Kfir; Charar, Chayki; Gruenbaum, Yosef

2015-01-01

Carbon dioxide (CO2) is a key molecule in many biological processes. Studies in humans, mice, D. melanogaster, C. elegans, unicellular organisms and plants have shed light on the molecular pathways activated by elevated levels of CO2. However, the mechanisms that organisms use to sense and respond to high CO2 levels remain largely unknown. Previous work has shown that C. elegans quickly avoid elevated CO2 levels using mechanisms that involve the BAG, ASE and AFD neurons via cGMP- and calcium- signaling pathways. Here, we discuss our recent finding that exposure of C. elegans to high CO2 levels leads to a very rapid cessation in the contraction of the pharynx muscles. Surprisingly, none of the tested CO2 avoidance mutants affected the rapid pumping inhibition response to elevated CO2 levels. A forward genetic screen identified that the hid-1-mediated pathway of dense core vesicle maturation regulates the pumping inhibition, probably through affecting neuropeptide secretion. Genetic studies and laser ablation experiments showed that the CO2 response of the pharyngeal muscle pumping is regulated by the BAG neurons, the same neurons that mediate CO2 avoidance. PMID:26430557

Temperature, oxygen, and salt-sensing neurons in C. elegans are carbon dioxide sensors that control avoidance behavior.

PubMed

Bretscher, Andrew Jonathan; Kodama-Namba, Eiji; Busch, Karl Emanuel; Murphy, Robin Joseph; Soltesz, Zoltan; Laurent, Patrick; de Bono, Mario

2011-03-24

Homeostatic control of body fluid CO(2) is essential in animals but is poorly understood. C. elegans relies on diffusion for gas exchange and avoids environments with elevated CO(2). We show that C. elegans temperature, O(2), and salt-sensing neurons are also CO(2) sensors mediating CO(2) avoidance. AFD thermosensors respond to increasing CO(2) by a fall and then rise in Ca(2+) and show a Ca(2+) spike when CO(2) decreases. BAG O(2) sensors and ASE salt sensors are both activated by CO(2) and remain tonically active while high CO(2) persists. CO(2)-evoked Ca(2+) responses in AFD and BAG neurons require cGMP-gated ion channels. Atypical soluble guanylate cyclases mediating O(2) responses also contribute to BAG CO(2) responses. AFD and BAG neurons together stimulate turning when CO(2) rises and inhibit turning when CO(2) falls. Our results show that C. elegans senses CO(2) using functionally diverse sensory neurons acting homeostatically to minimize exposure to elevated CO(2). Copyright © 2011 Elsevier Inc. All rights reserved.

Avoidance of 20% carbon dioxide-enriched air with humans.

PubMed Central

Lejuez, C W; O'Donnell, J; Wirth, O; Zvolensky, M J; Eifert, G H

1998-01-01

Four college students were exposed to a Sidman avoidance procedure to determine if an avoidance contingency involving 20% carbon dioxide-enriched air (CO2) would produce and maintain responding. In Phase 1, two conditions (contingent and noncontingent) were conducted each day. These conditions were distinguished by the presence or absence of a blue or green box on a computer screen. In the contingent condition, CO2 presentation were delivered every 3 s unless a subject pulled a plunger. Each plunger pull postponed CO2 presentations for 10 s. In the noncontingent condition, CO2 presentations occurred on the average of every 5 min independent of responding. Following stable responding in Phase 1, condition-correlated stimuli were reversed. In both conditions, plunger response rate was high during the contingent condition and low or zero during the noncontingent condition. Furthermore, subjects avoided most CO2 presentations. However, CO2 presentations did not increase verbal reports of fear. Overall, the results from the present study suggest that CO2 can be used effectively in basic studies of aversive control and in laboratory analogues of response patterns commonly referred to as anxiety. PMID:9684345

Optimization of Chlorella vulgaris and bioflocculant-producing bacteria co-culture: enhancing microalgae harvesting and lipid content.

PubMed

Wang, Y; Yang, Y; Ma, F; Xuan, L; Xu, Y; Huo, H; Zhou, D; Dong, S

2015-05-01

Microalgae are a sustainable bioresource, and the biofuel they produce is widely considered to be an alternative to limited natural fuel resources. However, microalgae harvesting is a bottleneck in the development of technology. Axenic Chlorella vulgaris microalgae exhibit poor harvesting, as expressed by a flocculation efficiency of 0·2%. This work optimized the co-culture conditions of C. vulgaris and bioflocculant-producing bacteria in synthetic wastewater using response surface methodology (RSM), thus aiming to enhance C. vulgaris harvesting and lipid content. Three significant process variables- inoculation ratio of bacteria and microalgae, initial glucose concentration, and co-culture time- were proposed in the RSM model. F-values (3·98/8·46) and R(2) values (0·7817/0·8711) both indicated a reasonable prediction by the RSM model. The results showed that C. vulgaris harvesting efficiency reached 45·0-50·0%, and the lipid content was over 21·0% when co-cultured with bioflocculant-producing bacteria under the optimized culture conditions of inoculation ratio of bacteria and microalgae of 0·20-0·25, initial glucose concentration of <1·5 kg m(-3) and co-culture time of 9-14 days. This work provided new insights into microalgae harvesting and cost-effective microalgal bioproducts, and confirmed the promising prospect of introducing bioflocculant-producing bacteria into microalgae bioenergy production. This work optimized the co-culture conditions of microalgae (C. vulgaris) and bioflocculant-producing bacteria (F2, Rhizobium radiobacter) in synthetic wastewater using response surface methodology, aiming to enhance C. vulgaris harvesting and lipid produced content. Bioflocculant-producing microbes are environmentally friendly functional materials. They avoid the negative effects of traditional chemical flocculants. This work provided new insights into microalgae harvesting and cost-effective production of microalgal bioproducts, and confirmed the promising prospect of introducing bioflocculant-producing bacteria into microalgae bioenergy production. © 2015 The Society for Applied Microbiology.

Global carbon assimilation system using a local ensemble Kalman filter with multiple ecosystem models

NASA Astrophysics Data System (ADS)

Zhang, Shupeng; Yi, Xue; Zheng, Xiaogu; Chen, Zhuoqi; Dan, Bo; Zhang, Xuanze

2014-11-01

In this paper, a global carbon assimilation system (GCAS) is developed for optimizing the global land surface carbon flux at 1° resolution using multiple ecosystem models. In GCAS, three ecosystem models, Boreal Ecosystem Productivity Simulator, Carnegie-Ames-Stanford Approach, and Community Atmosphere Biosphere Land Exchange, produce the prior fluxes, and an atmospheric transport model, Model for OZone And Related chemical Tracers, is used to calculate atmospheric CO2 concentrations resulting from these prior fluxes. A local ensemble Kalman filter is developed to assimilate atmospheric CO2 data observed at 92 stations to optimize the carbon flux for six land regions, and the Bayesian model averaging method is implemented in GCAS to calculate the weighted average of the optimized fluxes based on individual ecosystem models. The weights for the models are found according to the closeness of their forecasted CO2 concentration to observation. Results of this study show that the model weights vary in time and space, allowing for an optimum utilization of different strengths of different ecosystem models. It is also demonstrated that spatial localization is an effective technique to avoid spurious optimization results for regions that are not well constrained by the atmospheric data. Based on the multimodel optimized flux from GCAS, we found that the average global terrestrial carbon sink over the 2002-2008 period is 2.97 ± 1.1 PgC yr-1, and the sinks are 0.88 ± 0.52, 0.27 ± 0.33, 0.67 ± 0.39, 0.90 ± 0.68, 0.21 ± 0.31, and 0.04 ± 0.08 PgC yr-1 for the North America, South America, Africa, Eurasia, Tropical Asia, and Australia, respectively. This multimodel GCAS can be used to improve global carbon cycle estimation.

Model-Free Optimal Tracking Control via Critic-Only Q-Learning.

PubMed

Luo, Biao; Liu, Derong; Huang, Tingwen; Wang, Ding

2016-10-01

Model-free control is an important and promising topic in control fields, which has attracted extensive attention in the past few years. In this paper, we aim to solve the model-free optimal tracking control problem of nonaffine nonlinear discrete-time systems. A critic-only Q-learning (CoQL) method is developed, which learns the optimal tracking control from real system data, and thus avoids solving the tracking Hamilton-Jacobi-Bellman equation. First, the Q-learning algorithm is proposed based on the augmented system, and its convergence is established. Using only one neural network for approximating the Q-function, the CoQL method is developed to implement the Q-learning algorithm. Furthermore, the convergence of the CoQL method is proved with the consideration of neural network approximation error. With the convergent Q-function obtained from the CoQL method, the adaptive optimal tracking control is designed based on the gradient descent scheme. Finally, the effectiveness of the developed CoQL method is demonstrated through simulation studies. The developed CoQL method learns with off-policy data and implements with a critic-only structure, thus it is easy to realize and overcome the inadequate exploration problem.

Assessment of aversion to different concentrations of CO2 gas by weaned pigs using an approach-avoidance paradigm

USDA-ARS?s Scientific Manuscript database

The objective of this study was to examine the aversiveness of carbon dioxide (CO2) to weaned pigs using approach-avoidance and condition place avoidance paradigms. A preference-testing device was custom designed with two connected chambers maintained at static gas concentrations. The control chambe...

Acute carbon dioxide avoidance in Caenorhabditis elegans

PubMed Central

Hallem, Elissa A.; Sternberg, Paul W.

2008-01-01

Carbon dioxide is produced as a by-product of cellular respiration by all aerobic organisms and thus serves for many animals as an important indicator of food, mates, and predators. However, whether free-living terrestrial nematodes such as Caenorhabditis elegans respond to CO2 was unclear. We have demonstrated that adult C. elegans display an acute avoidance response upon exposure to CO2 that is characterized by the cessation of forward movement and the rapid initiation of backward movement. This response is mediated by a cGMP signaling pathway that includes the cGMP-gated heteromeric channel TAX-2/TAX-4. CO2 avoidance is modulated by multiple signaling molecules, including the neuropeptide Y receptor NPR-1 and the calcineurin subunits TAX-6 and CNB-1. Nutritional status also modulates CO2 responsiveness via the insulin and TGFβ signaling pathways. CO2 response is mediated by a neural circuit that includes the BAG neurons, a pair of sensory neurons of previously unknown function. TAX-2/TAX-4 function in the BAG neurons to mediate acute CO2 avoidance. Our results demonstrate that C. elegans senses and responds to CO2 using multiple signaling pathways and a neural network that includes the BAG neurons and that this response is modulated by the physiological state of the worm. PMID:18524955

Acute carbon dioxide avoidance in Caenorhabditis elegans.

PubMed

Hallem, Elissa A; Sternberg, Paul W

2008-06-10

Carbon dioxide is produced as a by-product of cellular respiration by all aerobic organisms and thus serves for many animals as an important indicator of food, mates, and predators. However, whether free-living terrestrial nematodes such as Caenorhabditis elegans respond to CO2 was unclear. We have demonstrated that adult C. elegans display an acute avoidance response upon exposure to CO2 that is characterized by the cessation of forward movement and the rapid initiation of backward movement. This response is mediated by a cGMP signaling pathway that includes the cGMP-gated heteromeric channel TAX-2/TAX-4. CO2 avoidance is modulated by multiple signaling molecules, including the neuropeptide Y receptor NPR-1 and the calcineurin subunits TAX-6 and CNB-1. Nutritional status also modulates CO2 responsiveness via the insulin and TGFbeta signaling pathways. CO2 response is mediated by a neural circuit that includes the BAG neurons, a pair of sensory neurons of previously unknown function. TAX-2/TAX-4 function in the BAG neurons to mediate acute CO2 avoidance. Our results demonstrate that C. elegans senses and responds to CO2 using multiple signaling pathways and a neural network that includes the BAG neurons and that this response is modulated by the physiological state of the worm.

Synthesis of asymmetric polyetherimide membrane for CO2/N2 separation

NASA Astrophysics Data System (ADS)

Ahmad, A. L.; Salaudeen, Y. O.; Jawad, Z. A.

2017-06-01

Large emission of carbon dioxide (CO2) to the environment requires mitigation to avoid unbearable consequences on global climate change. The CO2 emissions generated by fossil fuel combustion within the power and industrial sectors need to be quickly curbed. The gas emission can be abated using membrane technology; this is one of the most promising approaches for selective separation of CO2/N2. The purpose of the study is to synthesis an asymmetric polyetherimide (PEI) membrane and to establish its morphological characteristics for CO2/N2 separation. The PEI flat-sheet asymmetric membrane was fabricated using phase inversion with N-methyl-2-pyrrolidone (NMP) as solvent and water-isopropanol as a coagulant. Particularly, polymer concentration of 20, 25, and 30 wt. % were studied. In addition, the structure and morphology of the produced membrane were observed using scanning electron microscopy (SEM). Importantly, results showed that the membrane with high PEI concentration of 30 wt. % yield an optimal selectivity of 10.7 for CO2/Nitrogen (N2) separation at 1 bar and 25 ºC for pure gas, aided by the membrane surface morphology. The dense skin present was as a result of non-solvent (water) while isopropanol generates a porous sponge structure. This appreciable separation performance makes the PEI asymmetric membrane an attractive alternative for CO2/N2 separation.

Absorber modeling for NGCC carbon capture with aqueous piperazine.

PubMed

Zhang, Yue; Freeman, Brice; Hao, Pingjiao; Rochelle, Gary T

2016-10-20

A hybrid system combining amine scrubbing with membrane technology for carbon capture from natural gas combined cycle (NGCC) power plants is proposed in this paper. In this process, the CO 2 in the flue gas can be enriched from 4% to 18% by the membrane, and the amine scrubbing system will have lower capture costs. Aqueous piperazine (PZ) is chosen as the solvent. Different direct contact cooler (DCC) options, multiple absorber operating conditions, optimal intercooling designs, and different cooling options have been evaluated across a wide range of inlet CO 2 . Amine scrubbing without DCC is a superior design for NGCC carbon capture. Pump-around cooling at the bottom of the absorber can effectively manage the temperature of the hot flue gas, and still be effective for CO 2 absorption. The absorber gas inlet must be designed to avoid excessive localized temperature and solvent evaporation. When the inlet CO 2 increases from 4% to 18%, total absorber CAPEX decreases by 60%; another 10% of the total absorber CAPEX can be saved by eliminating the DCC. In-and-out intercooling works well for high CO 2 , while pump-around intercooling is more effective for low CO 2 . Dry cooling requires more packing and energy but appears to be technically and economically feasible if cooling water availability is limited.

Super-optimal CO2 reduces seed yield but not vegetative growth in wheat

NASA Technical Reports Server (NTRS)

Grotenhuis, T. P.; Bugbee, B.

1997-01-01

Although terrestrial atmospheric CO2 levels will not reach 1000 micromoles mol-1 (0.1%) for decades, CO2 levels in growth chambers and greenhouses routinely exceed that concentration. CO2 levels in life support systems in space can exceed 10000 micromoles mol-1(1%). Numerous studies have examined CO2 effects up to 1000 micromoles mol-1, but biochemical measurements indicate that the beneficial effects of CO2 can continue beyond this concentration. We studied the effects of near-optimal (approximately 1200 micromoles mol-1) and super-optimal CO2 levels (2400 micromoles mol-1) on yield of two cultivars of hydroponically grown wheat (Triticum aestivum L.) in 12 trials in growth chambers. Increasing CO2 from sub-optimal to near-optimal (350-1200 micromoles mol-1) increased vegetative growth by 25% and seed yield by 15% in both cultivars. Yield increases were primarily the result of an increased number of heads per square meter. Further elevation of CO2 to 2500 micromoles mol-1 reduced seed yield by 22% (P < 0.001) in cv. Veery-10 and by 15% (P < 0.001) in cv. USU-Apogee. Super-optimal CO2 did not decrease the number of heads per square meter, but reduced seeds per head by 10% and mass per seed by 11%. The toxic effect of CO2 was similar over a range of light levels from half to full sunlight. Subsequent trials revealed that super-optimal CO2 during the interval between 2 wk before and after anthesis mimicked the effect of constant super-optimal CO2. Furthermore, near-optimal CO2 during the same interval mimicked the effect of constant near-optimal CO2. Nutrient concentration of leaves and heads was not affected by CO2. These results suggest that super-optimal CO2 inhibits some process that occurs near the time of seed set resulting in decreased seed set, seed mass, and yield.

Natural Carbonation of Peridotite and Applications for Carbon Storage

NASA Astrophysics Data System (ADS)

Streit, E.; Kelemen, P.; Matter, J.

2009-05-01

Natural carbonation of peridotite in the Samail Ophiolite of Oman is surprisingly rapid and could be further enhanced to provide a safe, permanent method of CO2 storage through in situ formation of carbonate minerals. Carbonate veins form by low-temperature reaction between peridotite and groundwater in a shallow weathering horizon. Reaction with peridotite drives up the pH of the water, and extensive travertine terraces form where this groundwater emerges at the surface in alkaline springs. The potential sink for CO2 in peridotite is enormous: adding 1wt% CO2 to the peridotite in Oman could consume 1/4 of all atmospheric carbon, and several peridotite bodies of comparable size exist throughout the world. Thus carbonation rate and cost, not reservoir size, are the limiting factors on the usefulness of in situ mineral carbonation of peridotite for carbon storage. The carbonate veins in Oman are much younger than previously believed, yielding average 14C ages of 28,000 years. Age data plus estimated volumes of carbonate veins and terraces suggest 10,000 to 100,000 tons per year of CO2 are consumed by these peridotite weathering reactions in Oman. This rate can be enhanced by drilling, hydraulic fracture, injecting CO2-rich fluid, and increasing reaction temperature. Drilling and hydraulic fracture can increase volume of peridotite available for reaction. Additional fracture may occur due to the solid volume increase of the carbonation reaction, and field observations suggest that such reaction-assisted fracture may be responsible for hierarchical carbonate vein networks in peridotite. Natural carbonation of peridotite in Oman occurs at low pCO2, resulting in partial carbonation of peridotite, forming magnesite and serpentine. Raising pCO2 increases carbonation efficiency, forming of magnesite + talc, or at complete carbonation, magnesite + quartz, allowing ˜30wt% CO2 to be added to the peridotite. Increasing the temperature to 185°C can improve the reaction rate by a factor of more than 100,000. Thermal modeling suggests that after an initial heating stage, CO2-rich fluids injected at relatively low temperature can be heated by exothermic carbonation reactions, offsetting diffusive heat loss to maintain optimal temperatures for rapid carbonation without additional energy input. With these enhancements, in situ carbonation could consume more than 1 billion tons of CO2 per cubic kilometer of peridotite per year. Costs associated with this method include drilling, hydraulic fracture, initial heating, CO2 capture and transport, fluid injection and monitoring. The techniques for drilling, fracture and injection are routinely used by oil companies. Compared with other carbon storage methods, in situ mineral carbonation has several advantages. It offers permanent storage that is safer and easier to monitor than storage of CO2-rich fluids in porous underground reservoirs or in the ocean. It may also be less costly than ex situ mineral carbonation, which requires quarrying and transportation of peridotite, grinding and heat treatment, reactions in pressure vessels at elevated temperature, production of catalysts, and disposal of carbonated material. An alternative method, carbonation by reaction of offshore peridotite with shallow seawater rather than CO2-rich fluids, would consume less CO2, but would avoid the costs of CO2 capture and transport inherent in other CCS methods. Drilling to depths where rocks are already close to the optimal carbonation temperature would avoid pre-heating costs and circulate water by thermal convection rather than pumping fluids.

Effects of elevated CO2 on fish behaviour undiminished by transgenerational acclimation

NASA Astrophysics Data System (ADS)

Welch, Megan J.; Watson, Sue-Ann; Welsh, Justin Q.; McCormick, Mark I.; Munday, Philip L.

2014-12-01

Behaviour and sensory performance of marine fishes are impaired at CO2 levels projected to occur in the ocean in the next 50-100 years, and there is limited potential for within-generation acclimation to elevated CO2 (refs , ). However, whether fish behaviour can acclimate or adapt to elevated CO2 over multiple generations remains unanswered. We tested for transgenerational acclimation of reef fish olfactory preferences and behavioural lateralization at moderate (656 μatm) and high (912 μatm) end-of-century CO2 projections. Juvenile spiny damselfish, Acanthochromis polyacanthus, from control parents (446 μatm) exhibited an innate avoidance to chemical alarm cue (CAC) when reared in control conditions. In contrast, juveniles lost their innate avoidance of CAC and even became strongly attracted to CAC when reared at elevated CO2 levels. Juveniles from parents maintained at mid-CO2 and high-CO2 levels also lost their innate avoidance of CAC when reared in elevated CO2, demonstrating no capacity for transgenerational acclimation of olfactory responses. Behavioural lateralization was also disrupted for juveniles reared under elevated CO2, regardless of parental conditioning. Our results show minimal potential for transgenerational acclimation in this fish, suggesting that genetic adaptation will be necessary to overcome the effects of ocean acidification on behaviour.

Cross-Modulation of Homeostatic Responses to Temperature, Oxygen and Carbon Dioxide in C. elegans

PubMed Central

Kodama-Namba, Eiji; Fenk, Lorenz A.; Bretscher, Andrew J.; Gross, Einav; Busch, K. Emanuel; de Bono, Mario

2013-01-01

Different interoceptive systems must be integrated to ensure that multiple homeostatic insults evoke appropriate behavioral and physiological responses. Little is known about how this is achieved. Using C. elegans, we dissect cross-modulation between systems that monitor temperature, O2 and CO2. CO2 is less aversive to animals acclimated to 15°C than those grown at 22°C. This difference requires the AFD neurons, which respond to both temperature and CO2 changes. CO2 evokes distinct AFD Ca2+ responses in animals acclimated at 15°C or 22°C. Mutants defective in synaptic transmission can reprogram AFD CO2 responses according to temperature experience, suggesting reprogramming occurs cell autonomously. AFD is exquisitely sensitive to CO2. Surprisingly, gradients of 0.01% CO2/second evoke very different Ca2+ responses from gradients of 0.04% CO2/second. Ambient O2 provides further contextual modulation of CO2 avoidance. At 21% O2 tonic signalling from the O2-sensing neuron URX inhibits CO2 avoidance. This inhibition can be graded according to O2 levels. In a natural wild isolate, a switch from 21% to 19% O2 is sufficient to convert CO2 from a neutral to an aversive cue. This sharp tuning is conferred partly by the neuroglobin GLB-5. The modulatory effects of O2 on CO2 avoidance involve the RIA interneurons, which are post-synaptic to URX and exhibit CO2-evoked Ca2+ responses. Ambient O2 and acclimation temperature act combinatorially to modulate CO2 responsiveness. Our work highlights the integrated architecture of homeostatic responses in C. elegans. PMID:24385919

Optimism Moderates the Influence of Pain Catastrophizing on Shoulder Pain Outcome: A Longitudinal Analysis.

PubMed

Coronado, Rogelio A; Simon, Corey B; Lentz, Trevor A; Gay, Charles W; Mackie, Lauren N; George, Steven Z

2017-01-01

Study Design Secondary analysis of prospectively collected data. Background An abundance of evidence has highlighted the influence of pain catastrophizing and fear avoidance on clinical outcomes. Less is known about the interaction of positive psychological resources with these pain-associated distress factors. Objective To assess whether optimism moderates the influence of pain catastrophizing and fear avoidance on 3-month clinical outcomes in patients with shoulder pain. Methods Data from 63 individuals with shoulder pain (mean ± SD age, 38.8 ± 14.9 years; 30 female) were examined. Demographic, psychological, and clinical characteristics were obtained at baseline. Validated measures were used to assess optimism (Life Orientation Test-Revised), pain catastrophizing (Pain Catastrophizing Scale), fear avoidance (Fear-Avoidance Beliefs Questionnaire physical activity subscale), shoulder pain intensity (Brief Pain Inventory), and shoulder function (Pennsylvania Shoulder Score function subscale). Shoulder pain and function were reassessed at 3 months. Regression models assessed the influence of (1) pain catastrophizing and optimism and (2) fear avoidance and optimism. The final multivariable models controlled for factors of age, sex, education, and baseline scores, and included 3-month pain intensity and function as separate dependent variables. Results Shoulder pain (mean difference, -1.6; 95% confidence interval [CI]: -2.1, -1.2) and function (mean difference, 2.4; 95% CI: 0.3, 4.4) improved over 3 months. In multivariable analyses, there was an interaction between pain catastrophizing and optimism (β = 0.19; 95% CI: 0.02, 0.35) for predicting 3-month shoulder function (F = 16.8, R 2 = 0.69, P<.001), but not pain (P = .213). Further examination of the interaction with the Johnson-Neyman technique showed that higher levels of optimism lessened the influence of pain catastrophizing on function. There was no evidence of significant moderation of fear-avoidance beliefs for 3-month shoulder pain (P = .090) or function (P = .092). Conclusion Optimism decreased the negative influence of pain catastrophizing on shoulder function, but not pain intensity. Optimism did not alter the influence of fear-avoidance beliefs on these outcomes. Level of Evidence Prognosis, level 2b. J Orthop Sports Phys Ther 2017;47(1):21-30. Epub 5 Nov 2016. doi:10.2519/jospt.2017.7068.

WE-FG-206-08: Pulmonary Functional Imaging Biomarkers of NSCLC to Guide and Optimize Functional Lung Avoidance Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheikh, Khadija; Capaldi, Dante PI; Parraga, Grace

Purpose: Functional lung avoidance radiotherapy promises optimized therapy planning by minimizing dose to well-functioning lung and maximizing dose to the rest of the lung. Patients with NSCLC commonly present with co-morbid COPD and heterogeneously distributed ventilation abnormalities stemming from emphysema, airways disease, and tumour burden. We hypothesized that pulmonary functional imaging methods may be used to optimize radiotherapy plans to avoid regions of well-functioning lung and significantly improve outcomes like quality-of-life and survival. To ascertain the utility of functional lung avoidance therapy in clinical practice, we measured COPD phenotypes in NSCLC patients enrolled in a randomized-controlled-clinical-trial prior to curative intentmore » therapy. Methods: Thirty stage IIIA/IIIB NSCLC patients provided written informed consent to a randomized-controlled-clinical-trial ( http://clinicaltrials.gov/ct2/show/NCT02002052 ) comparing outcomes in patients randomized to standard or image-guided radiotherapy. Hyperpolarized noble gas MRI ventilation-defect-percent (VDP) (Kirby et al, Acad Radiol, 2012) as well as CT-emphysema measurements were determined. Patients were stratified based on quantitative imaging evidence of ventilation-defects and emphysema into two subgroups: 1) tumour-specific ventilation defects only (TSD), and, 2) tumour-specific and other ventilation defects with and without emphysema (TSD{sub VE}). Receiver-operating-characteristic (ROC) curves were used to characterize the performance of clinical measures as predictors of the presence of non-tumour specific ventilation defects. Results: Twenty-one out of thirty subjects (70%) had non-tumour specific ventilation defects (TSD{sub VE}) and nine subjects had ONLY tumour-specific defects (TSD). Subjects in the TSD{sub VE} group had significantly greater smoking-history (p=.006) and airflow obstruction (FEV{sub 1}/FVC) (p=.001). ROC analysis demonstrated an 87% classification rate for smoking pack-years, 90% for FEV{sub 1}/FVC, and 56% for tumour RECIST measurements for identifying patients with non-tumour and tumour-specific ventilation abnormalities. Conclusion: 70% of NSCLC patients had ventilation abnormalities stemming from emphysema, airways disease and tumour burden. Smoking-history and airflow obstruction, but not RECIST, identified NSCLC patients with ventilation abnormalities appropriate for functional lung avoidance therapy.« less

NEOTEC: Negative-CO2-Emissions Marine Energy With Direct Mitigation of Global Warming, Sea-Level Rise and Ocean Acidification

NASA Astrophysics Data System (ADS)

Rau, G. H.; Baird, J.; Noland, G.

2016-12-01

The vertical thermal energy potential in the ocean is a massive renewable energy resource that is growing due to anthropogenic warming of the surface and near-surface ocean. The conversion of this thermal energy to useful forms via Ocean Thermal Energy Conversion (OTEC) has been demonstrated over the past century, albeit at small scales. Because OTEC removes heat from the surface ocean, this could help directly counter ongoing, deleterious ocean/atmosphere warming. The only other climate intervention that could do this is solar radiation "geoengineering". Conventional OTEC requires energy intensive, vertical movement of seawater resulting in ocean and atmospheric chemistry alteration, but this can be avoided via more energy efficient, vertical closed-cycle heating and cooling of working fluid like CO2 or NH3. An energy carrier such as H2 is required to transport energy optimally extracted far offshore, and methods of electrochemically generating H2 while also consuming CO2 and converting it to ocean alkalinity have been demonstrated. The addition of such alkalinity to the ocean would provide vast, stable, carbon storage, while also helping chemically counter the effects of ocean acidification. The process might currently be profitable given the >$100/tonne CO2 credit offered by California's Low Carbon Fuel Standard for transportation fuels like H2. Negative-Emissions OTEC, NEOTEC, thus can potentially provide constant, cost effective, high capacity, negative-emissions energy while: a) reducing surface ocean heat load, b) reducing thermal ocean expansion and sea-level rise, c) utilizing a very large, natural marine carbon storage reservoir, and d) helping mitigate ocean acidification. The technology also avoids the biophysical and land use limitations posed by negative emissions methods that rely on terrestrial biology, such as afforestation and BECCS. NEOTEC and other marine-based, renewable energy and CO2 removal approaches could therefore greatly increase the likelihood of satisfying growing global energy demand while helping to stabilize or reduce atmospheric CO2 and its impacts. Policies supporting the search and evaluation of renewable energy and negative emissions options beyond biotic- and land-based methods are needed.

A Statistical approach to optimize the production of Polyhydroxyalkanoates from Wickerhamomyces anomalus VIT-NN01 using Response Surface Methodology.

PubMed

Ojha, Nupur; Das, Nilanjana

2018-02-01

Polyhydroxyalkanoates (PHAs) are three-level group of biodegradable polymers and attractive substitutes over conventional plastics to avoid the pollution problems. The yeast strain isolated from sugarcane juice, identified as Wickerhamomyces anomalus VIT-NN01, was used for the production of polyhydroxyalkanoates (PHA). Response surface methodology (RSM), three-level six variables Box-Behnken design (BBD), was employed to optimize the factors such as pH 8.0, temperature 37°C, sugarcane molasses (35g/L) supplemented with co-substrate palm oil (0.5%),corn steep liquor (2%) after a period of 96h of incubation for the maximum yield (19.50±0.3g/L) of PHA. It was well in close agreement with the predicted value obtained by RSM model yield (19.55±0.1g/L).Characterization of the extracted polymer was done using FTIR, GC-MS, XRD, TGA and AFM analysis. NMR spectroscopic analysis revealed that the biopolymer was poly (3-hydroxybutyrate-co-3-hydroxyvalerate), copolymer of PHA. This is the first report on optimization of PHA production using yeast strain isolated from natural sources. Copyright © 2017 Elsevier B.V. All rights reserved.

Carbon dioxide sequestration using NaHSO4 and NaOH: A dissolution and carbonation optimisation study.

PubMed

Sanna, Aimaro; Steel, Luc; Maroto-Valer, M Mercedes

2017-03-15

The use of NaHSO 4 to leach out Mg fromlizardite-rich serpentinite (in form of MgSO 4 ) and the carbonation of CO 2 (captured in form of Na 2 CO 3 using NaOH) to form MgCO 3 and Na 2 SO 4 was investigated. Unlike ammonium sulphate, sodium sulphate can be separated via precipitation during the recycling step avoiding energy intensive evaporation process required in NH 4 -based processes. To determine the effectiveness of the NaHSO 4 /NaOH process when applied to lizardite, the optimisation of the dissolution and carbonation steps were performed using a UK lizardite-rich serpentine. Temperature, solid/liquid ratio, particle size, concentration and molar ratio were evaluated. An optimal dissolution efficiency of 69.6% was achieved over 3 h at 100 °C using 1.4 M sodium bisulphate and 50 g/l serpentine with particle size 75-150 μm. An optimal carbonation efficiency of 95.4% was achieved over 30 min at 90 °C and 1:1 magnesium:sodium carbonate molar ratio using non-synthesised solution. The CO 2 sequestration capacity was 223.6 g carbon dioxide/kg serpentine (66.4% in terms of Mg bonded to hydromagnesite), which is comparable with those obtained using ammonium based processes. Therefore, lizardite-rich serpentinites represent a valuable resource for the NaHSO 4 /NaOH based pH swing mineralisation process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Health co-benefits in mortality avoidance from implementation of the mass rapid transit (MRT) system in Kuala Lumpur, Malaysia.

PubMed

Kwan, Soo Chen; Tainio, Marko; Woodcock, James; Hashim, Jamal Hisham

2016-03-01

The mass rapid transit (MRT) is the largest transport infrastructure project under the national key economic area (NKEA) in Malaysia. As urban rail is anticipated to be the future spine of public transport network in the Greater Kuala Lumpur city, it is important to mainstream climate change mitigation and public health benefits in the local transport development. This study quantifies the health co-benefits in terms of mortality among the urbanites when the first line of the 150 km MRT system in Kuala Lumpur commences by 2017. Using comparative health risk assessment, we estimated the potential health co-benefits from the establishment of the MRT system. We estimated the reduced CO2 emissions and air pollution (PM2.5) exposure reduction among the general population from the reduced use of motorized vehicles. Mortality avoided from traffic incidents involving motorcycles and passenger cars, and from increased physical activity from walking while using the MRT system was also estimated. A total of 363,130 tonnes of CO2 emissions could be reduced annually from the modal shift from cars and motorcycles to the MRT system. Atmospheric PM2.5 concentration could be reduced 0.61 μg/m3 annually (2%). This could avoid a total of 12 deaths, mostly from cardio-respiratory diseases among the city residents. For traffic injuries, 37 deaths could be avoided annually from motorcycle and passenger cars accidents especially among the younger age categories (aged 15-30). One additional death was attributed to pedestrian walking. The additional daily physical activity to access the MRT system could avoid 21 deaths among its riders. Most of the mortality avoided comes from cardiovascular diseases. Overall, a total of 70 deaths could be avoided annually among both the general population and the MRT users in the city. The implementation of the MRT system in Greater Kuala Lumpur could bring substantial health co-benefits to both the general population and the MRT users mainly from the avoidance of mortality from traffic injuries.

Model-based analysis of avoidance of ozone stress by stomatal closure in Siebold's beech (Fagus crenata)

PubMed Central

Hoshika, Yasutomo; Watanabe, Makoto; Inada, Naoki; Koike, Takayoshi

2013-01-01

Background and Aims Resistance of plants to ozone stress can be classified as either avoidance or tolerance. Avoidance of ozone stress may be explained by decreased stomatal conductance during ozone exposure because stomata are the principal interface for entry of ozone into plants. In this study, a coupled photosynthesis–stomatal model was modified to test whether the presence of ozone can induce avoidance of ozone stress by stomatal closure. Methods The response of Siebold's beech (Fagus crenata), a representative deciduous tree species, to ozone was studied in a free-air ozone exposure experiment in Japan. Photosynthesis and stomatal conductance were measured under ambient and elevated ozone. An optimization model of stomata involving water, CO2 and ozone flux was tested using the leaf gas exchange data. Key Results The data suggest that there are two phases in the avoidance of ozone stress via stomatal closure for Siebold's beech: (1) in early summer ozone influx is efficiently limited by a reduction in stomatal conductance, without any clear effect on photosynthetic capacity; and (2) in late summer and autumn the efficiency of ozone stress avoidance was decreased because the decrease in stomatal conductance was small and accompanied by an ozone-induced decline of photosynthetic capacity. Conclusions Ozone-induced stomatal closure in Siebold's beech during early summer reduces ozone influx and allows the maximum photosynthetic capacity to be reached, but is not sufficient in older leaves to protect the photosynthetic system. PMID:23904447

Long-term operation of microbial electrosynthesis cell reducing CO2 to multi-carbon chemicals with a mixed culture avoiding methanogenesis.

PubMed

Bajracharya, Suman; Yuliasni, Rustiana; Vanbroekhoven, Karolien; Buisman, Cees J N; Strik, David P B T B; Pant, Deepak

2017-02-01

In microbial electrosynthesis (MES), CO 2 can be reduced preferably to multi-carbon chemicals by a biocathode-based process which uses electrochemically active bacteria as catalysts. A mixed anaerobic consortium from biological origin typically produces methane from CO 2 reduction which circumvents production of multi-carbon compounds. This study aimed to develop a stable and robust CO 2 reducing biocathode from a mixed culture inoculum avoiding the methane generation. An effective approach was demonstrated based on (i) an enrichment procedure involving inoculum pre-treatment and several culture transfers in H 2 :CO 2 media, (ii) a transfer from heterotrophic to autotrophic growth and (iii) a sequential batch operation. Biomass growth and gradual acclimation to CO 2 electro-reduction accomplished a maximum acetate production rate of 400mgL catholyte -1 d -1 at -1V (vs. Ag/AgCl). Methane was never detected in more than 300days of operation. Accumulation of acetate up to 7-10gL -1 was repeatedly attained by supplying (80:20) CO 2 :N 2 mixture at -0.9 to -1V (vs. Ag/AgCl). In addition, ethanol and butyrate were also produced from CO 2 reduction. Thus, a robust CO 2 reducing biocathode can be developed from a mixed culture avoiding methane generation by adopting the specific culture enrichment and operation procedures without the direct addition of chemical inhibitor. Copyright © 2016 Elsevier B.V. All rights reserved.

Co-benefits of global, domestic, and sectoral greenhouse gas mitigation for US air quality and human health in 2050

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yuqiang; Smith, Steven J.; Bowden, Jared H.

Policies to reduce greenhouse gas (GHG) emissions can bring ancillary benefits of improved air quality and reduced premature mortality, in addition to slowing climate change. Here we study the co-benefits of global and domestic GHG mitigation on US air quality and human health in 2050 at fine resolution using dynamical downscaling, and quantify for the first time the co-benefits from foreign GHG mitigation. Relative to a reference scenario, global GHG reductions in RCP4.5 avoid 16000 PM2.5-related all-cause deaths yr-1 (90% confidence interval, 11700-20300), and 8000 (3600-12400) O3-related respiratory deaths yr-1 in the US in 2050. Foreign GHG mitigation avoids 15%more » and 62% of PM2.5- and O3-related total avoided deaths, highlighting the importance of foreign GHG mitigation on US human health benefits. GHG mitigation in the US residential sector brings the largest co-benefits for PM2.5-related deaths (21% of total domestic co-benefits), and industry for O3 (17%). Monetized benefits, for avoided deaths from ozone, PM2.5, and heat stress from a related study, are $148 ($96-201) per ton CO2 at high valuation and $49 ($32-67) at low valuation, of which 36% are from foreign GHG reductions. These benefits likely exceed the marginal cost of GHG reductions in 2050. The US gains significantly greater co-benefits when coordinating GHG reductions with foreign countries. Similarly, previous studies estimating co-benefits locally or regionally may greatly underestimate the full co-benefits of coordinated global actions.« less

Optimization of CO2 Storage in Saline Aquifers Using Water-Alternating Gas (WAG) Scheme - Case Study for Utsira Formation

NASA Astrophysics Data System (ADS)

Agarwal, R. K.; Zhang, Z.; Zhu, C.

2013-12-01

For optimization of CO2 storage and reduced CO2 plume migration in saline aquifers, a genetic algorithm (GA) based optimizer has been developed which is combined with the DOE multi-phase flow and heat transfer numerical simulation code TOUGH2. Designated as GA-TOUGH2, this combined solver/optimizer has been verified by performing optimization studies on a number of model problems and comparing the results with brute-force optimization which requires a large number of simulations. Using GA-TOUGH2, an innovative reservoir engineering technique known as water-alternating-gas (WAG) injection has been investigated to determine the optimal WAG operation for enhanced CO2 storage capacity. The topmost layer (layer # 9) of Utsira formation at Sleipner Project, Norway is considered as a case study. A cylindrical domain, which possesses identical characteristics of the detailed 3D Utsira Layer #9 model except for the absence of 3D topography, was used. Topographical details are known to be important in determining the CO2 migration at Sleipner, and are considered in our companion model for history match of the CO2 plume migration at Sleipner. However, simplification on topography here, without compromising accuracy, is necessary to analyze the effectiveness of WAG operation on CO2 migration without incurring excessive computational cost. Selected WAG operation then can be simulated with full topography details later. We consider a cylindrical domain with thickness of 35 m with horizontal flat caprock. All hydrogeological properties are retained from the detailed 3D Utsira Layer #9 model, the most important being the horizontal-to-vertical permeability ratio of 10. Constant Gas Injection (CGI) operation with nine-year average CO2 injection rate of 2.7 kg/s is considered as the baseline case for comparison. The 30-day, 15-day, and 5-day WAG cycle durations are considered for the WAG optimization design. Our computations show that for the simplified Utsira Layer #9 model, the WAG operation with 5-day cycle leads to most noticeable reduction in plume migration. For 5-day WAG cycle, the values of design variables corresponding to optimal WAG operation are found as optimal CO2 injection ICO2,optimal = 11.56 kg/s, and optimal water injection Iwater,optimal = 7.62 kg/s. The durations of CO2 and water injection in one WAG cycle are 11 and 19 days, respectively. Identical WAG cycles are repeated 20 times to complete a two-year operation. Significant reduction (22%) in CO2 migration is achieved compared to CGI operation after only two years of WAG operation. In addition, CO2 dissolution is also significantly enhanced from about 9% to 22% of the total injected CO2 . The results obtained from this and other optimization studies suggest that over 50% reduction of in situ CO2 footprint, greatly enhanced CO2 dissolution, and significantly improved well injectivity can be achieved by employing GA-TOUGH2. The optimization code has also been employed to determine the optimal well placement in a multi-well injection operation. GA-TOUGH2 appears to hold great promise for studying a host of other optimization problems related to Carbon Storage.

Departures From Optimality When Pursuing Multiple Approach or Avoidance Goals

PubMed Central

2016-01-01

This article examines how people depart from optimality during multiple-goal pursuit. The authors operationalized optimality using dynamic programming, which is a mathematical model used to calculate expected value in multistage decisions. Drawing on prospect theory, they predicted that people are risk-averse when pursuing approach goals and are therefore more likely to prioritize the goal in the best position than the dynamic programming model suggests is optimal. The authors predicted that people are risk-seeking when pursuing avoidance goals and are therefore more likely to prioritize the goal in the worst position than is optimal. These predictions were supported by results from an experimental paradigm in which participants made a series of prioritization decisions while pursuing either 2 approach or 2 avoidance goals. This research demonstrates the usefulness of using decision-making theories and normative models to understand multiple-goal pursuit. PMID:26963081

Design technology co-optimization for 14/10nm metal1 double patterning layer

NASA Astrophysics Data System (ADS)

Duan, Yingli; Su, Xiaojing; Chen, Ying; Su, Yajuan; Shao, Feng; Zhang, Recco; Lei, Junjiang; Wei, Yayi

2016-03-01

Design and technology co-optimization (DTCO) can satisfy the needs of the design, generate robust design rule, and avoid unfriendly patterns at the early stage of design to ensure a high level of manufacturability of the product by the technical capability of the present process. The DTCO methodology in this paper includes design rule translation, layout analysis, model validation, hotspots classification and design rule optimization mainly. The correlation of the DTCO and double patterning (DPT) can optimize the related design rule and generate friendlier layout which meets the requirement of the 14/10nm technology node. The experiment demonstrates the methodology of DPT-compliant DTCO which is applied to a metal1 layer from the 14/10nm node. The DTCO workflow proposed in our job is an efficient solution for optimizing the design rules for 14/10 nm tech node Metal1 layer. And the paper also discussed and did the verification about how to tune the design rule of the U-shape and L-shape structures in a DPT-aware metal layer.

SUBSURFACE PROPERTY RIGHTS: IMPLICATIONS FOR GEOLOGIC CO2 STORAGE

EPA Science Inventory

The paper discusses subsurface property rights as they apply to geologic sequestration (GS) of carbon dioxide (CO2). GS projects inject captured CO2 into deep (greater than ~1 km) geologic formations for the explicit purpose of avoiding atmospheric emission of CO2. Because of the...

SUBSURFACE PROPERTY RIGHTS: IMPLICATIONS FOR GEOLOGIC CO2 SEQUESTRATION

EPA Science Inventory

The chapter discusses subsurface property rights as they apply to geologic sequestration (GS) of carbon dioxide (CO2). GS projects inject captured CO2 into deep (greater than ~1 km) geologic formations for the explicit purpose of avoiding atmospheric emission of CO2. Because of t...

COMPARISON OF SODIUM AND POTASSIUM CARBONATES AS LITHIUM ZIRCONATE MODIFIERS FOR HIGH-TEMPERATURE CARBON DIOXIDE CAPTURE FROM BIOMASS-DERIVED SYNTHESIS GAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olstad, J.L.; Phillips, S.D.

2009-01-01

The process of gasifi cation converts biomass into synthesis gas (syngas), which can be used to produce biofuels. Solid-phase sorbents were investigated for the removal of CO2 from a N2/CO2 gas stream using a CO2 concentration similar to that found in a biomass gasifi cation process. During the gasifying process, large amounts of carbon dioxide (CO2) are created along with the syngas. The produced CO2 must be removed before the syngas can be used for fuel synthesis and to avoid the possible formation of unwanted byproducts. A thermogravimetric analyzer was used to test the CO2 absorption rates of sorbents composedmore » of lithium zirconate (Li2ZrO3), as well as mixtures of Li2ZrO3 with potassium carbonate (K2CO3) and sodium carbonate (Na2CO3). The experimental results show that Li2ZrO3 has a low absorption rate, but sorbents containing combinations of Li2ZrO3 and the K2CO3 and Na2CO3 additives have high uptake rates. Using different proportions of K2CO3 and Na2CO3 produces varying uptake rates, so an optimization experiment was performed to obtain an improved sorbent. The CO2 absorption and regeneration stability of the solid-phase sorbents were also examined. A sorbent composed of Li2ZrO3 and 12.1 weight % Na2CO3 was shown to be stable, based on the consistent CO2 uptake rates. Sorbents prepared with Li2ZrO3, 17.6 weight % K2CO3 and 18.1 weight % Na2CO3 showed instability during regeneration cycles in air at 800 °C. Sorbent stability improved during regeneration cycles at 700 °C. Further testing of the Li2ZrO3 sorbent under actual syngas conditions, including higher pressure and composition, should be done. Once the optimum sorbent has been found, a suitable support will be needed to use the sorbent in an actual reactor.« less

SUBSURFACE PROPERTY RIGHTS: IMPLICATIONS FOR GEOLOGIC CO2 SEQUESTRATION (PRESENTATION)

EPA Science Inventory

The paper discusses subsurface property rights as they apply to geologic sequestration (GS) of carbon dioxide (CO2). GS projects inject captured CO2 into deep (greater than ~1 km) geologic formations for the explicit purpose of avoiding atmospheric emission of CO2. Because of the...

Co-optimization of CO 2 -EOR and Storage Processes under Geological Uncertainty

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ampomah, William; Balch, Robert; Will, Robert

This paper presents an integrated numerical framework to co-optimize EOR and CO 2 storage performance in the Farnsworth field unit (FWU), Ochiltree County, Texas. The framework includes a field-scale compositional reservoir flow model, an uncertainty quantification model and a neural network optimization process. The reservoir flow model has been constructed based on the field geophysical, geological, and engineering data. A laboratory fluid analysis was tuned to an equation of state and subsequently used to predict the thermodynamic minimum miscible pressure (MMP). A history match of primary and secondary recovery processes was conducted to estimate the reservoir and multiphase flow parametersmore » as the baseline case for analyzing the effect of recycling produced gas, infill drilling and water alternating gas (WAG) cycles on oil recovery and CO 2 storage. A multi-objective optimization model was defined for maximizing both oil recovery and CO 2 storage. The uncertainty quantification model comprising the Latin Hypercube sampling, Monte Carlo simulation, and sensitivity analysis, was used to study the effects of uncertain variables on the defined objective functions. Uncertain variables such as bottom hole injection pressure, WAG cycle, injection and production group rates, and gas-oil ratio among others were selected. The most significant variables were selected as control variables to be used for the optimization process. A neural network optimization algorithm was utilized to optimize the objective function both with and without geological uncertainty. The vertical permeability anisotropy (Kv/Kh) was selected as one of the uncertain parameters in the optimization process. The simulation results were compared to a scenario baseline case that predicted CO 2 storage of 74%. The results showed an improved approach for optimizing oil recovery and CO 2 storage in the FWU. The optimization process predicted more than 94% of CO 2 storage and most importantly about 28% of incremental oil recovery. The sensitivity analysis reduced the number of control variables to decrease computational time. A risk aversion factor was used to represent results at various confidence levels to assist management in the decision-making process. The defined objective functions were proved to be a robust approach to co-optimize oil recovery and CO 2 storage. The Farnsworth CO 2 project will serve as a benchmark for future CO 2–EOR or CCUS projects in the Anadarko basin or geologically similar basins throughout the world.« less

Co-optimization of CO 2 -EOR and Storage Processes under Geological Uncertainty

DOE PAGES

Ampomah, William; Balch, Robert; Will, Robert; ...

2017-07-01

This paper presents an integrated numerical framework to co-optimize EOR and CO 2 storage performance in the Farnsworth field unit (FWU), Ochiltree County, Texas. The framework includes a field-scale compositional reservoir flow model, an uncertainty quantification model and a neural network optimization process. The reservoir flow model has been constructed based on the field geophysical, geological, and engineering data. A laboratory fluid analysis was tuned to an equation of state and subsequently used to predict the thermodynamic minimum miscible pressure (MMP). A history match of primary and secondary recovery processes was conducted to estimate the reservoir and multiphase flow parametersmore » as the baseline case for analyzing the effect of recycling produced gas, infill drilling and water alternating gas (WAG) cycles on oil recovery and CO 2 storage. A multi-objective optimization model was defined for maximizing both oil recovery and CO 2 storage. The uncertainty quantification model comprising the Latin Hypercube sampling, Monte Carlo simulation, and sensitivity analysis, was used to study the effects of uncertain variables on the defined objective functions. Uncertain variables such as bottom hole injection pressure, WAG cycle, injection and production group rates, and gas-oil ratio among others were selected. The most significant variables were selected as control variables to be used for the optimization process. A neural network optimization algorithm was utilized to optimize the objective function both with and without geological uncertainty. The vertical permeability anisotropy (Kv/Kh) was selected as one of the uncertain parameters in the optimization process. The simulation results were compared to a scenario baseline case that predicted CO 2 storage of 74%. The results showed an improved approach for optimizing oil recovery and CO 2 storage in the FWU. The optimization process predicted more than 94% of CO 2 storage and most importantly about 28% of incremental oil recovery. The sensitivity analysis reduced the number of control variables to decrease computational time. A risk aversion factor was used to represent results at various confidence levels to assist management in the decision-making process. The defined objective functions were proved to be a robust approach to co-optimize oil recovery and CO 2 storage. The Farnsworth CO 2 project will serve as a benchmark for future CO 2–EOR or CCUS projects in the Anadarko basin or geologically similar basins throughout the world.« less

The optimal atmospheric CO2 concentration for the growth of winter wheat (Triticum aestivum).

PubMed

Xu, Ming

2015-07-20

This study examined the optimal atmospheric CO2 concentration of the CO2 fertilization effect on the growth of winter wheat with growth chambers where the CO2 concentration was controlled at 400, 600, 800, 1000, and 1200 ppm respectively. I found that initial increase in atmospheric CO2 concentration dramatically enhanced winter wheat growth through the CO2 fertilization effect. However, this CO2 fertilization effect was substantially compromised with further increase in CO2 concentration, demonstrating an optimal CO2 concentration of 889.6, 909.4, and 894.2 ppm for aboveground, belowground, and total biomass, respectively, and 967.8 ppm for leaf photosynthesis. Also, high CO2 concentrations exceeding the optima not only reduced leaf stomatal density, length and conductance, but also changed the spatial distribution pattern of stomata on leaves. In addition, high CO2 concentration also decreased the maximum carboxylation rate (Vc(max)) and the maximum electron transport rate (J(max)) of leaf photosynthesis. However, the high CO2 concentration had little effect on leaf length and plant height. The optimal CO2 fertilization effect found in this study can be used as an indicator in selecting and breeding new wheat strains in adapting to future high atmospheric CO2 concentrations and climate change. Copyright © 2015. Published by Elsevier GmbH.

SYSTEM LEVEL IMPLICATIONS OF FLEXIBLE CO2 CAPTURE OPERATION

EPA Science Inventory

In ERCOT, turning flexible CO₂ capture systems off during infrequent periods of peak electricity demand can avoid hundreds of millions to billions of dollars in capital costs to replace the power output lost to CO₂ capture energy requirements.  When CO...

Optimization of sampling parameters for collection and preconcentration of alveolar air by needle traps.

PubMed

Filipiak, Wojciech; Filipiak, Anna; Ager, Clemens; Wiesenhofer, Helmut; Amann, Anton

2012-06-01

The approach for breath-VOCs' collection and preconcentration by applying needle traps was developed and optimized. The alveolar air was collected from only a few exhalations under visual control of expired CO(2) into a large gas-tight glass syringe and then warmed up to 45 °C for a short time to avoid condensation. Subsequently, a specially constructed sampling device equipped with Bronkhorst® electronic flow controllers was used for automated adsorption. This sampling device allows time-saving collection of expired/inspired air in parallel onto three different needle traps as well as improvement of sensitivity and reproducibility of NT-GC-MS analysis by collection of relatively large (up to 150 ml) volume of exhaled breath. It was shown that the collection of alveolar air derived from only a few exhalations into a large syringe followed by automated adsorption on needle traps yields better results than manual sorption by up/down cycles with a 1 ml syringe, mostly due to avoided condensation and electronically controlled stable sample flow rate. The optimal profile and composition of needle traps consists of 2 cm Carbopack X and 1 cm Carboxen 1000, allowing highly efficient VOCs' enrichment, while injection by a fast expansive flow technique requires no modifications in instrumentation and fully automated GC-MS analysis can be performed with a commercially available autosampler. This optimized analytical procedure considerably facilitates the collection and enrichment of alveolar air, and is therefore suitable for application at the bedside of critically ill patients in an intensive care unit. Due to its simplicity it can replace the time-consuming sampling of sufficient breath volume by numerous up/down cycles with a 1 ml syringe.

Carbon dioxide sensing in an obligate insect-fungus symbiosis: CO2 preferences of leaf-cutting ants to rear their mutualistic fungus.

PubMed

Römer, Daniela; Bollazzi, Martin; Roces, Flavio

2017-01-01

Defense against biotic or abiotic stresses is one of the benefits of living in symbiosis. Leaf-cutting ants, which live in an obligate mutualism with a fungus, attenuate thermal and desiccation stress of their partner through behavioral responses, by choosing suitable places for fungus-rearing across the soil profile. The underground environment also presents hypoxic (low oxygen) and hypercapnic (high carbon dioxide) conditions, which can negatively influence the symbiont. Here, we investigated whether workers of the leaf-cutting ant Acromyrmex lundii use the CO2 concentration as an orientation cue when selecting a place to locate their fungus garden, and whether they show preferences for specific CO2 concentrations. We also evaluated whether levels preferred by workers for fungus-rearing differ from those selected for themselves. In the laboratory, CO2 preferences were assessed in binary choices between chambers with different CO2 concentrations, by quantifying number of workers in each chamber and amount of relocated fungus. Leaf-cutting ants used the CO2 concentration as a spatial cue when selecting places for fungus-rearing. A. lundii preferred intermediate CO2 levels, between 1 and 3%, as they would encounter at soil depths where their nest chambers are located. In addition, workers avoided both atmospheric and high CO2 levels as they would occur outside the nest and at deeper soil layers, respectively. In order to prevent fungus desiccation, however, workers relocated fungus to high CO2 levels, which were otherwise avoided. Workers' CO2 preferences for themselves showed no clear-cut pattern. We suggest that workers avoid both atmospheric and high CO2 concentrations not because they are detrimental for themselves, but because of their consequences for the symbiotic partner. Whether the preferred CO2 concentrations are beneficial for symbiont growth remains to be investigated, as well as whether the observed preferences for fungus-rearing influences the ants' decisions where to excavate new chambers across the soil profile.

Lattice based Kinetic Monte Carlo Simulations of a complex chemical reaction network

NASA Astrophysics Data System (ADS)

Danielson, Thomas; Savara, Aditya; Hin, Celine

Lattice Kinetic Monte Carlo (KMC) simulations offer a powerful alternative to using ordinary differential equations for the simulation of complex chemical reaction networks. Lattice KMC provides the ability to account for local spatial configurations of species in the reaction network, resulting in a more detailed description of the reaction pathway. In KMC simulations with a large number of reactions, the range of transition probabilities can span many orders of magnitude, creating subsets of processes that occur more frequently or more rarely. Consequently, processes that have a high probability of occurring may be selected repeatedly without actually progressing the system (i.e. the forward and reverse process for the same reaction). In order to avoid the repeated occurrence of fast frivolous processes, it is necessary to throttle the transition probabilities in such a way that avoids altering the overall selectivity. Likewise, as the reaction progresses, new frequently occurring species and reactions may be introduced, making a dynamic throttling algorithm a necessity. We present a dynamic steady-state detection scheme with the goal of accurately throttling rate constants in order to optimize the KMC run time without compromising the selectivity of the reaction network. The algorithm has been applied to a large catalytic chemical reaction network, specifically that of methanol oxidative dehydrogenation, as well as additional pathways on CeO2(111) resulting in formaldehyde, CO, methanol, CO2, H2 and H2O as gas products.

Co-benefits of mitigating global greenhouse gas emissions for future air quality and human health

DOE Office of Scientific and Technical Information (OSTI.GOV)

West, Jason; Smith, Steven J.; Silva, Raquel

2013-10-01

Reducing greenhouse gas (GHG) emissions also influences air quality. We simulate the co-benefits of global GHG reductions on air quality and human health via two mechanisms: a) reducing co-emitted air pollutants, and b) slowing climate change and its effect on air quality. Relative to a reference scenario, global GHG mitigation in the RCP4.5 scenario avoids 0.5±0.2, 1.3±0.6, and 2.2±1.6 million premature deaths in 2030, 2050, and 2100, from changes in fine particulate matter and ozone. Global average marginal co-benefits of avoided mortality are $40-400 (ton CO2)-1, exceeding marginal abatement costs in 2030 and 2050, and within the low range ofmore » costs in 2100. East Asian co-benefits are 10-80 times the marginal cost in 2030. These results indicate that transitioning to a low-carbon future might be justified by air quality and health co-benefits.« less

Co-electrolysis of steam and CO2 in full-ceramic symmetrical SOECs: a strategy for avoiding the use of hydrogen as a safe gas.

PubMed

Torrell, M; García-Rodríguez, S; Morata, A; Penelas, G; Tarancón, A

2015-01-01

The use of cermets as fuel electrodes for solid oxide electrolysis cells requires permanent circulation of reducing gas, e.g. H2 or CO, so called safe gas, in order to avoid oxidation of the metallic phase. Replacing metallic based electrodes by pure oxides is therefore proposed as an advantage for the industrial application of solid oxide electrolyzers. In this work, full-ceramic symmetrical solid oxide electrolysis cells have been investigated for steam/CO2 co-electrolysis. Electrolyte supported cells with La(0.75)Sr(0.25)Cr(0.5)Mn(0.5)O3-δ reversible electrodes have been fabricated and tested in co-electrolysis mode using different fuel compositions, from pure H2O to pure CO2, at temperatures between 850-900 °C. Electrochemical impedance spectroscopy and galvanostatic measurements have been carried out for the mechanistic understanding of the symmetrical cell performance. The content of H2 and CO in the product gas has been measured by in-line gas micro-chromatography. The effect of employing H2 as a safe gas has also been investigated. Maximum density currents of 750 mA cm(-2) and 620 mA cm(-2) have been applied at 1.7 V for pure H2O and for H2O : CO2 ratios of 1 : 1, respectively. Remarkable results were obtained for hydrogen-free fuel compositions, which confirmed the interest of using ceramic oxides as a fuel electrode candidate to reduce or completely avoid the use of safe gas in operation minimizing the contribution of the reverse water shift reaction (RWSR) in the process. H2 : CO ratios close to two were obtained for hydrogen-free tests fulfilling the basic requirements for synthetic fuel production. An important increase in the operation voltage was detected under continuous operation leading to a dramatic failure by delaminating of the oxygen electrode.

Gilbert damping of high anisotropy Co/Pt multilayers

NASA Astrophysics Data System (ADS)

Devolder, Thibaut; Couet, S.; Swerts, J.; Kar, G. S.

2018-04-01

Using broadband ferromagnetic resonance, we measure the damping parameter of [Co(5 Å)/Pt(3 Å)] {× 6} multilayers, whose growth was optimized to maximize the perpendicular anisotropy. Structural characterizations indicate abrupt interfaces essentially free of intermixing, despite the miscible character of Co and Pt. Gilbert damping parameters as low as 0.021 can be obtained, despite a magneto-crystalline anisotropy as large as 106 J m-3. The inhomogeneous broadening accounts for part of the ferromagnetic resonance linewidth, indicating some structural disorder leading to a equivalent 20 mT of inhomogenity of the effective field. The unexpectedly relatively low damping factor indicates that the presence of the Pt heavy metal within the multilayer may not be detrimental to the damping provided that intermixing is avoided at the Co/Pt interfaces.

High-power Laser Welding of Thick Steel-aluminum Dissimilar Joints

NASA Astrophysics Data System (ADS)

Lahdo, Rabi; Springer, André; Pfeifer, Ronny; Kaierle, Stefan; Overmeyer, Ludger

According to the Intergovernmental Panel on Climate Change (IPCC), a worldwide reduction of CO2-emissions is indispensable to avoid global warming. Besides the automotive sector, lightweight construction is also of high interest for the maritime industry in order to minimize CO2-emissions. Using aluminum, the weight of ships can be reduced, ensuring lower fuel consumption. Therefore, hybrid joints of steel and aluminum are of great interest to the maritime industry. In order to provide an efficient lap joining process, high-power laser welding of thick steel plates (S355, t = 5 mm) and aluminum plates (EN AW-6082, t = 8 mm) is investigated. As the weld seam quality greatly depends on the amount of intermetallic phases within the joint, optimized process parameters and control are crucial. Using high-power laser welding, a tensile strength of 10 kN was achieved. Based on metallographic analysis, hardness tests, and tensile tests the potential of this joining method is presented.

Designing management strategies for carbon dioxide storage and utilization under uncertainty using inexact modelling

NASA Astrophysics Data System (ADS)

Wang, Yu; Fan, Jie; Xu, Ye; Sun, Wei; Chen, Dong

2017-06-01

Effective application of carbon capture, utilization and storage (CCUS) systems could help to alleviate the influence of climate change by reducing carbon dioxide (CO2) emissions. The research objective of this study is to develop an equilibrium chance-constrained programming model with bi-random variables (ECCP model) for supporting the CCUS management system under random circumstances. The major advantage of the ECCP model is that it tackles random variables as bi-random variables with a normal distribution, where the mean values follow a normal distribution. This could avoid irrational assumptions and oversimplifications in the process of parameter design and enrich the theory of stochastic optimization. The ECCP model is solved by an equilibrium change-constrained programming algorithm, which provides convenience for decision makers to rank the solution set using the natural order of real numbers. The ECCP model is applied to a CCUS management problem, and the solutions could be useful in helping managers to design and generate rational CO2-allocation patterns under complexities and uncertainties.

[Optimization for supercritical CO2 extraction with response surface methodology of Prunus armeniaca oil].

PubMed

Chen, Fei-Fei; Wu, Yan; Ge, Fa-Huan

2012-03-01

To optimize the extraction conditions of Prunus armeniaca oil by Supercritical CO2 extraction and identify its components by GC-MS. Optimized of SFE-CO extraction by response surface methodology and used GC-MS to analysis Prunus armeniaca oil compounds. Established the model of an equation for the extraction rate of Prunus armeniaca oil by supercritical CO2 extraction, and the optimal parameters for the supercritical CO2 extraction determined by the equation were: the extraction pressure was 27 MPa, temperature was 39 degrees C, the extraction rate of Prunus armeniaca oil was 44.5%. 16 main compounds of Prunus armeniaca oil extracted by supercritical CO2 were identified by GC-MS, unsaturated fatty acids were 92.6%. This process is simple, and can be used for the extraction of Prunus armeniaca oil.

The Response to High CO2 Levels Requires the Neuropeptide Secretion Component HID-1 to Promote Pumping Inhibition

PubMed Central

Sharabi, Kfir; Charar, Chayki; Friedman, Nurit; Mizrahi, Inbar; Zaslaver, Alon; Sznajder, Jacob I.; Gruenbaum, Yosef

2014-01-01

Carbon dioxide (CO2) is a key molecule in many biological processes; however, mechanisms by which organisms sense and respond to high CO2 levels remain largely unknown. Here we report that acute CO2 exposure leads to a rapid cessation in the contraction of the pharynx muscles in Caenorhabditis elegans. To uncover the molecular mechanisms underlying this response, we performed a forward genetic screen and found that hid-1, a key component in neuropeptide signaling, regulates this inhibition in muscle contraction. Surprisingly, we found that this hid-1-mediated pathway is independent of any previously known pathways controlling CO2 avoidance and oxygen sensing. In addition, animals with mutations in unc-31 and egl-21 (neuropeptide secretion and maturation components) show impaired inhibition of muscle contraction following acute exposure to high CO2 levels, in further support of our findings. Interestingly, the observed response in the pharynx muscle requires the BAG neurons, which also mediate CO2 avoidance. This novel hid-1-mediated pathway sheds new light on the physiological effects of high CO2 levels on animals at the organism-wide level. PMID:25101962

Biohydrogen from thermophilic co-fermentation of swine manure with fruit and vegetable waste: maximizing stable production without pH control.

PubMed

Tenca, A; Schievano, A; Perazzolo, F; Adani, F; Oberti, R

2011-09-01

Hydrogen production by dark fermentation may suffer of inhibition or instability due to pH deviations from optimality. The co-fermentation of promptly degradable feedstock with alkali-rich materials, such as livestock wastes, may represent a feasible and easy to implement approach to avoid external adjustments of pH. Experiments were designed to investigate the effect of the mixing ratio of fruit-vegetable waste with swine manure with the aim of maximizing biohydrogen production while obtaining process stability through the endogenous alkalinity of manure. Fruit-vegetable/swine manure ratio of 35/65 and HRT of 2d resulted to give the highest production rate of 3.27 ± 0.51 L(H2)L(-1)d(-1), with a corresponding hydrogen yield of 126 ± 22 mL(H2)g(-1)(VS-added) and H2 content in the biogas of 42 ± 5%. At these operating conditions the process exhibited also one of the highest measured stability, with daily productions deviating for less than 14% from the average. Copyright © 2011 Elsevier Ltd. All rights reserved.

Recycling of metals: accounting of greenhouse gases and global warming contributions.

PubMed

Damgaard, Anders; Larsen, Anna W; Christensen, Thomas H

2009-11-01

Greenhouse gas (GHG) emissions related to recycling of metals in post-consumer waste are assessed from a waste management perspective; here the material recovery facility (MRF), for the sorting of the recovered metal. The GHG accounting includes indirect upstream emissions, direct activities at the MRF as well as indirect downstream activities in terms of reprocessing of the metal scrap and savings in terms of avoided production of virgin metal. The global warming factor (GWF) shows that upstream activities and the MRF causes negligible GHG emissions (12.8 to 52.6 kg CO(2)-equivalents tonne(-1) recovered metal) compared to the reprocessing of the metal itself (360-1260 kg CO(2)-equivalents tonne(-1) of recovered aluminium and 400- 1020 kg CO(2)-equivalents tonne(- 1) of recovered steel).The reprocessing is however counterbalanced by large savings of avoided virgin production of steel and aluminium. The net downstream savings were found to be 5040-19 340 kg CO(2)-equivalents tonne(-1) of treated aluminium and 560-2360 kg CO(2)-equivalents tonne(-1) of treated steel. Due to the huge differences in reported data it is hard to compare general data on the recovery of metal scrap as they are very dependent on the technology and data choices. Furthermore, the energy used in both the recovery process as well as the avoided primary production is crucial. The range of avoided impact shows that recovery of metals will always be beneficial over primary production, due to the high energy savings, and that the GHG emissions associated with the sorting of metals are negligible.

CO 2 water-alternating-gas injection for enhanced oil recovery: Optimal well controls and half-cycle lengths

DOE PAGES

Chen, Bailian; Reynolds, Albert C.

2018-03-11

We report that CO 2 water-alternating-gas (WAG) injection is an enhanced oil recovery method designed to improve sweep efficiency during CO 2 injection with the injected water to control the mobility of CO 2 and to stabilize the gas front. Optimization of CO 2 -WAG injection is widely regarded as a viable technique for controlling the CO 2 and oil miscible process. Poor recovery from CO 2 -WAG injection can be caused by inappropriately designed WAG parameters. In previous study (Chen and Reynolds, 2016), we proposed an algorithm to optimize the well controls which maximize the life-cycle net-present-value (NPV). However,more » the effect of injection half-cycle lengths for each injector on oil recovery or NPV has not been well investigated. In this paper, an optimization framework based on augmented Lagrangian method and the newly developed stochastic-simplex-approximate-gradient (StoSAG) algorithm is proposed to explore the possibility of simultaneous optimization of the WAG half-cycle lengths together with the well controls. Finally, the proposed framework is demonstrated with three reservoir examples.« less

CO 2 water-alternating-gas injection for enhanced oil recovery: Optimal well controls and half-cycle lengths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Bailian; Reynolds, Albert C.

We report that CO 2 water-alternating-gas (WAG) injection is an enhanced oil recovery method designed to improve sweep efficiency during CO 2 injection with the injected water to control the mobility of CO 2 and to stabilize the gas front. Optimization of CO 2 -WAG injection is widely regarded as a viable technique for controlling the CO 2 and oil miscible process. Poor recovery from CO 2 -WAG injection can be caused by inappropriately designed WAG parameters. In previous study (Chen and Reynolds, 2016), we proposed an algorithm to optimize the well controls which maximize the life-cycle net-present-value (NPV). However,more » the effect of injection half-cycle lengths for each injector on oil recovery or NPV has not been well investigated. In this paper, an optimization framework based on augmented Lagrangian method and the newly developed stochastic-simplex-approximate-gradient (StoSAG) algorithm is proposed to explore the possibility of simultaneous optimization of the WAG half-cycle lengths together with the well controls. Finally, the proposed framework is demonstrated with three reservoir examples.« less

Analysis of nonlocal thermodynamic equilibrium CO 4.7 μm fundamental, isotopic, and hot band emissions measured by the Michelson Interferometer for Passive Atmospheric Sounding on Envisat

NASA Astrophysics Data System (ADS)

Funke, B.; López-Puertas, M.; Bermejo-Pantaleón, D.; von Clarmann, T.; Stiller, G. P.; HöPfner, M.; Grabowski, U.; Kaufmann, M.

2007-06-01

Nonlocal thermodynamic equilibrium (non-LTE) simulations of the 12C16O(1 → 0) fundamental band, the 12C16O(2 → 1) hot band, and the isotopic 13C16O(1 → 0) band performed with the Generic Radiative Transfer and non-LTE population Algorithm (GRANADA) and the Karlsruhe Optimized and Precise Radiative Transfer Algorithm (KOPRA) have been compared to spectrally resolved 4.7 μm radiances measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). The performance of the non-LTE simulation has been assessed in terms of band radiance ratios in order to avoid a compensation of possible non-LTE model errors by retrieval errors in the CO abundances inferred from MIPAS data with the same non-LTE algorithms. The agreement with the measurements is within 5% for the fundamental band and within 10% for the hot band. Simulated 13C16O radiances agree with the measurements within the instrumental noise error. Solar reflectance at the surface or clouds has been identified as an important additional excitation mechanism for the CO(2) state. The study represents a thorough validation of the non-LTE scheme used in the retrieval of CO abundances from MIPAS data.

Techno-economic assessment of polymer membrane systems for postcombustion carbon capture at coal-fired power plants.

PubMed

Zhai, Haibo; Rubin, Edward S

2013-03-19

This study investigates the feasibility of polymer membrane systems for postcombustion carbon dioxide (CO(2)) capture at coal-fired power plants. Using newly developed performance and cost models, our analysis shows that membrane systems configured with multiple stages or steps are capable of meeting capture targets of 90% CO(2) removal efficiency and 95+% product purity. A combined driving force design using both compressors and vacuum pumps is most effective for reducing the cost of CO(2) avoided. Further reductions in the overall system energy penalty and cost can be obtained by recycling a portion of CO(2) via a two-stage, two-step membrane configuration with air sweep to increase the CO(2) partial pressure of feed flue gas. For a typical plant with carbon capture and storage, this yielded a 15% lower cost per metric ton of CO(2) avoided compared to a plant using a current amine-based capture system. A series of parametric analyses also is undertaken to identify paths for enhancing the viability of membrane-based capture technology.

Ocean acidification erodes crucial auditory behaviour in a marine fish.

PubMed

Simpson, Stephen D; Munday, Philip L; Wittenrich, Matthew L; Manassa, Rachel; Dixson, Danielle L; Gagliano, Monica; Yan, Hong Y

2011-12-23

Ocean acidification is predicted to affect marine ecosystems in many ways, including modification of fish behaviour. Previous studies have identified effects of CO(2)-enriched conditions on the sensory behaviour of fishes, including the loss of natural responses to odours resulting in ecologically deleterious decisions. Many fishes also rely on hearing for orientation, habitat selection, predator avoidance and communication. We used an auditory choice chamber to study the influence of CO(2)-enriched conditions on directional responses of juvenile clownfish (Amphiprion percula) to daytime reef noise. Rearing and test conditions were based on Intergovernmental Panel on Climate Change predictions for the twenty-first century: current-day ambient, 600, 700 and 900 µatm pCO(2). Juveniles from ambient CO(2)-conditions significantly avoided the reef noise, as expected, but this behaviour was absent in juveniles from CO(2)-enriched conditions. This study provides, to our knowledge, the first evidence that ocean acidification affects the auditory response of fishes, with potentially detrimental impacts on early survival.

Ocean acidification erodes crucial auditory behaviour in a marine fish

PubMed Central

Simpson, Stephen D.; Munday, Philip L.; Wittenrich, Matthew L.; Manassa, Rachel; Dixson, Danielle L.; Gagliano, Monica; Yan, Hong Y.

2011-01-01

Ocean acidification is predicted to affect marine ecosystems in many ways, including modification of fish behaviour. Previous studies have identified effects of CO2-enriched conditions on the sensory behaviour of fishes, including the loss of natural responses to odours resulting in ecologically deleterious decisions. Many fishes also rely on hearing for orientation, habitat selection, predator avoidance and communication. We used an auditory choice chamber to study the influence of CO2-enriched conditions on directional responses of juvenile clownfish (Amphiprion percula) to daytime reef noise. Rearing and test conditions were based on Intergovernmental Panel on Climate Change predictions for the twenty-first century: current-day ambient, 600, 700 and 900 µatm pCO2. Juveniles from ambient CO2-conditions significantly avoided the reef noise, as expected, but this behaviour was absent in juveniles from CO2-enriched conditions. This study provides, to our knowledge, the first evidence that ocean acidification affects the auditory response of fishes, with potentially detrimental impacts on early survival. PMID:21632617

Effects of optimism on creativity under approach and avoidance motivation

PubMed Central

Icekson, Tamar; Roskes, Marieke; Moran, Simone

2014-01-01

Focusing on avoiding failure or negative outcomes (avoidance motivation) can undermine creativity, due to cognitive (e.g., threat appraisals), affective (e.g., anxiety), and volitional processes (e.g., low intrinsic motivation). This can be problematic for people who are avoidance motivated by nature and in situations in which threats or potential losses are salient. Here, we review the relation between avoidance motivation and creativity, and the processes underlying this relation. We highlight the role of optimism as a potential remedy for the creativity undermining effects of avoidance motivation, due to its impact on the underlying processes. Optimism, expecting to succeed in achieving success or avoiding failure, may reduce negative effects of avoidance motivation, as it eases threat appraisals, anxiety, and disengagement—barriers playing a key role in undermining creativity. People experience these barriers more under avoidance than under approach motivation, and beneficial effects of optimism should therefore be more pronounced under avoidance than approach motivation. Moreover, due to their eagerness, approach motivated people may even be more prone to unrealistic over-optimism and its negative consequences. PMID:24616690

Co-Optimization of CO 2-EOR and Storage Processes in Mature Oil Reservoirs

DOE PAGES

Ampomah, William; Balch, Robert S.; Grigg, Reid B.; ...

2016-08-02

This article presents an optimization methodology for CO 2 enhanced oil recovery in partially depleted reservoirs. A field-scale compositional reservoir flow model was developed for assessing the performance history of an active CO 2 flood and for optimizing both oil production and CO 2 storage in the Farnsworth Unit (FWU), Ochiltree County, Texas. A geological framework model constructed from geophysical, geological, and engineering data acquired from the FWU was the basis for all reservoir simulations and the optimization method. An equation of state was calibrated with laboratory fluid analyses and subsequently used to predict the thermodynamic minimum miscible pressure (MMP).more » Initial history calibrations of primary, secondary and tertiary recovery were conducted as the basis for the study. After a good match was achieved, an optimization approach consisting of a proxy or surrogate model was constructed with a polynomial response surface method (PRSM). The PRSM utilized an objective function that maximized both oil recovery and CO 2 storage. Experimental design was used to link uncertain parameters to the objective function. Control variables considered in this study included: water alternating gas cycle and ratio, production rates and bottom-hole pressure of injectors and producers. Other key parameters considered in the modeling process were CO 2 purchase, gas recycle and addition of infill wells and/or patterns. The PRSM proxy model was ‘trained’ or calibrated with a series of training simulations. This involved an iterative process until the surrogate model reached a specific validation criterion. A sensitivity analysis was first conducted to ascertain which of these control variables to retain in the surrogate model. A genetic algorithm with a mixed-integer capability optimization approach was employed to determine the optimum developmental strategy to maximize both oil recovery and CO 2 storage. The proxy model reduced the computational cost significantly. The validation criteria of the reduced order model ensured accuracy in the dynamic modeling results. The prediction outcome suggested robustness and reliability of the genetic algorithm for optimizing both oil recovery and CO 2 storage. The reservoir modeling approach used in this study illustrates an improved approach to optimizing oil production and CO 2 storage within partially depleted oil reservoirs such as FWU. Lastly, this study may serve as a benchmark for potential CO 2–EOR projects in the Anadarko basin and/or geologically similar basins throughout the world.« less

Co-Optimization of CO 2-EOR and Storage Processes in Mature Oil Reservoirs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ampomah, William; Balch, Robert S.; Grigg, Reid B.

This article presents an optimization methodology for CO 2 enhanced oil recovery in partially depleted reservoirs. A field-scale compositional reservoir flow model was developed for assessing the performance history of an active CO 2 flood and for optimizing both oil production and CO 2 storage in the Farnsworth Unit (FWU), Ochiltree County, Texas. A geological framework model constructed from geophysical, geological, and engineering data acquired from the FWU was the basis for all reservoir simulations and the optimization method. An equation of state was calibrated with laboratory fluid analyses and subsequently used to predict the thermodynamic minimum miscible pressure (MMP).more » Initial history calibrations of primary, secondary and tertiary recovery were conducted as the basis for the study. After a good match was achieved, an optimization approach consisting of a proxy or surrogate model was constructed with a polynomial response surface method (PRSM). The PRSM utilized an objective function that maximized both oil recovery and CO 2 storage. Experimental design was used to link uncertain parameters to the objective function. Control variables considered in this study included: water alternating gas cycle and ratio, production rates and bottom-hole pressure of injectors and producers. Other key parameters considered in the modeling process were CO 2 purchase, gas recycle and addition of infill wells and/or patterns. The PRSM proxy model was ‘trained’ or calibrated with a series of training simulations. This involved an iterative process until the surrogate model reached a specific validation criterion. A sensitivity analysis was first conducted to ascertain which of these control variables to retain in the surrogate model. A genetic algorithm with a mixed-integer capability optimization approach was employed to determine the optimum developmental strategy to maximize both oil recovery and CO 2 storage. The proxy model reduced the computational cost significantly. The validation criteria of the reduced order model ensured accuracy in the dynamic modeling results. The prediction outcome suggested robustness and reliability of the genetic algorithm for optimizing both oil recovery and CO 2 storage. The reservoir modeling approach used in this study illustrates an improved approach to optimizing oil production and CO 2 storage within partially depleted oil reservoirs such as FWU. Lastly, this study may serve as a benchmark for potential CO 2–EOR projects in the Anadarko basin and/or geologically similar basins throughout the world.« less

Does optimism act as a buffer against posttraumatic stress over time? A longitudinal study of the protective role of optimism after the 2011 Oslo bombing.

PubMed

Birkeland, Marianne Skogbrott; Blix, Ines; Solberg, Øivind; Heir, Trond

2017-03-01

Cross-sectional studies have revealed that high levels of optimism can protect against high levels of posttraumatic stress after exposure to trauma. However, this is the first study to explore (a) the protective role of optimism in a longitudinal perspective and (b) optimism's protective effects on specific symptom clusters within the posttraumatic stress symptomatology. This study used prospective survey data from ministerial employees (n = 256) collected approximately 1, 2, and 3 years after the 2011 Oslo bombing. To examine relationships between optimism and development of posttraumatic stress, we applied a series of latent growth curve analyses of both overall posttraumatic stress and the 5 clusters within the posttraumatic stress symptomatology (intrusions, avoidance, numbing, dysphoric arousal, and anxious arousal) with predictors and interaction terms. The results showed that levels of exposure and optimism had main effects on starting levels of all clusters of posttraumatic stress. In addition, optimism had a protective-stabilizing effect on starting levels of avoidance, numbing, and dysphoric arousal. No associations between optimism and rate of change in symptoms clusters were found. These results suggest that optimism may help to neutralize the effects of high exposure on levels of symptoms of avoidance, numbing, and dysphoric arousal but not on the symptoms of intrusions and anxious arousal. Thus, individuals high in optimism still experience intrusions and anxious arousal after trauma, but may be better equipped to cope with these so they do not develop into avoidance, numbing and dyshorical arousal. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Numerical Simulation of the Francis Turbine and CAD used to Optimized the Runner Design (2nd).

NASA Astrophysics Data System (ADS)

Sutikno, Priyono

2010-06-01

Hydro Power is the most important renewable energy source on earth. The water is free of charge and with the generation of electric energy in a Hydroelectric Power station the production of green house gases (mainly CO2) is negligible. Hydro Power Generation Stations are long term installations and can be used for 50 years and more, care must be taken to guarantee a smooth and safe operation over the years. Maintenance is necessary and critical parts of the machines have to be replaced if necessary. Within modern engineering the numerical flow simulation plays an important role in order to optimize the hydraulic turbine in conjunction with connected components of the plant. Especially for rehabilitation and upgrading existing Power Plants important point of concern are to predict the power output of turbine, to achieve maximum hydraulic efficiency, to avoid or to minimize cavitations, to avoid or to minimized vibrations in whole range operation. Flow simulation can help to solve operational problems and to optimize the turbo machinery for hydro electric generating stations or their component through, intuitive optimization, mathematical optimization, parametric design, the reduction of cavitations through design, prediction of draft tube vortex, trouble shooting by using the simulation. The classic design through graphic-analytical method is cumbersome and can't give in evidence the positive or negative aspects of the designing options. So it was obvious to have imposed as necessity the classical design methods to an adequate design method using the CAD software. There are many option chose during design calculus in a specific step of designing may be verified in ensemble and detail form a point of view. The final graphic post processing would be realized only for the optimal solution, through a 3 D representation of the runner as a whole for the final approval geometric shape. In this article it was investigated the redesign of the hydraulic turbine's runner, medium head Francis type, with following value for the most important parameter, the rated specific speed ns.

Stuart Cohen | NREL

Science.gov Websites

;Optimizing post-combustion CO2 capture in response to volatile electricity prices." International , S.M., H.L. Chalmers, M.E. Webber, C.W. King, and J. Gibbins. "Comparing post-combustion CO2 ., G.T. Rochelle, and M.E. Webber. "Optimal operation of flexible post- combustion CO2 capture in

Towards Stochastic Optimization-Based Electric Vehicle Penetration in a Novel Archipelago Microgrid.

PubMed

Yang, Qingyu; An, Dou; Yu, Wei; Tan, Zhengan; Yang, Xinyu

2016-06-17

Due to the advantage of avoiding upstream disturbance and voltage fluctuation from a power transmission system, Islanded Micro-Grids (IMG) have attracted much attention. In this paper, we first propose a novel self-sufficient Cyber-Physical System (CPS) supported by Internet of Things (IoT) techniques, namely "archipelago micro-grid (MG)", which integrates the power grid and sensor networks to make the grid operation effective and is comprised of multiple MGs while disconnected with the utility grid. The Electric Vehicles (EVs) are used to replace a portion of Conventional Vehicles (CVs) to reduce CO 2 emission and operation cost. Nonetheless, the intermittent nature and uncertainty of Renewable Energy Sources (RESs) remain a challenging issue in managing energy resources in the system. To address these issues, we formalize the optimal EV penetration problem as a two-stage Stochastic Optimal Penetration (SOP) model, which aims to minimize the emission and operation cost in the system. Uncertainties coming from RESs (e.g., wind, solar, and load demand) are considered in the stochastic model and random parameters to represent those uncertainties are captured by the Monte Carlo-based method. To enable the reasonable deployment of EVs in each MGs, we develop two scheduling schemes, namely Unlimited Coordinated Scheme (UCS) and Limited Coordinated Scheme (LCS), respectively. An extensive simulation study based on a modified 9 bus system with three MGs has been carried out to show the effectiveness of our proposed schemes. The evaluation data indicates that our proposed strategy can reduce both the environmental pollution created by CO 2 emissions and operation costs in UCS and LCS.

Towards Stochastic Optimization-Based Electric Vehicle Penetration in a Novel Archipelago Microgrid

PubMed Central

Yang, Qingyu; An, Dou; Yu, Wei; Tan, Zhengan; Yang, Xinyu

2016-01-01

Due to the advantage of avoiding upstream disturbance and voltage fluctuation from a power transmission system, Islanded Micro-Grids (IMG) have attracted much attention. In this paper, we first propose a novel self-sufficient Cyber-Physical System (CPS) supported by Internet of Things (IoT) techniques, namely “archipelago micro-grid (MG)”, which integrates the power grid and sensor networks to make the grid operation effective and is comprised of multiple MGs while disconnected with the utility grid. The Electric Vehicles (EVs) are used to replace a portion of Conventional Vehicles (CVs) to reduce CO2 emission and operation cost. Nonetheless, the intermittent nature and uncertainty of Renewable Energy Sources (RESs) remain a challenging issue in managing energy resources in the system. To address these issues, we formalize the optimal EV penetration problem as a two-stage Stochastic Optimal Penetration (SOP) model, which aims to minimize the emission and operation cost in the system. Uncertainties coming from RESs (e.g., wind, solar, and load demand) are considered in the stochastic model and random parameters to represent those uncertainties are captured by the Monte Carlo-based method. To enable the reasonable deployment of EVs in each MGs, we develop two scheduling schemes, namely Unlimited Coordinated Scheme (UCS) and Limited Coordinated Scheme (LCS), respectively. An extensive simulation study based on a modified 9 bus system with three MGs has been carried out to show the effectiveness of our proposed schemes. The evaluation data indicates that our proposed strategy can reduce both the environmental pollution created by CO2 emissions and operation costs in UCS and LCS. PMID:27322281

Automatic Data Filter Customization Using a Genetic Algorithm

NASA Technical Reports Server (NTRS)

Mandrake, Lukas

2013-01-01

This work predicts whether a retrieval algorithm will usefully determine CO2 concentration from an input spectrum of GOSAT (Greenhouse Gases Observing Satellite). This was done to eliminate needless runtime on atmospheric soundings that would never yield useful results. A space of 50 dimensions was examined for predictive power on the final CO2 results. Retrieval algorithms are frequently expensive to run, and wasted effort defeats requirements and expends needless resources. This algorithm could be used to help predict and filter unneeded runs in any computationally expensive regime. Traditional methods such as the Fischer discriminant analysis and decision trees can attempt to predict whether a sounding will be properly processed. However, this work sought to detect a subsection of the dimensional space that can be simply filtered out to eliminate unwanted runs. LDAs (linear discriminant analyses) and other systems examine the entire data and judge a "best fit," giving equal weight to complex and problematic regions as well as simple, clear-cut regions. In this implementation, a genetic space of "left" and "right" thresholds outside of which all data are rejected was defined. These left/right pairs are created for each of the 50 input dimensions. A genetic algorithm then runs through countless potential filter settings using a JPL computer cluster, optimizing the tossed-out data s yield (proper vs. improper run removal) and number of points tossed. This solution is robust to an arbitrary decision boundary within the data and avoids the global optimization problem of whole-dataset fitting using LDA or decision trees. It filters out runs that would not have produced useful CO2 values to save needless computation. This would be an algorithmic preprocessing improvement to any computationally expensive system.

Near-Zero Emissions Oxy-Combustion Flue Gas Purification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Minish Shah; Nich Degenstein; Monica Zanfir

2012-06-30

The objectives of this project were to carry out an experimental program to enable development and design of near zero emissions (NZE) CO{sub 2} processing unit (CPU) for oxy-combustion plants burning high and low sulfur coals and to perform commercial viability assessment. The NZE CPU was proposed to produce high purity CO{sub 2} from the oxycombustion flue gas, to achieve > 95% CO{sub 2} capture rate and to achieve near zero atmospheric emissions of criteria pollutants. Two SOx/NOx removal technologies were proposed depending on the SOx levels in the flue gas. The activated carbon process was proposed for power plantsmore » burning low sulfur coal and the sulfuric acid process was proposed for power plants burning high sulfur coal. For plants burning high sulfur coal, the sulfuric acid process would convert SOx and NOx in to commercial grade sulfuric and nitric acid by-products, thus reducing operating costs associated with SOx/NOx removal. For plants burning low sulfur coal, investment in separate FGD and SCR equipment for producing high purity CO{sub 2} would not be needed. To achieve high CO{sub 2} capture rates, a hybrid process that combines cold box and VPSA (vacuum pressure swing adsorption) was proposed. In the proposed hybrid process, up to 90% of CO{sub 2} in the cold box vent stream would be recovered by CO{sub 2} VPSA and then it would be recycled and mixed with the flue gas stream upstream of the compressor. The overall recovery from the process will be > 95%. The activated carbon process was able to achieve simultaneous SOx and NOx removal in a single step. The removal efficiencies were >99.9% for SOx and >98% for NOx, thus exceeding the performance targets of >99% and >95%, respectively. The process was also found to be suitable for power plants burning both low and high sulfur coals. Sulfuric acid process did not meet the performance expectations. Although it could achieve high SOx (>99%) and NOx (>90%) removal efficiencies, it could not produce by-product sulfuric and nitric acids that meet the commercial product specifications. The sulfuric acid will have to be disposed of by neutralization, thus lowering the value of the technology to same level as that of the activated carbon process. Therefore, it was decided to discontinue any further efforts on sulfuric acid process. Because of encouraging results on the activated carbon process, it was decided to add a new subtask on testing this process in a dual bed continuous unit. A 40 days long continuous operation test confirmed the excellent SOx/NOx removal efficiencies achieved in the batch operation. This test also indicated the need for further efforts on optimization of adsorption-regeneration cycle to maintain long term activity of activated carbon material at a higher level. The VPSA process was tested in a pilot unit. It achieved CO{sub 2} recovery of > 95% and CO{sub 2} purity of >80% (by vol.) from simulated cold box feed streams. The overall CO{sub 2} recovery from the cold box VPSA hybrid process was projected to be >99% for plants with low air ingress (2%) and >97% for plants with high air ingress (10%). Economic analysis was performed to assess value of the NZE CPU. The advantage of NZE CPU over conventional CPU is only apparent when CO{sub 2} capture and avoided costs are compared. For greenfield plants, cost of avoided CO{sub 2} and cost of captured CO{sub 2} are generally about 11-14% lower using the NZE CPU compared to using a conventional CPU. For older plants with high air intrusion, the cost of avoided CO{sub 2} and capture CO{sub 2} are about 18-24% lower using the NZE CPU. Lower capture costs for NZE CPU are due to lower capital investment in FGD/SCR and higher CO{sub 2} capture efficiency. In summary, as a result of this project, we now have developed one technology option for NZE CPU based on the activated carbon process and coldbox-VPSA hybrid process. This technology is projected to work for both low and high sulfur coal plants. The NZE CPU technology is projected to achieve near zero stack emissions, produce high purity CO{sub 2} relatively free of trace impurities and achieve ~99% CO{sub 2} capture rate while lowering the CO{sub 2} capture costs.« less

Application of dead space fraction to titrate optimal positive end-expiratory pressure in an ARDS swine model.

PubMed

Bian, Weishuai; Chen, Wei; Chao, Yangong; Wang, Lan; Li, Liming; Guan, Jian; Zang, Xuefeng; Zhen, Jie; Sheng, Bo; Zhu, Xi

2017-04-01

This study aimed to apply the dead space fraction [ratio of dead space to tidal volume (VD/VT)] to titrate the optimal positive end-expiratory pressure (PEEP) in a swine model of acute respiratory distress syndrome (ARDS). Twelve swine models of ARDS were constructed. A lung recruitment maneuver was then conducted and the PEEP was set at 20 cm H 2 O. The PEEP was reduced by 2 cm H 2 O every 10 min until 0 cm H 2 O was reached, and VD/VT was measured after each decrement step. VD/VT was measured using single-breath analysis of CO 2 , and calculated from arterial CO 2 partial pressure (PaCO 2 ) and mixed expired CO 2 (PeCO 2 ) using the following formula: VD/VT = (PaCO 2 - PeCO 2 )/PaCO 2 . The optimal PEEP was identified by the lowest VD/VT method. Respiration and hemodynamic parameters were recorded during the periods of pre-injury and injury, and at 4 and 2 cm H 2 O below and above the optimal PEEP (Po). The optimal PEEP in this study was found to be 13.25±1.36 cm H 2 O. During the Po period, VD/VT decreased to a lower value (0.44±0.08) compared with that during the injury period (0.68±0.10) (P<0.05), while the intrapulmonary shunt fraction reached its lowest value. In addition, a significant change of dynamic tidal respiratory compliance and oxygenation index was induced by PEEP titration. These results indicate that minimal VD/VT can be used for PEEP titration in ARDS.

Permanent downhole fiber optic pressure and temperature monitoring during CO2 injection

NASA Astrophysics Data System (ADS)

Schmidt-Hattenberger, C.; Moeller, F.; Liebscher, A.; Koehler, S.

2009-04-01

Permanent downhole monitoring of pressure and temperature, ideally over the entire length of the injection string, is essential for any smooth and safe CO2 injection within the framework of geological CO2 storage: i) To avoid fracturing of the cap-rock, a certain, site dependent pressure threshold within the reservoir should not be exceeded; ii) Any CO2 phase transition within the injection string, i.e. either condensation or evaporation, should be avoided. Such phase transitions cause uncontrolled and undetermined P-T regimes within the injection string that may ultimately result in a shut-in of the injection facility; and iii) Precise knowledge of the P and T response of the reservoir to the CO2 injection is a prerequisite to any reservoir modeling. The talk will present first results from our permanent downhole P-T monitoring program from the Ketzin CO2 storage test site (CO2SINK). At Ketzin, a fiber Bragg grating pressure sensor has been installed at the end of the injection string in combination with distributed temperature profiling over the entire length (about 550 m) of the string for continuous P-T monitoring during operation. Such fiber optic monitoring technique is used by default in the oil and gas industry but has not yet been applied as standard on a long-term routine mode for CO2 injection. Pressure is measured every 5 seconds with a resolution of < 1 bar. The data are later processed by user-defined program. The temperature logs along the injection string are measured every 3 minutes with a spatial resolution of one meter and with a temperature resolution of about 0.1°C. The long-term stability under full operational conditions is currently under investigation. The main computer of the P-T system operates as a stand-alone data-acquisition unit, and is connected with a secure intranet in order to ensure remote data access and system maintenance. The on-line measurements are displayed on the operator panel of the injection facility for direct control. The monitoring program started already prior to CO2 injection and runs since 6 months without any fatal errors. The recorded data cover the pre-injection well-testing phase, the initial injection phase as well as several shut-in and re-start phases during routine injection. Especially during the initial and re-start phases the monitoring results significantly optimized and improved the operation of the injection facility in terms of injection rate and injection temperature. Due to the high qualitative and also quantitative resolution of this technique even shortest-term transient disturbances of the reservoir and injection regime could be monitored as they may occur due to fluid sampling or logging in neighboring wells. Such short-term transient effects are normally overlooked using non-permanent monitoring techniques. On the long-term perspective, this monitoring technique will also support the control of CO2 injection tubing integrity, which is a prerequisite for any secure long-lasting CO2 injection and storage.

CO2 Mitigation Measures of Power Sector and Its Integrated Optimization in China

PubMed Central

Dai, Pan; Chen, Guang; Zhou, Hao; Su, Meirong; Bao, Haixia

2012-01-01

Power sector is responsible for about 40% of the total CO2 emissions in the world and plays a leading role in climate change mitigation. In this study, measures that lower CO2 emissions from the supply side, demand side, and power grid are discussed, based on which, an integrated optimization model of CO2 mitigation (IOCM) is proposed. Virtual energy, referring to energy saving capacity in both demand side and the power grid, together with conventional energy in supply side, is unified planning for IOCM. Consequently, the optimal plan of energy distribution, considering both economic benefits and mitigation benefits, is figured out through the application of IOCM. The results indicate that development of demand side management (DSM) and smart grid can make great contributions to CO2 mitigation of power sector in China by reducing the CO2 emissions by 10.02% and 12.59%, respectively, in 2015, and in 2020. PMID:23213305

40 CFR 75.5 - Prohibitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... (c) No owner or operator of an affected unit shall use any alternative monitoring system, alternative... be discharged, emissions of SO2, NOX or CO2 to the atmosphere without accounting for all such... approved emission monitoring method, and thereby avoid monitoring and recording SO2, NOX, or CO2 emissions...

Analyses of the Integration of Carbon Dioxide Removal Assembly, Compressor, Accumulator and Sabatier Carbon Dioxide Reduction Assembly

NASA Technical Reports Server (NTRS)

Jeng, Frank F.; Lafuse, Sharon; Smith, Frederick D.; Lu, Sao-Dung; Knox, James C.; Campbell, Mellssa L.; Scull, Timothy D.; Green Steve

2010-01-01

A tool has been developed by the Sabatier Team for analyzing/optimizing CO2 removal assembly, CO2 compressor size, its operation logic, water generation from Sabatier, utilization of CO2 from crew metabolic output, and Hz from oxygen generation assembly. Tests had been conducted using CDRA/Simulation compressor set-up at MSFC in 2003. Analysis of test data has validated CO2 desorption rate profile, CO2 compressor performance, CO2 recovery and CO2 vacuum vent in CDRA desorption. Optimizing the compressor size and compressor operation logic for an integrated closed air revitalization system Is being conducted by the Sabatier Team.

Reducing the cost of Ca-based direct air capture of CO2.

PubMed

Zeman, Frank

2014-10-07

Direct air capture, the chemical removal of CO2 directly from the atmosphere, may play a role in mitigating future climate risk or form the basis of a sustainable transportation infrastructure. The current discussion is centered on the estimated cost of the technology and its link to "overshoot" trajectories, where atmospheric CO2 levels are actively reduced later in the century. The American Physical Society (APS) published a report, later updated, estimating the cost of a one million tonne CO2 per year air capture facility constructed today that highlights several fundamental concepts of chemical air capture. These fundamentals are viewed through the lens of a chemical process that cycles between removing CO2 from the air and releasing the absorbed CO2 in concentrated form. This work builds on the APS report to investigate the effect of modifications to the air capture system based on suggestions in the report and subsequent publications. The work shows that reduced carbon electricity and plastic packing materials (for the contactor) may have significant effects on the overall price, reducing the APS estimate from $610 to $309/tCO2 avoided. Such a reduction does not challenge postcombustion capture from point sources, estimated at $80/tCO2, but does make air capture a feasible alternative for the transportation sector and a potential negative emissions technology. Furthermore, air capture represents atmospheric reductions rather than simply avoided emissions.

Painted Goby Larvae under High-CO2 Fail to Recognize Reef Sounds.

PubMed

Castro, Joana M; Amorim, M Clara P; Oliveira, Ana P; Gonçalves, Emanuel J; Munday, Philip L; Simpson, Stephen D; Faria, Ana M

2017-01-01

Atmospheric CO2 levels have been increasing at an unprecedented rate due to anthropogenic activity. Consequently, ocean pCO2 is increasing and pH decreasing, affecting marine life, including fish. For many coastal marine fishes, selection of the adult habitat occurs at the end of the pelagic larval phase. Fish larvae use a range of sensory cues, including sound, for locating settlement habitat. This study tested the effect of elevated CO2 on the ability of settlement-stage temperate fish to use auditory cues from adult coastal reef habitats. Wild late larval stages of painted goby (Pomatoschistus pictus) were exposed to control pCO2 (532 μatm, pH 8.06) and high pCO2 (1503 μatm, pH 7.66) conditions, likely to occur in nearshore regions subjected to upwelling events by the end of the century, and tested in an auditory choice chamber for their preference or avoidance to nighttime reef recordings. Fish reared in control pCO2 conditions discriminated reef soundscapes and were attracted by reef recordings. This behaviour changed in fish reared in the high CO2 conditions, with settlement-stage larvae strongly avoiding reef recordings. This study provides evidence that ocean acidification might affect the auditory responses of larval stages of temperate reef fish species, with potentially significant impacts on their survival.

Painted Goby Larvae under High-CO2 Fail to Recognize Reef Sounds

PubMed Central

Castro, Joana M.; Amorim, M. Clara P.; Oliveira, Ana P.; Gonçalves, Emanuel J.; Munday, Philip L.; Simpson, Stephen D.

2017-01-01

Atmospheric CO2 levels have been increasing at an unprecedented rate due to anthropogenic activity. Consequently, ocean pCO2 is increasing and pH decreasing, affecting marine life, including fish. For many coastal marine fishes, selection of the adult habitat occurs at the end of the pelagic larval phase. Fish larvae use a range of sensory cues, including sound, for locating settlement habitat. This study tested the effect of elevated CO2 on the ability of settlement-stage temperate fish to use auditory cues from adult coastal reef habitats. Wild late larval stages of painted goby (Pomatoschistus pictus) were exposed to control pCO2 (532 μatm, pH 8.06) and high pCO2 (1503 μatm, pH 7.66) conditions, likely to occur in nearshore regions subjected to upwelling events by the end of the century, and tested in an auditory choice chamber for their preference or avoidance to nighttime reef recordings. Fish reared in control pCO2 conditions discriminated reef soundscapes and were attracted by reef recordings. This behaviour changed in fish reared in the high CO2 conditions, with settlement-stage larvae strongly avoiding reef recordings. This study provides evidence that ocean acidification might affect the auditory responses of larval stages of temperate reef fish species, with potentially significant impacts on their survival. PMID:28125690

Muscle Co-activation: Definitions, Mechanisms, and Functions.

PubMed

Latash, Mark L

2018-03-28

The phenomenon of agonist-antagonist muscle co-activation is discussed with respect to its consequences for movement mechanics (such as increasing joint apparent stiffness, facilitating faster movements, and effects on action stability), implication for movement optimization, and involvement of different neurophysiological structures. Effects of co-activation on movement stability are ambiguous and depend on the effector representing a kinematic chain with a fixed origin or free origin. Further, co-activation is discussed within the framework of the equilibrium-point hypothesis and the idea of hierarchical control with spatial referent coordinates. Relations of muscle co-activation to changes in one of the basic commands, the c-command, are discussed and illustrated. A hypothesis is suggested that agonist-antagonist co-activation reflects a deliberate neural control strategy to preserve effector-level control and avoid making it degenerate and facing the necessity to control at the level of signals to individual muscles. This strategy, in particular, allows stabilizing motor actions by co-varied adjustments in spaces of control variables. This hypothesis is able to account for higher levels of co-activation in young healthy persons performing challenging tasks and across various populations with movement impairments.

Standardized Postnatal Management of Infants with Congenital Diaphragmatic Hernia in Europe: The CDH EURO Consortium Consensus - 2015 Update.

PubMed

Snoek, Kitty G; Reiss, Irwin K M; Greenough, Anne; Capolupo, Irma; Urlesberger, Berndt; Wessel, Lucas; Storme, Laurent; Deprest, Jan; Schaible, Thomas; van Heijst, Arno; Tibboel, Dick

2016-01-01

In 2010, the congenital diaphragmatic hernia (CDH) EURO Consortium published a standardized neonatal treatment protocol. Five years later, the number of participating centers has been raised from 13 to 22. In this article the relevant literature is updated, and consensus has been reached between the members of the CDH EURO Consortium. Key updated recommendations are: (1) planned delivery after a gestational age of 39 weeks in a high-volume tertiary center; (2) neuromuscular blocking agents to be avoided during initial treatment in the delivery room; (3) adapt treatment to reach a preductal saturation of between 80 and 95% and postductal saturation >70%; (4) target PaCO2 to be between 50 and 70 mm Hg; (5) conventional mechanical ventilation to be the optimal initial ventilation strategy, and (6) intravenous sildenafil to be considered in CDH patients with severe pulmonary hypertension. This article represents the current opinion of all consortium members in Europe for the optimal neonatal treatment of CDH. © 2016 The Author(s) Published by S. Karger AG, Basel.

The problem of hole localization in inner-shell states of N2 and CO2 revisited with complete active space self-consistent field approach.

PubMed

Rocha, Alexandre B; de Moura, Carlos E V

2011-12-14

Potential energy curves for inner-shell states of nitrogen and carbon dioxide molecules are calculated by inner-shell complete active space self-consistent field (CASSCF) method, which is a protocol, recently proposed, to obtain specifically converged inner-shell states at multiconfigurational level. This is possible since the collapse of the wave function to a low-lying state is avoided by a sequence of constrained optimization in the orbital mixing step. The problem of localization of K-shell states is revisited by calculating their energies at CASSCF level based on both localized and delocalized orbitals. The localized basis presents the best results at this level of calculation. Transition energies are also calculated by perturbation theory, by taking the above mentioned MCSCF function as zeroth order wave function. Values for transition energy are in fairly good agreement with experimental ones. Bond dissociation energies for N(2) are considerably high, which means that these states are strongly bound. Potential curves along ground state normal modes of CO(2) indicate the occurrence of Renner-Teller effect in inner-shell states. © 2011 American Institute of Physics

Techno-economic analysis of sorption-enhanced steam methane reforming in a fixed bed reactor network integrated with fuel cell

NASA Astrophysics Data System (ADS)

Diglio, Giuseppe; Hanak, Dawid P.; Bareschino, Piero; Mancusi, Erasmo; Pepe, Francesco; Montagnaro, Fabio; Manovic, Vasilije

2017-10-01

Sorption-enhanced steam methane reforming (SE-SMR) is a promising alternative for H2 production with inherent CO2 capture. This study evaluates the techno-economic performance of SE-SMR in a network of fixed beds and its integration with a solid oxide fuel cell (SE-SMR-SOFC) for power generation. The analysis revealed that both proposed systems are characterised by better economic performance than the reference systems. In particular, for SE-SMR the levelised cost of hydrogen is 1.6 €ṡkg-1 and the cost of CO2 avoided is 29.9 €ṡtCO2-1 (2.4 €ṡkg-1 and 50 €ṡtCO2-1, respectively, for SMR with CO2 capture) while for SE-SMR-SOFC the levelised cost of electricity is 0.078 €ṡkWh-1 and the cost of CO2 avoided is 36.9 €ṡtCO2-1 (0.080 €ṡkWh-1 and 80 €ṡtCO2-1, respectively, for natural gas-fired power plant with carbon capture). The sensitivity analysis showed that the specific cost of fuel and the capital cost of fuel cell mainly affect the economic performance of SE-SMR and SE-SMR-SOFC, respectively. The daily revenue of the SE-SMR-SOFC system is higher than that of the natural gas-fired power plant if the difference between the carbon tax and the CO2 transport and storage cost is > 6 €ṡtCO2-1.

Air traffic simulation in chemistry-climate model EMAC 2.41: AirTraf 1.0

NASA Astrophysics Data System (ADS)

Yamashita, Hiroshi; Grewe, Volker; Jöckel, Patrick; Linke, Florian; Schaefer, Martin; Sasaki, Daisuke

2016-09-01

Mobility is becoming more and more important to society and hence air transportation is expected to grow further over the next decades. Reducing anthropogenic climate impact from aviation emissions and building a climate-friendly air transportation system are required for a sustainable development of commercial aviation. A climate optimized routing, which avoids climate-sensitive regions by re-routing horizontally and vertically, is an important measure for climate impact reduction. The idea includes a number of different routing strategies (routing options) and shows a great potential for the reduction. To evaluate this, the impact of not only CO2 but also non-CO2 emissions must be considered. CO2 is a long-lived gas, while non-CO2 emissions are short-lived and are inhomogeneously distributed. This study introduces AirTraf (version 1.0) that performs global air traffic simulations, including effects of local weather conditions on the emissions. AirTraf was developed as a new submodel of the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model. Air traffic information comprises Eurocontrol's Base of Aircraft Data (BADA Revision 3.9) and International Civil Aviation Organization (ICAO) engine performance data. Fuel use and emissions are calculated by the total energy model based on the BADA methodology and Deutsches Zentrum für Luft- und Raumfahrt (DLR) fuel flow method. The flight trajectory optimization is performed by a genetic algorithm (GA) with respect to a selected routing option. In the model development phase, benchmark tests were performed for the great circle and flight time routing options. The first test showed that the great circle calculations were accurate to -0.004 %, compared to those calculated by the Movable Type script. The second test showed that the optimal solution found by the algorithm sufficiently converged to the theoretical true-optimal solution. The difference in flight time between the two solutions is less than 0.01 %. The dependence of the optimal solutions on the initial set of solutions (called population) was analyzed and the influence was small (around 0.01 %). The trade-off between the accuracy of GA optimizations and computational costs is clarified and the appropriate population and generation (one iteration of GA) sizing is discussed. The results showed that a large reduction in the number of function evaluations of around 90 % can be achieved with only a small decrease in the accuracy of less than 0.1 %. Finally, AirTraf simulations are demonstrated with the great circle and the flight time routing options for a typical winter day. The 103 trans-Atlantic flight plans were used, assuming an Airbus A330-301 aircraft. The results confirmed that AirTraf simulates the air traffic properly for the two routing options. In addition, the GA successfully found the time-optimal flight trajectories for the 103 airport pairs, taking local weather conditions into account. The consistency check for the AirTraf simulations confirmed that calculated flight time, fuel consumption, NOx emission index and aircraft weights show good agreement with reference data.

29 CFR 776.2 - Employee basis of coverage.

Code of Federal Regulations, 2010 CFR

2010-07-01

... in covered work, their employer cannot avoid his obligations to them under the Act on the ground that.... Callus, 325 U.S. 578; Armour & Co. v. Wantock, 323 U.S. 126; Donovan v. Shell Oil Co., 168 F. 2d 229 (C.A...

Development of supercritical CO2 extraction of bioactive phytochemicals from black poplar (Populus nigra L.) buds followed by GC-MS and UHPLC-DAD-QqTOF-MS.

PubMed

Kuś, Piotr M; Okińczyc, Piotr; Jakovljević, Martina; Jokić, Stela; Jerković, Igor

2018-05-25

The supercritical CO 2 (SC-CO 2 ) extraction process of black poplar (Populus nigra L.) buds was optimized (pressure, temperature) based on the yields of major phytochemicals (volatiles and non-volatiles). The optimal settings were 30 MPa/60 °C. Major volatiles determined by GC-MS in the optimized SC-CO 2 extract (mg of benzyl salicylate equivalent (BSE) per 100 g of buds) were: pinostrobin chalcone (1574.2), β-eudesmol (640.8), α-eudesmol (581.9), 2-methyl-2-butenyl-p-coumarate (289.9), pentyl-p-coumarate (457.0), γ-eudesmol (294.4), and benzyl salicylate (289.2). Partial qualitative similarity was observed between SC-CO 2 extracts and corresponding hydrodistilled essential oil dominated by sesquiterpenes, but with lower yields. Major compounds (mg per 100 g of buds) identified by UHPLC-DAD-QqTOF-MS in the optimized SC-CO 2 extract were: pinostrobin (751.7), pinocembrin (485.6), 3-O-pinobanksin acetate and methyl-butenyl-p-coumarate (290.2; 144.9 of pinobanksin and p-coumaric acid equivalents, respectively). SC-CO 2 extraction was found useful for green, efficient and simultaneous extraction of both volatile/non-volatile, bioactive phytochemicals of poplar buds - precursors of poplar-type propolis. Copyright © 2018 Elsevier B.V. All rights reserved.

Physical and economic potential of geological CO2 storage in saline aquifers.

PubMed

Eccles, Jordan K; Pratson, Lincoln; Newell, Richard G; Jackson, Robert B

2009-03-15

Carbon sequestration in sandstone saline reservoirs holds great potential for mitigating climate change, but its storage potential and cost per ton of avoided CO2 emissions are uncertain. We develop a general model to determine the maximum theoretical constraints on both storage potential and injection rate and use it to characterize the economic viability of geosequestration in sandstone saline aquifers. When applied to a representative set of aquifer characteristics, the model yields results that compare favorably with pilot projects currently underway. Over a range of reservoir properties, maximum effective storage peaks at an optimal depth of 1600 m, at which point 0.18-0.31 metric tons can be stored per cubic meter of bulk volume of reservoir. Maximum modeled injection rates predict minima for storage costs in a typical basin in the range of $2-7/ ton CO2 (2005 U.S.$) depending on depth and basin characteristics in our base-case scenario. Because the properties of natural reservoirs in the United States vary substantially, storage costs could in some cases be lower or higher by orders of magnitude. We conclude that available geosequestration capacity exhibits a wide range of technological and economic attractiveness. Like traditional projects in the extractive industries, geosequestration capacity should be exploited starting with the low-cost storage options first then moving gradually up the supply curve.

Urban cross-sector actions for carbon mitigation with local health co-benefits in China

NASA Astrophysics Data System (ADS)

Ramaswami, Anu; Tong, Kangkang; Fang, Andrew; Lal, Raj M.; Nagpure, Ajay Singh; Li, Yang; Yu, Huajun; Jiang, Daqian; Russell, Armistead G.; Shi, Lei; Chertow, Marian; Wang, Yangjun; Wang, Shuxiao

2017-10-01

Cities offer unique strategies to reduce fossil fuel use through the exchange of energy and materials across homes, businesses, infrastructure and industries co-located in urban areas. However, the large-scale impact of such strategies has not been quantified. Using new models and data sets representing 637 Chinese cities, we find that such cross-sectoral strategies--enabled by compact urban design and circular economy policies--contribute an additional 15%-36% to national CO2 mitigation, compared to conventional single-sector strategies. As a co-benefit, ~25,500 to ~57,500 deaths annually are avoided from air pollution reduction. The benefits are highly variable across cities, ranging from <1%-37% for CO2 emission reduction and <1%-47% for avoided premature deaths. These results, using multi-scale, multi-sector physical systems modelling, identify cities with high carbon and health co-benefit potential and show that urban-industrial symbiosis is a significant carbon mitigation strategy, achievable with a combination of existing and advanced technologies in diverse city types.

Optimal plant nitrogen use improves model representation of vegetation response to elevated CO2

NASA Astrophysics Data System (ADS)

Caldararu, Silvia; Kern, Melanie; Engel, Jan; Zaehle, Sönke

2017-04-01

Existing global vegetation models often cannot accurately represent observed ecosystem behaviour under transient conditions such as elevated atmospheric CO2, a problem that can be attributed to an inflexibility in model representation of plant responses. Plant optimality concepts have been proposed as a solution to this problem as they offer a way to represent plastic plant responses in complex models. Here we present a novel, next generation vegetation model which includes optimal nitrogen allocation to and within the canopy as well as optimal biomass allocation between above- and belowground components in response to nutrient and water availability. The underlying hypothesis is that plants adjust their use of nitrogen in response to environmental conditions and nutrient availability in order to maximise biomass growth. We show that for two FACE (Free Air CO2 enrichment) experiments, the Duke forest and Oak Ridge forest sites, the model can better predict vegetation responses over the duration of the experiment when optimal processes are included. Specifically, under elevated CO2 conditions, the model predicts a lower optimal leaf N concentration as well as increased biomass allocation to fine roots, which, combined with a redistribution of leaf N between the Rubisco and chlorophyll components, leads to a continued NPP response under high CO2, where models with a fixed canopy stoichiometry predict a quick onset of N limitation.Existing global vegetation models often cannot accurately represent observed ecosystem behaviour under transient conditions such as elevated atmospheric CO2, a problem that can be attributed to an inflexibility in model representation of plant responses. Plant optimality concepts have been proposed as a solution to this problem as they offer a way to represent plastic plant responses in complex models. Here we present a novel, next generation vegetation model which includes optimal nitrogen allocation to and within the canopy as well as optimal biomass allocation between above- and belowground components in response to nutrient and water availability. The underlying hypothesis is that plants adjust their use of nitrogen in response to environmental conditions and nutrient availability in order to maximise biomass growth. We show that for two FACE (Free Air CO2 enrichment) experiments, the Duke forest and Oak Ridge forest sites, the model can better predict vegetation responses over the duration of the experiment when optimal processes are included. Specifically, under elevated CO2 conditions, the model predicts a lower optimal leaf N concentration as well as increased biomass allocation to fine roots, which, combined with a redistribution of leaf N between the Rubisco and chlorophyll components, leads to a continued NPP response under high CO2, where models with a fixed canopy stoichiometry predict a quick onset of N limitation.

Effects of composition of the micro porous layer and the substrate on performance in the electrochemical reduction of CO2 to CO

NASA Astrophysics Data System (ADS)

Kim, Byoungsu; Hillman, Febrian; Ariyoshi, Miho; Fujikawa, Shigenori; Kenis, Paul J. A.

2016-04-01

With the development of better catalysts, mass transport limitations are becoming a challenge to high throughput electrochemical reduction of CO2 to CO. In contrast to optimization of electrodes for fuel cells, optimization of gas diffusion electrodes (GDE) - consisting of a carbon fiber substrate (CFS), a micro porous layer (MPL), and a catalyst layer (CL) - for CO2 reduction has not received a lot of attention. Here, we studied the effect of the MPL and CFS composition on cathode performance in electroreduction of CO2 to CO. In a flow reactor, optimized GDEs exhibited a higher partial current density for CO production than Sigracet 35BC, a commercially available GDE. By performing electrochemical impedance spectroscopy in a CO2 flow reactor we determined that a loading of 20 wt% PTFE in the MPL resulted in the best performance. We also investigated the influence of the thickness and wet proof level of CFS with two different feeds, 100% CO2 and the mixture of 50% CO2 and N2, determining that thinner and lower wet proofing of the CFS yields better cathode performance than when using a thicker and higher wet proof level of CFS.

The comparison of psychological adjustment of patients with cleft lip and palate after maxillary distraction osteogenesis and conventional orthognathic surgery.

PubMed

Chua, Hannah Daile P; Ho, Samuel M Y; Cheung, Lim Kwong

2012-11-01

The objective of this study was to compare the psychological changes of patients with cleft lip and palate (CLP) undergoing maxillary Le Fort I advancement by distraction osteogenesis (DO) and conventional orthognathic surgery (CO). Prospective randomized controlled study. Participants completed a set of questionnaires to measure their psychological states preoperatively and postoperatively. When compared with CO, CLP patients treated with DO had lower social self-esteem and higher social avoidance and distress levels during the first 3 postoperative months. Their self-esteem, social avoidance, and distress levels improved after the distractors were removed. Both CO and DO patients had similar levels of self-esteem, social avoidance, and distress levels 2 years postoperatively. The CLP patients treated with DO were more satisfied with their lives after 2 years. DO may induce short-term distress to patients up to 3 months but CLP patients who received DO were more satisfied with their lives in the long term. Copyright © 2012 Elsevier Inc. All rights reserved.

STTR Phase I: Low-Cost, High-Accuracy, Whole-Building Carbon Dioxide Monitoring for Demand Control Ventilation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hallstrom, Jason O.; Ni, Zheng Richard

This STTR Phase I project assessed the feasibility of a new CO 2 sensing system optimized for low-cost, high-accuracy, whole-building monitoring for use in demand control ventilation. The focus was on the development of a wireless networking platform and associated firmware to provide signal conditioning and conversion, fault- and disruptiontolerant networking, and multi-hop routing at building scales to avoid wiring costs. Early exploration of a bridge (or “gateway”) to direct digital control services was also explored. Results of the project contributed to an improved understanding of a new electrochemical sensor for monitoring indoor CO 2 concentrations, as well as themore » electronics and networking infrastructure required to deploy those sensors at building scales. New knowledge was acquired concerning the sensor’s accuracy, environmental response, and failure modes, and the acquisition electronics required to achieve accuracy over a wide range of CO 2 concentrations. The project demonstrated that the new sensor offers repeatable correspondence with commercial optical sensors, with supporting electronics that offer gain accuracy within 0.5%, and acquisition accuracy within 1.5% across three orders of magnitude variation in generated current. Considering production, installation, and maintenance costs, the technology presents a foundation for achieving whole-building CO 2 sensing at a price point below $0.066 / sq-ft – meeting economic feasibility criteria established by the Department of Energy. The technology developed under this award addresses obstacles on the critical path to enabling whole-building CO 2 sensing and demand control ventilation in commercial retrofits, small commercial buildings, residential complexes, and other highpotential structures that have been slow to adopt these technologies. It presents an opportunity to significantly reduce energy use throughout the United States.« less

Confinement in Wendelstein 7-X Limiter Plasmas

DOE PAGES

Hirsch, M.; Dinklage, A.; Alonso, A.; ...

2017-06-14

Observations on confinement in the first experimental campaign on the optimized Stellarator Wendelstein 7-X are summarized. In this phase W7-X was equipped with five inboard limiters only and thus the discharge length restricted to avoid local overheating. Stationary plasmas are limited to low densities <2–3 centerdot 10 19 m -3. With the available 4.3 MW ECR Heating core T e ~ 8 keV, T i ~ 1–2 keV are achieved routinely resulting in energy confinement time τ E between 80 ms to 150 ms. For these conditions the plasmas show characteristics of core electron root confinement with peaked T e-profilesmore » and positive E r up to about half of the minor radius. Lastly, profiles and plasma currents respond to on- and off-axis heating and co- and counter ECCD respectively.« less

Co-benefits of mitigating global greenhouse gas emissions for future air quality and human health

NASA Astrophysics Data System (ADS)

West, J. Jason; Smith, Steven J.; Silva, Raquel A.; Naik, Vaishali; Zhang, Yuqiang; Adelman, Zachariah; Fry, Meridith M.; Anenberg, Susan; Horowitz, Larry W.; Lamarque, Jean-Francois

2013-10-01

Actions to reduce greenhouse gas (GHG) emissions often reduce co-emitted air pollutants, bringing co-benefits for air quality and human health. Past studies typically evaluated near-term and local co-benefits, neglecting the long-range transport of air pollutants, long-term demographic changes, and the influence of climate change on air quality. 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: reducing co-emitted air pollutants, and slowing climate change and its effect on air quality. We use new relationships between chronic mortality and exposure to fine particulate matter and ozone, global modelling methods and new future scenarios. 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 US$50-380 per tonne of CO2, 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.

Cost-effectiveness of reducing emissions from tropical deforestation, 2016-2050

NASA Astrophysics Data System (ADS)

Busch, Jonah; Engelmann, Jens

2017-12-01

Reducing tropical deforestation is potentially a large-scale and low-cost strategy for mitigating climate change. Yet previous efforts to project the cost-effectiveness of policies to reduce greenhouse gas emissions from future deforestation across the tropics were hampered by crude available data on historical forest loss. Here we use recently available satellite-based maps of annual forest loss between 2001-2012, along with information on topography, accessibility, protected status, potential agricultural revenue, and an observed inverted-U-shaped relationship between forest cover loss and forest cover, to project tropical deforestation from 2016-2050 under alternative policy scenarios and to construct new marginal abatement cost curves for reducing emissions from tropical deforestation. We project that without new forest conservation policies 289 million hectares of tropical forest will be cleared from 2016-2050, releasing 169 GtCO2. A carbon price of US20/tCO2 (50/tCO2) across tropical countries would avoid 41 GtCO2 (77 GtCO2) from 2016-2050. By comparison, we estimate that Brazil’s restrictive policies in the Amazon between 2004-2012 successfully decoupled potential agricultural revenue from deforestation and reduced deforestation by 47% below what would have otherwise occurred, preventing the emission of 5.2 GtCO2. All tropical countries enacting restrictive anti-deforestation policies as effective as those in the Brazilian Amazon between 2004-2012 would avoid 58 GtCO2 from 2016-2050.

A technical, economic, and environmental assessment of amine-based CO2 capture technology for power plant greenhouse gas control.

PubMed

Rao, Anand B; Rubin, Edward S

2002-10-15

Capture and sequestration of CO2 from fossil fuel power plants is gaining widespread interest as a potential method of controlling greenhouse gas emissions. Performance and cost models of an amine (MEA)-based CO2 absorption system for postcombustion flue gas applications have been developed and integrated with an existing power plant modeling framework that includes multipollutant control technologies for other regulated emissions. The integrated model has been applied to study the feasibility and cost of carbon capture and sequestration at both new and existing coal-burning power plants. The cost of carbon avoidance was shown to depend strongly on assumptions about the reference plant design, details of the CO2 capture system design, interactions with other pollution control systems, and method of CO2 storage. The CO2 avoidance cost for retrofit systems was found to be generally higher than for new plants, mainly because of the higher energy penalty resulting from less efficient heat integration as well as site-specific difficulties typically encountered in retrofit applications. For all cases, a small reduction in CO2 capture cost was afforded by the SO2 emission trading credits generated by amine-based capture systems. Efforts are underway to model a broader suite of carbon capture and sequestration technologies for more comprehensive assessments in the context of multipollutant environmental management.

Online optimal obstacle avoidance for rotary-wing autonomous unmanned aerial vehicles

NASA Astrophysics Data System (ADS)

Kang, Keeryun

This thesis presents an integrated framework for online obstacle avoidance of rotary-wing unmanned aerial vehicles (UAVs), which can provide UAVs an obstacle field navigation capability in a partially or completely unknown obstacle-rich environment. The framework is composed of a LIDAR interface, a local obstacle grid generation, a receding horizon (RH) trajectory optimizer, a global shortest path search algorithm, and a climb rate limit detection logic. The key feature of the framework is the use of an optimization-based trajectory generation in which the obstacle avoidance problem is formulated as a nonlinear trajectory optimization problem with state and input constraints over the finite range of the sensor. This local trajectory optimization is combined with a global path search algorithm which provides a useful initial guess to the nonlinear optimization solver. Optimization is the natural process of finding the best trajectory that is dynamically feasible, safe within the vehicle's flight envelope, and collision-free at the same time. The optimal trajectory is continuously updated in real time by the numerical optimization solver, Nonlinear Trajectory Generation (NTG), which is a direct solver based on the spline approximation of trajectory for dynamically flat systems. In fact, the overall approach of this thesis to finding the optimal trajectory is similar to the model predictive control (MPC) or the receding horizon control (RHC), except that this thesis followed a two-layer design; thus, the optimal solution works as a guidance command to be followed by the controller of the vehicle. The framework is implemented in a real-time simulation environment, the Georgia Tech UAV Simulation Tool (GUST), and integrated in the onboard software of the rotary-wing UAV test-bed at Georgia Tech. Initially, the 2D vertical avoidance capability of real obstacles was tested in flight. The flight test evaluations were extended to the benchmark tests for 3D avoidance capability over the virtual obstacles, and finally it was demonstrated on real obstacles located at the McKenna MOUT site in Fort Benning, Georgia. Simulations and flight test evaluations demonstrate the feasibility of the developed framework for UAV applications involving low-altitude flight in an urban area.

[Optimization for supercritical CO2 extraction with response surface methodology and component analysis of Sapindus mukorossi oil].

PubMed

Wu, Yan; Xiao, Xin-yu; Ge, Fa-huan

2012-02-01

To study the extraction conditions of Sapindus mukorossi oil by Supercritical CO2 Extraction and identify its components. Optimized SFE-CO2 Extraction by response surface methodology and used GC-MS to analysie Sapindus mukorossi oil compounds. Established the model of an equation for the extraction rate of Sapindus mukorossi oil by Supercritical CO2 Extraction, and the optimal parameters for the Supercritical CO2 Extraction determined by the equation were: the extraction pressure was 30 MPa, temperature was 40 degrees C; The separation I pressure was 14 MPa, temperature was 45 degrees C; The separation II pressure was 6 MPa, temperature was 40 degrees C; The extraction time was 60 min and the extraction rate of Sapindus mukorossi oil of 17.58%. 22 main compounds of Sapindus mukorossi oil extracted by supercritical CO2 were identified by GC-MS, unsaturated fatty acids were 86.59%. This process is reliable, safe and with simple operation, and can be used for the extraction of Sapindus mukorossi oil.

Using dissolved carbon dioxide to alter the behavior of invasive round goby

USGS Publications Warehouse

Cupp, Aaron R.; Tix, John; Smerud, Justin R.; Erickson, Richard A.; Fredricks, Kim; Amberg, Jon J.; Suski, Cory D.; Wakeman, Robert

2017-01-01

Fisheries managers need effective methods to limit the spread of invasive round goby Neogobius melanostomus in North America. Elevating carbon dioxide (CO2) in water at pinch points of rivers (e.g., inside locks) is one approach showing potential to deter the passage of invasive fishes, such as bigheaded carps Hypophthalmichthys spp., but the effectiveness of this method to alter round goby behavior has not been determined. The goal for this study was to determine CO2 concentrations that alter round goby behavior across a range of water temperatures. Free-swimming avoidance (voluntary response) and loss of equilibrium (involuntary response) were quantified by exposing round goby to increasing CO2 concentrations at 5, 15, and 25 °C using a shuttle box choice arena and static tank. Water chemistry was measured concurrent with behavioral endpoints and showed that round goby avoided a threshold of 99–169 mg/L CO2(79,000–178,000 µatm) and lost equilibrium at 197–280 mg/L CO2 (163,000–303,000 µatm). Approximately 50% lower CO2 concentrations were found to modify behavior at 5 °C relative to 25 °C, suggesting greater effectiveness at lower water temperatures. We conclude that CO2 modified round goby behavior and concentrations determined in this study are intended to guide field testing of CO2 as an invasive fish deterrent.

Disruption avoidance by means of electron cyclotron waves

NASA Astrophysics Data System (ADS)

Esposito, B.; Granucci, G.; Maraschek, M.; Nowak, S.; Lazzaro, E.; Giannone, L.; Gude, A.; Igochine, V.; McDermott, R.; Poli, E.; Reich, M.; Sommer, F.; Stober, J.; Suttrop, W.; Treutterer, W.; Zohm, H.; ASDEX Upgrade, the; FTU Teams

2011-12-01

Disruptions are very challenging to ITER operation as they may cause damage to plasma facing components due to direct plasma heating, forces on structural components due to halo and eddy currents and the production of runaway electrons. Electron cyclotron (EC) waves have been demonstrated as a tool for disruption avoidance by a large set of recent experiments performed in ASDEX Upgrade and FTU using various disruption types, plasma operating scenarios and power deposition locations. The technique is based on the stabilization of magnetohydrodynamic (MHD) modes (mainly m/n = 2/1) through the localized injection of EC power on the resonant surface. This paper presents new results obtained in ASDEX Upgrade regarding stable operation above the Greenwald density achieved after avoidance of density limit disruptions by means of ECRH and suitable density feedback control (L-mode ohmic plasmas, Ip = 0.6 MA, Bt = 2.5 T) and NTM-driven disruptions at high-β limit delayed/avoided by means of both co-current drive (co-ECCD) and pure heating (ECRH) with power <=1.7 MW (H-mode NBI-heated plasmas, PNBI ~ 7.5 MW, Ip = 1 MA, Bt = 2.1 T, q95 ~ 3.6). The localized perpendicular injection of ECRH/ECCD onto a resonant surface leads to the delay and/or complete avoidance of disruptions. The experiments indicate the existence of a power threshold for mode stabilization to occur. An analysis of the MHD mode evolution using the generalized Rutherford equation coupled to the frequency and phase evolution equations shows that control of the modes is due to EC heating close to the resonant surface. The ECRH contribution (Δ'H term) is larger than the co-ECCD one in the initial and more important phase when the discharge is 'saved'. Future research and developments of the disruption avoidance technique are also discussed.

Cooperative Position Aware Mobility Pattern of AUVs for Avoiding Void Zones in Underwater WSNs.

PubMed

Javaid, Nadeem; Ejaz, Mudassir; Abdul, Wadood; Alamri, Atif; Almogren, Ahmad; Niaz, Iftikhar Azim; Guizani, Nadra

2017-03-13

In this paper, we propose two schemes; position-aware mobility pattern (PAMP) and cooperative PAMP (Co PAMP). The first one is an optimization scheme that avoids void hole occurrence and minimizes the uncertainty in the position estimation of glider's. The second one is a cooperative routing scheme that reduces the packet drop ratio by using the relay cooperation. Both techniques use gliders that stay at sojourn positions for a predefined time, at sojourn position self-confidence (s-confidence) and neighbor-confidence (n-confidence) regions that are estimated for balanced energy consumption. The transmission power of a glider is adjusted according to those confidence regions. Simulation results show that our proposed schemes outperform the compared existing one in terms of packet delivery ratio, void zones and energy consumption.

Nitrous oxide as a humane method for piglet euthanasia: Behavior and electroencephalography (EEG).

PubMed

Rault, Jean-Loup; Kells, Nikki; Johnson, Craig; Dennis, Rachel; Sutherland, Mhairi; Lay, Donald C

2015-11-01

The search for humane methods to euthanize piglets is critical to address public concern that current methods are not optimal. Blunt force trauma is considered humane but esthetically objectionable. Carbon dioxide (CO2) is used but criticized as aversive. This research sought to: 1) evaluate the aversiveness of inhaling nitrous oxide (N2O; 'laughing gas') using an approach-avoidance test relying on the piglet's perspective, and 2) validate its humaneness to induce loss of consciousness by electroencephalography (EEG). The gas mixtures tested were N2O and air (90%:10%; '90 N'); N2O, oxygen and air (60%:30%:10%; '60 N'); and CO2 and air (90%:10%; '90 C'). Experiment 1 allowed piglets to walk freely between one chamber filled with air and another prefilled with 60 N or 90 N. All piglets exposed to 60 N lasted for the 10 min test duration whereas all piglets exposed to 90 N had to be removed within 5 min because they fell recumbent and unresponsive and then started to flail. Experiment 2 performed the same test except the gas chamber held N2O prefilled at 25%, 50%, or 75% or CO2 prefilled at 7%, 14%, or 21%. The test was terminated more quickly at higher concentrations due to the piglets' responses. Time spent ataxic was greater in the middle concentration gradients. Flailing behavior tended to correlate with increasing concentrations of CO2 but not N2O. Experiment 3, using the minimal anesthesia model, showed that both 90 N and 90 C induced isoelectric EEG, in 71 and 59 s respectively, but not 60 N within 15 min. The EEG results together with the observed behavioral changes reflect differences in the animal's perceptive experience. The implications for animal welfare are that N2O is much less aversive than CO2, and 90% N2O can euthanize piglets. Copyright © 2015 Elsevier Inc. All rights reserved.

The Physiologic Effects of Pneumoperitoneum in the Morbidly Obese

PubMed Central

Nguyen, Ninh T.; Wolfe, Bruce M.

2005-01-01

Objective: To review the physiologic effects of carbon dioxide (CO2) pneumoperitoneum in the morbidly obese. Summary Background Data: The number of laparoscopic bariatric operations performed in the United States has increased dramatically over the past several years. Laparoscopic bariatric surgery requires abdominal insufflation with CO2 and an increase in the intraabdominal pressure up to 15 mm Hg. Many studies have demonstrated the adverse consequences of pneumoperitoneum; however, few studies have examined the physiologic effects of pneumoperitoneum in the morbidly obese. Methods: A MEDLINE search from 1994 to 2003 was performed using the key words morbid obesity, laparoscopy, bariatric surgery, pneumoperitoneum, and gastric bypass. The authors reviewed papers evaluating the physiologic effects of pneumoperitoneum in morbidly obese subjects undergoing laparoscopy. The topics examined included alteration in acid-base balance, hemodynamics, femoral venous flow, and hepatic, renal, and cardiorespiratory function. Results: Physiologically, morbidly obese patients have a higher intraabdominal pressure at 2 to 3 times that of nonobese patients. The adverse consequences of pneumoperitoneum in morbidly obese patients are similar to those observed in nonobese patients. Laparoscopy in the obese can lead to systemic absorption of CO2 and increased requirements for CO2 elimination. The increased intraabdominal pressure enhances venous stasis, reduces intraoperative portal venous blood flow, decreases intraoperative urinary output, lowers respiratory compliance, increases airway pressure, and impairs cardiac function. Intraoperative management to minimize the adverse changes include appropriate ventilatory adjustments to avoid hypercapnia and acidosis, the use of sequential compression devices to minimizes venous stasis, and optimize intravascular volume to minimize the effects of increased intraabdominal pressure on renal and cardiac function. Conclusions: Morbidly obese patients undergoing laparoscopic bariatric surgery are at risk for intraoperative complications relating to the use of CO2 pneumoperitoneum. Surgeons performing laparoscopic bariatric surgery should understand the physiologic effects of CO2 pneumoperitoneum in the morbidly obese and make appropriate intraoperative adjustments to minimize the adverse changes. PMID:15650630

Making C4 crops more water efficient under current and future climate: Tradeoffs between carbon gain and water loss

NASA Astrophysics Data System (ADS)

Srinivasan, V.; Pignon, C.

2017-12-01

C4 plants have a carbon concentrating mechanism that has evolved under historically low CO2 concentrations of around 200 ppm. However, increases in global CO2 concentrations in recent times (current CO2 concentrations are at 400 ppm and it is projected to be 550 ppm by mid-century) have diminished the relative advantage of C4 plants over C3 plants, which lack the expensive carbon concentrating machinery. Here we show by employing model simulations that under pre-historic CO2 concentrations, C4 plants are near optimal in their stomatal behavior and nitrogen partitioning between carbon concentrating machinery and carboxylation machinery, and they are significantly supra-optimal under current and future elevated CO2 concentrations. Model simulations performed at current CO2 concentrations of 400 ppm show that, under high light conditions, decreasing stomatal conductance by 20% results in a 15% increase in water use efficiency with negligible loss in photosynthesis. Under future elevated CO2 concentrations of 550 ppm, a 40% decrease in stomatal conductance produces a 35% increase in water use efficiency. Furthermore, stomatal closure is shown to be more effective in decreasing whole canopy transpiration compared to canopy top leaf transpiration, since shaded leaves are more supra-optimal than sunlit leaves. Model simulations for optimizing nitrogen distribution in C4 leaves show that under high light conditions, C4 plants over invest in carbon concentrating machinery and under invest in carboxylation machinery. A 20% redistribution in leaf nitrogen results in a 10% increase in leaf carbon assimilation without significant increases in transpiration under current CO2 concentrations of 400 ppm. Similarly, a 40% redistribution in leaf nitrogen results in a 15% increase in leaf carbon assimilation without significant increases in transpiration under future elevated CO2 concentrations of 550 ppm. Our model optimality simulations show that C4 leaves a supra optimal in their stomatal behavior and leaf nitrogen distribution and by decreasing stomatal conductance and redistributing nitrogen away from carbon concentrating mechanism and towards carboxylation machinery, we can significantly decrease transpiration and increase carbon assimilation thereby increasing water use efficiency.

Effect of Data Assimilation Parameters on The Optimized Surface CO2 Flux in Asia

NASA Astrophysics Data System (ADS)

Kim, Hyunjung; Kim, Hyun Mee; Kim, Jinwoong; Cho, Chun-Ho

2018-02-01

In this study, CarbonTracker, an inverse modeling system based on the ensemble Kalman filter, was used to evaluate the effects of data assimilation parameters (assimilation window length and ensemble size) on the estimation of surface CO2 fluxes in Asia. Several experiments with different parameters were conducted, and the results were verified using CO2 concentration observations. The assimilation window lengths tested were 3, 5, 7, and 10 weeks, and the ensemble sizes were 100, 150, and 300. Therefore, a total of 12 experiments using combinations of these parameters were conducted. The experimental period was from January 2006 to December 2009. Differences between the optimized surface CO2 fluxes of the experiments were largest in the Eurasian Boreal (EB) area, followed by Eurasian Temperate (ET) and Tropical Asia (TA), and were larger in boreal summer than in boreal winter. The effect of ensemble size on the optimized biosphere flux is larger than the effect of the assimilation window length in Asia, but the importance of them varies in specific regions in Asia. The optimized biosphere flux was more sensitive to the assimilation window length in EB, whereas it was sensitive to the ensemble size as well as the assimilation window length in ET. The larger the ensemble size and the shorter the assimilation window length, the larger the uncertainty (i.e., spread of ensemble) of optimized surface CO2 fluxes. The 10-week assimilation window and 300 ensemble size were the optimal configuration for CarbonTracker in the Asian region based on several verifications using CO2 concentration measurements.

The role of attachment styles in regulating the effects of dopamine on the behavior of salespersons

PubMed Central

Verbeke, Willem; Bagozzi, Richard P.; van den Berg, Wouter E.

2014-01-01

Two classic strategic orientations have been found to pervade the behavior of modern salespersons: a sales orientation (SO) where salespersons use deception or guile to get customers to buy even if they do not need a product, and a customer orientation (CO) where salespersons first attempt to discover the customer's needs and adjust their product and selling approach to meet those needs. Study 1 replicates recent research and finds that the Taq A1 variant of the DRD2 gene is not related to either sales or CO, whereas the 7-repeat variant of the DRD4 gene is related to CO but not SO. Study 2 investigates gene × phenotype explanations of orientation of salespersons, drawing upon recent research in molecular genetics and biological/psychological attachment theory. The findings show that attachment style regulates the effects of DRD2 on CO, such that greater avoidant attachment styles lead to higher CO for persons with the A2/A2 variant but neither the A1/A2 nor A1/A1 variants. Likewise, attachment style regulates the effects of DRD4 on CO, such that greater avoidant attachment styles lead to higher CO for persons with the 7-repeat variant but not other variants. No effects were found on a SO, and secure and anxious attachment styles did not function as moderators. PMID:24550811

Advanced Amine Solvent Formulations and Process Integration for Near-Term CO2 Capture Success

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fisher, Kevin S.; Searcy, Katherine; Rochelle, Gary T.

2007-06-28

This Phase I SBIR project investigated the economic and technical feasibility of advanced amine scrubbing systems for post-combustion CO2 capture at coal-fired power plants. Numerous combinations of advanced solvent formulations and process configurations were screened for energy requirements, and three cases were selected for detailed analysis: a monoethanolamine (MEA) base case and two “advanced” cases: an MEA/Piperazine (PZ) case, and a methyldiethanolamine (MDEA) / PZ case. The MEA/PZ and MDEA/PZ cases employed an advanced “double matrix” stripper configuration. The basis for calculations was a model plant with a gross capacity of 500 MWe. Results indicated that CO2 capture increased themore » base cost of electricity from 5 cents/kWh to 10.7 c/kWh for the MEA base case, 10.1 c/kWh for the MEA / PZ double matrix, and 9.7 c/kWh for the MDEA / PZ double matrix. The corresponding cost per metric tonne CO2 avoided was 67.20 $/tonne CO2, 60.19 $/tonne CO2, and 55.05 $/tonne CO2, respectively. Derated capacities, including base plant auxiliary load of 29 MWe, were 339 MWe for the base case, 356 MWe for the MEA/PZ double matrix, and 378 MWe for the MDEA / PZ double matrix. When compared to the base case, systems employing advanced solvent formulations and process configurations were estimated to reduce reboiler steam requirements by 20 to 44%, to reduce derating due to CO2 capture by 13 to 30%, and to reduce the cost of CO2 avoided by 10 to 18%. These results demonstrate the potential for significant improvements in the overall economics of CO2 capture via advanced solvent formulations and process configurations.« less

Climate, Health, Agricultural and Economic Impacts of Tighter Vehicle-Emission Standards

NASA Technical Reports Server (NTRS)

Shindell, Drew; Faluvegi, Greg; Walsh, Michael; Anenberg, Susan C.; VanDingen, Rita; Muller, Nicholas Z.; Austin, Jeff; Koch, Dorothy; Milly, George

2011-01-01

Non-CO2 air pollutants from motor vehicles have traditionally been controlled to protect air quality and health, but also affect climate. We use global composition climate modelling to examine the integrated impacts of adopting stringent European on-road vehicle-emission standards for these pollutants in 2015 in many developing countries. Relative to no extra controls, the tight standards lead to annual benefits in 2030 and beyond of 120,000-280,000 avoided premature air pollution-related deaths, 6.1-19.7 million metric tons of avoided ozone-related yield losses of major food crops, $US0.6-2.4 trillion avoided health damage and $US1.1-4.3 billion avoided agricultural damage, and mitigation of 0.20 (+0.14/-0.17) C of Northern Hemisphere extratropical warming during 2040-2070. Tighter vehicle-emission standards are thus extremely likely to mitigate short-term climate change in most cases, in addition to providing large improvements in human health and food security. These standards will not reduce CO2 emissions, however, which is required to mitigate long-term climate change.

Characteristics of MSW and heat energy recovery between residential and commercial areas in Seoul.

PubMed

Yi, Sora; Yoo, Kee-Young; Hanaki, Keisuke

2011-03-01

This paper analyzes the amount and characteristics of municipal solid waste (MSW) according to the inhabitant density of population and the business concentration in 25 districts in Seoul. Further, the heat energy recovery and avoided CO(2) emissions of four incineration plants located in residential and commercial areas in Seoul are examined. The amount of residential waste per capita tended to increase as the density of inhabitants decreased. The amount of commercial waste per capita tended to increase as the business concentration increased. The examination of the heat energy recovery characteristics indicated that the four incineration plants produced heat energy that depended on residential or commercial areas based on population and business. The most important result regarding avoided CO(2) emissions was that commercial areas with many office-type businesses had the most effective CO(2) emission savings by combusting 1 kg of waste. Assuming the full-scale operation of the four incineration plants, the amount of saved CO(2) emissions per year was 444 Gg CO(2) and 57,006 households in Seoul can be provided with heat energy equivalent to 542,711 Nm(3) of LNG. Copyright © 2010 Elsevier Ltd. All rights reserved.

Optimal consensus algorithm integrated with obstacle avoidance

NASA Astrophysics Data System (ADS)

Wang, Jianan; Xin, Ming

2013-01-01

This article proposes a new consensus algorithm for the networked single-integrator systems in an obstacle-laden environment. A novel optimal control approach is utilised to achieve not only multi-agent consensus but also obstacle avoidance capability with minimised control efforts. Three cost functional components are defined to fulfil the respective tasks. In particular, an innovative nonquadratic obstacle avoidance cost function is constructed from an inverse optimal control perspective. The other two components are designed to ensure consensus and constrain the control effort. The asymptotic stability and optimality are proven. In addition, the distributed and analytical optimal control law only requires local information based on the communication topology to guarantee the proposed behaviours, rather than all agents' information. The consensus and obstacle avoidance are validated through simulations.

A review on optimization production and upgrading biogas through CO2 removal using various techniques.

PubMed

Andriani, Dian; Wresta, Arini; Atmaja, Tinton Dwi; Saepudin, Aep

2014-02-01

Biogas from anaerobic digestion of organic materials is a renewable energy resource that consists mainly of CH4 and CO2. Trace components that are often present in biogas are water vapor, hydrogen sulfide, siloxanes, hydrocarbons, ammonia, oxygen, carbon monoxide, and nitrogen. Considering the biogas is a clean and renewable form of energy that could well substitute the conventional source of energy (fossil fuels), the optimization of this type of energy becomes substantial. Various optimization techniques in biogas production process had been developed, including pretreatment, biotechnological approaches, co-digestion as well as the use of serial digester. For some application, the certain purity degree of biogas is needed. The presence of CO2 and other trace components in biogas could affect engine performance adversely. Reducing CO2 content will significantly upgrade the quality of biogas and enhancing the calorific value. Upgrading is generally performed in order to meet the standards for use as vehicle fuel or for injection in the natural gas grid. Different methods for biogas upgrading are used. They differ in functioning, the necessary quality conditions of the incoming gas, and the efficiency. Biogas can be purified from CO2 using pressure swing adsorption, membrane separation, physical or chemical CO2 absorption. This paper reviews the various techniques, which could be used to optimize the biogas production as well as to upgrade the biogas quality.

Optimization of A 2-Micron Laser Frequency Stabilization System for a Double-Pulse CO2 Differential Absorption Lidar

NASA Technical Reports Server (NTRS)

Chen, Songsheng; Yu, Jirong; Bai, Yingsin; Koch, Grady; Petros, Mulugeta; Trieu, Bo; Petzar, Paul; Singh, Upendra N.; Kavaya, Michael J.; Beyon, Jeffrey

2010-01-01

A carbon dioxide (CO2) Differential Absorption Lidar (DIAL) for accurate CO2 concentration measurement requires a frequency locking system to achieve high frequency locking precision and stability. We describe the frequency locking system utilizing Frequency Modulation (FM), Phase Sensitive Detection (PSD), and Proportional Integration Derivative (PID) feedback servo loop, and report the optimization of the sensitivity of the system for the feed back loop based on the characteristics of a variable path-length CO2 gas cell. The CO2 gas cell is characterized with HITRAN database (2004). The method can be applied for any other frequency locking systems referring to gas absorption line.

Personality features in ultra-high risk for psychosis: a comparative study with schizophrenia and control subjects using the Temperament and Character Inventory-Revised (TCI-R).

PubMed

Fresán, Ana; León-Ortiz, Pablo; Robles-García, Rebeca; Azcárraga, Mariana; Guizar, Diana; Reyes-Madrigal, Francisco; Tovilla-Zárate, Carlos Alfonso; de la Fuente-Sandoval, Camilo

2015-02-01

Several variables have been identified as risk factors for conversion to overt psychosis in ultra-high risk for psychosis (UHR) individuals. Although almost two-thirds of them do not experience a transition to psychosis, they still exhibit functional disabilities. Other subjective developmental features may be useful for a more precise identification of individuals at UHR. Avoidant behaviors are consistently reported in schizophrenia and in UHR individuals and may be the reflection of a pattern of personality. Thus, personality features in UHR individuals deserves further research. The objective of the present study was to compare temperament and character dimensions between UHR individuals, patients with schizophrenia and healthy controls. One hundred participants (25 UHR individuals, 25 schizophrenia patients and 50 control subjects) where evaluated with the Temperament and Character Inventory-Revised (TCI-R). Univariate ANOVAs followed by Bonferroni tests were used. UHR individuals and schizophrenia patients exhibited higher levels of Harm Avoidance (HA) when compared to control subjects. For HA1 Anticipatory worry vs Uninhibited optimism and HA4 Fatigability & asthenia, UHR and schizophrenia groups showed similar scores and both groups were higher compared to control subjects. With respect to Cooperativeness (CO), UHR and schizophrenia reported lower scores than control subjects, in particular CO2 Empathy vs Social disinterest and CO3 Helpfulness vs unhelpfulness. This study replicates and extends the consideration of HA as a psychopathological related endophenotype and gives us further information of the possible role of personality features in the expression of some of the social dysfunctions observed both in prodromal subjects and schizophrenia patients. Copyright © 2014 Elsevier Ltd. All rights reserved.

Response of Photosynthesis and Yield of Sweetpotato and Peanut to Super-optimal CO2 levels

NASA Astrophysics Data System (ADS)

Bonsi, C.; Bullard, J.; Hileman, D.; Mortley, D.; Hill, J.; Hill, W.; Morrris, C.

The fate of persons involved in long-term space travel and habitation will depend greatly on the ability to provide food and a livable environment for them In the National Aeronautics and Space Administration NASA Advanced Life Support ALS program photosynthesis of higher plants will be utilized to provide food and oxygen while removing carbon dioxide produced by humans and other heterotrophs as well as transpiring water that can be recycled for drinking This plant-mediated process is collectively referred to as Bioregenerative Life Support Carbon dioxide concentrations on board a space shuttle cabin atmosphere range between 4000 and 6000 mu mol mol -1 CO 2 but with large crews may exceed 10 000- mu mol mol -1 CO 2 Thus it is critical to evaluate the responses of candidate crops to super optimal levels of CO 2 Soybean and potato have been exposed to CO 2 concentrations up to 5000 and 10 000- mu mol mol -1 Very little research has been published about the effects of super-optimal CO 2 levels on sweetpotato and peanut growth and physiology thus indicating a need for extensive research on these plants The aim of this study was to evaluate the effects of super-optimal CO 2 enrichment on growth of TU-82-155 sweetpotato and Georgia Red peanut in a Microporous Tube Membrane MPT using Turface Media and Nutrient Film Technique NFT nutrient delivery systems Sweetpotato Ipomoea batatas L Lam and peanut Arachis hypogaea L were exposed to three CO 2 levels of 400

Improved NADPH Regeneration for Fungal Cytochrome P450 Monooxygenase by Co-Expressing Bacterial Glucose Dehydrogenase in Resting-Cell Biotransformation of Recombinant Yeast.

PubMed

Jeon, Hyunwoo; Durairaj, Pradeepraj; Lee, Dowoo; Ahsan, Md Murshidul; Yun, Hyungdon

2016-12-28

Fungal cytochrome P450 (CYP) enzymes catalyze versatile monooxygenase reactions and play a major role in fungal adaptations owing to their essential roles in the production avoid metabolites critical for pathogenesis, detoxification of xenobiotics, and exploitation avoid substrates. Although fungal CYP-dependent biotransformation for the selective oxidation avoid organic compounds in yeast system is advantageous, it often suffers from a shortage avoid intracellular NADPH. In this study, we aimed to investigate the use of bacterial glucose dehydrogenase (GDH) for the intracellular electron regeneration of fungal CYP monooxygenase in a yeast reconstituted system. The benzoate hydroxylase FoCYP53A19 and its homologous redox partner FoCPR from Fusarium oxysporum were co-expressed with the BsGDH from Bacillus subtilis in Saccharomyces cerevisiae for heterologous expression and biotransformations. We attempted to optimize several bottlenecks concerning the efficiency of fungal CYP-mediated whole-cell-biotransformation to enhance the conversion. The catalytic performance of the intracellular NADPH regeneration system facilitated the hydroxylation of benzoic acid to 4-hydroxybenzoic acid with high conversion in the resting-cell reaction. The FoCYP53A19 +FoCPR+BsGDH reconstituted system produced 0.47 mM 4-hydroxybenzoic acid (94% conversion) in the resting-cell biotransformations performed in 50 mM phosphate buffer (pH 6.0) containing 0.5 mM benzoic acid and 0.25% glucose for 24 h at 30°C. The "coupled-enzyme" system can certainly improve the overall performance of NADPH-dependent whole-cell biotransformations in a yeast system.

The right place for the right job in the photovoltaic life cycle.

PubMed

Kawajiri, Kotaro; Genchi, Yutaka

2012-07-03

The potential for photovoltaic power generation (PV) to reduce primary energy consumption (PEC) and CO(2) emissions depends on the physical locations of each stage of its life cycle. When stages are optimally located, CO(2) emissions are reduced nearly ten times as much as when each stage is located in the country having the largest current market share. The usage stage contributes the most to reducing CO(2) emissions and PEC, and total CO(2) emissions actually increase when PV is installed in countries having small CO(2) emissions from electricity generation. Global maps of CO(2) reduction potential indicate that Botswana and Gobi in Mongolia are the optimal locations to install PV due to favorable conditions for PV power generation and high CO(2) emissions from current electricity generation. However, the small electricity demand in those countries limits the contribution to global CO(2) reduction. The type of PVs has a small but significant effect on life cycle PEC and CO(2) emissions.

77 FR 55171 - Approval and Promulgation of Air Quality Implementation Plans; Maryland; Deferral for CO2

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-07

... consider your comment. Electronic files should avoid the use of special characters, any form of encryption... copy form. Publicly available docket materials are available either electronically in www.regulations... biologically-based materials other than fossil fuels and mineral sources of carbon. Examples of ``biogenic CO 2...

CO2 Removal from Biogas by Cyanobacterium Leptolyngbya sp. CChF1 Isolated from the Lake Chapala, Mexico: Optimization of the Temperature and Light Intensity.

PubMed

Choix, Francisco J; Snell-Castro, Raúl; Arreola-Vargas, Jorge; Carbajal-López, Alberto; Méndez-Acosta, Hugo O

2017-12-01

In the present study, the capacity of the cyanobacterium Leptolyngbya sp. CChF1 to remove CO 2 from real and synthetic biogas was evaluated. The identification of the cyanobacterium, isolated from the lake Chapala, was carried out by means of morphological and molecular analyses, while its potential for CO 2 removal from biogas streams was evaluated by kinetic experiments and optimized by a central composite design coupled to a response surface methodology. Results demonstrated that Leptolyngbya sp. CChF1 is able to remove CO 2 and grow indistinctly in real or synthetic biogas streams, showing tolerance to high concentrations of CO 2 and CH 4 , 25 and 75%, respectively. The characterization of the biomass composition at the end of the kinetic assays revealed that the main accumulated by-products under both biogas streams were lipids, followed by proteins and carbohydrates. Regarding the optimization experiments, light intensity and temperature were the studied variables, while synthetic biogas was the carbon source. Results showed that light intensity was significant for CO 2 capture efficiency (p = 0.0290), while temperature was significant for biomass production (p = 0.0024). The predicted CO 2 capture efficiency under optimal conditions (27.1 °C and 920 lx) was 93.48%. Overall, the results of the present study suggest that Leptolyngbya sp. CChF1 is a suitable candidate for biogas upgrading.

Maximum warming occurs about one decade after a carbon dioxide emission

NASA Astrophysics Data System (ADS)

Ricke, Katharine L.; Caldeira, Ken

2014-12-01

It is known that carbon dioxide emissions cause the Earth to warm, but no previous study has focused on examining how long it takes to reach maximum warming following a particular CO2 emission. Using conjoined results of carbon-cycle and physical-climate model intercomparison projects (Taylor et al 2012, Joos et al 2013), we find the median time between an emission and maximum warming is 10.1 years, with a 90% probability range of 6.6-30.7 years. We evaluate uncertainties in timing and amount of warming, partitioning them into three contributing factors: carbon cycle, climate sensitivity and ocean thermal inertia. If uncertainty in any one factor is reduced to zero without reducing uncertainty in the other factors, the majority of overall uncertainty remains. Thus, narrowing uncertainty in century-scale warming depends on narrowing uncertainty in all contributing factors. Our results indicate that benefit from avoided climate damage from avoided CO2 emissions will be manifested within the lifetimes of people who acted to avoid that emission. While such avoidance could be expected to benefit future generations, there is potential for emissions avoidance to provide substantial benefit to current generations.

Numerical approach of collision avoidance and optimal control on robotic manipulators

NASA Technical Reports Server (NTRS)

Wang, Jyhshing Jack

1990-01-01

Collision-free optimal motion and trajectory planning for robotic manipulators are solved by a method of sequential gradient restoration algorithm. Numerical examples of a two degree-of-freedom (DOF) robotic manipulator are demonstrated to show the excellence of the optimization technique and obstacle avoidance scheme. The obstacle is put on the midway, or even further inward on purpose, of the previous no-obstacle optimal trajectory. For the minimum-time purpose, the trajectory grazes by the obstacle and the minimum-time motion successfully avoids the obstacle. The minimum-time is longer for the obstacle avoidance cases than the one without obstacle. The obstacle avoidance scheme can deal with multiple obstacles in any ellipsoid forms by using artificial potential fields as penalty functions via distance functions. The method is promising in solving collision-free optimal control problems for robotics and can be applied to any DOF robotic manipulators with any performance indices and mobile robots as well. Since this method generates optimum solution based on Pontryagin Extremum Principle, rather than based on assumptions, the results provide a benchmark against which any optimization techniques can be measured.

Mild Palladium Catalyzed ortho C-H Bond Functionalizations of Aniline Derivatives.

PubMed

Tischler, Ms Orsolya; Tóth, Mr Balázs; Novák, Zoltán

2017-02-01

This account collects the developments and transformations which avoid the utilization of harsh reaction conditions in the field of palladium catalyzed, ortho-directed C-H activation of aniline derivatives from the first attempts to up-to-date results, including the results of our research laboratory. The discussed functionalizations performed under mild conditions include acylation, olefination, arylation, alkylation, alkoxylation reactions. Beside the optimization studies and the synthetic applications mechanistic investigations are also presented. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimized spectroscopic scheme for enhanced precision CO measurements with applications to urban source attribution

NASA Astrophysics Data System (ADS)

Nottrott, A.; Hoffnagle, J.; Farinas, A.; Rella, C.

2014-12-01

Carbon monoxide (CO) is an urban pollutant generated by internal combustion engines which contributes to the formation of ground level ozone (smog). CO is also an excellent tracer for emissions from mobile combustion sources. In this work we present an optimized spectroscopic sampling scheme that enables enhanced precision CO measurements. The scheme was implemented on the Picarro G2401 Cavity Ring-Down Spectroscopy (CRDS) analyzer which measures CO2, CO, CH4 and H2O at 0.2 Hz. The optimized scheme improved the raw precision of CO measurements by 40% from 5 ppb to 3 ppb. Correlations of measured CO2, CO, CH4 and H2O from an urban tower were partitioned by wind direction and combined with a concentration footprint model for source attribution. The application of a concentration footprint for source attribution has several advantages. The upwind extent of the concentration footprint for a given sensor is much larger than the flux footprint. Measurements of mean concentration at the sensor location can be used to estimate source strength from a concentration footprint, while measurements of the vertical concentration flux are necessary to determine source strength from the flux footprint. Direct measurement of vertical concentration flux requires high frequency temporal sampling and increases the cost and complexity of the measurement system.

Cooperative Position Aware Mobility Pattern of AUVs for Avoiding Void Zones in Underwater WSNs

PubMed Central

Javaid, Nadeem; Ejaz, Mudassir; Abdul, Wadood; Alamri, Atif; Almogren, Ahmad; Niaz, Iftikhar Azim; Guizani, Nadra

2017-01-01

In this paper, we propose two schemes; position-aware mobility pattern (PAMP) and cooperative PAMP (Co PAMP). The first one is an optimization scheme that avoids void hole occurrence and minimizes the uncertainty in the position estimation of glider’s. The second one is a cooperative routing scheme that reduces the packet drop ratio by using the relay cooperation. Both techniques use gliders that stay at sojourn positions for a predefined time, at sojourn position self-confidence (s-confidence) and neighbor-confidence (n-confidence) regions that are estimated for balanced energy consumption. The transmission power of a glider is adjusted according to those confidence regions. Simulation results show that our proposed schemes outperform the compared existing one in terms of packet delivery ratio, void zones and energy consumption. PMID:28335377

Optimization by means of an analytical heat transfer model of a thermal insulation for CSP applications based on radiative shields

NASA Astrophysics Data System (ADS)

Gaetano, A.; Roncolato, J.; Montorfano, D.; Barbato, M. C.; Ambrosetti, G.; Pedretti, A.

2016-05-01

The employment of new gaseous heat transfer fluids as air or CO2, which are cheaper and environmentally friendly, is drawing more and more attention within the field of Concentrated Solar Power applications. However, despite the advantages, their use requires receivers with a larger heat transfer area and flow cross section with a consequent greater volume of thermal insulation. Solid thermal insulations currently used present high thermal inertia which is energetically penalizing during the daily transient phases faced by the main plant components (e.g. receivers). With the aim of overcoming this drawback a thermal insulation based on radiative shields is presented in this study. Starting from an initial layout comprising a solid thermal insulation layer, the geometry was optimized avoiding the use of the solid insulation keeping performance and fulfilling the geometrical constraints. An analytical Matlab model was implemented to assess the system thermal behavior in terms of heat loss taking into account conductive, convective and radiative contributions. Accurate 2D Computational Fluid Dynamics (CFD) simulations were run to validate the Matlab model which was then used to select the most promising among three new different designs.

Regolith Volatile Characterization (RVC) in RESOLVE

NASA Technical Reports Server (NTRS)

Captain, Janine; Lueck, Dale; Gibson, Tracy; Levine, Lanfang

2010-01-01

Resource investigation in the lunar poles is of importance to the potential impact of in-situ resource utilization (ISRU). The RESOLVE project developed a payload to investigate the permanently shadowed areas of the lunar poles and demonstrate ISRU technology. As a part of the RESOLVE project, the regolith volatile characterization (RVC) subsystem was designed to examine the release of volatiles from sample cores. The test sample was heated in the reactor to release the volatiles where they were analyzed with gas chromatography. Subsequently, the volatile sample was introduced into the lunar water resource demonstration (LWRD) subsystem where the released hydrogen and water were selectively captured. The objective of the Regolith Volatile Characterization (RVC) subsystem was to heat the crushed core sample and determine the desorption of volatile species of interest. The RVC subsystem encompasses the reactor and the system for volatile analysis. The system was designed to analyze H2, He, CO, CO2, N2, 02, CH4, H2S and H2O. The GC chosen for this work is a Siemens MicroSAM process GC with 3 columns and 8 TCD detectors. Neon was chosen as the carrier gas to enhance the analysis of hydrogen and helium.The limit of detection for the gases is approx.1000ppm for H2, CO. CO2 , N2, O2 and H2 S. The limit of detection for CH4 is approx.4000ppm and the water limit of detection is -10000 ppm with a sample analysis time of 2-3 minutes. These values (with the exception of water and H2S) were determined by dilution of a six gas mixture from Scott Gas (5% CO2, CO, O2, N2, 4% CH4 and H2) using mass flow controllers (MFC5). Water was calibrated at low levels using an in house relative humidity (RH) generator. H 2S and high concentrations of H2 were calibrated by diluting a pure stream of gas with MFCs. Higher concentrations of N2 and 02 were calibrated using Air again diluting with MFCs. There were three modification goals for the GC in EBU2 that would allow this process GC to be used in the field demo for RESOLVE. The first modification was to decrease the weight associated with the GC, this included eliminating the explosion proof case (Figure 1) and replacing it with a lightweight case as well as using an on board COPV tank for the neon carrier gas. The next goal was to add a second oven for the molecular sieve column to allow for dual temperature control during GC operation; the separation of hydrogen and helium is optimum at lower temperatures while the water analysis required higher temperatures creating a competing design requirement. The second oven also allows a lower limit of detection for water quantification and avoids the possibility of water condensing in the GC which could ruin the column characteristics. The final goal was to modify the column arrangement to optimize the system for our specific application. Figure 2 shows the internal details of the module optimized optimized for our field application. The modifications and performance of the gas analysis system will be discussed in detail.

Development of WRF-CO2 4DVAR Data Assimilation System

NASA Astrophysics Data System (ADS)

Zheng, T.; French, N. H. F.

2016-12-01

Four dimensional variational (4DVar) assimilation systems have been widely used for CO2 inverse modeling at global scale. At regional scale, however, 4DVar assimilation systems have been lacking. At present, most regional CO2 inverse models use Lagrangian particle backward trajectory tools to compute influence function in an analytical/synthesis framework. To provide a 4DVar based alternative, we developed WRF-CO2 4DVAR based on Weather Research and Forecasting (WRF), its chemistry extension (WRF-Chem), and its data assimilation system (WRFDA/WRFPLUS). Different from WRFDA, WRF-CO2 4DVAR does not optimize meteorology initial condition, instead it solves for the optimized CO2 surface fluxes (sources/sink) constrained by atmospheric CO2 observations. Based on WRFPLUS, we developed tangent linear and adjoint code for CO2 emission, advection, vertical mixing in boundary layer, and convective transport. Furthermore, we implemented an incremental algorithm to solve for optimized CO2 emission scaling factors by iteratively minimizing the cost function in a Bayes framework. The model sensitivity (of atmospheric CO2 with respect to emission scaling factor) calculated by tangent linear and adjoint model agrees well with that calculated by finite difference, indicating the validity of the newly developed code. The effectiveness of WRF-CO2 4DVar for inverse modeling is tested using forward-model generated pseudo-observation data in two experiments: first-guess CO2 fluxes has a 50% overestimation in the first case and 50% underestimation in the second. In both cases, WRF-CO2 4DVar reduces cost function to less than 10-4 of its initial values in less than 20 iterations and successfully recovers the true values of emission scaling factors. We expect future applications of WRF-CO2 4DVar with satellite observations will provide insights for CO2 regional inverse modeling, including the impacts of model transport error in vertical mixing.

Co-regulation of photosynthetic processes under potassium deficiency across CO2 levels in soybean: mechanisms of limitations and adaptations

USDA-ARS?s Scientific Manuscript database

Plants photosynthesis-related traits are often co-regulated to capture light and CO2 to optimize the rate of CO2 fixation (A) via photo-biochemical processes. However, potassium (K) limitations and adaptations strategies of photosynthetic processes across CO2 levels are not well understood. To evalu...

One step synthesis of Co/Cr-codoped ZnO nanoparticle with superb adsorption properties for various anionic organic pollutants and its regeneration.

PubMed

Li, Zhenjiang; Sun, Yongkai; Xing, Jing; Xing, Yucheng; Meng, Alan

2018-06-15

Adsorption is an effective means to remove organic pollutant. However, it is challenging to prepare the adsorbents with high adsorption capacities and their regeneration. Herein, Co/Cr-codoped ZnO nanoparticles (NPs) with superb adsorption for dyes and antibiotics have been successfully synthesized by a mild solvothermal method. At the optimal Co:Cr:Zn doping moral ratio of 4:6:100, the maximum adsorption capacities of methyl orange (MO) and tetracycline hydrochloride (TC-HCl) on Co/Cr-codoped ZnO NPs is 1057.90 mg g -1 and 874.46 mg g -1 , respectively. The adsorption process of the sample over MO and TC-HCl both agreed well with the pseudo-second-order kinetic model and Langmuir isotherm model. Adsorption thermodynamics proved that the adsorption of MO and TC-HCl on Co/Cr-codoped ZnO NPs was a spontaneous and endothermic process. The mechanism shows that the surface of Co/Cr-codoped ZnO NPs have more positive charges, larger specific surface area and more crystal defects due to Co 3+ and Cr 3+ substitutes Zn 2+ in ZnO lattice, improving their adsorption property. In addition, Co/Cr-codoped ZnO NPs have also excellent adsorption capacity for Direct Red, Congo Red, Evans Blue and Methyl Blue. More importantly, the regeneration of adsorbents was studied to achieve the reuse of materials, and avoid secondary pollution. Co/Cr-codoped ZnO NPs will be a promising choice for wastewater treatment owing to its excellent adsorption capacity and relatively low cost. Copyright © 2018 Elsevier B.V. All rights reserved.

Efficiency enhancement for natural gas liquefaction with CO2 capture and sequestration through cycles innovation and process optimization

NASA Astrophysics Data System (ADS)

Alabdulkarem, Abdullah

Liquefied natural gas (LNG) plants are energy intensive. As a result, the power plants operating these LNG plants emit high amounts of CO2 . To mitigate global warming that is caused by the increase in atmospheric CO2, CO2 capture and sequestration (CCS) using amine absorption is proposed. However, the major challenge of implementing this CCS system is the associated power requirement, increasing power consumption by about 15--25%. Therefore, the main scope of this work is to tackle this challenge by minimizing CCS power consumption as well as that of the entire LNG plant though system integration and rigorous optimization. The power consumption of the LNG plant was reduced through improving the process of liquefaction itself. In this work, a genetic algorithm (GA) was used to optimize a propane pre-cooled mixed-refrigerant (C3-MR) LNG plant modeled using HYSYS software. An optimization platform coupling Matlab with HYSYS was developed. New refrigerant mixtures were found, with savings in power consumption as high as 13%. LNG plants optimization with variable natural gas feed compositions was addressed and the solution was proposed through applying robust optimization techniques, resulting in a robust refrigerant which can liquefy a range of natural gas feeds. The second approach for reducing the power consumption is through process integration and waste heat utilization in the integrated CCS system. Four waste heat sources and six potential uses were uncovered and evaluated using HYSYS software. The developed models were verified against experimental data from the literature with good agreement. Net available power enhancement in one of the proposed CCS configuration is 16% more than the conventional CCS configuration. To reduce the CO2 pressurization power into a well for enhanced oil recovery (EOR) applications, five CO2 pressurization methods were explored. New CO2 liquefaction cycles were developed and modeled using HYSYS software. One of the developed liquefaction cycles using NH3 as a refrigerant resulted in 5% less power consumption than the conventional multi-stage compression cycle. Finally, a new concept of providing the CO2 regeneration heat is proposed. The proposed concept is using a heat pump to provide the regeneration heat as well as process heat and CO2 liquefaction heat. Seven configurations of heat pumps integrated with CCS were developed. One of the heat pumps consumes 24% less power than the conventional system or 59% less total equivalent power demand than the conventional system with steam extraction and CO2 compression.

A Machine-Learning and Filtering Based Data Assimilation Framework for Geologic Carbon Sequestration Monitoring Optimization

NASA Astrophysics Data System (ADS)

Chen, B.; Harp, D. R.; Lin, Y.; Keating, E. H.; Pawar, R.

2017-12-01

Monitoring is a crucial aspect of geologic carbon sequestration (GCS) risk management. It has gained importance as a means to ensure CO2 is safely and permanently stored underground throughout the lifecycle of a GCS project. Three issues are often involved in a monitoring project: (i) where is the optimal location to place the monitoring well(s), (ii) what type of data (pressure, rate and/or CO2 concentration) should be measured, and (iii) What is the optimal frequency to collect the data. In order to address these important issues, a filtering-based data assimilation procedure is developed to perform the monitoring optimization. The optimal monitoring strategy is selected based on the uncertainty reduction of the objective of interest (e.g., cumulative CO2 leak) for all potential monitoring strategies. To reduce the computational cost of the filtering-based data assimilation process, two machine-learning algorithms: Support Vector Regression (SVR) and Multivariate Adaptive Regression Splines (MARS) are used to develop the computationally efficient reduced-order-models (ROMs) from full numerical simulations of CO2 and brine flow. The proposed framework for GCS monitoring optimization is demonstrated with two examples: a simple 3D synthetic case and a real field case named Rock Spring Uplift carbon storage site in Southwestern Wyoming.

Design and elaboration of freeze-dried PLGA nanoparticles for the transcorneal permeation of carprofen: Ocular anti-inflammatory applications.

PubMed

Parra, Alexander; Mallandrich, Mireia; Clares, Beatriz; Egea, María A; Espina, Marta; García, María L; Calpena, Ana C

2015-12-01

This work aimed the design and development of poly(lactic-co-glycolic) acid (PLGA) nanoparticles (NPs) for the ocular delivery of Carprofen (CP) by a central rotatable composite design 2(3)+ star. NPs showed adequate size for ocular administration (189.50 ± 1.67 nm), low polydispersity (0.01 ± 0.01), negative charge surface (-22.80 ± 0.66 mV) and optimal entrapment efficiency (74.70 ± 0.95%). Physicochemical analysis confirmed that CP was dispersed inside the NPs. The drug release followed a first order kinetic model providing greater sustained CP release after lyophilization. Ex vivo permeation analysis through isolated rabbit cornea revealed that a sufficient amount of CP was retained in the tissue avoiding excessive permeation and thus, potential systemic levels. Ex vivo ocular tolerance results showed no signs of ocular irritancy, which was also confirmed by in vivo Draize test. In vivo ocular anti-inflammatory efficacy test confirmed an optimal efficacy of NPs and its potential application in eye surgery. Copyright © 2015 Elsevier B.V. All rights reserved.

Emotional Avoidance and Panicogenic Responding to a Biological Challenge Procedure

ERIC Educational Resources Information Center

Karekla, Maria; Forsyth, John P.; Kelly, Megan M.

2004-01-01

Healthy undergraduates high (n = 27) and low (n = 27) in experiential avoidance underwent twelve 20 s inhalations of 20% carbon dioxide-enriched air, while physiological (e.g., skin conductance, heart rate, EMG, and end-tidal CO[subscript 2]) and subjective (e.g., subjective units of distress, evaluative ratings, number and severity of panic…

An optimal control strategy for collision avoidance of mobile robots in non-stationary environments

NASA Technical Reports Server (NTRS)

Kyriakopoulos, K. J.; Saridis, G. N.

1991-01-01

An optimal control formulation of the problem of collision avoidance of mobile robots in environments containing moving obstacles is presented. Collision avoidance is guaranteed if the minimum distance between the robot and the objects is nonzero. A nominal trajectory is assumed to be known from off-line planning. The main idea is to change the velocity along the nominal trajectory so that collisions are avoided. Furthermore, time consistency with the nominal plan is desirable. A numerical solution of the optimization problem is obtained. Simulation results verify the value of the proposed strategy.

The conversion of CO 2 to methanol on orthorhombic β-Mo 2C and Cu/β-Mo 2C catalysts: Mechanism for admetal induced change in the selectivity and activity

DOE PAGES

Posada-Pérez, Sergio; Ramírez, Pedro J.; Gutiérrez, Ramón A.; ...

2016-02-01

Here, the conversion of CO 2 into methanol catalyzed by β-Mo 2C and Cu/β-Mo 2C surfaces has been investigated by means of a combined experimental and theoretical study. Experiments have shown the direct activation and dissociation of the CO 2 molecule on bare β-Mo 2C, whereas on Cu/β-Mo 2C, CO 2 must be assisted by hydrogen for its conversion. Methane and CO are the main products on the clean surface and methanol production is lower. However, the deposition of Cu clusters avoids methane formation and increases methanol production even above that corresponding to a model of the technical catalyst. DFTmore » calculations on surface models of both possible C- and Mo-terminations corroborate the experimental observations. Calculations for the clean Mo-terminated surface reveal the existence of two possible routes for methane production (C + 4H → CH 4; CH 3O + 3H → CH 4 + H 2O) which are competitive with methanol synthesis, displaying slightly lower energy barriers. On the other hand, a model for Cu deposited clusters on the Mo-terminated surface points towards a new route for methanol and CO production avoiding methane formation. The new route is a direct consequence of the generation of a Mo 2C–Cu interface. The present experimental and theoretical results entail the interesting catalytic properties of Mo 2C as an active support of metallic nanoparticles, and also illustrate how the deposition of a metal can drastically change the activity and selectivity of a carbide substrate for CO 2 hydrogenation.« less

Technoeconomic Assessment of an Advanced Aqueous Ammonia-Based Postcombustion Capture Process Integrated with a 650-MW Coal-Fired Power Station.

PubMed

Li, Kangkang; Yu, Hai; Yan, Shuiping; Feron, Paul; Wardhaugh, Leigh; Tade, Moses

2016-10-04

Using a rigorous, rate-based model and a validated economic model, we investigated the technoeconomic performance of an aqueous NH 3 -based CO 2 capture process integrated with a 650-MW coal-fired power station. First, the baseline NH 3 process was explored with the process design of simultaneous capture of CO 2 and SO 2 to replace the conventional FGD unit. This reduced capital investment of the power station by US$425/kW (a 13.1% reduction). Integration of this NH 3 baseline process with the power station takes the CO 2 -avoided cost advantage over the MEA process (US$67.3/tonne vs US$86.4/tonne). We then investigated process modifications of a two-stage absorption, rich-split configuration and interheating stripping to further advance the NH 3 process. The modified process reduced energy consumption by 31.7 MW/h (20.2% reduction) and capital costs by US$55.4 million (6.7% reduction). As a result, the CO 2 -avoided cost fell to $53.2/tonne: a savings of $14.1 and $21.9/tonne CO 2 compared with the NH 3 baseline and advanced MEA process, respectively. The analysis of energy breakdown and cost distribution indicates that the technoeconomic performance of the NH 3 process still has great potential to be improved.

Optimal motion planning for collision avoidance of mobile robots in non-stationary environments

NASA Technical Reports Server (NTRS)

Kyriakopoulos, K. J.; Saridis, G. N.

1992-01-01

An optimal control formulation of the problem of collision avoidance of mobile robots moving in general terrains containing moving obstacles is presented. A dynamic model of the mobile robot and the dynamic constraints are derived. Collision avoidance is guaranteed if the minimum distance between the robot and the object is nonzero. A nominal trajectory is assumed to be known from off-line planning. The main idea is to change the velocity along the nominal trajectory so that collisions are avoided. Time consistency with the nominal plan is desirable. A numerical solution of the optimization problem is obtained. A perturbation control type of approach is used to update the optimal plan. Simulation results verify the value of the proposed strategy.

Rapid and enhanced activation of microporous coordination polymers by flowing supercritical CO.sub.2

DOEpatents

Matzger, Adam J.; Liu, Baojian; Wong-Foy, Antek G.

2016-07-19

Flowing supercritical CO.sub.2 is used to activate metal organic framework materials (MOF). MOFs are activated directly from N,N-dimethylformamide (DMF) thus avoiding exchange with a volatile solvent. Most MCPs display increased surface areas directly after treatment although those with coordinatively unsaturated metal centers benefit from additional heating.

Design of a secondary ionization target for direct production of a C- beam from CO2 pulses for online AMS.

PubMed

Salazar, Gary; Ognibene, Ted

2013-01-01

We designed and optimized a novel device "target" that directs a CO 2 gas pulse onto a Ti surface where a Cs + beam generates C - from the CO 2 . This secondary ionization target enables an accelerator mass spectrometer to ionize pulses of CO 2 in the negative mode to measure 14 C/ 12 C isotopic ratios in real time. The design of the targets were based on computational flow dynamics, ionization mechanism and empirical optimization. As part of the ionization mechanism, the adsorption of CO 2 on the Ti surface was fitted with the Jovanovic-Freundlich isotherm model using empirical and simulation data. The inferred adsorption constants were in good agreement with other works. The empirical optimization showed that amount of injected carbon and the flow speed of the helium carrier gas improve the ionization efficiency and the amount of 12 C - produced until reaching a saturation point. Linear dynamic range between 150 and 1000 ng of C and optimum carrier gas flow speed of around 0.1 mL/min were shown. It was also shown that the ionization depends on the area of the Ti surface and Cs + beam cross-section. A range of ionization efficiency of 1-2.5% was obtained by optimizing the described parameters.

Receptor-type guanylate cyclase is required for carbon dioxide sensation by Caenorhabditis elegans.

PubMed

Hallem, Elissa A; Spencer, W Clay; McWhirter, Rebecca D; Zeller, Georg; Henz, Stefan R; Rätsch, Gunnar; Miller, David M; Horvitz, H Robert; Sternberg, Paul W; Ringstad, Niels

2011-01-04

CO(2) is both a critical regulator of animal physiology and an important sensory cue for many animals for host detection, food location, and mate finding. The free-living soil nematode Caenorhabditis elegans shows CO(2) avoidance behavior, which requires a pair of ciliated sensory neurons, the BAG neurons. Using in vivo calcium imaging, we show that CO(2) specifically activates the BAG neurons and that the CO(2)-sensing function of BAG neurons requires TAX-2/TAX-4 cyclic nucleotide-gated ion channels and the receptor-type guanylate cyclase GCY-9. Our results delineate a molecular pathway for CO(2) sensing and suggest that activation of a receptor-type guanylate cyclase is an evolutionarily conserved mechanism by which animals detect environmental CO(2).

New approaches to optimization in aerospace conceptual design

NASA Technical Reports Server (NTRS)

Gage, Peter J.

1995-01-01

Aerospace design can be viewed as an optimization process, but conceptual studies are rarely performed using formal search algorithms. Three issues that restrict the success of automatic search are identified in this work. New approaches are introduced to address the integration of analyses and optimizers, to avoid the need for accurate gradient information and a smooth search space (required for calculus-based optimization), and to remove the restrictions imposed by fixed complexity problem formulations. (1) Optimization should be performed in a flexible environment. A quasi-procedural architecture is used to conveniently link analysis modules and automatically coordinate their execution. It efficiently controls a large-scale design tasks. (2) Genetic algorithms provide a search method for discontinuous or noisy domains. The utility of genetic optimization is demonstrated here, but parameter encodings and constraint-handling schemes must be carefully chosen to avoid premature convergence to suboptimal designs. The relationship between genetic and calculus-based methods is explored. (3) A variable-complexity genetic algorithm is created to permit flexible parameterization, so that the level of description can change during optimization. This new optimizer automatically discovers novel designs in structural and aerodynamic tasks.

Reactive Collision Avoidance Algorithm

NASA Technical Reports Server (NTRS)

Scharf, Daniel; Acikmese, Behcet; Ploen, Scott; Hadaegh, Fred

2010-01-01

The reactive collision avoidance (RCA) algorithm allows a spacecraft to find a fuel-optimal trajectory for avoiding an arbitrary number of colliding spacecraft in real time while accounting for acceleration limits. In addition to spacecraft, the technology can be used for vehicles that can accelerate in any direction, such as helicopters and submersibles. In contrast to existing, passive algorithms that simultaneously design trajectories for a cluster of vehicles working to achieve a common goal, RCA is implemented onboard spacecraft only when an imminent collision is detected, and then plans a collision avoidance maneuver for only that host vehicle, thus preventing a collision in an off-nominal situation for which passive algorithms cannot. An example scenario for such a situation might be when a spacecraft in the cluster is approaching another one, but enters safe mode and begins to drift. Functionally, the RCA detects colliding spacecraft, plans an evasion trajectory by solving the Evasion Trajectory Problem (ETP), and then recovers after the collision is avoided. A direct optimization approach was used to develop the algorithm so it can run in real time. In this innovation, a parameterized class of avoidance trajectories is specified, and then the optimal trajectory is found by searching over the parameters. The class of trajectories is selected as bang-off-bang as motivated by optimal control theory. That is, an avoiding spacecraft first applies full acceleration in a constant direction, then coasts, and finally applies full acceleration to stop. The parameter optimization problem can be solved offline and stored as a look-up table of values. Using a look-up table allows the algorithm to run in real time. Given a colliding spacecraft, the properties of the collision geometry serve as indices of the look-up table that gives the optimal trajectory. For multiple colliding spacecraft, the set of trajectories that avoid all spacecraft is rapidly searched on-line. The optimal avoidance trajectory is implemented as a receding-horizon model predictive control law. Therefore, at each time step, the optimal avoidance trajectory is found and the first time step of its acceleration is applied. At the next time step of the control computer, the problem is re-solved and the new first time step is again applied. This continual updating allows the RCA algorithm to adapt to a colliding spacecraft that is making erratic course changes.

Optimizing Binding Energies of Key Intermediates for CO 2 Hydrogenation to Methanol over Oxide-Supported Copper

DOE PAGES

None, None

2016-08-29

Rational optimization of catalytic performance has been one of the major challenges in catalysis. We report a bottom-up study on the ability of TiO 2 and ZrO 2 to optimize the CO 2 conversion to methanol on Cu, using combined density functional theory (DFT) calculations, kinetic Monte Carlo (KMC) simulations, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements, and steady-state flow reactor tests. Furthermore, the theoretical results from DFT and KMC agree with in situ DRIFTS measurements, showing that both TiO 2 and ZrO 2 help to promote methanol synthesis on Cu via carboxyl intermediates and the reversemore » water–gas-shift (RWGS) pathway; the formate intermediates, on the other hand, likely act as a spectator eventually. The origin of the superior promoting effect of ZrO 2 is associated with the fine-tuning capability of reduced Zr 3+ at the interface, being able to bind the key reaction intermediates, e.g. *CO 2, *CO, *HCO, and *H 2CO, moderately to facilitate methanol formation. Our study demonstrates the importance of synergy between theory and experiments to elucidate the complex reaction mechanisms of CO 2 hydrogenation for the realization of a better catalyst by design.« less

Preparation, optimization, and evaluation of Zaltoprofen-loaded microemulsion and microemulsion-based gel for transdermal delivery.

PubMed

Mishra, Ratnesh; Prabhavalkar, Kedar S; Bhatt, Lokesh Kumar

2016-12-01

Zaltoprofen, a non-steroidal anti-inflammatory drug, has potent inhibitory action against nociceptive responses. However, gastrointestinal ulcer accompanied with anemia due to the bleeding are most cited side effects associated with it. Due to this, administration of Zaltoprofen is not suitable for individuals with gastric ulcer. Thus, there is unmet need to develop an alternative delivery system that will be easy to administer and can avoid ulcerogenic side effects associated with it. Present study was aimed to prepare and evaluate microemulsion (ME) and microemulsion-based gel formulation of Zaltoprofen for transdermal delivery. Pseudo-ternary phase diagrams were utilized to prepare ME formulations. Effect of surfactant and co-surfactant mass ratio on the ME formation and permeation of ME were evaluated and formulation was optimized. Permeation studies were performed using excised pigskin was studied. Efficacy of optimized formulations was evaluated in rat model of inflammation and pain. Composition of optimized formulation was 1% (w/w) Zaltoprofen, 20% (w/w) Capryol 90, 50% (w/w) Smix (2:1, Cremophor RH 40 and Transcutol P). Optimized formulation showed globule size of 22.11 nm, polydispersity index of 0.251 and zeta potential of -11.4 mV. ME gel was found safe in skin irritation study. Significant analgesic activity and anti-inflammatory activity of ME gel was observed in hot plate test and rat paw edema test, respectively. In conclusion, results of present study suggest that ME could be a promising formulation for transdermal administration of Zaltoprofen.

Thermal protection during percutaneous thermal ablation procedures: interest of carbon dioxide dissection and temperature monitoring.

PubMed

Buy, Xavier; Tok, Chung-Hong; Szwarc, Daniel; Bierry, Guillaume; Gangi, Afshin

2009-05-01

Percutaneous image-guided thermal ablation of tumor is widely used, and thermal injury to collateral structures is a known complication of this technique. To avoid thermal damage to surrounding structures, several protection techniques have been reported. We report the use of a simple and effective protective technique combining carbon dioxide dissection and thermocouple: CO(2) displaces the nontarget structures, and its low thermal conductivity provides excellent insulation; insertion of a thermocouple in contact with vulnerable structures achieves continuous thermal monitoring. We performed percutaneous thermal ablation of 37 tumors in 35 patients (4 laser, 10 radiofrequency, and 23 cryoablations) with protection of adjacent vulnerable structures by using CO(2) dissection combined with continuous thermal monitoring with thermocouple. Tumor locations were various (19 intra-abdominal tumors including 4 livers and 9 kidneys, 18 musculoskeletal tumors including 11 spinal tumors). CO(2) volume ranged from 10 ml (epidural space) to 1500 ml (abdominal). Repeated insufflations were performed if necessary, depending on the information given by the thermocouple and imaging control. Dissection with optimal thermal protection was achieved in all cases except two patients where adherences (one postoperative, one arachnoiditis) blocked proper gaseous distribution. No complication referred to this technique was noted. This safe, cost-effective, and simple method increases the safety and the success rate of percutaneous thermal ablation procedures. It also offers the potential to increase the number of tumors that can be treated via a percutaneous approach.

Homogeneous Reduction of Carbon Dioxide with Hydrogen.

PubMed

Dong, Kaiwu; Razzaq, Rauf; Hu, Yuya; Ding, Kuiling

2017-04-01

Carbon dioxide (CO 2 ), a key greenhouse gas produced from both anthropogenic and natural sources, has been recently considered to be an important C1 building-block for the synthesis of many industrial fuels and chemicals. Catalytic hydrogenation of CO 2 using a homogeneous system is regarded as an efficient process for CO 2 valorization. This approach leads to the direct products including formic acid (HCOOH), carbon monoxide (CO), methanol (MeOH), and methane (CH 4 ). The hydrogenation of CO 2 to CO followed by alkene carbonylation provides value-added compounds, which also avoids the tedious separation and transportation of toxic CO. Moreover, the reduction of CO 2 with H 2 in the presence of amines is of significance to attain fine chemicals through catalytic formylation and methylation reactions. The synthesis of higher alcohols and dialkoxymethane from CO 2 and H 2 has been demonstrated recently, which opens access to new molecular structures using CO 2 as an important C1 source.

Quantifying the Contribution of Urban-Industrial Efficiency and Symbiosis to Deep Decarbonization: Impact of 637 Chinese Cities

NASA Astrophysics Data System (ADS)

Ramaswami, A.; Tong, K.; Fang, A.; Lal, R.; Nagpure, A.; Li, Y.; Yu, H.; Jiang, D.; Russell, A. G.; Shi, L.; Chertow, M.; Wang, Y.; Wang, S.

2016-12-01

Urban activities in China contribute significantly to global greenhouse gas (GHG) emissions and to local air pollution-related health risks. Co-location analysis can help inform the potential for energy- and material-exchanges across homes, businesses, infrastructure and industries co-located in cities. Such co-location dependent urban-industrial symbiosis strategies offer a new pathway toward urban energy efficiency and health that have not previously been quantified. Key examples includes the use of waste industrial heat in other co-located industries, and in residential-commercial district heating-cooling systems of cities. To quantify the impact of these strategies: (1) We develop a new data-set of 637 Chinese cities to assess the potential for efficiency and symbiosis across co-located homes, businesses, industries and the energy and construction sectors in the different cities. (2) A multi-scalar urban systems model quantifies trans-boundary CO2 impacts as well as local health benefits of these uniquely urban, co-location-dependent strategies. (3) CO2 impacts are aggregated across the 637 Chinese cities (home to 701 million people) to quantify national CO2 mitigation potential. (4) The local health benefits are modeled specific to each city and mapped geospatially to identify areas where co-benefits between GHG mitigation and health are maximized. Results: A first order conservative analysis of co-location dependent urban symbiosis indicates potential for reducing 6% of China's national total CO2 emissions in a relatively short time period, yielding a new pathway not previously considered in China's energy futures models. The magnitude of these reductions (6%) was similar in magnitude to sector specific industrial, power sector and buildings efficiency strategeies that together contributed 9% CO2 reduction aggregated across the nation. CO2 reductions mapped to the 637 cities ranged from <1% to 40%, depending upon co-location patterns, climate and other features of the cities. The modeled reductions in fossil-fuel use yield reductions in PM-2.5 emissions from <1% to 73%, depending on the city, and avoided annual mortality >40,000 premature deaths (avoided) across all cities. These results demonstrate the contribution urban symbiosis on decarbonization and health co-benefits.

Supercritical Carbon Dioxide Extraction of the Oak Silkworm (Antheraea pernyi) Pupal Oil: Process Optimization and Composition Determination

PubMed Central

Pan, Wen-Juan; Liao, Ai-Mei; Zhang, Jian-Guo; Dong, Zeng; Wei, Zhao-Jun

2012-01-01

Supercritical carbon dioxide (SC-CO2) extraction of oil from oak silkworm pupae was performed in the present research. Response surface methodology (RSM) was applied to optimize the parameters of SC-CO2 extraction, including extraction pressure, temperature, time and CO2 flow rate on the yield of oak silkworm pupal oil (OSPO). The optimal extraction condition for oil yield within the experimental range of the variables researched was at 28.03 MPa, 1.83 h, 35.31 °C and 20.26 L/h as flow rate of CO2. Under this condition, the oil yield was predicted to be 26.18%. The oak silkworm pupal oil contains eight fatty acids, and is rich in unsaturated fatty acids and α-linolenic acid (ALA), accounting for 77.29% and 34.27% in the total oil respectively. PMID:22408458

Empirically constrained estimates of Alaskan regional Net Ecosystem Exchange of CO2, 2012-2014

NASA Astrophysics Data System (ADS)

Commane, R.; Lindaas, J.; Benmergui, J. S.; Luus, K. A.; Chang, R. Y. W.; Miller, S. M.; Henderson, J.; Karion, A.; Miller, J. B.; Sweeney, C.; Miller, C. E.; Lin, J. C.; Oechel, W. C.; Zona, D.; Euskirchen, E. S.; Iwata, H.; Ueyama, M.; Harazono, Y.; Veraverbeke, S.; Randerson, J. T.; Daube, B. C.; Pittman, J. V.; Wofsy, S. C.

2015-12-01

We present data-driven estimates of the regional net ecosystem exchange of CO2 across Alaska for three years (2012-2014) derived from CARVE (Carbon in the Arctic Reservoirs Vulnerability Experiment) aircraft measurements. Integrating optimized estimates of annual NEE, we find that the Alaskan region was a small sink of CO2 during 2012 and 2014, but a significant source of CO2 in 2013, even before including emissions from the large forest fire season during 2013. We investigate the drivers of this interannual variability, and the larger spring and fall emissions of CO2 in 2013. To determine the optimized fluxes, we couple the Polar Weather Research and Forecasting (PWRF) model with the Stochastic Time-Inverted Lagrangian Transport (STILT) model, to produce footprints of surface influence that we convolve with a remote-sensing driven model of NEE across Alaska, the Polar Vegetation Photosynthesis and Respiration Model (Polar-VPRM). For each month we calculate a spatially explicit additive flux (ΔF) by minimizing the difference between the measured profiles of the aircraft CO2 data and the modeled profiles, using a framework that combines a uniform correction at regional scales and a Bayesian inversion of residuals at smaller scales. A rigorous estimate of total uncertainty (including atmospheric transport, measurement error, etc.) was made with a combination of maximum likelihood estimation and Monte Carlo error propagation. Our optimized fluxes are consistent with other measurements on multiple spatial scales, including CO2 mixing ratios from the CARVE Tower near Fairbanks and eddy covariance flux towers in both boreal and tundra ecosystems across Alaska. For times outside the aircraft observations (Dec-April) we use the un-optimized polar-VPRM, which has shown good agreement with both tall towers and eddy flux data outside the growing season. This approach allows us to robustly estimate the annual CO2 budget for Alaska and investigate the drivers of both the seasonal cycle and the interannual variability of CO2 for the region.

Manifold optimization-based analysis dictionary learning with an ℓ1∕2-norm regularizer.

PubMed

Li, Zhenni; Ding, Shuxue; Li, Yujie; Yang, Zuyuan; Xie, Shengli; Chen, Wuhui

2018-02-01

Recently there has been increasing attention towards analysis dictionary learning. In analysis dictionary learning, it is an open problem to obtain the strong sparsity-promoting solutions efficiently while simultaneously avoiding the trivial solutions of the dictionary. In this paper, to obtain the strong sparsity-promoting solutions, we employ the ℓ 1∕2 norm as a regularizer. The very recent study on ℓ 1∕2 norm regularization theory in compressive sensing shows that its solutions can give sparser results than using the ℓ 1 norm. We transform a complex nonconvex optimization into a number of one-dimensional minimization problems. Then the closed-form solutions can be obtained efficiently. To avoid trivial solutions, we apply manifold optimization to update the dictionary directly on the manifold satisfying the orthonormality constraint, so that the dictionary can avoid the trivial solutions well while simultaneously capturing the intrinsic properties of the dictionary. The experiments with synthetic and real-world data verify that the proposed algorithm for analysis dictionary learning can not only obtain strong sparsity-promoting solutions efficiently, but also learn more accurate dictionary in terms of dictionary recovery and image processing than the state-of-the-art algorithms. Copyright © 2017 Elsevier Ltd. All rights reserved.

CCS Site Optimization by Applying a Multi-objective Evolutionary Algorithm to Semi-Analytical Leakage Models

NASA Astrophysics Data System (ADS)

Cody, B. M.; Gonzalez-Nicolas, A.; Bau, D. A.

2011-12-01

Carbon capture and storage (CCS) has been proposed as a method of reducing global carbon dioxide (CO2) emissions. Although CCS has the potential to greatly retard greenhouse gas loading to the atmosphere while cleaner, more sustainable energy solutions are developed, there is a possibility that sequestered CO2 may leak and intrude into and adversely affect groundwater resources. It has been reported [1] that, while CO2 intrusion typically does not directly threaten underground drinking water resources, it may cause secondary effects, such as the mobilization of hazardous inorganic constituents present in aquifer minerals and changes in pH values. These risks must be fully understood and minimized before CCS project implementation. Combined management of project resources and leakage risk is crucial for the implementation of CCS. In this work, we present a method of: (a) minimizing the total CCS cost, the summation of major project costs with the cost associated with CO2 leakage; and (b) maximizing the mass of injected CO2, for a given proposed sequestration site. Optimization decision variables include the number of CO2 injection wells, injection rates, and injection well locations. The capital and operational costs of injection wells are directly related to injection well depth, location, injection flow rate, and injection duration. The cost of leakage is directly related to the mass of CO2 leaked through weak areas, such as abandoned oil wells, in the cap rock layers overlying the injected formation. Additional constraints on fluid overpressure caused by CO2 injection are imposed to maintain predefined effective stress levels that prevent cap rock fracturing. Here, both mass leakage and fluid overpressure are estimated using two semi-analytical models based upon work by [2,3]. A multi-objective evolutionary algorithm coupled with these semi-analytical leakage flow models is used to determine Pareto-optimal trade-off sets giving minimum total cost vs. maximum mass of CO2 sequestered. This heuristic optimization method is chosen because of its robustness in optimizing large-scale, highly non-linear problems. Trade-off curves are developed for multiple fictional sites with the intent of clarifying how variations in domain characteristics (aquifer thickness, aquifer and weak cap rock permeability, the number of weak cap rock areas, and the number of aquifer-cap rock layers) affect Pareto-optimal fronts. Computational benefits of using semi-analytical leakage models are explored and discussed. [1] Birkholzer, J. (2008) "Research Project on CO2 Geological Storage and Groundwater Resources: Water Quality Effects Caused by CO2 Intrusion into Shallow Groundwater" Berkeley (CA): Lawrence Berkeley National Laboratory (US); 2008 Oct. 473 p. Report No.: 510-486-7134. [2] Celia, M.A. and Nordbotten, J.M. (2011) "Field-scale application of a semi-analytical model for estimation of CO2 and brine leakage along old wells" International Journal of Greenhouse Gas Control, 5 (2011), 257-269. [3] Nordbotten, J.M. and Celia, M.A. (2009) "Model for CO2 leakage including multiple geological layers and multiple leaky wells" Environ. Sci. Technol., 43, 743-749.

Assessing CO2 Mitigation Options Utilizing Detailed Electricity Characteristics and Including Renewable Generation

NASA Astrophysics Data System (ADS)

Bensaida, K.; Alie, Colin; Elkamel, A.; Almansoori, A.

2017-08-01

This paper presents a novel techno-economic optimization model for assessing the effectiveness of CO2 mitigation options for the electricity generation sub-sector that includes renewable energy generation. The optimization problem was formulated as a MINLP model using the GAMS modeling system. The model seeks the minimization of the power generation costs under CO2 emission constraints by dispatching power from low CO2 emission-intensity units. The model considers the detailed operation of the electricity system to effectively assess the performance of GHG mitigation strategies and integrates load balancing, carbon capture and carbon taxes as methods for reducing CO2 emissions. Two case studies are discussed to analyze the benefits and challenges of the CO2 reduction methods in the electricity system. The proposed mitigations options would not only benefit the environment, but they will as well improve the marginal cost of producing energy which represents an advantage for stakeholders.

Optimal distribution of borehole geophones for monitoring CO2-injection-induced seismicity

NASA Astrophysics Data System (ADS)

Huang, L.; Chen, T.; Foxall, W.; Wagoner, J. L.

2016-12-01

The U.S. DOE initiative, National Risk Assessment Partnership (NRAP), aims to develop quantitative risk assessment methodologies for carbon capture, utilization and storage (CCUS). As part of tasks of the Strategic Monitoring Group of NRAP, we develop a tool for optimal design of a borehole geophones distribution for monitoring CO2-injection-induced seismicity. The tool consists of a number of steps, including building a geophysical model for a given CO2 injection site, defining target monitoring regions within CO2-injection/migration zones, generating synthetic seismic data, giving acceptable uncertainties in input data, and determining the optimal distribution of borehole geophones. We use a synthetic geophysical model as an example to demonstrate the capability our new tool to design an optimal/cost-effective passive seismic monitoring network using borehole geophones. The model is built based on the geologic features found at the Kimberlina CCUS pilot site located in southern San Joaquin Valley, California. This tool can provide CCUS operators with a guideline for cost-effective microseismic monitoring of geologic carbon storage and utilization.

A Study on the Optimal Generation Mix Based on Portfolio Theory with Considering the Basic Condition for Power Supply

NASA Astrophysics Data System (ADS)

Kato, Moritoshi; Zhou, Yicheng

This paper presents a novel method to analyze the optimal generation mix based on portfolio theory with considering the basic condition for power supply, which means that electricity generation corresponds with load curve. The optimization of portfolio is integrated with the calculation of a capacity factor of each generation in order to satisfy the basic condition for power supply. Besides, each generation is considered to be an asset, and risks of the generation asset both in its operation period and construction period are considered. Environmental measures are evaluated through restriction of CO2 emissions, which are indicated by CO2 price. Numerical examples show the optimal generation mix according to risks such as the deviation of capacity factor of nuclear power or restriction of CO2 emissions, the possibility of introduction of clean coal technology (IGCC, CCS) or renewable energy, and so on. The results of this work will be possibly applied as setting the target of the generation mix for the future according to prospects of risks of each generation and restrictions of CO2 emissions.

Mechanical-biological treatment: performance and potentials. An LCA of 8 MBT plants including waste characterization.

PubMed

Montejo, Cristina; Tonini, Davide; Márquez, María del Carmen; Astrup, Thomas Fruergaard

2013-10-15

In the endeavour of avoiding presence of biodegradable waste in landfills and increasing recycling, mechanical-biological treatment (MBT) plants have seen a significant increase in number and capacity in the last two decades. The aim of these plants is separating and stabilizing the quickly biodegradable fraction of the waste as well as recovering recyclables from mixed waste streams. In this study the environmental performance of eight MBT-based waste management scenarios in Spain was assessed by means of life cycle assessment. The focus was on the technical and environmental performance of the MBT plants. These widely differed in type of biological treatment and recovery efficiencies. The results indicated that the performance is strongly connected with energy and materials recovery efficiency. The recommendation for upgrading and/or commissioning of future plants is to optimize materials recovery through increased automation of the selection and to prioritize biogas-electricity production from the organic fraction over direct composting. The optimal strategy for refuse derived fuel (RDF) management depends upon the environmental compartment to be prioritized and the type of marginal electricity source in the system. It was estimated that, overall, up to ca. 180-190 kt CO2-eq. y(-1) may be saved by optimizing the MBT plants under assessment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Optimization of antitumor treatment conditions for transcutaneous CO2 application: An in vivo study.

PubMed

Ueha, Takeshi; Kawamoto, Teruya; Onishi, Yasuo; Harada, Risa; Minoda, Masaya; Toda, Mitsunori; Hara, Hitomi; Fukase, Naomasa; Kurosaka, Masahiro; Kuroda, Ryosuke; Akisue, Toshihiro; Sakai, Yoshitada

2017-06-01

Carbon dioxide (CO2) therapy can be applied to treat a variety of disorders. We previously found that transcutaneous application of CO2 with a hydrogel decreased the tumor volume of several types of tumors and induced apoptosis via the mitochondrial pathway. However, only one condition of treatment intensity has been tested. For widespread application in clinical antitumor therapy, the conditions must be optimized. In the present study, we investigated the relationship between the duration, frequency, and treatment interval of transcutaneous CO2 application and antitumor effects in murine xenograft models. Murine xenograft models of three types of human tumors (breast cancer, osteosarcoma, and malignant fibrous histiocytoma/undifferentiated pleomorphic sarcoma) were used to assess the antitumor effects of transcutaneous CO2 application of varying durations, frequencies, and treatment intervals. In all human tumor xenografts, apoptosis was significantly induced by CO2 treatment for ≥10 min, and a significant decrease in tumor volume was observed with CO2 treatments of >5 min. The effect on tumor volume was not dependent on the frequency of CO2 application, i.e., twice or five times per week. However, treatment using 3- and 4-day intervals was more effective at decreasing tumor volume than treatment using 2- and 5-day intervals. The optimal conditions of transcutaneous CO2 application to obtain the best antitumor effect in various tumors were as follows: greater than 10 min per application, twice per week, with 3- and 4-day intervals, and application to the site of the tumor. The results suggest that this novel transcutaneous CO2 application might be useful to treat primary tumors, while mitigating some side effects, and therefore could be safe for clinical trials.

Constraining gross primary production and ecosystem respiration estimates for North America using atmospheric observations of carbonyl sulfide (OCS) and CO2

NASA Astrophysics Data System (ADS)

He, W.; Ju, W.; Chen, H.; Peters, W.; van der Velde, I.; Baker, I. T.; Andrews, A. E.; Zhang, Y.; Launois, T.; Campbell, J. E.; Suntharalingam, P.; Montzka, S. A.

2016-12-01

Carbonyl sulfide (OCS) is a promising novel atmospheric tracer for studying carbon cycle processes. OCS shares a similar pathway as CO2 during photosynthesis but not released through a respiration-like process, thus could be used to partition Gross Primary Production (GPP) from Net Ecosystem-atmosphere CO2 Exchange (NEE). This study uses joint atmospheric observations of OCS and CO2 to constrain GPP and ecosystem respiration (Re). Flask data from tower and aircraft sites over North America are collected. We employ our recently developed CarbonTracker (CT)-Lagrange carbon assimilation system, which is based on the CT framework and the Weather Research and Forecasting - Stochastic Time-Inverted Lagrangian Transport (WRF-STILT) model, and the Simple Biosphere model with simulated OCS (SiB3-OCS) that provides prior GPP, Re and plant uptake fluxes of OCS. Derived plant OCS fluxes from both process model and GPP-scaled model are tested in our inversion. To investigate the ability of OCS to constrain GPP and understand the uncertainty propagated from OCS modeling errors to constrained fluxes in a dual-tracer system including OCS and CO2, two inversion schemes are implemented and compared: (1) a two-step scheme, which firstly optimizes GPP using OCS observations, and then simultaneously optimizes GPP and Re using CO2 observations with OCS-constrained GPP in the first step as prior; (2) a joint scheme, which simultaneously optimizes GPP and Re using OCS and CO2 observations. We will evaluate the result using an estimated GPP from space-borne solar-induced fluorescence observations and a data-driven GPP upscaled from FLUXNET data with a statistical model (Jung et al., 2011). Preliminary result for the year 2010 shows the joint inversion makes simulated mole fractions more consistent with observations for both OCS and CO2. However, the uncertainty of OCS simulation is larger than that of CO2. The two-step and joint schemes perform similarly in improving the consistence with observations for OCS, implicating that OCS could provide independent constraint in joint inversion. Optimization makes less total GPP and Re but more NEE, when testing with prior CO2 fluxes from two biosphere models. This study gives an in-depth insight into the role of joint atmospheric OCS and CO2 observations in constraining CO2 fluxes.

China's growing CO2 emissions--a race between increasing consumption and efficiency gains.

PubMed

Peters, Glen P; Weber, Christopher L; Guan, Dabo; Hubacek, Klaus

2007-09-01

China's rapidly growing economy and energy consumption are creating serious environmental problems on both local and global scales. Understanding the key drivers behind China's growing energy consumption and the associated CO2 emissions is critical for the development of global climate policies and provides insight into how other emerging economies may develop a low emissions future. Using recently released Chinese economic input-output data and structural decomposition analysis we analyze how changes in China's technology, economic structure, urbanization, and lifestyles affect CO2 emissions. We find that infrastructure construction and urban household consumption, both in turn driven by urbanization and lifestyle changes, have outpaced efficiency improvements in the growth of CO2 emissions. Net trade had a small effect on total emissions due to equal, but significant, growth in emissions from the production of exports and emissions avoided by imports. Technology and efficiency improvements have only partially offset consumption growth, but there remains considerable untapped potential to reduce emissions by improving both production and consumption systems. As China continues to rapidly develop there is an opportunity to further implement and extend policies, such as the Circular Economy, that will help China avoid the high emissions path taken by today's developed countries.

Use of avoidance response by rainbow trout to carbon dioxide for fish self-transfer between tanks

USGS Publications Warehouse

Clingerman, J.; Bebak, J.; Mazik, P.M.; Summerfelt, S.T.

2007-01-01

Convenient, economical, and reduced labor fish harvest and transfer systems are required to realize operating cost savings that can be achieved with the use of much larger and deeper circular culture tanks. To achieve these goals, we developed a new technology for transferring fish based on their avoidance behavior to elevated concentrations of dissolved carbon dioxide (CO2). We observed this behavioral response during controlled, replicated experiments that showed dissolved CO2 concentrations of 60-120 mg/L induced rainbow trout (Oncorhynchus mykiss) to swim out of their 11 m3 "growout" tank, through a transfer pipe carrying a flow with ???23 mg/L dissolved CO2, into a second 11 m3 "harvest" tank. The research was conducted using separate groups of rainbow trout held at commercially relevant densities (40-60 kg/m3). The average weight of fish ranged from 0.15 to 1.3 kg during the various trials. In all trials that used a constant flow of low CO2 water (???23 mg/L) entering the growout tank from the harvest tank, approximately 80-90% of the fish swam from the growout tank, through the transfer pipe, and into the harvest tank after the CO2 concentration in the growout tank had exceeded 60 mg/L. The fish that remained in the growout tank stayed within the area of relatively low CO2 water at the entrance of the transfer pipe. However, the rate of fish transfer from the growout tank to the harvest tank was more than doubled when the diameter of the transfer pipe was increased from 203 to 406 mm. To consistently achieve fish transfer efficiencies of 99%, water flow rate through the fish transfer pipe had to be reduced to 10-20% of the original flow just before the conclusion of each trial. Reducing the flow of relatively low CO2 water near the end of each fish transfer event, restricted the zone of relatively low CO2 water about the entrance of the fish transfer pipe, and provided the stimulus for all but a few remaining fish to swim out of the growout tank. Results indicate that the CO2 avoidance technique can provide a convenient, efficient, more economical, and reduced labor approach for fish transfer, especially in applications using large and well mixed circular culture tanks. ?? 2007 Elsevier B.V. All rights reserved.

Effect of heat treatment on ethylene and CO2 emissions rates during papaya (Carica papaya L.) fruit ripening

NASA Astrophysics Data System (ADS)

da Silva, M. G.; Santos, E. O.; Sthel, M. S.; Cardoso, S. L.; Cavalli, A.; Monteiro, A. R.; de Oliveira, J. G.; Pereira, M. G.; Vargas, H.

2003-01-01

Ripening studies of nontreated and treated papaya (papaya L) are accomplished by monitoring the ethylene and CO2 emission rates of that climacteric fruit, to evaluate its shelf life. The treatments simulate the commercial Phitosanitarian process used to avoid the fly infestation. Ethylene emission was measured using a commercial CO2 laser driven photoacoustic setup and CO2, using a commercial gas analysis also based on the photothermal effect. The results show a marked change in ethylene and CO2 emission rate pattern for treated fruits when compared to the ones obtained for nontreated fruits and a displacement of the climacteric pick shown that the treatment causes a decrease of shelf life of fruit.

Information Avoidance Tendencies, Threat Management Resources, and Interest in Genetic Sequencing Feedback.

PubMed

Taber, Jennifer M; Klein, William M P; Ferrer, Rebecca A; Lewis, Katie L; Harris, Peter R; Shepperd, James A; Biesecker, Leslie G

2015-08-01

Information avoidance is a defensive strategy that undermines receipt of potentially beneficial but threatening health information and may especially occur when threat management resources are unavailable. We examined whether individual differences in information avoidance predicted intentions to receive genetic sequencing results for preventable and unpreventable (i.e., more threatening) disease and, secondarily, whether threat management resources of self-affirmation or optimism mitigated any effects. Participants (N = 493) in an NIH study (ClinSeq®) piloting the use of genome sequencing reported intentions to receive (optional) sequencing results and completed individual difference measures of information avoidance, self-affirmation, and optimism. Information avoidance tendencies corresponded with lower intentions to learn results, particularly for unpreventable diseases. The association was weaker among individuals higher in self-affirmation or optimism, but only for results regarding preventable diseases. Information avoidance tendencies may influence decisions to receive threatening health information; threat management resources hold promise for mitigating this association.

Optimization of artemisinin extraction from Artemisia annua L. with supercritical carbon dioxide + ethanol using response surface methodology.

PubMed

Ciftci, Ozan Nazim; Cahyadi, Jessica; Guigard, Selma E; Saldaña, Marleny D A

2018-05-13

Malaria is a high priority life-threatening public health concern in developing countries, and therefore there is a growing interest to obtain artemisinin for the production of artemisinin-based combination therapy products. In this study, artemisinin was extracted from the Artemisia annua L. plant using supercritical carbon dioxide (SC-CO 2 ) modified with ethanol. Response surface methodology based on central composite rotatable design was employed to investigate and optimize the extraction conditions of pressure (9.9-30 MPa), temperature (33-67°C), and co-solvent (ethanol, 0-12.6 wt.%). Optimum SC-CO 2 extraction conditions were found to be 30 MPa and 33°C without ethanol. Under optimized conditions, the predicted artemisinin yield was 1.09% whereas the experimental value was 0.71 ± 0.07%. Soxhlet extraction with hexane resulted in higher artemisinin yields and there was no significant difference in the purity of the extracts obtained with SC-CO 2 and Soxhlet extractions. Results indicated that SC-CO 2 and SC-CO 2 +ethanol extraction is a promising alternative for the extraction of artemisinin to eliminate the use of organic solvents, such as hexane, and produce extracts that can be used for the production of antimalarial products. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Operando Synchrotron X-ray Powder Diffraction and Modulated-Excitation Infrared Spectroscopy Elucidate the CO2 Promotion on a Commercial Methanol Synthesis Catalyst.

PubMed

Martin, Oliver; Mondelli, Cecilia; Cervellino, Antonio; Ferri, Davide; Curulla-Ferré, Daniel; Pérez-Ramírez, Javier

2016-09-05

Optimal amounts of CO2 are added to syngas to boost the methanol synthesis rate on Cu-ZnO-Al2 O3 in the industrial process. The reason for CO2 promotion is not sufficiently understood at the particle level due to the catalyst complexity and the high demands of characterization under true reaction conditions. Herein, we applied operando synchrotron X-ray powder diffraction and modulated-excitation infrared spectroscopy on a commercial catalyst to gain insights into its morphology and surface chemistry. These studies unveiled that Cu and ZnO agglomerate and ZnO particles flatten under CO/H2 and/or CO2 /H2 . Under the optimal CO/CO2 /H2 mixture, sintering is prevented and ZnO crystals adopt an elongated shape due to the minimal presence of the H2 O byproduct, enhancing the water-gas shift activity and thus the methanol production. Our results provide a rationale to the CO2 promotion emphasizing the importance of advanced analytical methods to establish structure-performance relations in heterogeneous catalysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ABSORPTION OF CO2 AND SUBSEQUENT VISCOSITY REDUCTION OF AN ACRYLONITRILE COPOLYMER. (R829555)

EPA Science Inventory

Acrylonitrile (AN) copolymers (AN content greater than about 85 mol%) are traditionally solution processed to avoid a cyclization and crosslinking reaction that takes place at temperatures where melt processing would be feasible. It is well known that carbon dioxide (CO

Carbon Capture and Sequestration- A Review

NASA Astrophysics Data System (ADS)

Sood, Akash; Vyas, Savita

2017-08-01

The Drastic increase of CO2 emission in the last 30 years is due to the combustion of fossil fuels and it causes a major change in the environment such as global warming. In India, the emission of fossil fuels is developed in the recent years. The alternate energy sources are not sufficient to meet the values of this emission reduction and the framework of climate change demands the emission reduction, the CCS technology can be used as a mitigation tool which evaluates the feasibility for implementation of this technology in India. CCS is a process to capture the carbon dioxide from large sources like fossil fuel station to avoid the entrance of CO2 in the atmosphere. IPCC accredited this technology and its path for mitigation for the developing countries. In this paper, we present the technologies of CCS with its development and external factors. The main goal of this process is to avoid the release the CO2 into the atmosphere and also investigates the sequestration and mitigation technologies of carbon.

Effects of elevated CO2 on predator avoidance behaviour by reef fishes is not altered by experimental test water.

PubMed

Munday, Philip L; Welch, Megan J; Allan, Bridie J M; Watson, Sue-Ann; McMahon, Shannon J; McCormick, Mark I

2016-01-01

Pioneering studies into the effects of elevated CO 2 on the behaviour of reef fishes often tested high-CO 2 reared fish using control water in the test arena. While subsequent studies using rearing treatment water (control or high CO 2 ) in the test arena have confirmed the effects of high CO 2 on a range of reef fish behaviours, a further investigation into the use of different test water in the experimental arena is warranted. Here, we used a fully factorial design to test the effect of rearing treatment water (control or high CO 2 ) and experimental test water (control or high CO 2 ) on antipredator responses of larval reef fishes. We tested antipredator behaviour in larval clownfish Amphiprion percula and ambon damselfish Pomacentrus amboinensis , two species that have been used in previous high CO2 experiments. Specifically, we tested if: (1) using control or high CO 2 water in a two channel flume influenced the response of larval clownfish to predator odour; and (2) using control or high CO 2 water in the test arena influenced the escape response of larval damselfish to a startle stimulus. Finally, (3) because the effects of high CO 2 on fish behaviour appear to be caused by altered function of the GABA-A neurotransmitter we tested if antipredator behaviours were restored in clownfish treated with a GABA antagonist (gabazine) in high CO 2 water. Larval clownfish reared from hatching in control water (496 µatm) strongly avoided predator cue whereas larval clownfish reared from hatching in high CO 2 (1,022 µatm) were attracted to the predator cue, as has been reported in previous studies. There was no effect on fish responses of using either control or high CO 2 water in the flume. Larval damselfish reared for four days in high CO 2 (1,051 µatm) exhibited a slower response to a startle stimulus and slower escape speed compared with fish reared in control conditions (464 µatm). There was no effect of test water on escape responses. Treatment of high-CO 2 reared clownfish with 4 mg l -1 gabazine in high CO 2 seawater restored the normal response to predator odour, as has been previously reported with fish tested in control water. Our results show that using control water in the experimental trials did not influence the results of previous studies on antipredator behaviour of reef fishes and also supports the results of novel experiments conducted in natural reef habitat at ambient CO 2 levels.

Effects of elevated CO2 on predator avoidance behaviour by reef fishes is not altered by experimental test water

PubMed Central

Welch, Megan J.; Allan, Bridie J.M.; Watson, Sue-Ann; McMahon, Shannon J.; McCormick, Mark I.

2016-01-01

Pioneering studies into the effects of elevated CO2 on the behaviour of reef fishes often tested high-CO2 reared fish using control water in the test arena. While subsequent studies using rearing treatment water (control or high CO2) in the test arena have confirmed the effects of high CO2 on a range of reef fish behaviours, a further investigation into the use of different test water in the experimental arena is warranted. Here, we used a fully factorial design to test the effect of rearing treatment water (control or high CO2) and experimental test water (control or high CO2) on antipredator responses of larval reef fishes. We tested antipredator behaviour in larval clownfish Amphiprion percula and ambon damselfish Pomacentrus amboinensis, two species that have been used in previous high CO2 experiments. Specifically, we tested if: (1) using control or high CO2 water in a two channel flume influenced the response of larval clownfish to predator odour; and (2) using control or high CO2 water in the test arena influenced the escape response of larval damselfish to a startle stimulus. Finally, (3) because the effects of high CO2 on fish behaviour appear to be caused by altered function of the GABA-A neurotransmitter we tested if antipredator behaviours were restored in clownfish treated with a GABA antagonist (gabazine) in high CO2 water. Larval clownfish reared from hatching in control water (496 µatm) strongly avoided predator cue whereas larval clownfish reared from hatching in high CO2 (1,022 µatm) were attracted to the predator cue, as has been reported in previous studies. There was no effect on fish responses of using either control or high CO2 water in the flume. Larval damselfish reared for four days in high CO2 (1,051 µatm) exhibited a slower response to a startle stimulus and slower escape speed compared with fish reared in control conditions (464 µatm). There was no effect of test water on escape responses. Treatment of high-CO2 reared clownfish with 4 mg l−1 gabazine in high CO2 seawater restored the normal response to predator odour, as has been previously reported with fish tested in control water. Our results show that using control water in the experimental trials did not influence the results of previous studies on antipredator behaviour of reef fishes and also supports the results of novel experiments conducted in natural reef habitat at ambient CO2 levels. PMID:27761317

Optimization of Enzyme Co-Immobilization with Sodium Alginate and Glutaraldehyde-Activated Chitosan Beads.

PubMed

Gür, Sinem Diken; İdil, Neslihan; Aksöz, Nilüfer

2018-02-01

In this study, two different materials-alginate and glutaraldehyde-activated chitosan beads-were used for the co-immobilization of α-amylase, protease, and pectinase. Firstly, optimization of multienzyme immobilization with Na alginate beads was carried out. Optimum Na alginate and CaCl 2 concentration were found to be 2.5% and 0.1 M, respectively, and optimal enzyme loading ratio was determined as 2:1:0.02 for pectinase, protease, and α-amylase, respectively. Next, the immobilization of multiple enzymes on glutaraldehyde-activated chitosan beads was optimized (3% chitosan concentration, 0.25% glutaraldehyde with 3 h of activation and 3 h of coupling time). While co-immobilization was successfully performed with both materials, the specific activities of enzymes were found to be higher for the enzymes co-immobilized with glutaraldehyde-activated chitosan beads. In this process, glutaraldehyde was acting as a spacer arm. SEM and FTIR were used for the characterization of activated chitosan beads. Moreover, pectinase and α-amylase enzymes immobilized with chitosan beads were also found to have higher activity than their free forms. Three different enzymes were co-immobilized with these two materials for the first time in this study.

Setting cumulative emissions targets to reduce the risk of dangerous climate change

PubMed Central

Zickfeld, Kirsten; Eby, Michael; Matthews, H. Damon; Weaver, Andrew J.

2009-01-01

Avoiding “dangerous anthropogenic interference with the climate system” requires stabilization of atmospheric greenhouse gas concentrations and substantial reductions in anthropogenic emissions. Here, we present an inverse approach to coupled climate-carbon cycle modeling, which allows us to estimate the probability that any given level of carbon dioxide (CO2) emissions will exceed specified long-term global mean temperature targets for “dangerous anthropogenic interference,” taking into consideration uncertainties in climate sensitivity and the carbon cycle response to climate change. We show that to stabilize global mean temperature increase at 2 °C above preindustrial levels with a probability of at least 0.66, cumulative CO2 emissions from 2000 to 2500 must not exceed a median estimate of 590 petagrams of carbon (PgC) (range, 200 to 950 PgC). If the 2 °C temperature stabilization target is to be met with a probability of at least 0.9, median total allowable CO2 emissions are 170 PgC (range, −220 to 700 PgC). Furthermore, these estimates of cumulative CO2 emissions, compatible with a specified temperature stabilization target, are independent of the path taken to stabilization. Our analysis therefore supports an international policy framework aimed at avoiding dangerous anthropogenic interference formulated on the basis of total allowable greenhouse gas emissions. PMID:19706489

Setting cumulative emissions targets to reduce the risk of dangerous climate change.

PubMed

Zickfeld, Kirsten; Eby, Michael; Matthews, H Damon; Weaver, Andrew J

2009-09-22

Avoiding "dangerous anthropogenic interference with the climate system" requires stabilization of atmospheric greenhouse gas concentrations and substantial reductions in anthropogenic emissions. Here, we present an inverse approach to coupled climate-carbon cycle modeling, which allows us to estimate the probability that any given level of carbon dioxide (CO2) emissions will exceed specified long-term global mean temperature targets for "dangerous anthropogenic interference," taking into consideration uncertainties in climate sensitivity and the carbon cycle response to climate change. We show that to stabilize global mean temperature increase at 2 degrees C above preindustrial levels with a probability of at least 0.66, cumulative CO2 emissions from 2000 to 2500 must not exceed a median estimate of 590 petagrams of carbon (PgC) (range, 200 to 950 PgC). If the 2 degrees C temperature stabilization target is to be met with a probability of at least 0.9, median total allowable CO2 emissions are 170 PgC (range, -220 to 700 PgC). Furthermore, these estimates of cumulative CO2 emissions, compatible with a specified temperature stabilization target, are independent of the path taken to stabilization. Our analysis therefore supports an international policy framework aimed at avoiding dangerous anthropogenic interference formulated on the basis of total allowable greenhouse gas emissions.

Flavonoids released by carrot (Daucus carota) seedlings stimulate hyphal development of vesicular-arbuscular mycorrhizal fungi in the presence of optimal CO2 enrichment.

PubMed

Poulin, M J; Bel-Rhlid, R; Piché, Y; Chênevert, R

1993-10-01

Carbon dioxide has been previously identified as a critical volatile factor that stimulates hyphal growth ofGigaspora margarita, a vesiculararbuscular mycorrhizal fungus, and we determined the optimal concentration at 2.0%. The beneficial effect of CO2 on fungal development is also visible in the presence of stimulatory (quercetin, myricetin) or inhibitory (naringenin) flavonoids. Sterile root exudates from carrot seedlings stimulate the hyphal development ofG. margarita in the presence of optimal CO2 enrichment. Three flavonols (quercetin, kaempferol, rutin or quercetin 3-rutinoside) and two flavones (apigenin, luteolin) were identified in carrot root exudates by means of HPLC retention time. Flavonols like quercetin and kaempferol are known to have stimulatory effects on hyphal growth ofG. margarita.

Windshear avoidance - Requirements and proposed system for airborne lidar detection

NASA Technical Reports Server (NTRS)

Targ, Russell; Bowles, Roland L.

1988-01-01

A generalized windshear hazard index is derived from considerations of wind conditions and an aircraft's present and potential altitude. Based on a systems approach to the windshear threat, lidar appears to be a viable methodology for windshear detection and avoidance, even in conditions of moderately heavy precipitation. The airborne CO2 and Ho:YAG lidar windshear detection systems analyzed can each give the pilot information about the line-of-sight component of windshear threat from his present position to a region extending 1 to 3 km in front of the aircraft. This constitutes a warning time of 15 to 45 s. The technology necessary to design, build and test such a brassboard 10.6-micron CO2 lidar is at hand.

Local Approximation and Hierarchical Methods for Stochastic Optimization

NASA Astrophysics Data System (ADS)

Cheng, Bolong

In this thesis, we present local and hierarchical approximation methods for two classes of stochastic optimization problems: optimal learning and Markov decision processes. For the optimal learning problem class, we introduce a locally linear model with radial basis function for estimating the posterior mean of the unknown objective function. The method uses a compact representation of the function which avoids storing the entire history, as is typically required by nonparametric methods. We derive a knowledge gradient policy with the locally parametric model, which maximizes the expected value of information. We show the policy is asymptotically optimal in theory, and experimental works suggests that the method can reliably find the optimal solution on a range of test functions. For the Markov decision processes problem class, we are motivated by an application where we want to co-optimize a battery for multiple revenue, in particular energy arbitrage and frequency regulation. The nature of this problem requires the battery to make charging and discharging decisions at different time scales while accounting for the stochastic information such as load demand, electricity prices, and regulation signals. Computing the exact optimal policy becomes intractable due to the large state space and the number of time steps. We propose two methods to circumvent the computation bottleneck. First, we propose a nested MDP model that structure the co-optimization problem into smaller sub-problems with reduced state space. This new model allows us to understand how the battery behaves down to the two-second dynamics (that of the frequency regulation market). Second, we introduce a low-rank value function approximation for backward dynamic programming. This new method only requires computing the exact value function for a small subset of the state space and approximate the entire value function via low-rank matrix completion. We test these methods on historical price data from the PJM Interconnect and show that it outperforms the baseline approach used in the industry.

Pt/SnO2-based CO-oxidation catalysts for CO2 lasers

NASA Technical Reports Server (NTRS)

Upchurch, Billy T.; Schryer, David R.; Hess, Robert V.; Brown, Kenneth G.; Van Norman, John D.

1990-01-01

The activity of Pt/SnO2-based CO-oxidation catalysts has been maximized by optimizing pretreatment conditions and catalyst formulation. The role of H2O in activating these catalysts and of CO2 retention in deactivating them has been determined as has the interaction of these catalysts with rare-isotope C(0-18) and (O-18)2.

[Supercritical CO2 extraction and component analysis of Aesculus wilsonii seed oil].

PubMed

Chen, Guang-Yu; Shi, Zhao-Hua; Li, Hai-Chi; Ge, Fa-Huan; Zhan, Hua-Shu

2013-03-01

To research the optimal extraction process of supercritical CO2 extraction and analyze the component of the oil extracted from Aesculus wilsonii seed. Using the yield of Aesculus wilsonii seed oil as the index, optimized supercritical CO2 extraction parameter by orthogonal experiment methodology and analysed the compounds of Aesculus wilsonii seed oil by GC-MS. The optimal parameters of the supercritical CO2 extraction of the oil extracted from Aesculus wilsoniit seed were determined: the extraction pressure was 28 MPa and the temperature was 38 degrees C, the separation I pressure was 12 MPa and the temperature was 40 degrees C, the separation II pressure was 5 MPa and the temperature was 40 degrees C, the extraction time was 110 min. The average extraction rate of Aesculus wilsonii seed oil was 1.264%. 26 kinds of compounds were identified by GC-MS in Aesculus wilsonii seed oil extracted by supercritical CO2. The main components were fatty acids. Comparing with the petroleum ether extraction, the supercritical CO2 extraction has higher extraction rate, shorter extraction time, more clarity oil. The kinds of fatty acids with high amounts in Aesculus wilsonii seed oil is identical in general, the kinds of fatty acids with low amounts in Aesculus wilsonii seed oil have differences.

Real-time CO2 sensor for the optimal control of electronic EGR system

NASA Astrophysics Data System (ADS)

Kim, Gwang-jung; Choi, Byungchul; Choi, Inchul

2013-12-01

In modern diesel engines, EGR (Exhaust Gas Recirculation) is an important technique used in nitrogen oxide (NOx) emission reduction. This paper describes the development and experimental results of a fiber-optical sensor using a 2.7 μm wavelength absorption to quantify the simultaneous CO2 concentration which is the primary variable of EGR rate (CO2 in the exhaust gas versus CO2 in the intake gas, %). A real-time laser absorption method was developed using a DFB (distributed feedback) diode laser and waveguide to make optimal design and control of electronic EGR system required for `Euro-6' and `Tier 4 Final' NOx emission regulations. While EGR is effective to reduce NOx significantly, the amount of HC and CO is increased in the exhaust gas if EGR rate is not controlled based on driving conditions. Therefore, it is important to recirculate an appropriate amount of exhaust gas in the operation condition generating high volume of NOx. In this study, we evaluated basic characteristics and functions of our optical sensor and studied basically in order to find out optimal design condition. We demonstrated CO2 measurement speed, accuracy and linearity as making a condition similar to real engine through the bench-scale experiment.

Optimization of CO₂ bio-mitigation by Chlorella vulgaris.

PubMed

Anjos, Mariana; Fernandes, Bruno D; Vicente, António A; Teixeira, José A; Dragone, Giuliano

2013-07-01

Biofixation of CO2 by microalgae has been recognized as an attractive approach to CO2 mitigation. The main objective of this work was to maximize the rate of CO2 fixation ( [Formula: see text] ) by the green microalga Chlorella vulgaris P12 cultivated photoautotrophically in bubble column photobioreactors under different CO2 concentrations (ranging from 2% to 10%) and aeration rates (ranging from 0.1 to 0.7 vvm). Results showed that the maximum [Formula: see text] (2.22 gL(-1)d(-1)) was obtained by using 6.5% CO2 and 0.5 vvm after 7 days of cultivation at 30°C. Although final biomass concentration and maximum biomass productivity of microalgae were affected by the different cultivation conditions, no significant differences were obtained in the biochemical composition of microalgal cells for the evaluated levels of aeration and CO2. The present study demonstrated that optimization of microalgal cultivation conditions can be considered a useful strategy for maximizing CO2 bio-mitigation by C. vulgaris. Copyright © 2013 Elsevier Ltd. All rights reserved.

CO2 adsorption on diatomaceous earth modified with cetyltrimethylammonium bromide and functionalized with tetraethylenepentamine: Optimization and kinetics.

PubMed

Pornaroonthama, Phuwadej; Thouchprasitchai, Nutthavich; Pongstabodee, Sangobtip

2015-07-01

The carbon dioxide (CO2) adsorbent diatomaceous earth (DE) was modified with cetyltrimethylammonium bromide (CTAB) and functionalized with varying levels of tetraethylenepentamine (TEPA). The CO2 absorption at atmospheric pressure was optimized by varying the TEPA-loading level (0-40% (w/w)), operating temperature (40-80 °C) and water vapor concentration (0-16% (v/v)) in a 10% (v/v) CO2 feed stream in helium balance using a full 2(3) factorial design. The TEPA/CTAB-DE adsorbents were characterized by X-ray diffractometry, Fourier transform infrared spectrometry and thermogravimetric analyses. The CO2 adsorption capacity increased as each of these three factors increased. The TEPA loading level-water concentration interaction had a positive influence on the CO2 adsorption while the operating temperature-water concentration interaction was antagonistic. The optimal condition for CO2 adsorption on 40%TEPA/CTAB-DE, evaluated via a factorial design response surface method (RSM), was a temperature of 58-68 °C and a water vapor concentration of 9.5-14% (v/v), with a maximum CO2 adsorption capacity of 149.4 mg g(-1) at 63.5 °C and 12% (v/v) water vapor concentration in the feed. Validation and sensitivity tests revealed that the estimated CO2 adsorption capacity was within ±4% of the experimental values, suggesting that the RSM model was satisfied and acceptable. From three kinetic models (pseudo-first-order, pseudo-second-order model and Avrami's equation), assessed using an error function (Err) and the coefficient of determination (R(2)), Avrami's equation was the most appropriate to describe the kinetics of CO2 adsorption on the 40%TEPA/CTAB-DE adsorbent and suggested that more than one reaction pathway occurred in the CO2 adsorption. Copyright © 2015 Elsevier Ltd. All rights reserved.

Economic Analysis of Planting Forests on Rice Lands in Texas: Sequestering Carbon and Avoiding Methane Production

NASA Astrophysics Data System (ADS)

Kronrad, G. D.; Huang, C.

2005-12-01

Global climate change is predicted due to increases in greenhouse gasses (i.e. CO2, CH4, CFCs, N2O, O3) in the atmosphere caused by human activities. The atmospheric concentration of methane (CH4), which absorbs and retains heat 21 times more effectively than CO2, has increased. Anaerobic bacterial activity in rice paddies constitutes one of major emission sources of CH4. The rice fields of Texas, for example, accounted for an annual CH4 emission of between 1.1 and 1.6 million tons of CO2 equivalent between 1990 and 2000. Converting marginal rice fields to forests plantations will remove CO2 from the atmosphere, sequester carbon in the forests and prevent the production of CH4. Therefore, carbon credits can be claimed for the carbon sequestered and the avoidance of CH4 production. Analyses were conducted to calculate the amount of carbon sequestered and methane avoided, and the profitability, measured in net present worth (NPW), of managing loblolly pine plantation for 1) timber production only, 2) the dual products of timber products and carbon credits in forests planted on marginal agricultural and unused pastureland and 3) the dual products of timber and carbon storage in forests planted on marginal rice lands. Calculations were performed using three discount rates, three site qualities and five prices for carbon credits. The results indicate that on average quality land, using a discount rate of 8 percent, forests planted on marginal agricultural and unused pastureland earn a NPW of 346 per acre from timber production only; a NPW of 438 per acre from timber and carbon credits (54.4 tons of carbon sequestered), assuming carbon is worth 10 per ton, during one rotation (32 years). The profitability of forest management increases due to the inclusion of carbon credits. The profitability of planting forests on marginal rice fields is even higher, earning a NPW of 566 per acre from timber and carbon credits (54.4 tons of C sequestered and 33.3 tons of C emission avoided).

Adsorption separation of carbon dioxide from flue gas by a molecularly imprinted adsorbent.

PubMed

Zhao, Yi; Shen, Yanmei; Ma, Guoyi; Hao, Rongjie

2014-01-01

CO2 separation by molecularly imprinted adsorbent from coal-fired flue gas after desulfurization system has been studied. The adsorbent was synthesized by molecular imprinted technique, using ethanedioic acid, acrylamide, and ethylene glycol dimethacrylate as the template, functional monomer, and cross-linker, respectively. According to the conditions of coal-fired flue gas, the influencing factors, including adsorption temperature, desorption temperature, gas flow rate, and concentrations of CO2, H2O, O2, SO2, and NO, were studied by fixed bed breakthrough experiments. The experimental conditions were optimized to gain the best adsorption performance and reduce unnecessary energy consumption in future practical use. The optimized adsorption temperature, desorption temperature, concentrations of CO2, and gas flow rate are 60 °C, 80 °C, 13%, and 170 mL/min, respectively, which correspond to conditions of practical flue gases to the most extent. The CO2 adsorption performance was nearly unaffected by H2O, O2, and NO in the flue gas, and was promoted by SO2 within the emission limit stipulated in the Chinese emission standards of air pollutants for a thermal power plant. The maximum CO2 adsorption capacity, 0.57 mmol/g, was obtained under the optimized experimental conditions, and the SO2 concentration was 150 mg/m(3). The influence mechanisms of H2O, O2, SO2, and NO on CO2 adsorption capacity were investigated by infrared spectroscopic analysis.

Constraining Night Time Ecosystem Respiration by Inverse Approaches

NASA Astrophysics Data System (ADS)

Juang, J.; Stoy, P. C.; Siqueira, M. B.; Katul, G. G.

2004-12-01

Estimating nighttime ecosystem respiration remains a key challenge in quantifying ecosystem carbon budgets. Currently, nighttime eddy-covariance (EC) flux measurements are plagued by uncertainties often attributed to poor mixing within the canopy volume, non-turbulent transport of CO2 into and out of the canopy, and non-stationarity and intermittency. Here, we explore the use of second-order closure models to estimate nighttime ecosystem respiration by mathematically linking sources of CO2 to mean concentration profiles via the continuity and the CO2 flux budget equation modified to include thermal stratification. By forcing this model to match, in a root-mean squared sense, the nighttime measured mean CO2 concentration profiles within the canopy the above ground CO2 production and forest floor respiration can be estimated via multi-dimensional optimization techniques. We show that in a maturing pine and a mature hardwood forest, these optimized CO2 sources are (1) consistently larger than the eddy covariance flux measurements above the canopy, and (2) agree well with chamber-based measurements. We also show that by linking the optimized nighttime ecosystem respiration to temperature measurements, the estimated annual ecosystem respiration from this approach agrees well with biometric estimates, at least when compared to eddy-covariance methods conditioned on a friction velocity threshold. The difference between the annual ecosystem respiration obtained by this optimization method and the friction-velocity thresholded night-time EC fluxes can be as large as 700 g C m-2 (in 2003) for the maturing pine forest, which is about 40% of the ecosystem respiration. For 2001 and 2002, the annual ecosystem respiration differences between the EC-based and the proposed approach were on the order of 300 to 400 g C m-2.

Co-Design Method and Wafer-Level Packaging Technique of Thin-Film Flexible Antenna and Silicon CMOS Rectifier Chips for Wireless-Powered Neural Interface Systems.

PubMed

Okabe, Kenji; Jeewan, Horagodage Prabhath; Yamagiwa, Shota; Kawano, Takeshi; Ishida, Makoto; Akita, Ippei

2015-12-16

In this paper, a co-design method and a wafer-level packaging technique of a flexible antenna and a CMOS rectifier chip for use in a small-sized implantable system on the brain surface are proposed. The proposed co-design method optimizes the system architecture, and can help avoid the use of external matching components, resulting in the realization of a small-size system. In addition, the technique employed to assemble a silicon large-scale integration (LSI) chip on the very thin parylene film (5 μm) enables the integration of the rectifier circuits and the flexible antenna (rectenna). In the demonstration of wireless power transmission (WPT), the fabricated flexible rectenna achieved a maximum efficiency of 0.497% with a distance of 3 cm between antennas. In addition, WPT with radio waves allows a misalignment of 185% against antenna size, implying that the misalignment has a less effect on the WPT characteristics compared with electromagnetic induction.

Co-Design Method and Wafer-Level Packaging Technique of Thin-Film Flexible Antenna and Silicon CMOS Rectifier Chips for Wireless-Powered Neural Interface Systems

PubMed Central

Okabe, Kenji; Jeewan, Horagodage Prabhath; Yamagiwa, Shota; Kawano, Takeshi; Ishida, Makoto; Akita, Ippei

2015-01-01

In this paper, a co-design method and a wafer-level packaging technique of a flexible antenna and a CMOS rectifier chip for use in a small-sized implantable system on the brain surface are proposed. The proposed co-design method optimizes the system architecture, and can help avoid the use of external matching components, resulting in the realization of a small-size system. In addition, the technique employed to assemble a silicon large-scale integration (LSI) chip on the very thin parylene film (5 μm) enables the integration of the rectifier circuits and the flexible antenna (rectenna). In the demonstration of wireless power transmission (WPT), the fabricated flexible rectenna achieved a maximum efficiency of 0.497% with a distance of 3 cm between antennas. In addition, WPT with radio waves allows a misalignment of 185% against antenna size, implying that the misalignment has a less effect on the WPT characteristics compared with electromagnetic induction. PMID:26694407

Super-dry reforming of methane intensifies CO2 utilization via Le Chatelier's principle.

PubMed

Buelens, Lukas C; Galvita, Vladimir V; Poelman, Hilde; Detavernier, Christophe; Marin, Guy B

2016-10-28

Efficient CO 2 transformation from a waste product to a carbon source for chemicals and fuels will require reaction conditions that effect its reduction. We developed a "super-dry" CH 4 reforming reaction for enhanced CO production from CH 4 and CO 2 We used Ni/MgAl 2 O 4 as a CH 4 -reforming catalyst, Fe 2 O 3 /MgAl 2 O 4 as a solid oxygen carrier, and CaO/Al 2 O 3 as a CO 2 sorbent. The isothermal coupling of these three different processes resulted in higher CO production as compared with that of conventional dry reforming, by avoiding back reactions with water. The reduction of iron oxide was intensified through CH 4 conversion to syngas over Ni and CO 2 extraction and storage as CaCO 3 CO 2 is then used for iron reoxidation and CO production, exploiting equilibrium shifts effected with inert gas sweeping (Le Chatelier's principle). Super-dry reforming uses up to three CO 2 molecules per CH 4 and offers a high CO space-time yield of 7.5 millimole CO per second per kilogram of iron at 1023 kelvin. Copyright © 2016, American Association for the Advancement of Science.

Modeling of nonequilibrium CO Fourth-Positive and CN Violet emission in CO2-N2 gases

NASA Astrophysics Data System (ADS)

Johnston, C. O.; Brandis, A. M.

2014-12-01

This work develops a chemical kinetic rate model for simulating nonequilibrium radiation from CO2-N2 gases, representative of Mars or Venus entry shock layers. Using recent EAST shock tube measurements of nonequilibrium CO 4th Positive and CN Violet emission at pressures and velocities ranging from 0.10 to 1.0 Torr and 6 to 8 km/s, the rate model is developed through an optimization procedure that minimizes the disagreement between the measured and simulated nonequilibrium radiance profiles. Only the dissociation rates of CO2, CO, and NO, along with the CN + O and CO + N rates were treated as unknown in this optimization procedure, as the nonequilibrium radiance was found to be most sensitive to them. The other rates were set to recent values from the literature. Increases in over a factor of 5 in the CO dissociation rate relative to the previous widely used value were found to provide the best agreement with measurements, while the CO2 rate was not changed. The developed model is found to capture the measured nonequilibrium radiance of CO 4th Positive and CN Violet within error bars of ±30%.

CO2 Reduction Effect of the Utilization of Waste Heat and Solar Heat in City Gas System

NASA Astrophysics Data System (ADS)

Okamura, Tomohito; Matsuhashi, Ryuji; Yoshida, Yoshikuni; Hasegawa, Hideo; Ishitani, Hisashi

We evaluate total energy consumption and CO2 emissions in the phase of the city gas utilization system from obtaining raw materials to consuming the product. First, we develop a simulation model which calculates CO2 emissions for monthly and hourly demands of electricity, heats for air conditioning and hot-water in a typical hospital. Under the given standard capacity and operating time of CGS, energy consumption in the equipments is calculated in detail considering the partial load efficiency and the control by the temperature of exhaust heat. Then, we explored the optimal size and operation of city gas system that minimizes the life cycle CO2 emissions or total cost. The cost-effectiveness is compared between conventional co-generation, solar heat system, and hybrid co-generation utilizing solar heat. We formulate a problem of mixed integer programming that includes integral parameters that express the state of system devices such as on/off of switches. As a result of optimization, the hybrid co-generation can reduce annual CO2 emissions by forty-three percent compared with the system without co-generation. Sensitivity for the scale of CGS on CO2 reduction and cost is also analyzed.

Postsynthetic Functionalization of Mg-MOF-74 with Tetraethylenepentamine: Structural Characterization and Enhanced CO2 Adsorption.

PubMed

Su, Xiao; Bromberg, Lev; Martis, Vladimir; Simeon, Fritz; Huq, Ashfia; Hatton, T Alan

2017-03-29

Postsynthetic functionalization of magnesium 2,5-dihydroxyterephthalate (Mg-MOF-74) with tetraethylenepentamine (TEPA) resulted in improved CO 2 adsorption performance under dry and humid conditions. XPS, elemental analysis, and neutron powder diffraction studies indicated that TEPA was incorporated throughout the MOF particle, although it coordinated preferentially with the unsaturated metal sites located in the immediate proximity to the surface. Neutron and X-ray powder diffraction analyses showed that the MOF structure was preserved after amine incorporation, with slight changes in the lattice parameters. The adsorption capacity of the functionalized amino-Mg-MOF-74 (TEPA-MOF) for CO 2 was as high as 26.9 wt % versus 23.4 wt % for the original MOF due to the extra binding sites provided by the multiunit amines. The degree of functionalization with the amines was found to be important in enhancing CO 2 adsorption, as the optimal surface coverage improved performance and stability under both pure CO 2 and CO 2 /H 2 O coadsorption, and with partially saturated surface coverage, optimal CO 2 capacity could be achieved under both wet and dry conditions by a synergistic binding of CO 2 to the amines as well as metal centers.

Swarm intelligence application for optimization of CO2 diffusivity in polystyrene-b-polybutadiene-b-polystyrene (SEBS) foaming

NASA Astrophysics Data System (ADS)

Sharudin, Rahida Wati; Ajib, Norshawalina Muhamad; Yusoff, Marina; Ahmad, Mohd Aizad

2017-12-01

Thermoplastic elastomer SEBS foams were prepared by using carbon dioxide (CO2) as a blowing agent and the process is classified as physical foaming method. During the foaming process, the diffusivity of CO2 need to be controlled since it is one of the parameter that will affect the final cellular structure of the foam. Conventionally, the rate of CO2 diffusion was measured experimentally by using a highly sensitive device called magnetic suspension balance (MSB). Besides, this expensive MSB machine is not easily available and measurement of CO2 diffusivity is quite complicated as well as time consuming process. Thus, to overcome these limitations, a computational method was introduced. Particle Swarm Optimization (PSO) is a part of Swarm Intelligence system which acts as a beneficial optimization tool where it can solve most of nonlinear complications. PSO model was developed for predicting the optimum foaming temperature and CO2 diffusion rate in SEBS foam. Results obtained by PSO model are compared with experimental results for CO2 diffusivity at various foaming temperature. It is shown that predicted optimum foaming temperature at 154.6 °C was not represented the best temperature for foaming as the cellular structure of SEBS foamed at corresponding temperature consisted pores with unstable dimension and the structure was not visibly perceived due to foam shrinkage. The predictions were not agreed well with experimental result when single parameter of CO2 diffusivity is considered in PSO model because it is not the only factor that affected the controllability of foam shrinkage. The modification on the PSO model by considering CO2 solubility and rigidity of SEBS as additional parameters needs to be done for obtaining the optimum temperature for SEBS foaming. Hence stable SEBS foam could be prepared.

Use of an Atrial Lead with Very Short Tip-To-Ring Spacing Avoids Oversensing of Far-Field R-Wave

PubMed Central

Kolb, Christof; Nölker, Georg; Lennerz, Carsten; Jetter, Hansmartin; Semmler, Verena; Pürner, Klaus; Gutleben, Klaus-Jürgen; Reents, Tilko; Lang, Klaus; Lotze, Ulrich

2012-01-01

Objective The AVOID-FFS (Avoidance of Far-Field R-wave Sensing) study aimed to investigate whether an atrial lead with a very short tip-to-ring spacing without optimization of pacemaker settings shows equally low incidence of far-field R-wave sensing (FFS) when compared to a conventional atrial lead in combination with optimization of the programming. Methods Patients receiving a dual chamber pacemaker were randomly assigned to receive an atrial lead with a tip-to-ring spacing of 1.1 mm or a lead with a conventional tip-to-ring spacing of 10 mm. Postventricular atrial blanking (PVAB) was programmed to the shortest possible value of 60 ms in the study group, and to an individually determined optimized value in the control group. Atrial sensing threshold was programmed to 0.3 mV in both groups. False positive mode switch caused by FFS was evaluated at one and three months post implantation. Results A total of 204 patients (121 male; age 73±10 years) were included in the study. False positive mode switch caused by FFS was detected in one (1%) patient of the study group and two (2%) patients of the control group (p = 0.62). Conclusion The use of an atrial electrode with a very short tip-to-ring spacing avoids inappropriate mode switch caused by FFS without the need for individual PVAB optimization. Trial Registration ClinicalTrials.gov NCT00512915 PMID:22745661

Use of an atrial lead with very short tip-to-ring spacing avoids oversensing of far-field R-wave.

PubMed

Kolb, Christof; Nölker, Georg; Lennerz, Carsten; Jetter, Hansmartin; Semmler, Verena; Pürner, Klaus; Gutleben, Klaus-Jürgen; Reents, Tilko; Lang, Klaus; Lotze, Ulrich

2012-01-01

The AVOID-FFS (Avoidance of Far-Field R-wave Sensing) study aimed to investigate whether an atrial lead with a very short tip-to-ring spacing without optimization of pacemaker settings shows equally low incidence of far-field R-wave sensing (FFS) when compared to a conventional atrial lead in combination with optimization of the programming. Patients receiving a dual chamber pacemaker were randomly assigned to receive an atrial lead with a tip-to-ring spacing of 1.1 mm or a lead with a conventional tip-to-ring spacing of 10 mm. Postventricular atrial blanking (PVAB) was programmed to the shortest possible value of 60 ms in the study group, and to an individually determined optimized value in the control group. Atrial sensing threshold was programmed to 0.3 mV in both groups. False positive mode switch caused by FFS was evaluated at one and three months post implantation. A total of 204 patients (121 male; age 73±10 years) were included in the study. False positive mode switch caused by FFS was detected in one (1%) patient of the study group and two (2%) patients of the control group (p = 0.62). The use of an atrial electrode with a very short tip-to-ring spacing avoids inappropriate mode switch caused by FFS without the need for individual PVAB optimization. ClinicalTrials.gov NCT00512915.

An Ultrahigh CO2-Loaded Silicalite-1 Zeolite: Structural Stability and Physical Properties at High Pressures and Temperatures.

PubMed

Marqueño, Tomas; Santamaria-Perez, David; Ruiz-Fuertes, Javier; Chuliá-Jordán, Raquel; Jordá, Jose L; Rey, Fernando; McGuire, Chris; Kavner, Abby; MacLeod, Simon; Daisenberger, Dominik; Popescu, Catalin; Rodriguez-Hernandez, Placida; Muñoz, Alfonso

2018-06-04

We report the formation of an ultrahigh CO 2 -loaded pure-SiO 2 silicalite-1 structure at high pressure (0.7 GPa) from the interaction of empty zeolite and fluid CO 2 medium. The CO 2 -filled structure was characterized in situ by means of synchrotron powder X-ray diffraction. Rietveld refinements and Fourier recycling allowed the location of 16 guest carbon dioxide molecules per unit cell within the straight and sinusoidal channels of the porous framework to be analyzed. The complete filling of pores by CO 2 molecules favors structural stability under compression, avoiding pressure-induced amorphization below 20 GPa, and significantly reduces the compressibility of the system compared to that of the parental empty one. The structure of CO 2 -loaded silicalite-1 was also monitored at high pressures and temperatures, and its thermal expansivity was estimated.

New Directions for the Photocatalytic Reduction of CO2: Supramolecular, scCO2 or Biphasic Ionic Liquid-scCO2 Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grills, D.C.; Fujita, E.

2010-09-02

There is an urgent need for the discovery of carbon-neutral sources of energy to avoid the consequences of global warming caused by ever-increasing atmospheric CO{sub 2} levels. An attractive possibility is to use CO{sub 2} captured from industrial emissions as a feedstock for the production of useful fuels and precursors such as carbon monoxide and methanol. An active field of research to achieve this goal is the development of catalysts capable of harnessing solar energy for use in artificial photosynthetic processes for CO{sub 2} reduction. Transition-metal complexes are excellent candidates, and it has already been shown that they can bemore » used to reduce CO{sub 2} with high quantum efficiency. However, they generally suffer from poor visible light absorption, short catalyst lifetimes, and poor reaction rates. In this Perspective, the field of photocatalytic CO{sub 2} reduction is introduced, and recent developments that seek to improve the efficiency of such catalytic processes are highlighted, especially CO{sub 2} reduction with supramolecules and molecular systems in supercritical CO{sub 2} (scCO{sub 2}) or biphasic ionic liquid-scCO{sub 2} mixtures.« less

Optimization of Operation Parameters for Helical Flow Cleanout with Supercritical CO2 in Horizontal Wells Using Back-Propagation Artificial Neural Network.

PubMed

Song, Xianzhi; Peng, Chi; Li, Gensheng; He, Zhenguo; Wang, Haizhu

2016-01-01

Sand production and blockage are common during the drilling and production of horizontal oil and gas wells as a result of formation breakdown. The use of high-pressure rotating jets and annular helical flow is an effective way to enhance horizontal wellbore cleanout. In this paper, we propose the idea of using supercritical CO2 (SC-CO2) as washing fluid in water-sensitive formation. SC-CO2 is manifested to be effective in preventing formation damage and enhancing production rate as drilling fluid, which justifies tis potential in wellbore cleanout. In order to investigate the effectiveness of SC-CO2 helical flow cleanout, we perform the numerical study on the annular flow field, which significantly affects sand cleanout efficiency, of SC-CO2 jets in horizontal wellbore. Based on the field data, the geometry model and mathematical models were built. Then a numerical simulation of the annular helical flow field by SC-CO2 jets was accomplished. The influences of several key parameters were investigated, and SC-CO2 jets were compared to conventional water jets. The results show that flow rate, ambient temperature, jet temperature, and nozzle assemblies play the most important roles on wellbore flow field. Once the difference between ambient temperatures and jet temperatures is kept constant, the wellbore velocity distributions will not change. With increasing lateral nozzle size or decreasing rear/forward nozzle size, suspending ability of SC-CO2 flow improves obviously. A back-propagation artificial neural network (BP-ANN) was successfully employed to match the operation parameters and SC-CO2 flow velocities. A comprehensive model was achieved to optimize the operation parameters according to two strategies: cost-saving strategy and local optimal strategy. This paper can help to understand the distinct characteristics of SC-CO2 flow. And it is the first time that the BP-ANN is introduced to analyze the flow field during wellbore cleanout in horizontal wells.

Optimization of Operation Parameters for Helical Flow Cleanout with Supercritical CO2 in Horizontal Wells Using Back-Propagation Artificial Neural Network

PubMed Central

Song, Xianzhi; Peng, Chi; Li, Gensheng

2016-01-01

Sand production and blockage are common during the drilling and production of horizontal oil and gas wells as a result of formation breakdown. The use of high-pressure rotating jets and annular helical flow is an effective way to enhance horizontal wellbore cleanout. In this paper, we propose the idea of using supercritical CO2 (SC-CO2) as washing fluid in water-sensitive formation. SC-CO2 is manifested to be effective in preventing formation damage and enhancing production rate as drilling fluid, which justifies tis potential in wellbore cleanout. In order to investigate the effectiveness of SC-CO2 helical flow cleanout, we perform the numerical study on the annular flow field, which significantly affects sand cleanout efficiency, of SC-CO2 jets in horizontal wellbore. Based on the field data, the geometry model and mathematical models were built. Then a numerical simulation of the annular helical flow field by SC-CO2 jets was accomplished. The influences of several key parameters were investigated, and SC-CO2 jets were compared to conventional water jets. The results show that flow rate, ambient temperature, jet temperature, and nozzle assemblies play the most important roles on wellbore flow field. Once the difference between ambient temperatures and jet temperatures is kept constant, the wellbore velocity distributions will not change. With increasing lateral nozzle size or decreasing rear/forward nozzle size, suspending ability of SC-CO2 flow improves obviously. A back-propagation artificial neural network (BP-ANN) was successfully employed to match the operation parameters and SC-CO2 flow velocities. A comprehensive model was achieved to optimize the operation parameters according to two strategies: cost-saving strategy and local optimal strategy. This paper can help to understand the distinct characteristics of SC-CO2 flow. And it is the first time that the BP-ANN is introduced to analyze the flow field during wellbore cleanout in horizontal wells. PMID:27249026

Optimization Performance of a CO[subscript 2] Pulsed Tuneable Laser

ERIC Educational Resources Information Center

Ribeiro, J. H. F.; Lobo, R. F. M.

2009-01-01

In this paper, a procedure is presented that will allow (i) the power and (ii) the energy of a pulsed and tuneable TEA CO[subscript 2] laser to be optimized. This type of laser represents a significant improvement in performance and portability. Combining a pulse mode with a grating tuning facility, it enables us to scan the working wavelength…

[Preparation of ibuprofen/EC-PVP sustained-release composite particles by supercritical CO2 anti-solvent technology].

PubMed

Cai, Jin-Yuan; Huang, De-Chun; Wang, Zhi-Xiang; Dang, Bei-Lei; Wang, Qiu-Ling; Su, Xin-Guang

2012-06-01

Ibuprofen/ethyl-cellulose (EC)-polyvinylpyrrolidone (PVP) sustained-release composite particles were prepared by using supercritical CO2 anti-solvent technology. With drug loading as the main evaluation index, orthogonal experimental design was used to optimize the preparation process of EC-PVP/ibuprofen composite particles. The experiments such as encapsulation efficiency, particle size distribution, electron microscope analysis, infrared spectrum (IR), differential scanning calorimetry (DSC) and in vitro dissolution were used to analyze the optimal process combination. The orthogonal experimental optimization process conditions were set as follows: crystallization temperature 40 degrees C, crystallization pressure 12 MPa, PVP concentration 4 mgmL(-1), and CO2 velocity 3.5 Lmin(-1). Under the optimal conditions, the drug loading and encapsulation efficiency of ibuprofen/EC-PVP composite particles were 12.14% and 52.21%, and the average particle size of the particles was 27.621 microm. IR and DSC analysis showed that PVP might complex with EC. The experiments of in vitro dissolution showed that ibuprofen/EC-PVP composite particles had good sustained-release effect. Experiment results showed that, ibuprofen/EC-PVP sustained-release composite particles can be prepared by supercritical CO2 anti-solvent technology.

Coupling molecular catalysts with nanostructured surfaces for efficient solar fuel production

NASA Astrophysics Data System (ADS)

Jin, Tong

Solar fuel generation via carbon dioxide (CO2) reduction is a promising approach to meet the increasing global demand for energy and to minimize the impact of energy consumption on climate change. However, CO2 is thermodynamically stable; its activation often requires the use of appropriate catalysts. In particular, molecular catalysts with well-defined structures and tunability have shown excellent activity in photochemical CO2 reduction. These homogenous catalysts, however, suffer from poor stability under photochemical conditions and difficulty in recycling from the reaction media. Heterogenized molecular catalysts, particularly those prepared by coupling molecular catalysts with solid-state surfaces, have attracted more attention in recent years as potential solutions to address the issues associated with molecular catalysts. In this work, solar CO2 reduction is investigated using systems coupling molecular catalysts with robust nanostructured surfaces. In Chapter 2, heterogenization of macrocyclic cobalt(III) and nickel (II) complexes on mesoporous silica surface was achieved by different methods. Direct ligand derivatization significantly lowered the catalytic activity of Co(III) complex, while grafting the Co(III) complex onto silica surface through Si-O-Co linkage resulted in hybrid catalysts with excellent activity in CO2 reduction in the presence of p-terphenyl as a molecular photosensitizer. An interesting loading effect was observed, in which the optimal activity was achieved at a medium Co(III) surface density. Heterogenization of the Ni(II) complex on silica surface has also been implemented, the poor photocatalytic activity of the hybrid catalyst can be attributed to the intrinsic nature of the homogeneous analogue. This study highlighted the importance of appropriate linking strategies in preparing functional heterogenized molecular catalysts. Coupling molecular complexes with light-harvesting surfaces could avoid the use of expensive molecular photosensitizers. In Chapter 3, effective coupling of the macrocyclic Co(III) complex with titanium dioxide (TiO¬2) nanoparticles was achieved by two deposition methods. The synthesized hybrid photocatalysts were thoroughly characterized with a variety of techniques. Upon UV light irradiation, photoexcited electrons in TiO2 nanoparticles were transferred to the surface Co(III) catalyst for CO2 reduction. Production of carbon monoxide (CO) from CO2 was confirmed by isotope labeling combined with infrared spectroscopy. Deposition of the Co(III) catalyst through Ti-O-Co linkages was essential for the photo-induced electron transfer and CO2-reduction activity using the hybrid photocatalysts. In Chapter 4, molecular Re(I) and Co(II) catalysts were coupled with silicon-based photoelectrodes, including a silicon nanowire (SiNW) photoelectrode, to achieve photoelectrochemical CO2 reduction. Photovoltages between 300-600 mV were obtained using the molecular catalysts on the silicon photoelectrodes. SiNWs exhibited enhanced properties, including significantly higher photovoltages than a planar silicon photoelectrode, the ability to protect one of the molecular catalysts from photo-induced decomposition, and excellent selectivity towards CO production in CO2 reduction. Recent theoretical and experimental work have demonstrated low-energy, binuclear pathways for CO2-to-CO conversion using several molecular catalysts. In such binuclear pathways, two metal centers work cooperatively to achieve two-electron CO2 reduction. Chapter 5 describes our effort to promote the binuclear pathway by grafting the molecular Co(III) catalyst onto silica surfaces. Different linking strategies were attempted to achieve this goal by planting the surface Co(III) sites in close proximity.

Mechanisms controlling the dependence of surface warming on cumulative carbon emissions over the next century in a suite of Earth system models

NASA Astrophysics Data System (ADS)

Williams, Richard; Roussenov, Vassil; Goodwin, Philip; Resplandy, Laure; Bopp, Laurent

2017-04-01

Insight into how to avoid dangerous climate may be obtained from Earth system model projections, which reveal a near-linear dependence of global-mean surface warming on cumulative carbon emissions. This dependence of surface warming on carbon emissions is interpreted in terms of a product of three terms: the dependence of surface warming on radiative forcing, the fractional radiative forcing contribution from atmospheric CO2 and the dependence of radiative forcing from atmospheric CO2 on cumulative carbon emissions. Mechanistically each of these dependences varies, respectively, with ocean heat uptake, the CO2 and non-CO2 radiative forcing, and the ocean and terrestrial uptake of carbon. An ensemble of 9 Earth System models forced by up to 4 Representative Concentration Pathways are diagnosed. In all cases, the dependence of surface warming on carbon emissions evolves primarily due to competing effects of heat and carbon uptake over the upper ocean: there is a reduced effect of radiative forcing from CO2 due to ocean carbon uptake, which is partly compensated by enhanced surface warming due to a reduced effect of ocean heat uptake. There is a wide spread in the dependence of surface warming on carbon emissions, undermining the ability to identify the maximum permitted carbon emission to avoid dangerous climate. Our framework reveals how uncertainty in the future warming trend is high over the next few decades due to relatively high uncertainties in ocean heat uptake, non-CO2 radiative forcing and the undersaturation of carbon in the ocean.

Transition Delay in a Hypervelocity Boundary Layer using Nonequilibrium CO2 Injection

DTIC Science & Technology

2008-10-28

flows than for either air or N2 flows. The explanation for this phenomenon lies in the fact that when CO2 is in vibrational and chemical ... chemical non-equilibrium, these relax- ation processes absorb energy from acoustic disturbances whose growth is responsible for transition in high...atmosphere at hypersonic speeds, they must somehow provide for, avoid, or otherwise accommodate the enormous heat-transfer rates to the vehicle engen

Co-Optimization of Fuels and Engines | Transportation Research | NREL

Science.gov Websites

Co-Optimization of Fuels and Engines Co-Optimization of Fuels and Engines Photo of silver sedan in ), eight other national laboratories, and industry on the Co-Optimization of Fuels & Engines (Co-Optima research activities and accomplishments of the Co-Optima initiative in the Co-Optimization of Fuels &

Recombinant Cyanobacteria for the Asymmetric Reduction of C=C Bonds Fueled by the Biocatalytic Oxidation of Water.

PubMed

Köninger, Katharina; Gómez Baraibar, Álvaro; Mügge, Carolin; Paul, Caroline E; Hollmann, Frank; Nowaczyk, Marc M; Kourist, Robert

2016-04-25

A recombinant enoate reductase was expressed in cyanobacteria and used for the light-catalyzed, enantioselective reduction of C=C bonds. The coupling of oxidoreductases to natural photosynthesis allows asymmetric syntheses fueled by the oxidation of water. Bypassing the addition of sacrificial cosubstrates as electron donors significantly improves the atom efficiency and avoids the formation of undesired side products. Crucial factors for product formation are the availability of NADPH and the amount of active enzyme in the cells. The efficiency of the reaction is comparable to typical whole-cell biotransformations in E. coli. Under optimized conditions, a solution of 100 mg prochiral 2-methylmaleimide was reduced to optically pure 2-methylsuccinimide (99 % ee, 80 % yield of isolated product). High product yields and excellent optical purities demonstrate the synthetic usefulness of light-catalyzed whole-cell biotransformations using recombinant cyanobacteria. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimization of Maghemite (γ-Fe2O3) Nano-Powder Mixed micro-EDM of CoCrMo with Multiple Responses Using Gray Relational Analysis (GRA)

NASA Astrophysics Data System (ADS)

Mejid Elsiti, Nagwa; Noordin, M. Y.; Idris, Ani; Saed Majeed, Faraj

2017-10-01

This paper presents an optimization of process parameters of Micro-Electrical Discharge Machining (EDM) process with (γ-Fe2O3) nano-powder mixed dielectric using multi-response optimization Grey Relational Analysis (GRA) method instead of single response optimization. These parameters were optimized based on 2-Level factorial design combined with Grey Relational Analysis. The machining parameters such as peak current, gap voltage, and pulse on time were chosen for experimentation. The performance characteristics chosen for this study are material removal rate (MRR), tool wear rate (TWR), Taper and Overcut. Experiments were conducted using electrolyte copper as the tool and CoCrMo as the workpiece. Experimental results have been improved through this approach.

Constrained trajectory optimization for kinematically redundant arms

NASA Technical Reports Server (NTRS)

Carignan, Craig R.; Tarrant, Janice M.

1990-01-01

Two velocity optimization schemes for resolving redundant joint configurations are compared. The Extended Moore-Penrose Technique minimizes the joint velocities and avoids obstacles indirectly by adjoining a cost gradient to the solution. A new method can incorporate inequality constraints directly to avoid obstacles and singularities in the workspace. A four-link arm example is used to illustrate singularity avoidance while tracking desired end-effector paths.

North American CO2 fluxes for 2007-2015 from NOAA's CarbonTracker-Lagrange Regional Inverse Modeling Framework

NASA Astrophysics Data System (ADS)

Andrews, A. E.; Hu, L.; Thoning, K. W.; Nehrkorn, T.; Mountain, M. E.; Jacobson, A. R.; Michalak, A.; Dlugokencky, E. J.; Sweeney, C.; Worthy, D. E. J.; Miller, J. B.; Fischer, M. L.; Biraud, S.; van der Velde, I. R.; Basu, S.; Tans, P. P.

2017-12-01

CarbonTracker-Lagrange (CT-L) is a new high-resolution regional inverse modeling system for improved estimation of North American CO2 fluxes. CT-L uses footprints from the Stochastic Time-Inverted Lagrangian Transport (STILT) model driven by high-resolution (10 to 30 km) meteorological fields from the Weather Research and Forecasting (WRF) model. We performed a suite of synthetic-data experiments to evaluate a variety of inversion configurations, including (1) solving for scaling factors to an a priori flux versus additive corrections, (2) solving for fluxes at 3-hrly resolution versus at coarser temporal resolution, (3) solving for fluxes at 1o × 1o resolution versus at large eco-regional scales. Our framework explicitly and objectively solves for the optimal solution with a full error covariance matrix with maximum likelihood estimation, thereby enabling rigorous uncertainty estimates for the derived fluxes. In the synthetic-data inversions, we find that solving for weekly scaling factors of a priori Net Ecosystem Exchange (NEE) at 1o × 1o resolution with optimization of diurnal cycles of CO2 fluxes yields faithful retrieval of the specified "true" fluxes as those solved at 3-hrly resolution. In contrast, a scheme that does not allow for optimization of diurnal cycles of CO2 fluxes suffered from larger aggregation errors. We then applied the optimal inversion setup to estimate North American fluxes for 2007-2015 using real atmospheric CO2 observations, multiple prior estimates of NEE, and multiple boundary values estimated from the NOAA's global Eulerian CarbonTracker (CarbonTracker) and from an empirical approach. Our derived North American land CO2 fluxes show larger seasonal amplitude than those estimated from the CarbonTracker, removing seasonal biases in the CarbonTracker's simulated CO2 mole fractions. Independent evaluations using in-situ CO2 eddy covariance flux measurements and independent aircraft profiles also suggest an improved estimation on North American CO2 fluxes from CT-L. Furthermore, our derived CO2 flux anomalies over North America corresponding to the 2012 North American drought and the 2015 El Niño are larger than derived by the CarbonTracker. They also indicate different responses of ecosystems to those anomalous climatic events.

An efficient approach for inverse kinematics and redundancy resolution scheme of hyper-redundant manipulators

NASA Astrophysics Data System (ADS)

Chembuly, V. V. M. J. Satish; Voruganti, Hari Kumar

2018-04-01

Hyper redundant manipulators have a large number of degrees of freedom (DOF) than the required to perform a given task. Additional DOF of manipulators provide the flexibility to work in highly cluttered environment and in constrained workspaces. Inverse kinematics (IK) of hyper-redundant manipulators is complicated due to large number of DOF and these manipulators have multiple IK solutions. The redundancy gives a choice of selecting best solution out of multiple solutions based on certain criteria such as obstacle avoidance, singularity avoidance, joint limit avoidance and joint torque minimization. This paper focuses on IK solution and redundancy resolution of hyper-redundant manipulator using classical optimization approach. Joint positions are computed by optimizing various criteria for a serial hyper redundant manipulators while traversing different paths in the workspace. Several cases are addressed using this scheme to obtain the inverse kinematic solution while optimizing the criteria like obstacle avoidance, joint limit avoidance.

Optimization of intermolecular potential parameters for the CO2/H2O mixture.

PubMed

Orozco, Gustavo A; Economou, Ioannis G; Panagiotopoulos, Athanassios Z

2014-10-02

Monte Carlo simulations in the Gibbs ensemble were used to obtain optimized intermolecular potential parameters to describe the phase behavior of the mixture CO2/H2O, over a range of temperatures and pressures relevant for carbon capture and sequestration processes. Commonly used fixed-point-charge force fields that include Lennard-Jones 12-6 (LJ) or exponential-6 (Exp-6) terms were used to describe CO2 and H2O intermolecular interactions. For force fields based on the LJ functional form, changes of the unlike interactions produced higher variations in the H2O-rich phase than in the CO2-rich phase. A major finding of the present study is that for these potentials, no combination of unlike interaction parameters is able to adequately represent properties of both phases. Changes to the partial charges of H2O were found to produce significant variations in both phases and are able to fit experimental data in both phases, at the cost of inaccuracies for the pure H2O properties. By contrast, for the Exp-6 case, optimization of a single parameter, the oxygen-oxygen unlike-pair interaction, was found sufficient to give accurate predictions of the solubilities in both phases while preserving accuracy in the pure component properties. These models are thus recommended for future molecular simulation studies of CO2/H2O mixtures.

Migration of interfacial oxygen ions modulated resistive switching in oxide-based memory devices

NASA Astrophysics Data System (ADS)

Chen, C.; Gao, S.; Zeng, F.; Tang, G. S.; Li, S. Z.; Song, C.; Fu, H. D.; Pan, F.

2013-07-01

Oxides-based resistive switching memory induced by oxygen ions migration is attractive for future nonvolatile memories. Numerous works had focused their attentions on the sandwiched oxide materials for depressing the characteristic variations, but the comprehensive studies of the dependence of electrodes on the migration behavior of oxygen ions are overshadowed. Here, we investigated the interaction of various metals (Ni, Co, Al, Ti, Zr, and Hf) with oxygen atoms at the metal/Ta2O5 interface under electric stress and explored the effect of top electrode on the characteristic variations of Ta2O5-based memory device. It is demonstrated that chemically inert electrodes (Ni and Co) lead to the scattering switching characteristics and destructive gas bubbles, while the highly chemically active metals (Hf and Zr) formed a thick and dense interfacial intermediate oxide layer at the metal/Ta2O5 interface, which also degraded the resistive switching behavior. The relatively chemically active metals (Al and Ti) can absorb oxygen ions from the Ta2O5 film and avoid forming the problematic interfacial layer, which is benefit to the formation of oxygen vacancies composed conduction filaments in Ta2O5 film thus exhibit the minimum variations of switching characteristics. The clarification of oxygen ions migration behavior at the interface can lead further optimization of resistive switching performance in Ta2O5-based memory device and guide the rule of electrode selection for other oxide-based resistive switching memories.

Optimizing the ORR activity of Pd based nanocatalysts by tuning their strain and particle size

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Weiping; Liutheviciene Cordeiro, Marco Aurelio; Gong, Mingxing

Controlling of the particle size and surface strain is the key to tuning the surface chemistry and optimizing the catalytic performance of electrocatalysts. In this study, we show that by introducing both Fe and Co into Pd lattices, the surface strain of Pd nanocatalysts can be tuned to optimize their oxygen reduction activity in both fuel cells and Zn–air batteries. The Pd 2FeCo/C alloy particles are uniquely coated with an ultrathin Fe 2O 3 shell which is in situ formed during a thermal annealing treatment. The thin shell acts as an effective barrier that prevents the coalescence and ripening ofmore » Pd 2FeCo/C nanoparticles. Compared with Pd/C, Pd 2FeCo/C exhibits higher catalytic activity and long-term stability for the ORR, signifying changes in catalytic behavior due to particle sizes and strain effects. Moreover, by spontaneous decoration of Pt on the surface of Pd 2FeCo/C, the Pd 2FeCo@Pt/C core@shell structure was formed and the Pt mass activity was about 37.6 and 112.5 times higher than that on Pt/C in a 0.1 M HClO 4 and KOH solution at 0.9 V, respectively, suggesting an enhanced ORR performance after Pt decoration. More interestingly, Pd 2FeCo@Pt/C also shows a power density of ~308 mW cm -2, which is much higher than that of Pt/C (175 mW cm -2), and excellent durability in a home-made Zn–air battery.« less

Optimizing the ORR activity of Pd based nanocatalysts by tuning their strain and particle size

DOE PAGES

Xiao, Weiping; Liutheviciene Cordeiro, Marco Aurelio; Gong, Mingxing; ...

2017-04-18

Controlling of the particle size and surface strain is the key to tuning the surface chemistry and optimizing the catalytic performance of electrocatalysts. In this study, we show that by introducing both Fe and Co into Pd lattices, the surface strain of Pd nanocatalysts can be tuned to optimize their oxygen reduction activity in both fuel cells and Zn–air batteries. The Pd 2FeCo/C alloy particles are uniquely coated with an ultrathin Fe 2O 3 shell which is in situ formed during a thermal annealing treatment. The thin shell acts as an effective barrier that prevents the coalescence and ripening ofmore » Pd 2FeCo/C nanoparticles. Compared with Pd/C, Pd 2FeCo/C exhibits higher catalytic activity and long-term stability for the ORR, signifying changes in catalytic behavior due to particle sizes and strain effects. Moreover, by spontaneous decoration of Pt on the surface of Pd 2FeCo/C, the Pd 2FeCo@Pt/C core@shell structure was formed and the Pt mass activity was about 37.6 and 112.5 times higher than that on Pt/C in a 0.1 M HClO 4 and KOH solution at 0.9 V, respectively, suggesting an enhanced ORR performance after Pt decoration. More interestingly, Pd 2FeCo@Pt/C also shows a power density of ~308 mW cm -2, which is much higher than that of Pt/C (175 mW cm -2), and excellent durability in a home-made Zn–air battery.« less

Exclusive Ni-N4 Sites Realize Near-Unity CO Selectivity for Electrochemical CO2 Reduction.

PubMed

Li, Xiaogang; Bi, Wentuan; Chen, Minglong; Sun, Yuexiang; Ju, Huanxin; Yan, Wensheng; Zhu, Junfa; Wu, Xiaojun; Chu, Wangsheng; Wu, Changzheng; Xie, Yi

2017-10-25

Electrochemical reduction of carbon dioxide (CO 2 ) to value-added carbon products is a promising approach to reduce CO 2 levels and mitigate the energy crisis. However, poor product selectivity is still a major obstacle to the development of CO 2 reduction. Here we demonstrate exclusive Ni-N 4 sites through a topo-chemical transformation strategy, bringing unprecedentedly high activity and selectivity for CO 2 reduction. Topo-chemical transformation by carbon layer coating successfully ensures preservation of the Ni-N 4 structure to a maximum extent and avoids the agglomeration of Ni atoms to particles, providing abundant active sites for the catalytic reaction. The Ni-N 4 structure exhibits excellent activity for electrochemical reduction of CO 2 with particularly high selectivity, achieving high faradaic efficiency over 90% for CO in the potential range from -0.5 to -0.9 V and gives a maximum faradaic efficiency of 99% at -0.81 V with a current density of 28.6 mA cm -2 . We anticipate exclusive catalytic sites will shed new light on the design of high-efficiency electrocatalysts for CO 2 reduction.

Carbon and Energy Saving Financial Opportunities in the Industrial Compressed Air Sector

NASA Astrophysics Data System (ADS)

Vittorini, Diego; Cipollone, Roberto

2017-08-01

The transition towards a more sustainable energy scenario calls for both medium-to-long and short term interventions, with CO2 reduction and fossil fuel saving as main goals for all the Countries in the World. Among all others, one way to support these efforts is the setting-up of immaterial markets able to regulate, in the form of purchase and sales quotas, CO2 emissions avoided and fossil fuels not consumed. As a consequence, the upgrade of those sectors, characterized by high energy impact, is currently more than an option due to the related achievable financial advantage on the afore mentioned markets. Being responsible for about 10% electricity consumption in Industry, the compressed air sector is currently addressed as extremely appealing, when CO2 emissions and burned fossil fuels saving are in question. In the paper, once a standard is defined for compressors performances, based on data from the Compressed Air and Gas Institute and PNEUROP, the achievable energy saving is evaluated along with the effect in terms of CO2 emissions: with reference to those contexts in which mature intangible markets are established, an estimation of the financial benefit from savings sale on correspondent markets is possible, in terms of both avoided CO2 and fossil fuels not burned. The approach adopted allows to extend the analysis results to every context of interest, by applying the appropriate emission factor to the datum on compressor specific consumption.

Modeling of process parameters for enhanced production of coenzyme Q10 from Rhodotorula glutinis.

PubMed

Balakumaran, Palanisamy Athiyaman; Meenakshisundaram, Sankaranarayanan

2015-01-01

Coenzyme Q10 (CoQ10) plays an indispensable role in ATP generation through oxidative phosphorylation and helps in scavenging superoxides generated during electron transfer reactions. It finds extensive applications specifically related to oxidative damage and metabolic dysfunctions. This article reports the use of a statistical approach to optimize the concentration of key variables for the enhanced production of CoQ10 by Rhodotorula glutinis in a lab-scale fermenter. The culture conditions that promote optimum growth and CoQ10 production were optimized and the interaction of significant variables para-hydroxybenzoic acid (PHB, 819.34 mg/L) and soybean oil (7.78% [v/v]) was studied using response surface methodology (RSM). CoQ10 production increased considerably from 10 mg/L (in control) to 39.2 mg/L in batch mode with RSM-optimized precursor concentration. In the fed-batch mode, PHB and soybean oil feeding strategy enhanced CoQ10 production to 78.2 mg/L.

Chemical stability of high-temperature superconductors

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1992-01-01

A review of the available studies on the chemical stability of the high temperature superconductors (HTS) in various environments was made. The La(1.8)Ba(0.2)CuO4 HTS is unstable in the presence of H2O, CO2, and CO. The YBa2Cu3O(7-x) superconductor is highly susceptible to degradation in different environments, especially water. The La(2-x)Ba(x)CuO4 and Bi-Sr-Ca-Cu-O HTS are relatively less reactive than the YBa2Cu3O(7-x). Processing of YBa2Cu3O(7-x) HTS in purified oxygen, rather than in air, using high purity noncarbon containing starting materials is recommended. Exposure of this HTS to the ambient atmosphere should also be avoided at all stages during processing and storage. Devices and components made out of these oxide superconductors would have to be protected with an impermeable coating of a polymer, glass, or metal to avoid deterioration during use.

Optimization of silicon waveguides for gas detection application at mid-IR wavelengths

NASA Astrophysics Data System (ADS)

Butt, M. A.; Kozlova, E. S.

2018-04-01

There are several trace gases such as N2O, CO, CO2, NO, H2O, NO2, NH3, CH4 etc. which have their absorption peaks in Mid-IR spectrum These gases strongly absorb in the mid-IR > 2.5 μm spectral region due to their fundamental rotational and vibrational transitions. In this work, we modelled and optimized three different kinds of waveguides such as rib, strip and slot based on silicon platform to obtain maximum evanescent field ratio. These waveguides are designed at 3.39 μm and 4.67 μm which correspond to the absorption line of methane (CH4) and carbon monoxide (CO) respectively.

Optimizing the Calculation of DM,CO and VC via the Single Breath Single Oxygen Tension DLCO/NO Method

PubMed Central

Coffman, Kirsten E.; Taylor, Bryan J.; Carlson, Alex R.; Wentz, Robert J.; Johnson, Bruce D.

2015-01-01

Alveolar-capillary membrane conductance (DM,CO) and pulmonary-capillary blood volume (VC) are calculated via lung diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO) using the single breath, single oxygen tension (single-FiO2) method. However, two calculation parameters, the reaction rate of carbon monoxide with blood (θCO) and the DM,NO/DM,CO ratio (α-ratio), are controversial. This study systematically determined optimal θCO and α-ratio values to be used in the single-FiO2 method that yielded the most similar DM,CO and VC values compared to the ‘gold-standard’ multiple-FiO2 method. Eleven healthy subjects performed single breath DLCO/DLNO maneuvers at rest and during exercise. DM,CO and VC were calculated via the single-FiO2 and multiple-FiO2 methods by implementing seven θCO equations and a range of previously reported α-ratios. The RP θCO equation (Reeves and Park, Respiration physiology 88:1–21, 1992.) and an α-ratio of 4.0–4.4 yielded DM,CO and VC values that were most similar between methods. The RP θCO equation and an experimental α-ratio should be used in future studies. PMID:26521031

Co3O4/MnO2/Hierarchically Porous Carbon as Superior Bifunctional Electrodes for Liquid and All-Solid-State Rechargeable Zinc-Air Batteries.

PubMed

Li, Xuemei; Dong, Fang; Xu, Nengneng; Zhang, Tao; Li, Kaixi; Qiao, Jinli

2018-05-09

The design of efficient, durable, and affordable catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is very indispensable in liquid-type and flexible all-solid-state zinc-air batteries. Herein, we present a high-performance bifunctional catalyst with cobalt and manganese oxides supported on porous carbon (Co 3 O 4 /MnO 2 /PQ-7). The optimized Co 3 O 4 /MnO 2 /PQ-7 exhibited a comparable ORR performance with commercial Pt/C and a more superior OER performance than all of the other prepared catalysts, including commercial Pt/C. When applied to practical aqueous (6.0 M KOH) zinc-air batteries, the Co 3 O 4 /MnO 2 /porous carbon hybrid catalysts exhibited exceptional performance, such as a maximum discharge peak power density as high as 257 mW cm -2 and the most stable charge-discharge durability over 50 h with negligible deactivation to date. More importantly, a series of flexible all-solid-state zinc-air batteries can be fabricated by the Co 3 O 4 /MnO 2 /porous carbon with a layer-by-layer method. The optimal catalyst (Co 3 O 4 /MnO 2 /PQ-7) exhibited an excellent peak power density of 45 mW cm -2 . The discharge potentials almost remained unchanged for 6 h at 5 mA cm -2 and possessed a long cycle life (2.5 h@5 mA cm -2 ). These results make the optimized Co 3 O 4 /MnO 2 /PQ-7 a promising cathode candidate for both liquid-type and flexible all-solid-state zinc-air batteries.

Advanced air revitalization for optimized crew and plant environments

NASA Technical Reports Server (NTRS)

Lee, M. G.; Grigger, David J.; Brown, Mariann F.

1991-01-01

The Hybrid Air Revitalization System (HARS) closed ecosystem concept presented encompasses electrochemical CO2 and O2 separators, in conjunction with a mechanical condenser/separator for maintaining CO2, O2, and humidity levels in crew and plant habitats at optimal conditions. HARS requires no expendables, and allows flexible process control on the bases of electrochemical cell current, temperature, and airflow rate variations. HARS capacity can be easily increased through the incorporation of additional chemical cells. Detailed system flowcharts are provided.

Assessing variability in Orbiting Carbon Observatory-2 (OCO-2) XCO2 using high spatial resolution color slices and other retrieval parameters

NASA Astrophysics Data System (ADS)

Merrelli, A. J.; Taylor, T.; O'Dell, C.; Cronk, H. Q.; Eldering, A.; Crisp, D.

2017-12-01

The Orbiting Carbon Observatory-2 (OCO-2) measures reflected sunlight in the Oxygen A-band (0.76 μm), Weak CO2 band (1.61 μm) and Strong CO2 band (2.06 μm) with resolving powers 18,000, 19,500 and 19,500, respectively. Soundings are collected at 3Hz, yielding 8 contiguous <1.3 km x 2.3 km footprints across a narrow (<0.8°) swath. After cloud screening, these high-resolution spectra are used in an optimal estimation retrieval to produce estimates of the column averaged carbon dioxide dry air mole fraction (XCO2). In the absence of strong CO2 absorbers, e.g., intense agricultural regions, or strong emitters, e.g., mega-cities, the variability of XCO2 over small scales, e.g., tens of kilometers, is expected to be less than 1 ppm. However, deviations on the order of +/- 2 ppm, or more, are often observed in the production Version 7 (B7) data product. We hypothesize that most of this variability is spurious, with contributions from both retrieval errors and undetected cloud and aerosol contamination. The contiguous nature of the OCO-2 spatial sampling allows for analysis of the variability in XCO2 and correlation with variables, such as the full spatial resolution "color slices" and other retrieved parameters. Color slices avoid the on-board averaging across the detector focal plane array, providing increased spatial information compared to the nominal spectra. This work explores the new B8 production data set using MODIS visible imagery from the CSU Vistool to provide visual context to the OCO-2 parameters. The large volume of data that has been collected since September 2014 allows for statistical analysis of parameters in relation to XCO2 variability. Some detailed case studies are presented.

CO2 mitigation potential of mineral carbonation with industrial alkalinity sources in the United States.

PubMed

Kirchofer, Abby; Becker, Austin; Brandt, Adam; Wilcox, Jennifer

2013-07-02

The availability of industrial alkalinity sources is investigated to determine their potential for the simultaneous capture and sequestration of CO2 from point-source emissions in the United States. Industrial alkalinity sources investigated include fly ash, cement kiln dust, and iron and steel slag. Their feasibility for mineral carbonation is determined by their relative abundance for CO2 reactivity and their proximity to point-source CO2 emissions. In addition, the available aggregate markets are investigated as possible sinks for mineral carbonation products. We show that in the U.S., industrial alkaline byproducts have the potential to mitigate approximately 7.6 Mt CO2/yr, of which 7.0 Mt CO2/yr are CO2 captured through mineral carbonation and 0.6 Mt CO2/yr are CO2 emissions avoided through reuse as synthetic aggregate (replacing sand and gravel). The emission reductions represent a small share (i.e., 0.1%) of total U.S. CO2 emissions; however, industrial byproducts may represent comparatively low-cost methods for the advancement of mineral carbonation technologies, which may be extended to more abundant yet expensive natural alkalinity sources.

Operating wind turbines in strong wind conditions by using feedforward-feedback control

NASA Astrophysics Data System (ADS)

Feng, Ju; Sheng, Wen Zhong

2014-12-01

Due to the increasing penetration of wind energy into power systems, it becomes critical to reduce the impact of wind energy on the stability and reliability of the overall power system. In precedent works, Shen and his co-workers developed a re-designed operation schema to run wind turbines in strong wind conditions based on optimization method and standard PI feedback control, which can prevent the typical shutdowns of wind turbines when reaching the cut-out wind speed. In this paper, a new control strategy combing the standard PI feedback control with feedforward controls using the optimization results is investigated for the operation of variable-speed pitch-regulated wind turbines in strong wind conditions. It is shown that the developed control strategy is capable of smoothening the power output of wind turbine and avoiding its sudden showdown at high wind speeds without worsening the loads on rotor and blades.

Turboexpander plant designs can provide high ethane recovery without inlet CO/sub 2/ removal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilkinson, J.D.; Hudson, H.M.

1982-05-03

New turboexpander plant designs can process natural gas streams containing moderate amounts of carbon dioxide (CO/sub 2/) for high ethane recovery without inlet gas treating. The designs will handle a wide range of inlet ethane-plus fractions. They also offer reduced horsepower requirements compared to other processes. CO/sub 2/ is a typical component of most natural gas streams. In many cases, processing of these gas streams in a turboexpander plant for high ethane recovery requires pre-treatment of the gas for CO/sub 2/ removal. This is required to avoid the formation of solid CO/sub 2/ (freezing) in the cold sections of themore » process and/or to meet necessary residue gas and liquid product CO/sub 2/ specifications. Depending on the quantities involved, the CO/sub 2/ removal systems is generally a significant portion of both the installed cost and operating cost for the ethane recovery facility. Therefore, turboexpander plant designs that are capable of handling increased quantities of CO/sub 2/ in the feed gas without freezing can offer the gas processor substantial economic benefits.« less

Adaptive management for subsurface pressure and plume control in application to geological CO2 storage

NASA Astrophysics Data System (ADS)

Gonzalez-Nicolas, A.; Cihan, A.; Birkholzer, J. T.; Petrusak, R.; Zhou, Q.; Riestenberg, D. E.; Trautz, R. C.; Godec, M.

2016-12-01

Industrial-scale injection of CO2 into the subsurface can cause reservoir pressure increases that must be properly controlled to prevent any potential environmental impact. Excessive pressure buildup in reservoir may result in ground water contamination stemming from leakage through conductive pathways, such as improperly plugged abandoned wells or distant faults, and the potential for fault reactivation and possibly seal breaching. Brine extraction is a viable approach for managing formation pressure, effective stress, and plume movement during industrial-scale CO2 injection projects. The main objectives of this study are to investigate suitable different pressure management strategies involving active brine extraction and passive pressure relief wells. Adaptive optimized management of CO2 storage projects utilizes the advanced automated optimization algorithms and suitable process models. The adaptive management integrates monitoring, forward modeling, inversion modeling and optimization through an iterative process. In this study, we employ an adaptive framework to understand primarily the effects of initial site characterization and frequency of the model update (calibration) and optimization calculations for controlling extraction rates based on the monitoring data on the accuracy and the success of the management without violating pressure buildup constraints in the subsurface reservoir system. We will present results of applying the adaptive framework to test appropriateness of different management strategies for a realistic field injection project.

[Preparation of curcumin-EC sustained-release composite particles by supercritical CO2 anti-solvent technology].

PubMed

Bai, Wei-li; Yan, Ting-yuan; Wang, Zhi-xiang; Huang, De-chun; Yan, Ting-xuan; Li, Ping

2015-01-01

Curcumin-ethyl-cellulose (EC) sustained-release composite particles were prepared by using supercritical CO2 anti-solvent technology. With drug loading and yield of inclusion complex as evaluation indexes, on the basis of single factor tests, orthogonal experimental design was used to optimize the preparation process of curcumin-EC sustained-release composite particles. The experiments such as drug loading, yield, particle size distribution, electron microscope analysis (SEM) , infrared spectrum (IR), differential scanning calorimetry (DSC) and in vitro dissolution were used to analyze the optimal process combination. The orthogonal experimental optimization process conditions were set as follows: crystallization temperature 45 degrees C, crystallization pressure 10 MPa, curcumin concentration 8 g x L(-1), solvent flow rate 0.9 mL x min(-1), and CO2 velocity 4 L x min(-1). Under the optimal conditions, the average drug loading and yield of curcumin-EC sustained-release composite particles were 33.01% and 83.97%, and the average particle size of the particles was 20.632 μm. IR and DSC analysis showed that curcumin might complex with EC. The experiments of in vitro dissolution showed that curcumin-EC composite particles had good sustained-release effect. Curcumin-EC sustained-release composite particles can be prepared by supercritical CO2 anti-solvent technology.

Implementation and optimization of automated dispensing cabinet technology.

PubMed

McCarthy, Bryan C; Ferker, Michael

2016-10-01

A multifaceted automated dispensing cabinet (ADC) optimization initiative at a large hospital is described. The ADC optimization project, which was launched approximately six weeks after activation of ADCs in 30 patient care unit medication rooms of a newly established adult hospital, included (1) adjustment of par inventory levels (desired on-hand quantities of medications) and par reorder quantities to reduce the risk of ADC supply exhaustion and improve restocking efficiency, (2) expansion of ADC "common stock" (medications assigned to ADC inventories) to increase medication availability at the point of care, and (3) removal of some infrequently prescribed medications from ADCs to reduce the likelihood of product expiration. The purpose of the project was to address organizational concerns regarding widespread ADC medication stockouts, growing reliance on cart-fill medication delivery systems, and suboptimal medication order turnaround times. Leveraging of the ADC technology platform's reporting functionalities for enhanced inventory control yielded a number of benefits, including cost savings resulting from reduced pharmacy technician labor requirements (estimated at $2,728 annually), a substantial reduction in the overall weekly stockout percentage (from 3.2% before optimization to 0.5% eight months after optimization), an improvement in the average medication turnaround time, and estimated cost avoidance of $19,660 attributed to the reduced potential for product expiration. Efforts to optimize ADCs through par level optimization, expansion of common stock, and removal of infrequently used medications reduced pharmacy technician labor, decreased stockout percentages, generated opportunities for cost avoidance, and improved medication turnaround times. Copyright © 2016 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

Catholyte-Free Electrocatalytic CO2 Reduction to Formate.

PubMed

Lee, Wonhee; Kim, Young Eun; Youn, Min Hye; Jeong, Soon Kwan; Park, Ki Tae

2018-04-16

Electrochemical reduction of carbon dioxide (CO 2 ) into value-added chemicals is a promising strategy to reduce CO 2 emission and mitigate climate change. One of the most serious problems in electrocatalytic CO 2 reduction (CO 2 R) is the low solubility of CO 2 in an aqueous electrolyte, which significantly limits the cathodic reaction rate. This paper proposes a facile method of catholyte-free electrocatalytic CO 2 reduction to avoid the solubility limitation using commercial tin nanoparticles as a cathode catalyst. Interestingly, as the reaction temperature rises from 303 K to 363 K, the partial current density (PCD) of formate improves more than two times with 52.9 mA cm -2 , despite the decrease in CO 2 solubility. Furthermore, a significantly high formate concentration of 41.5 g L -1 is obtained as a one-path product at 343 K with high PCD (51.7 mA cm -2 ) and high Faradaic efficiency (93.3 %) via continuous operation in a full flow cell at a low cell voltage of 2.2 V. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bedside end-tidal CO2 tension as a screening tool to exclude pulmonary embolism.

PubMed

Hemnes, A R; Newman, A L; Rosenbaum, B; Barrett, T W; Zhou, C; Rice, T W; Newman, J H

2010-04-01

End tidal carbon dioxide tension (P(ET,CO(2))) is a surrogate for dead space ventilation which may be useful in the evaluation of pulmonary embolism (PE). We aimed to define the optimal P(ET,CO(2)) level to exclude PE in patients evaluated for possible thromboembolism. 298 patients were enrolled over 6 months at a single academic centre. P(ET,CO(2)) was measured within 24 h of contrast-enhanced helical computed tomography, lower extremity duplex or ventilation/perfusion scan. Performance characteristics were measured by comparing test results with clinical diagnosis of PE. PE was diagnosed in 39 (13%) patients. Mean P( ET,CO(2)) in healthy volunteers did not differ from P( ET,CO(2)) in patients without PE (36.3+/-2.8 versus 35.5+/-6.8 mmHg). P(ET,CO(2 )) in patients with PE was 30.5+/-5.5 mmHg (p<0.001 versus patients without PE). A P(ET,CO(2)) of >or=36 mmHg had optimal sensitivity and specificity (87.2 and 53.0%, respectively) with a negative predictive value of 96.6% (95% CI 92.3-98.5). This increased to 97.6% (95% CI 93.2-99.) when combined with Wells score <4. A P(ET,CO(2)) of >or=36 mmHg may reliably exclude PE. Accuracy is augmented by combination with Wells score. P( ET,CO(2)) should be prospectively compared to D-dimer in accuracy and simplicity to exclude PE.

Optimizing the calculation of DM,CO and VC via the single breath single oxygen tension DLCO/NO method.

PubMed

Coffman, Kirsten E; Taylor, Bryan J; Carlson, Alex R; Wentz, Robert J; Johnson, Bruce D

2016-01-15

Alveolar-capillary membrane conductance (D(M,CO)) and pulmonary-capillary blood volume (V(C)) are calculated via lung diffusing capacity for carbon monoxide (DL(CO)) and nitric oxide (DL(NO)) using the single breath, single oxygen tension (single-FiO2) method. However, two calculation parameters, the reaction rate of carbon monoxide with blood (θ(CO)) and the D(M,NO)/D(M,CO) ratio (α-ratio), are controversial. This study systematically determined optimal θ(CO) and α-ratio values to be used in the single-FiO2 method that yielded the most similar D(M,CO) and V(C) values compared to the 'gold-standard' multiple-FiO2 method. Eleven healthy subjects performed single breath DL(CO)/DL(NO) maneuvers at rest and during exercise. D(M,CO) and V(C) were calculated via the single-FiO2 and multiple-FiO2 methods by implementing seven θ(CO) equations and a range of previously reported α-ratios. The RP θ(CO) equation (Reeves, R.B., Park, H.K., 1992. Respiration Physiology 88 1-21) and an α-ratio of 4.0-4.4 yielded DM,CO and VC values that were most similar between methods. The RP θ(CO) equation and an experimental α-ratio should be used in future studies. Copyright © 2015 Elsevier B.V. All rights reserved.

Joint optimization of green vehicle scheduling and routing problem with time-varying speeds

PubMed Central

Zhang, Dezhi; Wang, Xin; Ni, Nan; Zhang, Zhuo

2018-01-01

Based on an analysis of the congestion effect and changes in the speed of vehicle flow during morning and evening peaks in a large- or medium-sized city, the piecewise function is used to capture the rules of the time-varying speed of vehicles, which are very important in modelling their fuel consumption and CO2 emission. A joint optimization model of the green vehicle scheduling and routing problem with time-varying speeds is presented in this study. Extra wages during nonworking periods and soft time-window constraints are considered. A heuristic algorithm based on the adaptive large neighborhood search algorithm is also presented. Finally, a numerical simulation example is provided to illustrate the optimization model and its algorithm. Results show that, (1) the shortest route is not necessarily the route that consumes the least energy, (2) the departure time influences the vehicle fuel consumption and CO2 emissions and the optimal departure time saves on fuel consumption and reduces CO2 emissions by up to 5.4%, and (3) extra driver wages have significant effects on routing and departure time slot decisions. PMID:29466370

Joint optimization of green vehicle scheduling and routing problem with time-varying speeds.

PubMed

Zhang, Dezhi; Wang, Xin; Li, Shuangyan; Ni, Nan; Zhang, Zhuo

2018-01-01

Based on an analysis of the congestion effect and changes in the speed of vehicle flow during morning and evening peaks in a large- or medium-sized city, the piecewise function is used to capture the rules of the time-varying speed of vehicles, which are very important in modelling their fuel consumption and CO2 emission. A joint optimization model of the green vehicle scheduling and routing problem with time-varying speeds is presented in this study. Extra wages during nonworking periods and soft time-window constraints are considered. A heuristic algorithm based on the adaptive large neighborhood search algorithm is also presented. Finally, a numerical simulation example is provided to illustrate the optimization model and its algorithm. Results show that, (1) the shortest route is not necessarily the route that consumes the least energy, (2) the departure time influences the vehicle fuel consumption and CO2 emissions and the optimal departure time saves on fuel consumption and reduces CO2 emissions by up to 5.4%, and (3) extra driver wages have significant effects on routing and departure time slot decisions.

Optimization of data retrieval process for spectroscopic CO2 isotopologue ratio measurements

NASA Astrophysics Data System (ADS)

Hovorka, J.; Čermák, P.; Veis, P.

2017-05-01

In this work, a numerical model was developed for critical evaluation of the 13CO2/12CO2 ratio retrievals ( Δ δ value) from laser absorption spectra. The goal of the analysis was to determine the dependency of the absolute error of δ on different experimental parameters, in order to find the optimal conditions for isotopic ratio retrievals without using calibrated reference samples. In our study, the target precision for Δ δ was set at a level of ≤slant 1 %. The analysis was performed in the spectral range of the {ν1}+{ν3} CO2 band at 1.6 μm, with the theoretical data originating from the HITRAN database. The proposed fitting algorithm allowed efficient compensation of the interference from weak transitions which are not well recognizable in a single spectrum. This effect was found to make a dominant contribution to the Δ δ value. Next, the optimal conditions for such an experiment regarding the pressure, spectral range and spectrum noise were found and discussed from the perspective of widely tunable laser applications.

Thermal analysis, optimization and design of a Martian oxygen production plant

NASA Technical Reports Server (NTRS)

Iyer, Venkatesh A.; Sridhar, K. R.

1991-01-01

The objective is to optimally design the thermal components of a system that uses carbon dioxide (CO2) from the Martian atmosphere to produce oxygen (O2) for spacecraft propulsion and/or life-support. Carbon dioxide is thermally decomposed into carbon monoxide (CO) and O2 followed by the electrochemical separation of O2. The design of the overall system and its various individual components depends on, among other things, the fraction of the stoichiometric yield of O2 that can be realized in the system and the temperature of operation of the electrochemical separation membrane. The analysis indicates that a substantial reduction could be obtained in the mass and power requirements of the system if the unreacted CO2 were to be recycled. The concepts of an optimum temperature of the zirconia cell and impracticality of plant operation at low cell efficiencies are also discussed. The design of the thermal equipment is such that the mass and power requirements of the individual components and of the overall system are optimized.

Adaptation to high CO2 concentration in an optimal environment: radiation capture, canopy quantum yield and carbon use efficiency

NASA Technical Reports Server (NTRS)

Monje, O.; Bugbee, B.

1998-01-01

The effect of elevated [CO2] on wheat (Triticum aestivum L. Veery 10) productivity was examined by analysing radiation capture, canopy quantum yield, canopy carbon use efficiency, harvest index and daily C gain. Canopies were grown at either 330 or 1200 micromoles mol-1 [CO2] in controlled environments, where root and shoot C fluxes were monitored continuously from emergence to harvest. A rapidly circulating hydroponic solution supplied nutrients, water and root zone oxygen. At harvest, dry mass predicted from gas exchange data was 102.8 +/- 4.7% of the observed dry mass in six trials. Neither radiation capture efficiency nor carbon use efficiency were affected by elevated [CO2], but yield increased by 13% due to a sustained increase in canopy quantum yield. CO2 enrichment increased root mass, tiller number and seed mass. Harvest index and chlorophyll concentration were unchanged, but CO2 enrichment increased average life cycle net photosynthesis (13%, P < 0.05) and root respiration (24%, P < 0.05). These data indicate that plant communities adapt to CO2 enrichment through changes in C allocation. Elevated [CO2] increases sink strength in optimal environments, resulting in sustained increases in photosynthetic capacity, canopy quantum yield and daily C gain throughout the life cycle.

Fuzzy multi-objective optimization case study based on an anaerobic co-digestion process of food waste leachate and piggery wastewater.

PubMed

Choi, Angelo Earvin Sy; Park, Hung Suck

2018-06-20

This paper presents the development and evaluation of fuzzy multi-objective optimization for decision-making that includes the process optimization of anaerobic digestion (AD) process. The operating cost criteria which is a fundamental research gap in previous AD analysis was integrated for the case study in this research. In this study, the mixing ratio of food waste leachate (FWL) and piggery wastewater (PWW), calcium carbonate (CaCO 3 ) and sodium chloride (NaCl) concentrations were optimized to enhance methane production while minimizing operating cost. The results indicated a maximum of 63.3% satisfaction for both methane production and operating cost under the following optimal conditions: mixing ratio (FWL: PWW) - 1.4, CaCO 3 - 2970.5 mg/L and NaCl - 2.7 g/L. In multi-objective optimization, the specific methane yield (SMY) was 239.0 mL CH 4 /g VS added , while 41.2% volatile solids reduction (VSR) was obtained at an operating cost of 56.9 US$/ton. In comparison with the previous optimization study that utilized the response surface methodology, the SMY, VSR and operating cost of the AD process were 310 mL/g, 54% and 83.2 US$/ton, respectively. The results from multi-objective fuzzy optimization proves to show the potential application of this technique for practical decision-making in the process optimization of AD process. Copyright © 2018 Elsevier Ltd. All rights reserved.

4D Optimization of Scanned Ion Beam Tracking Therapy for Moving Tumors

PubMed Central

Eley, John Gordon; Newhauser, Wayne David; Lüchtenborg, Robert; Graeff, Christian; Bert, Christoph

2014-01-01

Motion mitigation strategies are needed to fully realize the theoretical advantages of scanned ion beam therapy for patients with moving tumors. The purpose of this study was to determine whether a new four-dimensional (4D) optimization approach for scanned-ion-beam tracking could reduce dose to avoidance volumes near a moving target while maintaining target dose coverage, compared to an existing 3D-optimized beam tracking approach. We tested these approaches computationally using a simple 4D geometrical phantom and a complex anatomic phantom, that is, a 4D computed tomogram of the thorax of a lung cancer patient. We also validated our findings using measurements of carbon-ion beams with a motorized film phantom. Relative to 3D-optimized beam tracking, 4D-optimized beam tracking reduced the maximum predicted dose to avoidance volumes by 53% in the simple phantom and by 13% in the thorax phantom. 4D-optimized beam tracking provided similar target dose homogeneity in the simple phantom (standard deviation of target dose was 0.4% versus 0.3%) and dramatically superior homogeneity in the thorax phantom (D5-D95 was 1.9% versus 38.7%). Measurements demonstrated that delivery of 4D-optimized beam tracking was technically feasible and confirmed a 42% decrease in maximum film exposure in the avoidance region compared with 3D-optimized beam tracking. In conclusion, we found that 4D-optimized beam tracking can reduce the maximum dose to avoidance volumes near a moving target while maintaining target dose coverage, compared with 3D-optimized beam tracking. PMID:24889215

4D optimization of scanned ion beam tracking therapy for moving tumors

NASA Astrophysics Data System (ADS)

Eley, John Gordon; Newhauser, Wayne David; Lüchtenborg, Robert; Graeff, Christian; Bert, Christoph

2014-07-01

Motion mitigation strategies are needed to fully realize the theoretical advantages of scanned ion beam therapy for patients with moving tumors. The purpose of this study was to determine whether a new four-dimensional (4D) optimization approach for scanned-ion-beam tracking could reduce dose to avoidance volumes near a moving target while maintaining target dose coverage, compared to an existing 3D-optimized beam tracking approach. We tested these approaches computationally using a simple 4D geometrical phantom and a complex anatomic phantom, that is, a 4D computed tomogram of the thorax of a lung cancer patient. We also validated our findings using measurements of carbon-ion beams with a motorized film phantom. Relative to 3D-optimized beam tracking, 4D-optimized beam tracking reduced the maximum predicted dose to avoidance volumes by 53% in the simple phantom and by 13% in the thorax phantom. 4D-optimized beam tracking provided similar target dose homogeneity in the simple phantom (standard deviation of target dose was 0.4% versus 0.3%) and dramatically superior homogeneity in the thorax phantom (D5-D95 was 1.9% versus 38.7%). Measurements demonstrated that delivery of 4D-optimized beam tracking was technically feasible and confirmed a 42% decrease in maximum film exposure in the avoidance region compared with 3D-optimized beam tracking. In conclusion, we found that 4D-optimized beam tracking can reduce the maximum dose to avoidance volumes near a moving target while maintaining target dose coverage, compared with 3D-optimized beam tracking.

Click mechanochemistry: quantitative synthesis of "ready to use" chiral organocatalysts by efficient two-fold thiourea coupling to vicinal diamines.

PubMed

Štrukil, Vjekoslav; Igrc, Marina D; Eckert-Maksić, Mirjana; Friščić, Tomislav

2012-07-02

Mechanochemical methods of neat grinding and liquid-assisted grinding have been applied to the synthesis of mono- and bis(thiourea)s by using the click coupling of aromatic and aliphatic diamines with aromatic isothiocyanates. The ability to modify the reaction conditions allowed the optimization of each reaction, leading to the quantitative formation of chiral bis(thiourea)s with known uses as organocatalysts or anion sensors. Quantitative reaction yields, combined with the fact that mechanochemical reaction conditions avoid the use of bulk solvents, enabled solution-based purification methods (such as chromatography or recrystallization) to be completely avoided. Importantly, by using selected model reactions, we also show that the described mechanochemical reaction procedures can be readily scaled up to at least the one-gram scale. In that way, mechanochemical synthesis provides a facile method to fully transform valuable enantiomerically pure reagents into useful products that can immediately be applied in their designed purpose. This was demonstrated by using some of the mechanochemically prepared reagents as organocatalysts in a model Morita-Baylis-Hillman reaction and as cyanide ion sensors in organic solvents. The use of electronically and sterically hindered ortho-phenylenediamine revealed that mechanochemical reaction conditions can be readily optimized to form either the 1:1 or the 1:2 click-coupling product, demonstrating that reaction stoichiometry can be more efficiently controlled under these conditions than in solution-based syntheses. In this way, it was shown that excellent stoichiometric control by mechanochemistry, previously established for mechanochemical syntheses of cocrystals and coordination polymers, can also be achieved in the context of covalent-bond formation. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microbial fixation of CO2 in water bodies and in drylands to combat climate change, soil loss and desertification.

PubMed

Rossi, Federico; Olguín, Eugenia J; Diels, Ludo; De Philippis, Roberto

2015-01-25

The growing concern for the increase of the global warming effects due to anthropogenic activities raises the challenge of finding novel technological approaches to stabilize CO2 emissions in the atmosphere and counteract impinging interconnected issues such as desertification and loss of biodiversity. Biological-CO2 mitigation, triggered through biological fixation, is considered a promising and eco-sustainable method, mostly owing to its downstream benefits that can be exploited. Microorganisms such as cyanobacteria, green algae and some autotrophic bacteria could potentially fix CO2 more efficiently than higher plants, due to their faster growth. Some examples of the potential of biological-CO2 mitigation are reported and discussed in this paper. In arid and semiarid environments, soil carbon sequestration (CO2 fixation) by cyanobacteria and biological soil crusts is considered an eco-friendly and natural process to increase soil C content and a viable pathway to soil restoration after one disturbance event. Another way for biological-CO2 mitigation intensively studied in the last few years is related to the possibility to perform carbon dioxide sequestration using microalgae, obtaining at the same time bioproducts of industrial interest. Another possibility under study is the exploitation of specific chemotrophic bacteria, such as Ralstonia eutropha (or picketii) and related organisms, for CO2 fixation coupled with the production chemicals such as polyhydroxyalkanoates (PHAs). In spite of the potential of these processes, multiple factors still have to be optimized for maximum rate of CO2 fixation by these microorganisms. The optimization of culture conditions, including the optimal concentration of CO2 in the provided gas, the use of metabolic engineering and of dual purpose systems for the treatment of wastewater and production of biofuels and high value products within a biorefinery concept, the design of photobioreactors in the case of phototrophs are some of the issues that, among others, have to be addressed and tested for cost-effective CO2 sequestration. Copyright © 2013 Elsevier B.V. All rights reserved.

In vitro/in vivo evaluation of an optimized fast dissolving oral film containing olanzapine co-amorphous dispersion with selected carboxylic acids.

PubMed

Maher, Eman Magdy; Ali, Ahmed Mahmoud Abdelhaleem; Salem, Heba Farouk; Abdelrahman, Ahmed Abdelbary

2016-10-01

Improvement of water solubility, dissolution rate, oral bioavailability, and reduction of first pass metabolism of OL (OL), were the aims of this research. Co-amorphization of OL carboxylic acid dispersions at various molar ratios was carried out using rapid solvent evaporation. Characterization of the dispersions was performed using differential scanning calorimetry (DSC), Fourier transform infrared spectrometry (FTIR), X-ray diffractometry (XRD), and scanning electron microscopy (SEM). Dispersions with highest equilibrium solubility were formulated as fast dissolving oral films. Modeling and optimization of film formation were undertaken using artificial neural networks (ANNs). The results indicated co-amorphization of OL-ascorbic acid through H-bonding. The co-amorphous dispersions at 1:2 molar ratio showed more than 600-fold increase in solubility of OL. The model optimized fast dissolving film prepared from the dispersion was physically and chemically stable, demonstrated short disintegration time (8.5 s), fast dissolution (97% in 10 min) and optimum tensile strength (4.9 N/cm 2 ). The results of in vivo data indicated high bioavailability (144 ng h/mL) and maximum plasma concentration (14.2 ng/mL) compared with the marketed references. Therefore, the optimized co-amorphous OL-ascorbic acid fast dissolving film could be a valuable solution for enhancing the physicochemical and pharmacokinetic properties of OL.

Variation of photoautotrophic fatty acid production from a highly CO2 tolerant alga, Chlorococcum littorale, with inorganic carbon over narrow ranges of pH.

PubMed

Ota, Masaki; Takenaka, Motohiro; Sato, Yoshiyuki; Smith, Richard L; Inomata, Hiroshi

2015-01-01

Photoautotrophic fatty acid production of a highly CO2 -tolerant green alga Chlorococcum littorale in the presence of inorganic carbon at 295 K and light intensity of 170 µmol-photon m(-2) s(-1) was investigated. CO2 concentration in the bubbling gas was adjusted by mixing pure gas components of CO2 and N2 to avoid photorespiration and β-oxidation of fatty acids under O2 surrounding conditions. Maximum content of total fatty acid showed pH-dependence after nitrate depletion of the culture media and increased with the corresponding inorganic carbon ratio. Namely, [HCO3 (-) ]/([CO2 ]+n[ CO32-]) ratio in the culture media was found to be a controlling factor for photoautotrophic fatty acid production after the nitrate limitation. At a CO2 concentration of 5% (vol/vol) and a pH of 6.7, the fatty acid content was 47.8 wt % (dry basis) at its maximum that is comparable with land plant seed oils. © 2015 American Institute of Chemical Engineers.

Greenhouse gases emissions accounting for typical sewage sludge digestion with energy utilization and residue land application in China.

PubMed

Niu, Dong-jie; Huang, Hui; Dai, Xiao-hu; Zhao, You-cai

2013-01-01

About 20 million tonnes of sludge (with 80% moisture content) is discharged by the sewage treatment plants per year in China, which, if not treated properly, can be a significant source of greenhouse gases (GHGs) emissions. Anaerobic digestion is a conventional sewage sludge treatment method and will continue to be one of the main technologies in the following years. This research has taken into consideration GHGs emissions from typical processes of sludge thickening+anaerobic digestion+dewatering+residue land application in China. Fossil CO(2), biogenic CO(2), CH(4,) and avoided CO(2) as the main objects is discussed respectively. The results show that the total CO(2)-eq is about 1133 kg/t DM (including the biogenic CO(2)), while the net CO(2)-eq is about 372 kg/t DM (excluding the biogenic CO(2)). An anaerobic digestion unit as the main GHGs emission source occupies more than 91% CO(2)-eq of the whole process. The use of biogas is important for achieving carbon dioxide emission reductions, which could reach about 24% of the total CO(2)-eq reduction. Copyright © 2012 Elsevier Ltd. All rights reserved.

Alkaline in situ transesterification of Aurantiochytrium sp. KRS 101 using potassium carbonate.

PubMed

Sung, Mina; Han, Jong-In

2016-04-01

The aims of this work were to evaluate K2CO3 as a potent alkaline catalyst for in situ transesterification of Aurantiochytrium sp. KRS 101, one step process in which oil extraction and conversion take place together. This K2CO3-based in situ transesterification was optimized in terms of recovery yield of fatty acid methyl esters (FAMEs) by way of varying biomass concentration, reaction temperature, reaction time, and catalyst concentration. The optimal condition was achieved at 50g/L of biomass concentration and 1% of K2CO3 in the methanol, 25°C of reaction temperature, and 5min of reaction time, resulting in the FAME recovery yield over 90%. It was found that K2CO3 performed better than any other tested catalysts including acids, supporting the notion that K2CO3 is a promising catalyst, especially for in situ transesterification. Copyright © 2016. Published by Elsevier Ltd.

Airborne Detection and Tracking of Geologic Leakage Sites

NASA Astrophysics Data System (ADS)

Jacob, Jamey; Allamraju, Rakshit; Axelrod, Allan; Brown, Calvin; Chowdhary, Girish; Mitchell, Taylor

2014-11-01

Safe storage of CO2 to reduce greenhouse gas emissions without adversely affecting energy use or hindering economic growth requires development of monitoring technology that is capable of validating storage permanence while ensuring the integrity of sequestration operations. Soil gas monitoring has difficulty accurately distinguishing gas flux signals related to leakage from those associated with meteorologically driven changes of soil moisture and temperature. Integrated ground and airborne monitoring systems are being deployed capable of directly detecting CO2 concentration in storage sites. Two complimentary approaches to detecting leaks in the carbon sequestration fields are presented. The first approach focuses on reducing the requisite network communication for fusing individual Gaussian Process (GP) CO2 sensing models into a global GP CO2 model. The GP fusion approach learns how to optimally allocate the static and mobile sensors. The second approach leverages a hierarchical GP-Sigmoidal Gaussian Cox Process for airborne predictive mission planning to optimally reducing the entropy of the global CO2 model. Results from the approaches will be presented.

Optimized Unlike-Pair Interactions for Water-Carbon Dioxide Mixtures described by the SPC/E and EPM2 Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vlcek, Lukas; Chialvo, Ariel A; Cole, David

The unlike- pair interaction parameters for the SPC/E- EPM2 models have been optimized to reproduce the mutual solubility of water and carbon dioxide at the conditions of liquid- supercritical fluid phase equilibria. An efficient global optimization of the parameters is achieved through an implementation of the coupling parameter approach, adapted to phase equilibria calculations in the Gibbs ensemble, that explicitly corrects for the over- polarization of the SPC/E water molecule in the non- polar CO2 environments. The resulting H2O- CO2 force field reproduces accurately the available experimental solubilities at the two fluid phases in equilibria as well as the correspondingmore » species tracer diffusion coefficients.« less

Co-Optimization of Electricity Transmission and Generation Resources for Planning and Policy Analysis: Review of Concepts and Modeling Approaches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krishnan, Venkat; Ho, Jonathan; Hobbs, Benjamin F.

2016-05-01

The recognition of transmission's interaction with other resources has motivated the development of co-optimization methods to optimize transmission investment while simultaneously considering tradeoffs with investments in electricity supply, demand, and storage resources. For a given set of constraints, co-optimized planning models provide solutions that have lower costs than solutions obtained from decoupled optimization (transmission-only, generation-only, or iterations between them). This paper describes co-optimization and provides an overview of approaches to co-optimizing transmission options, supply-side resources, demand-side resources, and natural gas pipelines. In particular, the paper provides an up-to-date assessment of the present and potential capabilities of existing co-optimization tools, andmore » it discusses needs and challenges for developing advanced co-optimization models.« less

Application of Box-Behnken design to prepare gentamicin-loaded calcium carbonate nanoparticles.

PubMed

Maleki Dizaj, Solmaz; Lotfipour, Farzaneh; Barzegar-Jalali, Mohammad; Zarrintan, Mohammad-Hossein; Adibkia, Khosro

2016-09-01

The aim of this research was to prepare and optimize calcium carbonate (CaCO3) nanoparticles as carriers for gentamicin sulfate. A chemical precipitation method was used to prepare the gentamicin sulfate-loaded CaCO3 nanoparticles. A 3-factor, 3-level Box-Behnken design was used for the optimization procedure, with the molar ratio of CaCl2: Na2CO3 (X1), the concentration of drug (X2), and the speed of homogenization (X3) as the independent variables. The particle size and entrapment efficiency were considered as response variables. Mathematical equations and response surface plots were used, along with the counter plots, to relate the dependent and independent variables. The results indicated that the speed of homogenization was the main variable contributing to particle size and entrapment efficiency. The combined effect of all three independent variables was also evaluated. Using the response optimization design, the optimized Xl-X3 levels were predicted. An optimized formulation was then prepared according to these levels, resulting in a particle size of 80.23 nm and an entrapment efficiency of 30.80%. It was concluded that the chemical precipitation technique, together with the Box-Behnken experimental design methodology, could be successfully used to optimize the formulation of drug-incorporated calcium carbonate nanoparticles.

Experimental and feasibility assessment of biogas production by anaerobic digestion of fruit and vegetable waste from Joburg Market.

PubMed

Masebinu, S O; Akinlabi, E T; Muzenda, E; Aboyade, A O; Mbohwa, C

2018-05-01

Substrate-induced instability of anaerobic digestion from fruit and vegetable waste (FVW) results in low biogas yield. In this study, substrate management through fruit to vegetable mix ratio in a two-stage semi-continuous digester was investigated as a pathway for optimality of yield. The experiment conducted over 105 days with 62.52 kg of FVWs sourced from Joburg Market, South Africa showed that a stable process was achieved at a fruit to vegetable waste mix ratio of 2.2:2.8. At this ratio, optimal organic loading rate ranged between 2.68 and 2.97 kg VS/m 3 -d which resulted in a specific biogas yield of 0.87 Nm 3 /kg VS with 57.58% methane on average. The results of the experimental study were used as a feasibility assessment for a full-scale 45 tonnes/d plant for Joburg Market considering three energy pathways. The plant will produce 1,605,455 Nm 3 /y of biogas with the potential for offsetting 15.2% of the Joburg Market energy demand. Conversion of all biogas to biomethane was the most economically attractive energy pathway with a net present value of $2,428,021, an internal rate of return of 16.90% and a simple payback period of 6.17 years. This route avoided the greenhouse gas emission of 12,393 tonnes CO 2 , eq. The study shows that the anaerobic digestion of FVWs as sole substrate is possible with financial and environmental attractiveness. Copyright © 2018 Elsevier Ltd. All rights reserved.

Stochastic injection-strategy optimization for the preliminary assessment of candidate geological storage sites

NASA Astrophysics Data System (ADS)

Cody, Brent M.; Baù, Domenico; González-Nicolás, Ana

2015-09-01

Geological carbon sequestration (GCS) has been identified as having the potential to reduce increasing atmospheric concentrations of carbon dioxide (CO2). However, a global impact will only be achieved if GCS is cost-effectively and safely implemented on a massive scale. This work presents a computationally efficient methodology for identifying optimal injection strategies at candidate GCS sites having uncertainty associated with caprock permeability, effective compressibility, and aquifer permeability. A multi-objective evolutionary optimization algorithm is used to heuristically determine non-dominated solutions between the following two competing objectives: (1) maximize mass of CO2 sequestered and (2) minimize project cost. A semi-analytical algorithm is used to estimate CO2 leakage mass rather than a numerical model, enabling the study of GCS sites having vastly different domain characteristics. The stochastic optimization framework presented herein is applied to a feasibility study of GCS in a brine aquifer in the Michigan Basin (MB), USA. Eight optimization test cases are performed to investigate the impact of decision-maker (DM) preferences on Pareto-optimal objective-function values and carbon-injection strategies. This analysis shows that the feasibility of GCS at the MB test site is highly dependent upon the DM's risk-adversity preference and degree of uncertainty associated with caprock integrity. Finally, large gains in computational efficiency achieved using parallel processing and archiving are discussed.

Electrochemical Oxidation of Lithium Carbonate Generates Singlet Oxygen.

PubMed

Mahne, Nika; Renfrew, Sara E; McCloskey, Bryan D; Freunberger, Stefan A

2018-05-04

Solid alkali metal carbonates are universal passivation layer components of intercalation battery materials and common side products in metal-O 2 batteries, and are believed to form and decompose reversibly in metal-O 2 /CO 2 cells. In these cathodes, Li 2 CO 3 decomposes to CO 2 when exposed to potentials above 3.8 V vs. Li/Li + . However, O 2 evolution, as would be expected according to the decomposition reaction 2 Li 2 CO 3 →4 Li + +4 e - +2 CO 2 +O 2 , is not detected. O atoms are thus unaccounted for, which was previously ascribed to unidentified parasitic reactions. Here, we show that highly reactive singlet oxygen ( 1 O 2 ) forms upon oxidizing Li 2 CO 3 in an aprotic electrolyte and therefore does not evolve as O 2 . These results have substantial implications for the long-term cyclability of batteries: they underpin the importance of avoiding 1 O 2 in metal-O 2 batteries, question the possibility of a reversible metal-O 2 /CO 2 battery based on a carbonate discharge product, and help explain the interfacial reactivity of transition-metal cathodes with residual Li 2 CO 3 . © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Excise tax avoidance: the case of state cigarette taxes.

PubMed

DeCicca, Philip; Kenkel, Donald; Liu, Feng

2013-12-01

We conduct an applied welfare economics analysis of cigarette tax avoidance. We develop an extension of the standard formula for the optimal Pigouvian corrective tax to incorporate the possibility that consumers avoid the tax by making purchases in nearby lower tax jurisdictions. To provide a key parameter for our formula, we estimate a structural endogenous switching regression model of border-crossing and cigarette prices. In illustrative calculations, we find that for many states, after taking into account tax avoidance the optimal tax is at least 20% smaller than the standard Pigouvian tax that simply internalizes external costs. Our empirical estimate that tax avoidance strongly responds to the price differential is the main reason for this result. We also use our results to examine the benefits of replacing avoidable state excise taxes with a harder-to-avoid federal excise tax on cigarettes. Copyright © 2013 Elsevier B.V. All rights reserved.

Excise Tax Avoidance: The Case of State Cigarette Taxes

PubMed Central

DeCicca, Philip; Kenkel, Donald; Liu, Feng

2013-01-01

We conduct an applied welfare economics analysis of cigarette tax avoidance. We develop an extension of the standard formula for the optimal Pigouvian corrective tax to incorporate the possibility that consumers avoid the tax by making purchases in nearby lower-tax jurisdictions. To provide a key parameter for our formula, we estimate a structural endogenous switching regression model of border-crossing and cigarette prices. In illustrative calculations, we find that for many states, after taking into account tax avoidance the optimal tax is at least 20 percent smaller than the standard Pigouvian tax that simply internalizes external costs. Our empirical estimate that tax avoidance strongly responds to the price differential is the main reason for this result. We also use our results to examine the benefits of replacing avoidable state excise taxes with a harder-to-avoid federal excise tax on cigarettes. PMID:24140760

Effect of pH on desorption of CO2 from alkanolamine - rich solvents

NASA Astrophysics Data System (ADS)

Du, Min

2017-08-01

Adipic acid was used as a pH regulator, which was added to 0.4 mol/L MEA, DEA and MDEA solvents during CO2 desorption process. It is found that when pH value of the solvents swing between 8-10, CO2 desorption rate enhanced, and energy consumption has declined obviously. This research may have reference significance on optimization of alkanolamine CO2 capture process.

Conversion of carbon dioxide to carbon monoxide by pulse dielectric barrier discharge plasma

NASA Astrophysics Data System (ADS)

Wang, Taobo; Liu, Hongxia; Xiong, Xiang; Feng, Xinxin

2017-01-01

The conversion of carbon dioxide (CO2) to carbon monoxide (CO) was investigated in a non-thermal plasma dielectric barrier discharge (DBD) reactor, and the effects of different process conditions on the CO2 conversion were investigated. The results showed that the increase of input power could optimize the conversion of CO2 to CO. The CO2 conversion and CO yield were negatively correlated with the gas flow rate, but there was an optimum gas flow rate, that made the CO selectivity best. The carrier gas (N2, Ar) was conducive to the conversion of CO2, and the effect of N2 as carrier gas was better than Ar. The conversion of CO2 to CO was enhanced by addition of the catalyst (5A molecular sieve).

Temporal Stability of Multiple Response Systems to 7.5% Carbon Dioxide Challenge

PubMed Central

Roberson-Nay, Roxann; Gorlin, Eugenia I.; Beadel, Jessica R.; Cash, Therese; Vrana, Scott; Teachman, Bethany A.

2017-01-01

Self-reported anxiety, and potentially physiological response, to maintained inhalation of carbon dioxide (CO2) enriched air shows promise as a putative marker of panic reactivity and vulnerability. Temporal stability of response systems during low-dose, steady-state CO2 breathing challenge is lacking. Outcomes on multiple levels were measured two times, one week apart, in 93 individuals. Stability was highest during the CO2 breathing phase compared to pre-CO2 and recovery phases, with anxiety ratings, respiratory rate, skin conductance level, and heart rate demonstrating good to excellent temporal stability (ICCs ≥ 0.71). Cognitive symptoms tied to panic were somewhat less stable (ICC = 0.58) than physical symptoms (ICC = 0.74) during CO2 breathing. Escape/avoidance behaviors and DSM-5 panic attacks were not stable. Large effect sizes between task phases also were observed. Overall, results suggest good-excellent levels of temporal stability for multiple outcomes during respiratory stimulation via 7.5% CO2. PMID:28163046

Optimal Collision Avoidance Trajectories for Unmanned/Remotely Piloted Aircraft

DTIC Science & Technology

2014-12-26

projected operational tempos (OPTEMPOs)” [15]. The Oce of the Secretary of Defense (OSD) Unmanned Systems Roadmap [15] goes on to say that the airspace...methods [63]. In an indirect method, the researcher derives the first- order necessary conditions for optimality “via the calculus of variations and...region around the ownship using a variation of a superquadric. From [116], the standard equation for a superellipsoid appears as: ✓ x a1 ◆ 2 ✏ 2

Quantifying global fossil-fuel CO2 emissions: from OCO-2 to optimal observing designs

NASA Astrophysics Data System (ADS)

Ye, X.; Lauvaux, T.; Kort, E. A.; Oda, T.; Feng, S.; Lin, J. C.; Yang, E. G.; Wu, D.; Kuze, A.; Suto, H.; Eldering, A.

2017-12-01

Cities house more than half of the world's population and are responsible for more than 70% of the world anthropogenic CO2 emissions. Therefore, quantifications of emissions from major cities, which are only less than a hundred intense emitting spots across the globe, should allow us to monitor changes in global fossil-fuel CO2 emissions, in an independent, objective way. Satellite platforms provide favorable temporal and spatial coverage to collect urban CO2 data to quantify the anthropogenic contributions to the global carbon budget. We present here the optimal observation design for future NASA's OCO-2 and Japanese GOSAT missions, based on real-data (i.e. OCO-2) experiments and Observing System Simulation Experiments (OSSE's) to address different error components in the urban CO2 budget calculation. We identify the major sources of emission uncertainties for various types of cities with different ecosystems and geographical features, such as urban plumes over flat terrains, accumulated enhancements within basins, and complex weather regimes in coastal areas. Atmospheric transport errors were characterized under various meteorological conditions using the Weather Research and Forecasting (WRF) model at 1-km spatial resolution, coupled to the Open-source Data Inventory for Anthropogenic CO2 (ODIAC) emissions. We propose and discuss the optimized urban sampling strategies to address some difficulties from the seasonality in cloud cover and emissions, vegetation density in and around cities, and address the daytime sampling bias using prescribed diurnal cycles. These factors are combined in pseudo data experiments in which we evaluate the relative impact of uncertainties on inverse estimates of CO2 emissions for cities across latitudinal and climatological zones. We propose here several sampling strategies to minimize the uncertainties in target mode for tracking urban fossil-fuel CO2 emissions over the globe for future satellite missions, such as OCO-3 and future versions of GOSAT.

SILCC-Zoom: the dynamic and chemical evolution of molecular clouds

NASA Astrophysics Data System (ADS)

Seifried, D.; Walch, S.; Girichidis, P.; Naab, T.; Wünsch, R.; Klessen, R. S.; Glover, S. C. O.; Peters, T.; Clark, P.

2017-12-01

We present 3D 'zoom-in' simulations of the formation of two molecular clouds out of the galactic interstellar medium. We model the clouds - identified from the SILCC simulations - with a resolution of up to 0.06 pc using adaptive mesh refinement in combination with a chemical network to follow heating, cooling and the formation of H2 and CO including (self-) shielding. The two clouds are assembled within a few million years with mass growth rates of up to ∼10-2 M⊙ yr-1 and final masses of ∼50 000 M⊙. A spatial resolution of ≲0.1 pc is required for convergence with respect to the mass, velocity dispersion and chemical abundances of the clouds, although these properties also depend on the cloud definition such as based on density thresholds, H2 or CO mass fraction. To avoid grid artefacts, the progressive increase of resolution has to occur within the free-fall time of the densest structures (1-1.5 Myr) and ≳200 time-steps should be spent on each refinement level before the resolution is progressively increased further. This avoids the formation of spurious, large-scale, rotating clumps from unresolved turbulent flows. While CO is a good tracer for the evolution of dense gas with number densities n ≥ 300 cm-3, H2 is also found for n ≲ 30 cm-3 due to turbulent mixing and becomes dominant at column densities around 30-50 M⊙ pc-2. The CO-to-H2 ratio steadily increases within the first 2 Myr, whereas XCO ≃ 1-4 × 1020 cm-2 (K km s-1)-1 is approximately constant since the CO(1-0) line quickly becomes optically thick.

Optimization of Supercritical CO2 Extraction of Fish Oil from Viscera of African Catfish (Clarias gariepinus)

PubMed Central

Sarker, Mohamed Zaidul Islam; Selamat, Jinap; Habib, Abu Sayem Md. Ahsan; Ferdosh, Sahena; Akanda, Mohamed Jahurul Haque; Jaffri, Juliana Mohamed

2012-01-01

Fish oil was extracted from the viscera of African Catfish using supercritical carbon dioxide (SC-CO2). A Central Composite Design of Response Surface methodology (RSM) was employed to optimize the SC-CO2 extraction parameters. The oil yield (Y) as response variable was executed against the four independent variables, namely pressure, temperature, flow rate and soaking time. The oil yield varied with the linear, quadratic and interaction of pressure, temperature, flow rate and soaking time. Optimum points were observed within the variables of temperature from 35 °C to 80 °C, pressure from 10 MPa to 40 MPa, flow rate from 1 mL/min to 3 mL/min and soaking time from 1 h to 4 h. However, the extraction parameters were found to be optimized at temperature 57.5 °C, pressure 40 MPa, flow rate 2.0 mL/min and soaking time 2.5 h. At this optimized condition, the highest oil yields were found to be 67.0% (g oil/100 g sample on dry basis) in the viscera of catfish which was reasonable to the yields of 78.0% extracted using the Soxhlet method. PMID:23109854

Optimizing Value and Avoiding Problems in Building Schools.

ERIC Educational Resources Information Center

Brevard County School Board, Cocoa, FL.

This report describes school design and construction delivery processes used by the School Board of Brevard County (Cocoa, Florida) that help optimize value, avoid problems, and eliminate the cost of maintaining a large facility staff. The project phases are examined from project definition through design to construction. Project delivery…

Safety parameters for avoiding acute ocular damage from the reflected CO2 (10.6 microns) laser beam.

PubMed

Friedman, N R; Saleeby, E R; Rubin, M G; Sandu, T; Krull, E A

1987-11-01

Reflections from instruments in the surgical field involving the CO2 laser beam present a serious ocular hazard. In addition to the use of plastic or glass protective eyewear, this hazard can be minimized by utilizing anodized instruments and recognizing the specific distances at which various reflections are no longer hazardous depending upon certain variables, including laser output wattage, emergent beam lengths, and surface characteristics of the reflecting instruments.

Fatty acid composition and antioxidant activity of tea (Camellia sinensis L.) seed oil extracted by optimized supercritical carbon dioxide.

PubMed

Wang, Yuefei; Sun, Da; Chen, Hao; Qian, Lisheng; Xu, Ping

2011-01-01

Seeds are another product in addition to leaves (raw materials for teas) of tea (Camellia sinensis L.) plant. The great increase of tea consumption in recent years raises the challenge of finding commercial applications for tea seeds. In the present study, supercritical carbon dioxide (SC-CO(2)) extraction edible oil from tea seed was carried out, response surface methodology (RSM) was used to optimize processing parameters including time (20-90 min), temperature (35-45 °C) and pressure (50-90 MPa). The fatty acid composition and antioxidant activity of the extracted oil was also investigated. The highest yield of oil (29.2 ± 0.6%) was obtained under optimal SC-CO(2) extraction conditions (45 °C, 89.7 min and 32 MPa, respectively), which was significantly higher (p < 0.05) than that (25.3 ± 1.0%) given by Soxhlet extraction. Meanwhile, tea seed oil extracted by SC-CO(2) contained approximately 80% unsaturated fatty acids and showed a much stronger scavenging ability on the DPPH radical than that extracted by Soxhlet. SC-CO(2) is a promising alternative for efficient extraction of edible oil from tea seed. Moreover, tea seed oil extracted by SC-CO(2) is highly edible and has good antioxidant activity, and therefore may play a potential role as a health-promoting food resource in human diets.

Fatty Acid Composition and Antioxidant Activity of Tea (Camellia sinensis L.) Seed Oil Extracted by Optimized Supercritical Carbon Dioxide

PubMed Central

Wang, Yuefei; Sun, Da; Chen, Hao; Qian, Lisheng; Xu, Ping

2011-01-01

Seeds are another product in addition to leaves (raw materials for teas) of tea (Camellia sinensis L.) plant. The great increase of tea consumption in recent years raises the challenge of finding commercial applications for tea seeds. In the present study, supercritical carbon dioxide (SC-CO2) extraction edible oil from tea seed was carried out, response surface methodology (RSM) was used to optimize processing parameters including time (20–90 min), temperature (35–45 °C) and pressure (50–90 MPa). The fatty acid composition and antioxidant activity of the extracted oil was also investigated. The highest yield of oil (29.2 ± 0.6%) was obtained under optimal SC-CO2 extraction conditions (45 °C, 89.7 min and 32 MPa, respectively), which was significantly higher (p < 0.05) than that (25.3 ± 1.0%) given by Soxhlet extraction. Meanwhile, tea seed oil extracted by SC-CO2 contained approximately 80% unsaturated fatty acids and showed a much stronger scavenging ability on the DPPH radical than that extracted by Soxhlet. SC-CO2 is a promising alternative for efficient extraction of edible oil from tea seed. Moreover, tea seed oil extracted by SC-CO2 is highly edible and has good antioxidant activity, and therefore may play a potential role as a health-promoting food resource in human diets. PMID:22174626

Experiment and Optimization for Simultaneous Carbonation of Ca2+ and Mg2+ in A Two-phase System of Insoluble Diisobutylamine and Aqueous Solution

NASA Astrophysics Data System (ADS)

Wang, Wenlong; Wang, Man; Liu, Xin; Wang, Peng; Xi, Zhenqian

2015-06-01

An optimized approach of CO2 fixation in Ca2+/Mg2+-rich aqueous solutions using insoluble amine as an enhancing medium was reported. Apparent basicity was verified to be an effective indicator for the selection and optimization of organic amine systems and finally the diisobutylamine + n-octanol system was selected to enhance the carbonation reactions of CO2 in an artificial Ca2+/Mg2+-rich solution. In our experiments, when the volume ratio of insoluble organic phase to aqueous one was 2:1 and the reaction temperature was 28 °C, 92% of Ca2+ and 80% of Mg2+ could be converted to calcium and magnesium carbonate precipitates within 5 min of reaction with the bubbling-in of CO2. The organic amine system could be regenerated by using carbide slag as the regeneration agent and could still show attractive enhancement performances after 7 rounds of carbonation-regeneration experiments. In this way, the CO2 capture and sequestration was realized within one single process, with value-added Ca/Mg carbonates being the byproducts. In view of the vast availability of Ca2+/Mg2+-rich aqueous solutions and the feasible technical coordination with desalination industry, this novel process may have a good application potential in the future.

Challenges in Catalytic Manufacture of Renewable Pyrrolidinones from Fermentation Derived Succinate

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, James F.; Holladay, Johnathan E.; Zacher, Alan H.

2014-09-05

Fermentation derived succinic acid ammonium salt is an ideal precursor for manufacture of renewable N-methyl pyrrolidinone (NMP) or 2-pyrrolidinone (2P) via heterogeneous catalysis. However, there are many challenges to making this a practical reality. Chief among the challenges is avoiding catalyst poisoning by fermentation by- and co-products. Battelle / Pacific Northwest National Laboratory (PNNL) have developed an economically effective technology strategy for this purpose. The technology is a combination of purely thermal processing, followed by simple catalytic hydrogenation that together avoids catalyst poisoning from fermentation impurities and provides high selectivity and yields of NMP or 2P.

Co-Simulation for Advanced Process Design and Optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stephen E. Zitney

2009-01-01

Meeting the increasing demand for clean, affordable, and secure energy is arguably the most important challenge facing the world today. Fossil fuels can play a central role in a portfolio of carbon-neutral energy options provided CO{sub 2} emissions can be dramatically reduced by capturing CO{sub 2} and storing it safely and effectively. Fossil energy industry faces the challenge of meeting aggressive design goals for next-generation power plants with CCS. Process designs will involve large, highly-integrated, and multipurpose systems with advanced equipment items with complex geometries and multiphysics. APECS is enabling software to facilitate effective integration, solution, and analysis of high-fidelitymore » process/equipment (CFD) co-simulations. APECS helps to optimize fluid flow and related phenomena that impact overall power plant performance. APECS offers many advanced capabilities including ROMs, design optimization, parallel execution, stochastic analysis, and virtual plant co-simulations. NETL and its collaborative R&D partners are using APECS to reduce the time, cost, and technical risk of developing high-efficiency, zero-emission power plants with CCS.« less

Quest for Value in Big Earth Data

NASA Astrophysics Data System (ADS)

Kuo, Kwo-Sen; Oloso, Amidu O.; Rilee, Mike L.; Doan, Khoa; Clune, Thomas L.; Yu, Hongfeng

2017-04-01

Among all the V's of Big Data challenges, such as Volume, Variety, Velocity, Veracity, etc., we believe Value is the ultimate determinant, because a system delivering better value has a competitive edge over others. Although it is not straightforward to assess the value of scientific endeavors, we believe the ratio of scientific productivity increase to investment is a reasonable measure. Our research in Big Data approaches to data-intensive analysis for Earth Science has yielded some insights, as well as evidences, as to how optimal value might be attained. The first insight is that we should avoid, as much as possible, moving data through connections with relatively low bandwidth. That is, we recognize that moving data is expensive, albeit inevitable. They must at least be moved from the storage device into computer main memory and then to CPU registers for computation. When data must be moved it is better to move them via relatively high-bandwidth connections and avoid low-bandwidth ones. For this reason, a technology that can best exploit data locality will have an advantage over others. Data locality is easy to achieve and exploit with only one dataset. With multiple datasets, data colocation becomes important in addition to data locality. However, the organization of datasets can only be co-located for certain types of analyses. It is impossible for them to be co-located for all analyses. Therefore, our second insight is that we need to co-locate the datasets for the most commonly used analyses. In Earth Science, we believe the most common analysis requirement is "spatiotemporal coincidence". For example, when we analyze precipitation systems, we often would like to know the environment conditions "where and when" (i.e. at the same location and time) there is precipitation. This "where and when" indicates the "spatiotemporal coincidence" requirement. Thus, an associated insight is that datasets need to be partitioned per the physical dimensions, i.e. space and time, rather than their array index dimensions to achieve co-location for spatiotemporal coincidence. This leads further to the insight that, in terms of optimizing Value, achieving good scalability in Variety is more crucial than good scalability in Volume. Therefore, we will discuss our innovative approach to improving productivity by homogenizing the daunting varieties in Earth Science data to enable data co-location systematically. In addition, a Big Data system incorporating the capabilities described above has the potential to drastically shorten the data preparation period of machine learning, better facilitate automated machine learning operations, and further boost scientific productivity.

Geoengineering as an optimization problem

NASA Astrophysics Data System (ADS)

Ban-Weiss, George A.; Caldeira, Ken

2010-07-01

There is increasing evidence that Earth's climate is currently warming, primarily due to emissions of greenhouse gases from human activities, and Earth has been projected to continue warming throughout this century. Scientists have begun to investigate the potential for geoengineering options for reducing surface temperatures and whether such options could possibly contribute to environmental risk reduction. One proposed method involves deliberately increasing aerosol loading in the stratosphere to scatter additional sunlight to space. Previous modeling studies have attempted to predict the climate consequences of hypothetical aerosol additions to the stratosphere. These studies have shown that this method could potentially reduce surface temperatures, but could not recreate a low-CO2 climate in a high-CO2 world. In this study, we attempt to determine the latitudinal distribution of stratospheric aerosols that would most closely achieve a low-CO2 climate despite high CO2 levels. Using the NCAR CAM3.1 general circulation model, we find that having a stratospheric aerosol loading in polar regions higher than that in tropical regions leads to a temperature distribution that is more similar to the low-CO2 climate than that yielded by a globally uniform loading. However, such polar weighting of stratospheric sulfate tends to degrade the degree to which the hydrological cycle is restored, and thus does not markedly contribute to improved recovery of a low-CO2 climate. In the model, the optimal latitudinally varying aerosol distributions diminished the rms zonal mean land temperature change from a doubling of CO2 by 94% and the rms zonal mean land precipitation minus evaporation change by 74%. It is important to note that this idealized study represents a first attempt at optimizing the engineering of climate using a general circulation model; uncertainties are high and not all processes that are important in reality are modeled.

Can increased nitrogen uptake at elevated CO2 be explained by an hypothesis of optimal root function?

NASA Astrophysics Data System (ADS)

McMurtrie, R. E.; Norby, R. J.; Näsholm, T.; Iversen, C.; Dewar, R. C.; Medlyn, B. E.

2011-12-01

Forest free-air CO2 enrichment (FACE) experiments have shown that annual nitrogen (N) uptake increases when trees are grown at elevated CO2 (eCO2) and that increased N uptake is critical for a sustained growth response to eCO2. Processes contributing to increased N uptake at eCO2 may include: accelerated decomposition of soil organic matter due to enhanced root carbon (C) exudation (so-called rhizosphere priming); increased C allocation to fine roots and increased root production at depth, both of which enhance N acquisition; differences in soil N availability with depth; changes in the abundance of N in chemical forms with differing mobility in soil; and reduced N concentrations, reduced maintenance respiration rates, and increased longevities of deeper roots. These processes have been synthesised in a model of annual N uptake in relation to the spatial distribution of roots. We hypothesise that fine roots are distributed spatially in order to maximise annual N uptake. The optimisation hypothesis leads to equations for the optimal vertical distribution of root biomass in relation to the distribution of available soil N and for maximum annual N uptake. We show how maximum N uptake and rooting depth are related to total root mass, and compare the optimal solution with an empirical function that has been fitted to root-distribution data from all terrestrial biomes. Finally, the model is used to explore the consequences of rhizosphere priming at eCO2 as observed at the Duke forest FACE experiment (Drake et al. 2011, Ecology Letters 14: 349-357) and of increasing N limitation over time as observed at the Oak Ridge FACE experiment (Norby et al. 2010, Proc. Nat. Acad. Sci. USA 107: 19368-19373).

Evaluation and Optimization of China's Anthropogenic CO2 Emissions using Observations from Northern China (2005-2009).

NASA Astrophysics Data System (ADS)

Dayalu, A.; Munger, J. W.; Wang, Y.; Wofsy, S.; Zhao, Y.; Nielsen, C. P.; Nehrkorn, T.; McElroy, M. B.; Chang, R.

2017-12-01

China has pledged to peak carbon emissions by 2030, but there continues to be significant uncertainty in estimates of its anthropogenic carbon dioxide (CO2) emissions. In this study, we evaluate the performance of three anthropogenic CO2 inventories, two global and one regional, using five years of continuous hourly observations from a site in Northern China. We model five years of continuous hourly observations (2005 to 2009) using the Stochastic Time-Inverted Lagrangian Transport Model (STILT) run in backward time mode driven by high resolution meteorology from the Weather Research and Forecasting Model version 3.6.1 (WRF) with vegetation fluxes prescribed by a simple biosphere model. We calculate regional enhancements to advected background CO2 derived from NOAA CarbonTracker on seasonal and annual bases and use observations to optimize emissions inventories within the site's influence region at these timescales. Finally, we use annual enhancements to examine carbon intensity of provinces in and adjacent to Northern China as CO2 per unit of the region's GDP to evaluate the effects of local and global economic events on CO2 emissions. With the exception of peak growing season where discrepancies are confounded by errors in the vegetation model, we find the regional inventory agrees significantly better with observations than the global inventories at all timescales. Here we use a single measurement site; significant improvements in inventory optimizations can be achieved with a network of measurements stations. This study highlights the importance of China-specific data over global averages in emissions evaluation and demonstrates the value of top-down studies in independently evaluating inventory performance. We demonstrate the framework's ability to resolve differences of at least 20% among inventories, establishing a benchmark for ongoing efforts to decrease uncertainty in China's reported CO2 emissions estimates.

Optimal design of microtube recuperators for an indirect supercritical carbon dioxide recompression closed Brayton cycle

DOE PAGES

Jiang, Yuan; Liese, Eric; Zitney, Stephen E.; ...

2018-02-25

This paper presents a baseline design and optimization approach developed in Aspen Custom Modeler (ACM) for microtube shell-and-tube exchangers (MSTEs) used for high- and low-temperature recuperation in a 10 MWe indirect supercritical carbon dioxide (sCO 2) recompression closed Brayton cycle (RCBC). The MSTE-type recuperators are designed using one-dimensional models with thermal-hydraulic correlations appropriate for sCO 2 and properties models that capture considerable nonlinear changes in CO 2 properties near the critical and pseudo-critical points. Using the successive quadratic programming (SQP) algorithm in ACM, optimal recuperator designs are obtained for either custom or industry-standard microtubes considering constraints based on current advancedmore » manufacturing techniques. The three decision variables are the number of tubes, tube pitch-to-diameter ratio, and tube diameter. Five different objective functions based on different key design measures are considered: minimization of total heat transfer area, heat exchanger volume, metal weight, thermal residence time, and maximization of compactness. Sensitivities studies indicate the constraint on the maximum number of tubes per shell does affect the number of parallel heat exchanger trains but not the tube selection, total number of tubes, tube length and other key design measures in the final optimal design when considering industry-standard tubes. In this study, the optimally designed high- and low-temperature recuperators have 47,000 3/32 inch tubes and 63,000 1/16 inch tubes, respectively. In addition, sensitivities to the design temperature approach and maximum allowable pressure drop are studied, since these specifications significantly impact the optimal design of the recuperators as well as the thermal efficiency and the economic performance of the entire sCO 2 Brayton cycle.« less

Optimal design of microtube recuperators for an indirect supercritical carbon dioxide recompression closed Brayton cycle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Yuan; Liese, Eric; Zitney, Stephen E.

This paper presents a baseline design and optimization approach developed in Aspen Custom Modeler (ACM) for microtube shell-and-tube exchangers (MSTEs) used for high- and low-temperature recuperation in a 10 MWe indirect supercritical carbon dioxide (sCO 2) recompression closed Brayton cycle (RCBC). The MSTE-type recuperators are designed using one-dimensional models with thermal-hydraulic correlations appropriate for sCO 2 and properties models that capture considerable nonlinear changes in CO 2 properties near the critical and pseudo-critical points. Using the successive quadratic programming (SQP) algorithm in ACM, optimal recuperator designs are obtained for either custom or industry-standard microtubes considering constraints based on current advancedmore » manufacturing techniques. The three decision variables are the number of tubes, tube pitch-to-diameter ratio, and tube diameter. Five different objective functions based on different key design measures are considered: minimization of total heat transfer area, heat exchanger volume, metal weight, thermal residence time, and maximization of compactness. Sensitivities studies indicate the constraint on the maximum number of tubes per shell does affect the number of parallel heat exchanger trains but not the tube selection, total number of tubes, tube length and other key design measures in the final optimal design when considering industry-standard tubes. In this study, the optimally designed high- and low-temperature recuperators have 47,000 3/32 inch tubes and 63,000 1/16 inch tubes, respectively. In addition, sensitivities to the design temperature approach and maximum allowable pressure drop are studied, since these specifications significantly impact the optimal design of the recuperators as well as the thermal efficiency and the economic performance of the entire sCO 2 Brayton cycle.« less

Does Size Matter? Atmospheric CO2 May Be a Stronger Driver of Stomatal Closing Rate Than Stomatal Size in Taxa That Diversified under Low CO2.

PubMed

Elliott-Kingston, Caroline; Haworth, Matthew; Yearsley, Jon M; Batke, Sven P; Lawson, Tracy; McElwain, Jennifer C

2016-01-01

One strategy for plants to optimize stomatal function is to open and close their stomata quickly in response to environmental signals. It is generally assumed that small stomata can alter aperture faster than large stomata. We tested the hypothesis that species with small stomata close faster than species with larger stomata in response to darkness by comparing rate of stomatal closure across an evolutionary range of species including ferns, cycads, conifers, and angiosperms under controlled ambient conditions (380 ppm CO2; 20.9% O2). The two species with fastest half-closure time and the two species with slowest half-closure time had large stomata while the remaining three species had small stomata, implying that closing rate was not correlated with stomatal size in these species. Neither was response time correlated with stomatal density, phylogeny, functional group, or life strategy. Our results suggest that past atmospheric CO2 concentration during time of taxa diversification may influence stomatal response time. We show that species which last diversified under low or declining atmospheric CO2 concentration close stomata faster than species that last diversified in a high CO2 world. Low atmospheric [CO2] during taxa diversification may have placed a selection pressure on plants to accelerate stomatal closing to maintain adequate internal CO2 and optimize water use efficiency.

Does Size Matter? Atmospheric CO2 May Be a Stronger Driver of Stomatal Closing Rate Than Stomatal Size in Taxa That Diversified under Low CO2

PubMed Central

Elliott-Kingston, Caroline; Haworth, Matthew; Yearsley, Jon M.; Batke, Sven P.; Lawson, Tracy; McElwain, Jennifer C.

2016-01-01

One strategy for plants to optimize stomatal function is to open and close their stomata quickly in response to environmental signals. It is generally assumed that small stomata can alter aperture faster than large stomata. We tested the hypothesis that species with small stomata close faster than species with larger stomata in response to darkness by comparing rate of stomatal closure across an evolutionary range of species including ferns, cycads, conifers, and angiosperms under controlled ambient conditions (380 ppm CO2; 20.9% O2). The two species with fastest half-closure time and the two species with slowest half-closure time had large stomata while the remaining three species had small stomata, implying that closing rate was not correlated with stomatal size in these species. Neither was response time correlated with stomatal density, phylogeny, functional group, or life strategy. Our results suggest that past atmospheric CO2 concentration during time of taxa diversification may influence stomatal response time. We show that species which last diversified under low or declining atmospheric CO2 concentration close stomata faster than species that last diversified in a high CO2 world. Low atmospheric [CO2] during taxa diversification may have placed a selection pressure on plants to accelerate stomatal closing to maintain adequate internal CO2 and optimize water use efficiency. PMID:27605929

A marine secondary producer respires and feeds more in a high CO2 ocean.

PubMed

Li, Wei; Gao, Kunshan

2012-04-01

Climate change mediates marine chemical and physical environments and therefore influences marine organisms. While increasing atmospheric CO(2) level and associated ocean acidification has been predicted to stimulate marine primary productivity and may affect community structure, the processes that impact food chain and biological CO(2) pump are less documented. We hypothesized that copepods, as the secondary marine producer, may respond to future changes in seawater carbonate chemistry associated with ocean acidification due to increasing atmospheric CO(2) concentration. Here, we show that the copepod, Centropages tenuiremis, was able to perceive the chemical changes in seawater induced under elevated CO(2) concentration (>1700 μatm, pH<7.60) with avoidance strategy. The copepod's respiration increased at the elevated CO(2) (1000 μatm), associated acidity (pH 7.83) and its feeding rates also increased correspondingly, except for the initial acclimating period, when it fed less. Our results imply that marine secondary producers increase their respiration and feeding rate in response to ocean acidification to balance the energy cost against increased acidity and CO(2) concentration. Copyright © 2012 Elsevier Ltd. All rights reserved.

Research on UAV Intelligent Obstacle Avoidance Technology During Inspection of Transmission Line

NASA Astrophysics Data System (ADS)

Wei, Chuanhu; Zhang, Fei; Yin, Chaoyuan; Liu, Yue; Liu, Liang; Li, Zongyu; Wang, Wanguo

Autonomous obstacle avoidance of unmanned aerial vehicle (hereinafter referred to as UAV) in electric power line inspection process has important significance for operation safety and economy for UAV intelligent inspection system of transmission line as main content of UAV intelligent inspection system on transmission line. In the paper, principles of UAV inspection obstacle avoidance technology of transmission line are introduced. UAV inspection obstacle avoidance technology based on particle swarm global optimization algorithm is proposed after common obstacle avoidance technologies are studied. Stimulation comparison is implemented with traditional UAV inspection obstacle avoidance technology which adopts artificial potential field method. Results show that UAV inspection strategy of particle swarm optimization algorithm, adopted in the paper, is prominently better than UAV inspection strategy of artificial potential field method in the aspects of obstacle avoidance effect and the ability of returning to preset inspection track after passing through the obstacle. An effective method is provided for UAV inspection obstacle avoidance of transmission line.

Uncertainty Quantification for CO2-Enhanced Oil Recovery

NASA Astrophysics Data System (ADS)

Dai, Z.; Middleton, R.; Bauman, J.; Viswanathan, H.; Fessenden-Rahn, J.; Pawar, R.; Lee, S.

2013-12-01

CO2-Enhanced Oil Recovery (EOR) is currently an option for permanently sequestering CO2 in oil reservoirs while increasing oil/gas productions economically. In this study we have developed a framework for understanding CO2 storage potential within an EOR-sequestration environment at the Farnsworth Unit of the Anadarko Basin in northern Texas. By coupling a EOR tool--SENSOR (CEI, 2011) with a uncertainty quantification tool PSUADE (Tong, 2011), we conduct an integrated Monte Carlo simulation of water, oil/gas components and CO2 flow and reactive transport in the heterogeneous Morrow formation to identify the key controlling processes and optimal parameters for CO2 sequestration and EOR. A global sensitivity and response surface analysis are conducted with PSUADE to build numerically the relationship among CO2 injectivity, oil/gas production, reservoir parameters and distance between injection and production wells. The results indicate that the reservoir permeability and porosity are the key parameters to control the CO2 injection, oil and gas (CH4) recovery rates. The distance between the injection and production wells has large impact on oil and gas recovery and net CO2 injection rates. The CO2 injectivity increases with the increasing reservoir permeability and porosity. The distance between injection and production wells is the key parameter for designing an EOR pattern (such as a five (or nine)-spot pattern). The optimal distance for a five-spot-pattern EOR in this site is estimated from the response surface analysis to be around 400 meters. Next, we are building the machinery into our risk assessment framework CO2-PENS to utilize these response surfaces and evaluate the operation risk for CO2 sequestration and EOR at this site.

Carbon Dioxide Angiography: Scientific Principles and Practice

PubMed Central

Cho, Kyung Jae

2015-01-01

Carbon dioxide (CO2) is a colorless, odorless gas which occurs naturally in the atmosphere and human body. With the advent of digital subtraction angiography, the gas has been used as a safe and useful alternative contrast agent in both arteriography and venography. Because of its lack of renal toxicity and allergic potential, CO2 is a preferred contrast agent in patients with renal failure or contrast allergy, and particularly in patients who require large volumes of contrast medium for complex endovascular procedures. Understanding of the unique physical properties of CO2 (high solubility, low viscosity, buoyancy, and compressibility) is essential in obtaining a successful CO2 angiogram and in guiding endovascular intervention. Unlike iodinated contrast material, CO2 displaces the blood and produces a negative contrast for digital subtraction imaging. Indications for use of CO2 as a contrast agent include: aortography and runoff, detection of bleeding, renal transplant arteriography, portal vein visualization with wedged hepatic venous injection, venography, arterial and venous interventions, and endovascular aneurysm repair. CO2 should not be used in the thoracic aorta, the coronary artery, and cerebral circulation. Exploitation of CO2 properties, avoidance of air contamination and facile catheterization technique are important to the safe and effective performance of CO2 angiography and CO2-guided endovascular intervention. PMID:26509137

Multiwell CO2 injectivity: impact of boundary conditions and brine extraction on geologic CO2 storage efficiency and pressure buildup.

PubMed

Heath, Jason E; McKenna, Sean A; Dewers, Thomas A; Roach, Jesse D; Kobos, Peter H

2014-01-21

CO2 storage efficiency is a metric that expresses the portion of the pore space of a subsurface geologic formation that is available to store CO2. Estimates of storage efficiency for large-scale geologic CO2 storage depend on a variety of factors including geologic properties and operational design. These factors govern estimates on CO2 storage resources, the longevity of storage sites, and potential pressure buildup in storage reservoirs. This study employs numerical modeling to quantify CO2 injection well numbers, well spacing, and storage efficiency as a function of geologic formation properties, open-versus-closed boundary conditions, and injection with or without brine extraction. The set of modeling runs is important as it allows the comparison of controlling factors on CO2 storage efficiency. Brine extraction in closed domains can result in storage efficiencies that are similar to those of injection in open-boundary domains. Geomechanical constraints on downhole pressure at both injection and extraction wells lower CO2 storage efficiency as compared to the idealized scenario in which the same volumes of CO2 and brine are injected and extracted, respectively. Geomechanical constraints should be taken into account to avoid potential damage to the storage site.

Phase contrast imaging of preclinical portal vein embolization with CO2 microbubbles.

PubMed

Tang, Rongbiao; Yan, Fuhua; Yang, Guo Yuan; Chen, Ke Min

2017-11-01

Preoperative portal vein embolization (PVE) is employed clinically to avoid postoperative liver insufficiency. Animal models are usually used to study PVE in terms of mechanisms and pathophysiological changes. PVE is formerly monitored by conventional absorption contrast imaging (ACI) with iodine contrast agent. However, the side effects induced by iodine can give rise to animal damage and death. In this study, the feasibility of using phase contrast imaging (PCI) to show PVE using homemade CO 2 microbubbles in living rats has been investigated. CO 2 gas was first formed from the reaction between citric acid and sodium bicarbonate. The CO 2 gas was then encapsulated by egg white to fabricate CO 2 microbubbles. ACI and PCI of CO 2 microbubbles were performed and compared in vitro. An additional increase in contrast was detected in PCI. PCI showed that CO 2 microbubbles gradually dissolved over time, and the remaining CO 2 microbubbles became larger. By PCI, the CO 2 microbubbles were found to have certain stability, suggesting their potential use as embolic agents. CO 2 microbubbles were injected into the main portal trunk to perform PVE in living rats. PCI exploited the differences in the refractive index and facilitated clear visualization of the PVE after the injection of CO 2 microbubbles. Findings from this study suggest that homemade CO 2 microbubbles-based PCI is a novel modality for preclinical PVE research.

Aircraft Trajectory Optimization and Contrails Avoidance in the Presence of Winds

NASA Technical Reports Server (NTRS)

Ng, Hok K.; Chen, Neil Y.

2010-01-01

There are indications that persistent contrails can lead to adverse climate change, although the complete effect on climate forcing is still uncertain. A flight trajectory optimization algorithm with fuel and contrails models, which develops alternative flight paths, provides policy makers the necessary data to make tradeoffs between persistent contrails mitigation and aircraft fuel consumption. This study develops an algorithm that calculates wind-optimal trajectories for cruising aircraft while avoiding the regions of airspace prone to persistent contrails formation. The optimal trajectories are developed by solving a non-linear optimal control problem with path constraints. The regions of airspace favorable to persistent contrails formation are modeled as penalty areas that aircraft should avoid and are adjustable. The tradeoff between persistent contrails formation and additional fuel consumption is investigated, with and without altitude optimization, for 12 city-pairs in the continental United States. Without altitude optimization, the reduction in contrail travel times is gradual with increase in total fuel consumption. When altitude is optimized, a two percent increase in total fuel consumption can reduce the total travel times through contrail regions by more than six times. Allowing further increase in fuel consumption does not seem to result in proportionate decrease in contrail travel times.

Geological Sequestration Training and Research Program in Capture and Transport: Development of the Most Economical Separation Method for CO2 Capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vahdat, Nader

2013-09-30

The project provided hands-on training and networking opportunities to undergraduate students in the area of carbon dioxide (CO2) capture and transport, through fundamental research study focused on advanced separation methods that can be applied to the capture of CO2 resulting from the combustion of fossil-fuels for power generation . The project team’s approach to achieve its objectives was to leverage existing Carbon Capture and Storage (CCS) course materials and teaching methods to create and implement an annual CCS short course for the Tuskegee University community; conduct a survey of CO2 separation and capture methods; utilize data to verify and developmore » computer models for CO2 capture and build CCS networks and hands-on training experiences. The objectives accomplished as a result of this project were: (1) A comprehensive survey of CO2 capture methods was conducted and mathematical models were developed to compare the potential economics of the different methods based on the total cost per year per unit of CO2 avoidance; and (2) Training was provided to introduce the latest CO2 capture technologies and deployment issues to the university community.« less

Physiological effects on fishes in a high-CO2 world

NASA Astrophysics Data System (ADS)

Ishimatsu, Atsushi; Hayashi, Masahiro; Lee, Kyoung-Seon; Kikkawa, Takashi; Kita, Jun

2005-09-01

Fish are important members of both freshwater and marine ecosystems and constitute a major protein source in many countries. Thus potential reduction of fish resources by high-CO2 conditions due to the diffusion of atmospheric CO2 into the surface waters or direct CO2 injection into the deep sea can be considered as another potential threat to the future world population. Fish, and other water-breathing animals, are more susceptible to a rise in environmental CO2 than terrestrial animals because the difference in CO2 partial pressure (PCO2) of the body fluid of water-breathing animals and ambient medium is much smaller (only a few torr (1 torr = 0.1333 kPa = 1316 μatm)) than in terrestrial animals (typically 30-40 torr). A survey of the literature revealed that hypercapnia acutely affects vital physiological functions such as respiration, circulation, and metabolism, and changes in these functions are likely to reduce growth rate and population size through reproduction failure and change the distribution pattern due to avoidance of high-CO2 waters or reduced swimming activities. This paper reviews the acute and chronic effects of CO2 on fish physiology and tries to clarify necessary areas of future research.

[Efficacy of CO2 laser in the treatment of precancerous laryngeal lesions under phonomicrosurgery and its relative factors].

PubMed

Gu, Qingjia; Feng, Yong; Yu, Xiaoxu; Fan, Jian'gang; Li, Debing; He, Gang

2014-08-01

To investigate the efficacy of CO2 laser treatment for patients with precancerous laryngeal lesions under phonomicrosurgery and to explore the points for attention in operation. They were all treated with phonomicrosurgery techniques as mucosal epitheliumablation or mucosal stripping by using CO2 laser. Eight patients with laryngeal papilloma were excised by CO2 laser. All patients were treated with CO2 laser surgery successfully. During follow-up of 6 to 39 months, all patients survived. Local recurrence or canceration were detected in 3 cases, of which 2 cases with laryngeal papilloma underwent CO2 laser treatment in one year post-operatively, while the other case with severe dysplasia underwent laryngeal vertical partial laryngectomy and post-operative radiotherapy one and half year postoperatively due to canceration. No local recurrence occurred until the last follow up. No severe complications such as dyspnea and hemorrhage occured. CO2 laser surgery is an effective and minimally invasive treatment for precancerous laryngeal lesions. Through selecting the appropriate patient and paying attention to the operation during surgery, the adhesion of vocal cord can be reduced or even be avoided after CO2 laser surgery.

Automated Training of ReaxFF Reactive Force Fields for Energetics of Enzymatic Reactions.

PubMed

Trnka, Tomáš; Tvaroška, Igor; Koča, Jaroslav

2018-01-09

Computational studies of the reaction mechanisms of various enzymes are nowadays based almost exclusively on hybrid QM/MM models. Unfortunately, the success of this approach strongly depends on the selection of the QM region, and computational cost is a crucial limiting factor. An interesting alternative is offered by empirical reactive molecular force fields, especially the ReaxFF potential developed by van Duin and co-workers. However, even though an initial parametrization of ReaxFF for biomolecules already exists, it does not provide the desired level of accuracy. We have conducted a thorough refitting of the ReaxFF force field to improve the description of reaction energetics. To minimize the human effort required, we propose a fully automated approach to generate an extensive training set comprised of thousands of different geometries and molecular fragments starting from a few model molecules. Electrostatic parameters were optimized with QM electrostatic potentials as the main target quantity, avoiding excessive dependence on the choice of reference atomic charges and improving robustness and transferability. The remaining force field parameters were optimized using the VD-CMA-ES variant of the CMA-ES optimization algorithm. This method is able to optimize hundreds of parameters simultaneously with unprecedented speed and reliability. The resulting force field was validated on a real enzymatic system, ppGalNAcT2 glycosyltransferase. The new force field offers excellent qualitative agreement with the reference QM/MM reaction energy profile, matches the relative energies of intermediate and product minima almost exactly, and reduces the overestimation of transition state energies by 27-48% compared with the previous parametrization.

Optimization of Pressurized Oxy-Combustion with Flameless Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malavasi, Massimo; Landegger, Gregory

2014-06-30

Pressurized OxyECombustion is one of the most promising technologies for utility-scale power generation plants. Benefits include the ability to burn low rank coal and capture CO 2. By increasing the flue gas pressure during this process, greater efficiencies are derived from increased quantity and quality of thermal energy recovery. UPA with modeling support from MIT and testing and data verification by Georgia Tech’s Research Center designed and built a 100 kW system capable of demonstrating pressurized oxyEcombustion using a flameless combustor. Wyoming PRB coal was run at 15 and 32 bar. Additional tests were not completed but sampled data demonstratedmore » the viability of the technology over a broader range of operating pressures, Modeling results illustrated a flat efficiency curve over 20 bar, with optimum efficiency achieved at 29 bar. This resulted in a 33% (HHV) efficiency, a 5 points increase in efficiency versus atmospheric oxy-combustion, and a competitive cost of electricity plus greater CO 2 avoidance costs then prior study’s presented. UPA’s operation of the bench-scale system provided evidence that key performance targets were achieved: flue gas sampled at the combustor outlet had non-detectable residual fly ashes, and low levels of SO3 and heavy-metal. These results correspond to prior pressurized oxy-combustion testing completed by IteaEEnel.« less

CaO-based CO2 sorbents: from fundamentals to the development of new, highly effective materials.

PubMed

Kierzkowska, Agnieszka M; Pacciani, Roberta; Müller, Christoph R

2013-07-01

The enormous anthropogenic emission of the greenhouse gas CO2 is most likely the main reason for climate change. Considering the continuing and indeed growing utilisation of fossil fuels for electricity generation and transportation purposes, development and implementation of processes that avoid the associated emissions of CO2 are urgently needed. CO2 capture and storage, commonly termed CCS, would be a possible mid-term solution to reduce the emissions of CO2 into the atmosphere. However, the costs associated with the currently available CO2 capture technology, that is, amine scrubbing, are prohibitively high, thus making the development of new CO2 sorbents a highly important research challenge. Indeed, CaO, readily obtained through the calcination of naturally occurring limestone, has been proposed as an alternative CO2 sorbent that could substantially reduce the costs of CO2 capture. However, one of the major drawbacks of using CaO derived from natural sources is its rapidly decreasing CO2 uptake capacity with repeated carbonation-calcination reactions. Here, we review the current understanding of fundamental aspects of the cyclic carbonation-calcination reactions of CaO such as its reversibility and kinetics. Subsequently, recent attempts to develop synthetic, CaO-based sorbents that possess high and cyclically stable CO2 uptakes are presented. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Using infrastructure optimization to reduce greenhouse gas emissions from oil sands extraction and processing.

PubMed

Middleton, Richard S; Brandt, Adam R

2013-02-05

The Alberta oil sands are a significant source of oil production and greenhouse gas emissions, and their importance will grow as the region is poised for decades of growth. We present an integrated framework that simultaneously considers economic and engineering decisions for the capture, transport, and storage of oil sands CO(2) emissions. The model optimizes CO(2) management infrastructure at a variety of carbon prices for the oil sands industry. Our study reveals several key findings. We find that the oil sands industry lends itself well to development of CO(2) trunk lines due to geographic coincidence of sources and sinks. This reduces the relative importance of transport costs compared to nonintegrated transport systems. Also, the amount of managed oil sands CO(2) emissions, and therefore the CCS infrastructure, is very sensitive to the carbon price; significant capture and storage occurs only above 110$/tonne CO(2) in our simulations. Deployment of infrastructure is also sensitive to CO(2) capture decisions and technology, particularly the fraction of capturable CO(2) from oil sands upgrading and steam generation facilities. The framework will help stakeholders and policy makers understand how CCS infrastructure, including an extensive pipeline system, can be safely and cost-effectively deployed.

CO2 sequestration by mineral carbonation of steel slags under ambient temperature: parameters influence, and optimization.

PubMed

Ghacham, Alia Ben; Pasquier, Louis-César; Cecchi, Emmanuelle; Blais, Jean-François; Mercier, Guy

2016-09-01

This work focuses on the influence of different parameters on the efficiency of steel slag carbonation in slurry phase under ambient temperature. In the first part, a response surface methodology was used to identify the effect and the interactions of the gas pressure, liquid/solid (L/S) ratio, gas/liquid ratio (G/L), and reaction time on the CO2 removed/sample and to optimize the parameters. In the second part, the parameters' effect on the dissolution of CO2 and its conversion into carbonates were studied more in detail. The results show that the pressure and the G/L ratio have a positive effect on both the dissolution and the conversion of CO2. These results have been correlated with the higher CO2 mass introduced in the reactor. On the other hand, an important effect of the L/S ratio on the overall CO2 removal and more specifically on the carbonate precipitation has been identified. The best results were obtained L/S ratios of 4:1 and 10:1 with respectively 0.046 and 0.052 gCO2 carbonated/g sample. These yields were achieved after 10 min reaction, at ambient temperature, and 10.68 bar of total gas pressure following direct gas treatment.

Dynamic Obstacle Avoidance for Unmanned Underwater Vehicles Based on an Improved Velocity Obstacle Method

PubMed Central

Zhang, Wei; Wei, Shilin; Teng, Yanbin; Zhang, Jianku; Wang, Xiufang; Yan, Zheping

2017-01-01

In view of a dynamic obstacle environment with motion uncertainty, we present a dynamic collision avoidance method based on the collision risk assessment and improved velocity obstacle method. First, through the fusion optimization of forward-looking sonar data, the redundancy of the data is reduced and the position, size and velocity information of the obstacles are obtained, which can provide an accurate decision-making basis for next-step collision avoidance. Second, according to minimum meeting time and the minimum distance between the obstacle and unmanned underwater vehicle (UUV), this paper establishes the collision risk assessment model, and screens key obstacles to avoid collision. Finally, the optimization objective function is established based on the improved velocity obstacle method, and a UUV motion characteristic is used to calculate the reachable velocity sets. The optimal collision speed of UUV is searched in velocity space. The corresponding heading and speed commands are calculated, and outputted to the motion control module. The above is the complete dynamic obstacle avoidance process. The simulation results show that the proposed method can obtain a better collision avoidance effect in the dynamic environment, and has good adaptability to the unknown dynamic environment. PMID:29186878

Insight into the Li2CO3-K2CO3 eutectic mixture from classical molecular dynamics: Thermodynamics, structure, and dynamics

NASA Astrophysics Data System (ADS)

Corradini, Dario; Coudert, François-Xavier; Vuilleumier, Rodolphe

2016-03-01

We use molecular dynamics simulations to study the thermodynamics, structure, and dynamics of the Li2CO3-K2CO3 (62:38 mol. %) eutectic mixture. We present a new classical non-polarizable force field for this molten salt mixture, optimized using experimental and first principles molecular dynamics simulations data as reference. This simple force field allows efficient molecular simulations of phenomena at long time scales. We use this optimized force field to describe the behavior of the eutectic mixture in the 900-1100 K temperature range, at pressures between 0 and 5 GPa. After studying the equation of state in these thermodynamic conditions, we present molecular insight into the structure and dynamics of the melt. In particular, we present an analysis of the temperature and pressure dependence of the eutectic mixture's self-diffusion coefficients, viscosity, and ionic conductivity.

Insight into the Li2CO3-K2CO3 eutectic mixture from classical molecular dynamics: Thermodynamics, structure, and dynamics.

PubMed

Corradini, Dario; Coudert, François-Xavier; Vuilleumier, Rodolphe

2016-03-14

We use molecular dynamics simulations to study the thermodynamics, structure, and dynamics of the Li2CO3-K2CO3 (62:38 mol. %) eutectic mixture. We present a new classical non-polarizable force field for this molten salt mixture, optimized using experimental and first principles molecular dynamics simulations data as reference. This simple force field allows efficient molecular simulations of phenomena at long time scales. We use this optimized force field to describe the behavior of the eutectic mixture in the 900-1100 K temperature range, at pressures between 0 and 5 GPa. After studying the equation of state in these thermodynamic conditions, we present molecular insight into the structure and dynamics of the melt. In particular, we present an analysis of the temperature and pressure dependence of the eutectic mixture's self-diffusion coefficients, viscosity, and ionic conductivity.

Novel ZIF-300 Mixed-Matrix Membranes for Efficient CO2 Capture.

PubMed

Yuan, Jianwei; Zhu, Haipeng; Sun, Jiajia; Mao, Yangyang; Liu, Gongping; Jin, Wanqin

2017-11-08

Because of the high separation performance and easy preparation, mixed-matrix membranes (MMMs) consisting of metal-organic frameworks have received much attention. In this article, we report a novel ZIF-300/PEBA MMM consisting of zeolite imidazolate framework (ZIF-300) crystals and polyether block amide (PEBA) matrix. The ZIF-300 crystal size was effectively reduced by optimizing the hydrothermal reaction condition from ∼15 to ∼1 μm. The morphology and physicochemical and sorption properties of the synthesized ZIF-300 crystals and as-prepared ZIF-300/PEBA MMMs were systematically studied. The results showed that ZIF-300 crystals with a size of ∼1 μm maintained excellent preferential CO 2 sorption over N 2 without degradation of the crystal structure in the MMMs. As a result, uniformly incorporated ZIF-300 crystals highly enhanced both the CO 2 permeability and the CO 2 /N 2 selectivity of pure PEBA membrane. The optimized ZIF-300-PEBA MMMs with a ZIF-300 loading of 30 wt % exhibited a high and stable CO 2 permeability of 83 Barrer and CO 2 /N 2 selectivity of 84, which are 59.2% and 53.5% higher than pure PEBA membrane, respectively. The obtained performance surpassed the upper bound of state-of-the-art membranes for CO 2 /N 2 separation. This work demonstrated that the proposed ZIF-300/PEBA MMM could be a potential candidate for an efficient CO 2 capture process.

Contrasting Impact of Future CO2 Emission Scenarios on the Extent of CaCO3 Mineral Undersaturation in the Humboldt Current System

NASA Astrophysics Data System (ADS)

Franco, A. C.; Gruber, N.; Frölicher, T. L.; Kropuenske Artman, L.

2018-03-01

The eastern boundary upwelling systems are among those regions that are most vulnerable to an ocean acidification-induced transition toward undersaturated conditions with respect to mineral CaCO3, but no assessment exists yet for the Humboldt Current System. Here we use a high-resolution (˜7.5 km) regional ocean model to investigate past and future changes in ocean pH and CaCO3 saturation state in this system. We find that within the next few decades, the nearshore waters off Peru are projected to become corrosive year round with regard to aragonite, the more soluble form of CaCO3. The volume of aragonite undersaturated water off Peru will continue to increase in the future irrespective of the amount of CO2 emitted to the atmosphere. In contrast, the development of the saturation state with regard to calcite, a less soluble form of carbonate, depends strongly on the scenario followed. By 2050, calcite undersaturation appears in the nearshore waters off Peru occasionally, but by 2090 in a high-emission scenario (RCP8.5), ˜60% of the water in the euphotic zone will become permanently calcite undersaturated. Most of this calcite undersaturation off Peru can likely be avoided if a low emission scenario (RCP2.6) consistent with the Paris Agreement is followed. The progression of ocean acidification off Chile follows a similar pattern, except that the saturation states are overall higher. But also here, calcite undersaturated waters will become common in the subsurface waters under the RCP8.5 scenario by the end of this century, while this can be avoided under the RCP2.6 scenario.

Optimization of the anaerobic treatment of a waste stream from an enhanced oil recovery process.

PubMed

Alimahmoodi, Mahmood; Mulligan, Catherine N

2011-01-01

The aim of this work was to optimize the anaerobic treatment of a waste stream from an enhanced oil recovery (EOR) process. The treatment of a simulated waste water containing about 150 mg chemical oxygen demand (COD)/L of total petroleum hydrocarbons (TPH) and the saturation level of CO2 was evaluated. A two-step anaerobic system was undertaken in the mesophilic temperature range (30-40°C). The method of evolutionary operation EVOP factorial design was used to optimize pH, temperature and organic loading rate with the target parameters of CO2 reduction and CH4 production in the first reactor and TPH removal in the second reactor. The results showed 98% methanogenic removal of CO2 and CH4 yield of 0.38 L/gCOD in the first reactor and 83% TPH removal in the second reactor. In addition to enhancing CO2 and TPH removal and CH4 production, application of this method showed the degree of importance of the operational variables and their interactive effects for the two reactors in series. Copyright © 2010 Elsevier Ltd. All rights reserved.

Transcriptional and metabolic insights into the differential physiological responses of Arabidopsis to optimal and supraoptimal atomospheric CO2

USDA-ARS?s Scientific Manuscript database

Biological activity in tightly closed systems can lead to excessively high CO2 concentrations of between one and two orders of magnitude greater than current ambient levels in Earth’s atmosphere. While there is a wealth of information on the influence of elevated CO2 on plants at two to three times...

Supercritical carbon dioxide extraction of seed oil from winter melon (Benincasa hispida) and its antioxidant activity and fatty acid composition.

PubMed

Bimakr, Mandana; Rahman, Russly Abdul; Taip, Farah Saleena; Adzahan, Noranizan Mohd; Sarker, Md Zaidul Islam; Ganjloo, Ali

2013-01-15

In the present study, supercritical carbon dioxide (SC-CO(2)) extraction of seed oil from winter melon (Benincasa hispida) was investigated. The effects of process variables namely pressure (150-300 bar), temperature (40-50 °C) and dynamic extraction time (60-120 min) on crude extraction yield (CEY) were studied through response surface methodology (RSM). The SC-CO(2) extraction process was modified using ethanol (99.9%) as co-solvent. Perturbation plot revealed the significant effect of all process variables on the CEY. A central composite design (CCD) was used to optimize the process conditions to achieve maximum CEY. The optimum conditions were 244 bar pressure, 46 °C temperature and 97 min dynamic extraction time. Under these optimal conditions, the CEY was predicted to be 176.30 mg-extract/g-dried sample. The validation experiment results agreed with the predicted value. The antioxidant activity and fatty acid composition of crude oil obtained under optimized conditions were determined and compared with published results using Soxhlet extraction (SE) and ultrasound assisted extraction (UAE). It was found that the antioxidant activity of the extract obtained by SC-CO(2) extraction was strongly higher than those obtained by SE and UAE. Identification of fatty acid composition using gas chromatography (GC) showed that all the extracts were rich in unsaturated fatty acids with the most being linoleic acid. In contrast, the amount of saturated fatty acids extracted by SE was higher than that extracted under optimized SC-CO(2) extraction conditions.

Selective extraction of bisphenol A from water by one-monomer molecularly imprinted magnetic nanoparticles.

PubMed

Lin, Zhenkun; Zhang, Yanfang; Su, Yu; Qi, Jinxia; Jia, Yinhang; Huang, Changjiang; Dong, Qiaoxiang

2018-01-15

One-monomer molecularly imprinted magnetic nanoparticles were prepared as adsorbents for selective extraction of bisphenol A from water in this study. A single bi-functional monomer was adopted for preparation of the molecularly imprinted polymer, avoiding the tedious trial-and-error optimizations as traditional strategy. Moreover, bisphenol F was used as the dummy template for bisphenol A to avoid the interference from residual template molecules. These nanoparticles showed not only large adsorption capacity and good selectivity to the bisphenol A but also outstanding magnetic response performance. Furthermore, they were successfully used as magnetic solid-phase extraction adsorbents of bisphenol A from various water samples, including tap water, river water, and seawater. The developed method was found to be much more efficient, convenient, and economical for selective extraction of bisphenol A compared with the traditional solid-phase extraction. Separation of these nanoparticles can be easily achieved with an external magnetic field, and the optimized adsorption time was only 15 min. The recoveries of bisphenol A in different water samples ranged from 85.38 to 93.75%, with relative standard deviation lower than 7.47%. These results showed that one-monomer molecularly imprinted magnetic nanoparticles had the potential to be popular adsorbents for selective extraction of pollutants from water. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Exploring the effects of data quality, data worth, and redundancy of CO2 gas pressure and saturation data on reservoir characterization through PEST Inversion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, Zhufeng; Hou, Zhangshuan; Lin, Guang

2014-04-01

This study examined the impacts of reservoir properties on CO2 migration after subsurface injection and evaluated the possibility of characterizing reservoir properties using CO2 monitoring data such as saturation distribution. The injection reservoir was assumed to be located 1400-1500 m below the ground surface such that CO2 remained in the supercritical state. The reservoir was assumed to contain layers with alternating conductive and resistive properties, which is analogous to actual geological formations such as the Mount Simon Sandstone unit. The CO2 injection simulation used a cylindrical grid setting in which the injection well was situated at the center of themore » domain, which extended up to 8000 m from the injection well. The CO2 migration was simulated using the PNNL-developed simulator STOMP-CO2e (the water-salt-CO2 module). We adopted a nonlinear parameter estimation and optimization modeling software package, PEST, for automated reservoir parameter estimation. We explored the effects of data quality, data worth, and data redundancy on the detectability of reservoir parameters using CO2 saturation monitoring data, by comparing PEST inversion results using data with different levels of noises, various numbers of monitoring wells and locations, and different data collection spacing and temporal sampling intervals. This study yielded insight into the use of CO2 saturation monitoring data for reservoir characterization and how to design the monitoring system to optimize data worth and reduce data redundancy.« less

A Stochastic Approach to Path Planning in the Weighted-Region Problem

DTIC Science & Technology

1991-03-01

polynomial time. However, the polyhedrons in this three-dimensional obstacle-avoidance problem are all obstacles (i.e. travel is not permitted within...them). Therefore, optimal paths tend to avoid their vertices, and settle into closest approach tangents across polyhedron edges. So, in a sense...intersection update map database with new vertex for this edge 3. IF (C1 > D) and (C2 > D) THEN edge intersects ellipse at two points OR edge is

Statistical evaluation of nutritional components impacting phycocyanin production Synechocystis SP.

PubMed Central

Deshmukh, Devendra V.; Puranik, Pravin R.

2012-01-01

Alkaliphilic cyanobacterial cultures were isolated from Lonar lake (MS, India). Among the set of cultures, Synechocystis sp, was studied for phycocyanin production. A maximum yield was obtained in BG-11 medium at optimized conditions (pH 10 and 16 h light). In order to increase the phycocyanin yield media optimization based on the eight media components a Plackett-Burman design of the 12 experimental trials was used. As per the analysis CaCl2, 2H2O and Na2CO3 have been found to be the most influencing media components at 95% significance. Further the optimum concentrations of these components were estimated following a Box Wilson Central Composite Design (CCD) with four star points and five replicates at the center points for each of two factors was adopted for optimization of these two media components. The results indicated that there was an interlinked influence of CaCl2, 2H2O and Na2CO3 on 98% significance. The maximum yield of phycocyanin (12% of dry wt) could be obtained at 0.058 g/l and 0.115 g/l of CaCl2, 2H2O and Na2CO3, respectively. PMID:24031838

Grain Yield Observations Constrain Cropland CO2 Fluxes Over Europe

NASA Astrophysics Data System (ADS)

Combe, M.; de Wit, A. J. W.; Vilà-Guerau de Arellano, J.; van der Molen, M. K.; Magliulo, V.; Peters, W.

2017-12-01

Carbon exchange over croplands plays an important role in the European carbon cycle over daily to seasonal time scales. A better description of this exchange in terrestrial biosphere models—most of which currently treat crops as unmanaged grasslands—is needed to improve atmospheric CO2 simulations. In the framework we present here, we model gross European cropland CO2 fluxes with a crop growth model constrained by grain yield observations. Our approach follows a two-step procedure. In the first step, we calculate day-to-day crop carbon fluxes and pools with the WOrld FOod STudies (WOFOST) model. A scaling factor of crop growth is optimized regionally by minimizing the final grain carbon pool difference to crop yield observations from the Statistical Office of the European Union. In a second step, we re-run our WOFOST model for the full European 25 × 25 km gridded domain using the optimized scaling factors. We combine our optimized crop CO2 fluxes with a simple soil respiration model to obtain the net cropland CO2 exchange. We assess our model's ability to represent cropland CO2 exchange using 40 years of observations at seven European FluxNet sites and compare it with carbon fluxes produced by a typical terrestrial biosphere model. We conclude that our new model framework provides a more realistic and strongly observation-driven estimate of carbon exchange over European croplands. Its products will be made available to the scientific community through the ICOS Carbon Portal and serve as a new cropland component in the CarbonTracker Europe inverse model.

Exploring the range of climate biome projections for tropical South America: The role of CO2 fertilization and seasonality

NASA Astrophysics Data System (ADS)

Lapola, David M.; Oyama, Marcos D.; Nobre, Carlos A.

2009-09-01

Tropical South America vegetation cover projections for the end of the century differ considerably depending on climate scenario and also on how physiological processes are considered in vegetation models. In this paper we use a potential vegetation model (CPTEC-PVM2) to analyze biome distribution in tropical South America under a range of climate projections and a range of estimates about the effects of increased atmospheric CO2. We show that if the CO2 "fertilization effect" indeed takes place and is maintained in the long term in tropical forests, then it will avoid biome shifts in Amazonia in most of the climate scenarios, even if the effect of CO2 fertilization is halved. However, if CO2 fertilization does not play any important role on tropical forests in the future or if dry season is longer than 4 months (projected by 2/14 GCMs), then there is replacement of large portions of Amazonia by tropical savanna.

Fabrication of lead-free piezoelectric Li2CO3-added (Ba,Ca)(Ti,Sn)O3 ceramics under controlled low oxygen partial pressure and their properties

NASA Astrophysics Data System (ADS)

Noritake, Kouta; Sakamoto, Wataru; Yuitoo, Isamu; Takeuchi, Teruaki; Hayashi, Koichiro; Yogo, Toshinobu

2018-02-01

Reduction-resistant lead-free (Ba,Ca)(Ti,Sn)O3 piezoceramics with high piezoelectric constants were fabricated by optimizing the amount of Li2CO3 added. Oxygen partial pressure was controlled during the sintering of (Ba,Ca)(Ti,Sn)O3 ceramics in a reducing atmosphere using H2-CO2 gas. Enhanced grain growth and a high-polarization state after poling treatment were achieved by adding Li2CO3. Optimizing the amount of Li2CO3 added to (Ba0.95Ca0.05)(Ti0.95Sn0.05)O3 ceramics sintered under a low oxygen partial pressure resulted in improved piezoelectric properties while maintaining the high sintered density. The prepared Li2CO3-added ceramic samples had homogeneous microstructures with a uniform dispersion of each major constituent element. However, the residual Li content in the 3 mol % Li2CO3-added (Ba0.95Ca0.05)(Ti0.95Sn0.05)O3 ceramics after sintering was less than 0.3 mol %. Sintered bodies of this ceramic prepared in a CO2 (1.5%)-H2 (0.3%)/Ar reducing atmosphere (PO2 = 10-8 atm at 1350 °C), exhibited sufficient electrical resistivity and a piezoelectric constant (d 33) exceeding 500 pC/N. The piezoelectric properties of this nonreducible ceramic were comparable or superior to those of the same ceramic sintered in air.

Evaluating Interventions in the U.S. Electricity System: Assessments of Energy Efficiency, Renewable Energy, and Small-Scale Cogeneration

NASA Astrophysics Data System (ADS)

Siler-Evans, Kyle

There is growing interest in reducing the environmental and human-health impacts resulting from electricity generation. Renewable energy, energy efficiency, and energy conservation are all commonly suggested solutions. Such interventions may provide health and environmental benefits by displacing emissions from conventional power plants. However, the generation mix varies considerably from region to region and emissions vary by the type and age of a generator. Thus, the benefits of an intervention will depend on the specific generators that are displaced, which vary depending on the timing and location of the intervention. Marginal emissions factors (MEFs) give a consistent measure of the avoided emissions per megawatt-hour of displaced electricity, which can be used to evaluate the change in emissions resulting from a variety of interventions. This thesis presents the first systematic calculation of MEFs for the U.S. electricity system. Using regressions of hourly generation and emissions data from 2006 through 2011, I estimate regional MEFs for CO2, NO x, and SO2, as well as the share of marginal generation from coal-, gas-, and oil-fired generators. This work highlights significant regional differences in the emissions benefits of displacing a unit of electricity: compared to the West, displacing one megawatt-hour of electricity in the Midwest is expected to avoid roughly 70% more CO2, 12 times more SO 2, and 3 times more NOx emissions. I go on to explore regional variations in the performance of wind turbines and solar panels, where performance is measured relative to three objectives: energy production, avoided CO2 emissions, and avoided health and environmental damages from criteria pollutants. For 22 regions of the United States, I use regressions of historic emissions and generation data to estimate marginal impact factors, a measure of the avoided health and environmental damages per megawatt-hour of displaced electricity. Marginal impact factors are used to evaluate the effects of an additional wind turbine or solar panel in the U.S. electricity system. I find that the most attractive sites for renewables depend strongly on one's objective. A solar panel in Iowa displaces 20% more CO2 emissions than a panel in Arizona, though energy production from the Iowa panel is 25% less. Similarly, despite a modest wind resource, a wind turbine in West Virginia is expected to displace 7 times more health and environmental damages than a wind turbine in Oklahoma. Finally, I shift focus and explore the economics of small-scale cogeneration, which has long been recognized as a more efficient alternative to central-station power. Although the benefits of distributed cogeneration are widely cited, adoption has been slow in the U.S. Adoption could be encouraged by making cogeneration more economically attractive, either by increasing the expected returns or decreasing the risks of such investments. I present a case study of a 300-kilowatt cogeneration unit and evaluate the expected returns from: demand response, capacity markets, regulation markets, accelerated depreciation, a price on CO2 emissions, and net metering. In addition, I explore the effectiveness of feed-in tariffs at mitigating the energy-price risks to cogeneration projects.

Development of a process for efficient use of CO2 from flue gases in the production of photosynthetic microorganisms.

PubMed

González-López, C V; Acién Fernández, F G; Fernández-Sevilla, J M; Sánchez Fernández, J F; Molina Grima, E

2012-07-01

A new methodology to use efficiently flue gases as CO(2) source in the production of photosynthetic microorganisms is proposed. The CO(2) is absorbed in an aqueous phase that is then regenerated by microalgae. Carbonated solutions could absorb up to 80% of the CO(2) from diluted gas reaching total inorganic carbon (TIC) concentrations up to 2.0 g/L. The pH of the solution was maintained at 8.0-10.0 by the bicarbonate/carbonate buffer, so it is compatible with biological regeneration. The absorption process was modeled and the kinetic parameters were determined. Anabaena sp. demonstrated to tolerate pH (8.0-10.0) and TIC (up to 2.0 g/L) conditions imposed by the absorption step. Experiments of regeneration of the liquid phase demonstrated the feasibility of the overall process, converting CO(2) into organic matter. The developed process avoids heating to regenerate the liquid whereas maximizing the efficiency of CO(2) use, which is relevant to achieve the commercial production of biofuels from microalgae. Copyright © 2012 Wiley Periodicals, Inc.

Designing a CO2 supply strategy for microalgal biodiesel production under diurnal light in a cylindrical-membrane photobioreactor.

PubMed

Naira, Venkateswara R; Das, Debasish; Maiti, Soumen K

2018-02-01

A cylindrical membrane photobioreactor with high CO 2 mass transfer coefficient was designed and installed under customized unidirectional lighting. Combinatorial effect of light and CO 2 on the growth of Chlorella sp. FC2 IITG was studied and an optimal CO 2 supply without pH control strategy was developed under diurnal light similar to sunlight (17-2000-17 µE m -2  s -1 ). Unprecedentedly, broad range of saturated light levels (700-1500 µE m -2  s -1 ), reversible photoinhibition, no pH control requirement and dark-phase growth were noticed altogether in the strain. Under diurnal light, final biomass titer of 5.79 g L -1 and overall biomass productivity of 1.29 g L -1  day -1 were observed. The results were similar to optimal light (1130 µE m -2  s -1 ) and CO 2 (2%) conditions. Subsequently, a highest FAME productivity of 265 mg L -1  day -1 was observed in last two days of lipid induction phase. Copyright © 2017 Elsevier Ltd. All rights reserved.

Improving yield potential in crops under elevated CO2: Integrating the photosynthetic and nitrogen utilization efficiencies

PubMed Central

Kant, Surya; Seneweera, Saman; Rodin, Joakim; Materne, Michael; Burch, David; Rothstein, Steven J.; Spangenberg, German

2012-01-01

Increasing crop productivity to meet burgeoning human food demand is challenging under changing environmental conditions. Since industrial revolution atmospheric CO2 levels have linearly increased. Developing crop varieties with increased utilization of CO2 for photosynthesis is an urgent requirement to cope with the irreversible rise of atmospheric CO2 and achieve higher food production. The primary effects of elevated CO2 levels in most crop plants, particularly C3 plants, include increased biomass accumulation, although initial stimulation of net photosynthesis rate is only temporal and plants fail to sustain the maximal stimulation, a phenomenon known as photosynthesis acclimation. Despite this acclimation, grain yield is known to marginally increase under elevated CO2. The yield potential of C3 crops is limited by their capacity to exploit sufficient carbon. The “C fertilization” through elevated CO2 levels could potentially be used for substantial yield increase. Rubisco is the rate-limiting enzyme in photosynthesis and its activity is largely affected by atmospheric CO2 and nitrogen availability. In addition, maintenance of the C/N ratio is pivotal for various growth and development processes in plants governing yield and seed quality. For maximizing the benefits of elevated CO2, raising plant nitrogen pools will be necessary as part of maintaining an optimal C/N balance. In this review, we discuss potential causes for the stagnation in yield increases under elevated CO2 levels and explore possibilities to overcome this limitation by improved photosynthetic capacity and enhanced nitrogen use efficiency. Opportunities of engineering nitrogen uptake, assimilatory, and responsive genes are also discussed that could ensure optimal nitrogen allocation toward expanding source and sink tissues. This might avert photosynthetic acclimation partially or completely and drive for improved crop production under elevated CO2 levels. PMID:22833749

Improving yield potential in crops under elevated CO(2): Integrating the photosynthetic and nitrogen utilization efficiencies.

PubMed

Kant, Surya; Seneweera, Saman; Rodin, Joakim; Materne, Michael; Burch, David; Rothstein, Steven J; Spangenberg, German

2012-01-01

Increasing crop productivity to meet burgeoning human food demand is challenging under changing environmental conditions. Since industrial revolution atmospheric CO(2) levels have linearly increased. Developing crop varieties with increased utilization of CO(2) for photosynthesis is an urgent requirement to cope with the irreversible rise of atmospheric CO(2) and achieve higher food production. The primary effects of elevated CO(2) levels in most crop plants, particularly C(3) plants, include increased biomass accumulation, although initial stimulation of net photosynthesis rate is only temporal and plants fail to sustain the maximal stimulation, a phenomenon known as photosynthesis acclimation. Despite this acclimation, grain yield is known to marginally increase under elevated CO(2). The yield potential of C(3) crops is limited by their capacity to exploit sufficient carbon. The "C fertilization" through elevated CO(2) levels could potentially be used for substantial yield increase. Rubisco is the rate-limiting enzyme in photosynthesis and its activity is largely affected by atmospheric CO(2) and nitrogen availability. In addition, maintenance of the C/N ratio is pivotal for various growth and development processes in plants governing yield and seed quality. For maximizing the benefits of elevated CO(2), raising plant nitrogen pools will be necessary as part of maintaining an optimal C/N balance. In this review, we discuss potential causes for the stagnation in yield increases under elevated CO(2) levels and explore possibilities to overcome this limitation by improved photosynthetic capacity and enhanced nitrogen use efficiency. Opportunities of engineering nitrogen uptake, assimilatory, and responsive genes are also discussed that could ensure optimal nitrogen allocation toward expanding source and sink tissues. This might avert photosynthetic acclimation partially or completely and drive for improved crop production under elevated CO(2) levels.

Optimization of CO2 Surface Flux using GOSAT Total Column CO2: First Results for 2009-2010

NASA Astrophysics Data System (ADS)

Basu, S.; Houweling, S.

2011-12-01

Constraining surface flux estimates of CO2 using satellite measurements has been one of the long-standing goals of the atmospheric inverse modeling community. We present the first results of inverting GOSAT total column CO2 measurements for obtaining global monthly CO2 flux maps over one year (June 2009 to May 2010). We use the SRON RemoTeC retrieval of CO2 for our inversions. The SRON retrieval has been shown to have no bias when compared to TCCON total column measurements, and latitudinal gradients of the retrieved CO2 are consistent with gradients deduced from the surface flask network [Butz et al, 2011]. This makes this retrieval an ideal candidate for atmospheric inversions, which are highly sensitive to spurious gradients. Our inversion system is analogous to the CarbonTracker (CT) data assimilation system; it is initialized with the prior CO2 fluxes of CT, and uses the same atmospheric transport model, i.e., TM5. The two major differences are (a) we add GOSAT CO2 data to the inversion in addition to flask data, and (b) we use a 4DVAR optimization system instead of a Kalman filter. We compare inversions using (a) only GOSAT total column CO2 measurements, (b) only surface flask CO2 measurements, and (c) the joint data set of GOSAT and surface flask measurements. We validate GOSAT-only inversions against the NOAA surface flask network and joint inversions against CONTRAIL and other aircraft campaigns. We see that inverted fluxes from a GOSAT-only inversion are consistent with fluxes from a stations-only inversion, reaffirming the low biases in SRON retrievals. From the joint inversion, we estimate the amount of added constraints upon adding GOSAT total column measurements to existing surface layer measurements.

Development of the WRF-CO2 4D-Var assimilation system v1.0

NASA Astrophysics Data System (ADS)

Zheng, Tao; French, Nancy H. F.; Baxter, Martin

2018-05-01

Regional atmospheric CO2 inversions commonly use Lagrangian particle trajectory model simulations to calculate the required influence function, which quantifies the sensitivity of a receptor to flux sources. In this paper, an adjoint-based four-dimensional variational (4D-Var) assimilation system, WRF-CO2 4D-Var, is developed to provide an alternative approach. This system is developed based on the Weather Research and Forecasting (WRF) modeling system, including the system coupled to chemistry (WRF-Chem), with tangent linear and adjoint codes (WRFPLUS), and with data assimilation (WRFDA), all in version 3.6. In WRF-CO2 4D-Var, CO2 is modeled as a tracer and its feedback to meteorology is ignored. This configuration allows most WRF physical parameterizations to be used in the assimilation system without incurring a large amount of code development. WRF-CO2 4D-Var solves for the optimized CO2 flux scaling factors in a Bayesian framework. Two variational optimization schemes are implemented for the system: the first uses the limited memory Broyden-Fletcher-Goldfarb-Shanno (BFGS) minimization algorithm (L-BFGS-B) and the second uses the Lanczos conjugate gradient (CG) in an incremental approach. WRFPLUS forward, tangent linear, and adjoint models are modified to include the physical and dynamical processes involved in the atmospheric transport of CO2. The system is tested by simulations over a domain covering the continental United States at 48 km × 48 km grid spacing. The accuracy of the tangent linear and adjoint models is assessed by comparing against finite difference sensitivity. The system's effectiveness for CO2 inverse modeling is tested using pseudo-observation data. The results of the sensitivity and inverse modeling tests demonstrate the potential usefulness of WRF-CO2 4D-Var for regional CO2 inversions.

Risks and injuries in laser and high-frequency applications

NASA Astrophysics Data System (ADS)

Giering, K.; Philipp, Carsten M.; Berlien, Hans-Peter

1995-01-01

An analysis of injuries and risks using high frequency (HF) and lasers in medicine based on a literature search with MEDLINE was performed. The cases reported in the literature were classified according to the following criteria: (1) Avoidable in an optimal operational procedure. These kind of injuries are caused by a chain of unfortunate incidents. They are in principle avoidable by the 'right action at the right time' which presupposes an appropriate training of the operating team, selection of the optimal parameters for procedure and consideration of all safety instructions. (2) Avoidable, caused by malfunction of the equipment and/or accessories. The injuries classified into this group are avoidable if all safety regulations were fulfilled. This includes a pre-operational check-up and the use of medical lasers and high frequency devices only which meet the international safety standards. (3) Avoidable, caused by misuse/mistake. Injuries of this group were caused by an inappropriate selection of the procedure, wrong medical indication or mistakes during application. (4) Unavoidable, fateful. These injuries can be caused by risks inherent to the type of energy used, malfunction of the equipment and/or accessories though a pre-operational check-up was done. Some risks and complications are common to high frequency and laser application. But whereas these risks can be excluded easily in laser surgery there is often a great expenditure necessary or they are not avoidable if high frequency if used. No unavoidable risks due to laser energy occur.

Analysis of non-phthalates plasticizers on porous graphitic carbon by supercritical fluid chromatography using evaporative light scattering detection.

PubMed

Vaccher, Claude; Decaudin, Bertrand; Sautou, Valérie; Lecoeur, Marie

2014-09-12

The analysis of several plasticizers, widely used in the production of medical devices, was investigated on porous graphitic carbon (PGC) stationary phase in supercritical fluid chromatography (SFC) with an evaporative light scattering detector (ELSD). Due to strong interaction of compounds with the PGC support, solvents of strong eluotropic strength were added to the CO2 supercritical fluid. The effect of alkyl chain (pentane, hexane, heptane) and chlorinated (CH2Cl2, CHCl3, CCl4) solvents was studied on the retention and on the ELSD detection of plasticizers. A co-solvent mixture composed of CHCl3/heptane, eluted under gradient mode, allowed a significant improvement of the ELSD response compared to the use of each solvent individually. Then, a central composite design (CCD) was implemented to optimize both the separation and the detection of plasticizers. The parameters involved were the outlet pressure, the gradient slope, the co-solvent composition and the drift tube temperature of the ELSD. After optimization, baseline separation of plasticizers was achieved in 7min and best signal-to-noise ratios were obtained with outlet pressure and drift tube temperature of ELSD set at 200bar and 31°C, respectively. The co-solvent mixture was also composed of CHCl3/heptane (35/65 v/v) and a gradient from 15 to 60% of co-solvent in 2.2min was employed. The results demonstrated that CCD is a powerful tool for the optimization of SFC/ELSD method and the response surface model analysis can provide statistical understandings of the significant factors required to achieve optimal separation and ELSD sensitivity. Copyright © 2014 Elsevier B.V. All rights reserved.

Optimal Design of Biomass Utilization System for Rural Area Includes Technical and Economic Dimensions

NASA Astrophysics Data System (ADS)

Morioka, Yasuki; Nakata, Toshihiko

In order to design optimal biomass utilization system for rural area, OMNIBUS (The Optimization Model for Neo-Integrated Biomass Utilization System) has been developed. OMNIBUS can derive the optimal system configuration to meet different objective function, such as current account balance, amount of biomass energy supply, and CO2 emission. Most of biomass resources in a focused region e.g. wood biomass, livestock biomass, and crop residues are considered in the model. Conversion technologies considered are energy utilization technologies e.g. direct combustion and methane fermentation, and material utilization technologies e.g. composting and carbonization. Case study in Miyakojima, Okinawa prefecture, has been carried out for several objective functions and constraint conditions. Considering economics of the utilization system as a priority requirement, composting and combustion heat utilization are mainly chosen in the optimal system configuration. However gasification power plant and methane fermentation are included in optimal solutions, only when both biomass energy utilization and CO2 reduction have been set as higher priorities. External benefit of CO2 reduction has large impacts on the system configuration. Provided marginal external benefit of more than 50,000 JPY/t-C, external benefit becomes greater than the revenue from electricity and compost etc. Considering technological learning in the future, expensive technologies such as gasification power plant and methane fermentation will have economic feasibility as well as market competitiveness.

Temperature characteristics of fusion splicing Hollow Core Photonic Crystal Fiber by sinusoidal modulation CO2 laser

NASA Astrophysics Data System (ADS)

Fu, Guangwei; Li, Kuixing; Fu, Xinghu; Bi, Weihong

2013-07-01

During the fusion splicing Hollow Core Photonic Crystal Fiber (HC-PCF), the air-holes collapse easily due to the improper fusion duration time and optical power. To analyze the temperature characteristics of fusion splicing HC-PCF, a heating method by sinusoidal modulation CO2 laser has been proposed. In the sinusoidal modulation, the variation relationships among laser power, temperature difference and angular frequency are analyzed. The results show that the theoretical simulation is basically in accordance with the experimental data. Therefore, a low-loss fusion splicing can be achieved by modulating the CO2 laser frequency to avoid the air-holes collapse of HC-PCF. Further, the errors are also given.

Electrochemical synthesis of formic acid from CO2 catalyzed by Shewanella oneidensis MR-1 whole-cell biocatalyst.

PubMed

Le, Quang Anh Tuan; Kim, Hee Gon; Kim, Yong Hwan

2018-09-01

The electro-biocatalytic conversion of CO 2 into formic acid using whole-cell and isolated biocatalysts is useful as an alternative route for CO 2 sequestration. In this study, Shewanella oneidensis MR-1 (S. oneidensis MR-1), a facultative aerobic bacterium that has been extensively studied for its utility as biofuel cells as well as for the detoxification of heavy metal oxides (i.e., MnO 2 , uranium), has been applied for the first time as a whole-cell biocatalyst for formic acid synthesis from gaseous CO 2 and electrons supplied from an electrode. S. oneidensis MR-1, when aerobically grown in Luria-Bertani (LB) medium, exhibited its ability as a whole-cell biocatalyst for the conversion of CO 2 into formic acid with moderate productivity of 0.59 mM h -1 for 24 h. In addition, an optimization of growth conditions of S. oneidensis MR-1 resulted in a remarkable increase in productivity. The CO 2 reduction reaction catalyzed by S. oneidensis MR-1, when anaerobically grown in newly optimized LB medium supplemented with fumarate and nitrate, exhibited 3.2-fold higher productivity (1.9 mM h -1 for 72 h) compared to that grown aerobically in only LB medium. Furthermore, the average conversion rate of formic acid synthesis catalyzed by S. oneidensis MR-1 when grown in the optimal medium over a period of 72 h was 3.8 mM h -1  g -1 wet-cell, which is 9.6-fold higher than that catalyzed by Methylobacterium extorquens AM1 whole-cells in our previous study. Copyright © 2018 Elsevier Inc. All rights reserved.

Assessing the Health and Performance Risks of Carbon Dioxide Exposures

NASA Technical Reports Server (NTRS)

James, John T.; Meyers, V. E.; Alexander, D.

2010-01-01

Carbon dioxide (CO2) is an anthropogenic gas that accumulates in spacecraft to much higher levels than earth-normal levels. Controlling concentrations of this gas to acceptable levels to ensure crew health and optimal performance demands major commitment of resources. NASA has many decades of experience monitoring and controlling CO2, yet we are uncertain of the levels at which subtle performance decrements develop. There is limited evidence from ground-based studies that visual disturbances can occur during brief exposures and visual changes have been noted in spaceflight crews. These changes may be due to CO2 alone or in combination with other known spaceflight factors such as increased intracranial pressure due to fluid shifts. Discerning the comparative contribution of each to performance decrements is an urgent issue if we hope to optimize astronaut performance aboard the ISS. Long-term, we must know the appropriate control levels for exploration-class missions to ensure that crewmembers can remain cooperative and productive in a highly stressful environment. Furthermore, we must know the magnitude of interindividual variability in susceptibility to the adverse effects of CO2 so that the most tolerant crewmembers can be identified. Ground-based studies have been conducted for many years to set exposure limits for submariners; however, these studies are typically limited and incompletely reported. Nonetheless, NASA, in cooperation with the National Research Council, has set exposure limits for astronauts using this limited database. These studies do not consider the interactions of spaceflight-induced fluid shifts and CO2 exposures. In an attempt to discern whether CO2 levels affect the incidence of headache and visual disturbances in astronauts we performed a retrospective study comparing average CO2 levels and the prevalence of headache and visual disturbances. Our goal is to narrow gaps in the risk profile for in-flight CO2 exposures. Such studies can provide no more than partial answers to the questions of environmental interactions, interindividual variability, and optimal control levels. Future prospective studies should involve assessment of astronaut well being using sophisticated measures during exposures to levels of CO2 in the range from 2 to 8 mmHg.

The impact of low levels of carbon dioxide on rats.

PubMed

Krohn, Thomas C; Hansen, Axel Kornerup; Dragsted, Nils

2003-04-01

The widespread use of individually ventilated cage (IVC) systems today has made the impact of CO(2) on rodents a highly important matter. Leaving cages from these systems without ventilation increases CO(2) concentrations inside the cages, as CO(2) generated from the animals is no longer removed actively. In modern IVC systems the CO(2) levels may reach 3-5% within a very short time, as the cages are very tightly sealed. The aim of the present study was to investigate the effects of 1%, 3%, and 5% CO(2) by studying the preferences of the animals as well as changes in the heart rate and systolic blood pressure as measured by telemetry. The rats avoided the cages, which contained 3% CO(2). In the telemetric study an anaesthetic effect on the rats were seen at 3% as a drop in the heart rate, and at 5% CO(2) a drop in the systolic blood pressure was also seen. The results from the present study could indicate that CO(2) levels of up to 3% do not affect the animals, or at least only to a minor extent, but that if the animals are exposed to CO(2) levels of higher than 3% they are affected directly as seen by changes in physiological parameters and preferences.

Multi-scale textural feature extraction and particle swarm optimization based model selection for false positive reduction in mammography.

PubMed

Zyout, Imad; Czajkowska, Joanna; Grzegorzek, Marcin

2015-12-01

The high number of false positives and the resulting number of avoidable breast biopsies are the major problems faced by current mammography Computer Aided Detection (CAD) systems. False positive reduction is not only a requirement for mass but also for calcification CAD systems which are currently deployed for clinical use. This paper tackles two problems related to reducing the number of false positives in the detection of all lesions and masses, respectively. Firstly, textural patterns of breast tissue have been analyzed using several multi-scale textural descriptors based on wavelet and gray level co-occurrence matrix. The second problem addressed in this paper is the parameter selection and performance optimization. For this, we adopt a model selection procedure based on Particle Swarm Optimization (PSO) for selecting the most discriminative textural features and for strengthening the generalization capacity of the supervised learning stage based on a Support Vector Machine (SVM) classifier. For evaluating the proposed methods, two sets of suspicious mammogram regions have been used. The first one, obtained from Digital Database for Screening Mammography (DDSM), contains 1494 regions (1000 normal and 494 abnormal samples). The second set of suspicious regions was obtained from database of Mammographic Image Analysis Society (mini-MIAS) and contains 315 (207 normal and 108 abnormal) samples. Results from both datasets demonstrate the efficiency of using PSO based model selection for optimizing both classifier hyper-parameters and parameters, respectively. Furthermore, the obtained results indicate the promising performance of the proposed textural features and more specifically, those based on co-occurrence matrix of wavelet image representation technique. Copyright © 2015 Elsevier Ltd. All rights reserved.

Process for CO.sub.2 capture using zeolites from high pressure and moderate temperature gas streams

DOEpatents

Siriwardane, Ranjani V [Morgantown, WV; Stevens, Robert W [Morgantown, WV

2012-03-06

A method for separating CO.sub.2 from a gas stream comprised of CO.sub.2 and other gaseous constituents using a zeolite sorbent in a swing-adsorption process, producing a high temperature CO.sub.2 stream at a higher CO.sub.2 pressure than the input gas stream. The method utilizes CO.sub.2 desorption in a CO.sub.2 atmosphere and effectively integrates heat transfers for optimizes overall efficiency. H.sub.2O adsorption does not preclude effective operation of the sorbent. The cycle may be incorporated in an IGCC for efficient pre-combustion CO.sub.2 capture. A particular application operates on shifted syngas at a temperature exceeding 200.degree. C. and produces a dry CO.sub.2 stream at low temperature and high CO.sub.2 pressure, greatly reducing any compression energy requirements which may be subsequently required.

The Role of Electrode-Catalyst Interactions in Enabling Efficient CO2 Reduction with Mo(bpy)(CO)4 As Revealed by Vibrational Sum-Frequency Generation Spectroscopy.

PubMed

Neri, Gaia; Donaldson, Paul M; Cowan, Alexander J

2017-10-04

Group 6 metal carbonyl complexes ([M(bpy)(CO) 4 ], M = Cr, Mo, W) are potentially promising CO 2 reduction electrocatalysts. However, catalytic activity onsets at prohibitively negative potentials and is highly dependent on the nature of the working electrode. Here we report in situ vibrational SFG (VSFG) measurements of the electrocatalyst [Mo(bpy)(CO) 4 ] at platinum and gold electrodes. The greatly improved onset potential for electrocatalytic CO 2 reduction at gold electrodes is due to the formation of the catalytically active species [Mo(bpy)(CO) 3 ] 2- via a second pathway at more positive potentials, likely avoiding the need for the generation of [Mo(bpy)(CO) 4 ] 2- . VSFG studies demonstrate that the strength of the interaction between initially generated [Mo(bpy)(CO) 4 ] •- and the electrode is critical in enabling the formation of the active catalyst via the low energy pathway. By careful control of electrode material, solvent and electrolyte salt, it should therefore be possible to attain levels of activity with group 6 complexes equivalent to their much more widely studied group 7 analogues.

Optimization of enhanced coal-bed methane recovery using numerical simulation

NASA Astrophysics Data System (ADS)

Perera, M. S. A.; Ranjith, P. G.; Ranathunga, A. S.; Koay, A. Y. J.; Zhao, J.; Choi, S. K.

2015-02-01

Although the enhanced coal-bed methane (ECBM) recovery process is one of the potential coal bed methane production enhancement techniques, the effectiveness of the process is greatly dependent on the seam and the injecting gas properties. This study has therefore aimed to obtain a comprehensive knowledge of all possible major ECBM process-enhancing techniques by developing a novel 3D numerical model by considering a typical coal seam using the COMET 3 reservoir simulator. Interestingly, according to the results of the model, the generally accepted concept that there is greater CBM (coal-bed methane) production enhancement from CO2 injection, compared to the traditional water removal technique, is true only for high CO2 injection pressures. Generally, the ECBM process can be accelerated by using increased CO2 injection pressures and reduced temperatures, which are mainly related to the coal seam pore space expansion and reduced CO2 adsorption capacity, respectively. The model shows the negative influences of increased coal seam depth and moisture content on ECBM process optimization due to the reduced pore space under these conditions. However, the injection pressure plays a dominant role in the process optimization. Although the addition of a small amount of N2 into the injecting CO2 can greatly enhance the methane production process, the safe N2 percentage in the injection gas should be carefully predetermined as it causes early breakthroughs in CO2 and N2 in the methane production well. An increased number of production wells may not have a significant influence on long-term CH4 production (50 years for the selected coal seam), although it significantly enhances short-term CH4 production (10 years for the selected coal seam). Interestingly, increasing the number of injection and production wells may have a negative influence on CBM production due to the coincidence of pressure contours created by each well and the mixing of injected CO2 with CH4.

Synthesis of arbitrary pulse waveforms in QCL-seeded ns-pulse CO₂ laser for optimization of an LPP EUV source.

PubMed

Nowak, Krzysztof M; Kurosawa, Yoshiaki; Suganuma, Takashi; Kawasuji, Yasufumi; Nakarai, Hiroaki; Saito, Takashi; Fujimoto, Junichi; Mizoguchi, Hakaru

2016-07-01

One of the unique features of the quantum-cascade-laser-seeded, nanosecond-pulse CO₂ laser, invented for the purpose of generation of extreme UV by laser-produced-plasma, is a robust synthesis of arbitrary pulse waveforms. In the present Letter we report on experimental results that are, to our best knowledge, the first demonstration of such functionality obtainable from nanosecond-pulse CO₂ laser technology. An online pulse duration adjustment within 10-40 ns was demonstrated, and a few exemplary pulse waveforms were synthesized, such as "tophat," "tailspike," and "leadspike" shapes. Such output characteristics may be useful to optimize the performance of LPP EUV source.

Optimal versus observed vegetation responses to CO2 over the last 40 years

NASA Astrophysics Data System (ADS)

Roderick, M. L.; Yang, Y.; Donohue, R. J.; Farquhar, G. D.; McVicar, T.

2016-12-01

The ongoing increase in atmospheric CO2 presents an interesting opportunity for primary producers. Understanding the impacts on agriculture, natural ecological communities and water resources presents considerable challenges. We investigate this problem using a Budyko-type framework based around two end-members: (i) warm arid environments (e.g. warm deserts) and (ii) warm wet environments (e.g. tropical rainforests). We first make predictions of the effect of a change in atmospheric CO2 on the partitioning of precipitation between evapotranspiration and streamflow. We then use satellite observation of greenness and in-situ streamflow data to assess the predictions. We finish by contrasting the observed responses against those expected from a purely theoretical construct: the so-called optimal vegetation.

[How can we determine the best cerebral perfusion pressure in pediatric traumatic brain injury?].

PubMed

Vuillaume, C; Mrozek, S; Fourcade, O; Geeraerts, T

2013-12-01

The management of cerebral perfusion pressure (CPP) is the one of the main preoccupation for the care of paediatric traumatic brain injury (TBI). The physiology of cerebral autoregulation, CO2 vasoreactivity, cerebral metabolism changes with age as well as the brain compliance. Low CPP leads to high morbidity and mortality in pediatric TBI. The recent guidelines for the management of CPP for the paediatric TBI indicate a CPP threshold 40-50 mmHg (infants for the lower and adolescent for the upper). But we must consider the importance of age-related differences in the arterial pressure and CPP. The best CPP is the one that allows to avoid cerebral ischaemia and oedema. In this way, the adaptation of optimal CPP must be individual. To assess this objective, interesting tools are available. Transcranial Doppler can be used to determine the best level of CPP. Other indicators can predict the impairment of autoregulation like pressure reactivity index (PRx) taking into consideration the respective changes in ICP and CPP. Measurement of brain tissue oxygen partial pressure is an other tool that can be used to determine the optimal CPP. Copyright © 2013 Société française d’anesthésie et de réanimation (Sfar). Published by Elsevier SAS. All rights reserved.

In vivo estimates of NO and CO conductance for haemoglobin and for lung transfer in humans.

PubMed

Guénard, Hervé Jean-Pierre; Martinot, Jean-Benoit; Martin, Sebastien; Maury, Bertrand; Lalande, Sophie; Kays, Christian

2016-07-01

Membrane conductance (Dm) and capillary lung volume (Vc) derived from NO and CO lung transfer measurements in humans depend on the blood conductance (θ) values of both gases. Many θ values have been proposed in the literature. In the present study, measurements of CO and NO transfer while breathing 15% or 21% O2 allowed the estimation of θNO and the calculation of the optimal equation relating 1/θCO to pulmonary capillary oxygen pressure (PcapO2). In 10 healthy subjects, the mean calculated θNO value was similar to the θNO value previously reported in the literature (4.5mmHgmin(-1)) provided that one among three θCO equations from the literature was chosen. Setting 1/θCO=a·PcapO2+b, optimal values of a and b could be chosen using two methods: 1) by minimizing the difference between Dm/Vc ratios for any PcapO2, 2) by establishing a linear equation relating a and b. Using these methods, we are proposing the equation 1/θCO=0.0062·PcapO2+1.16, which is similar to two equations previously reported in the literature. With this set of θ values, DmCO reached the morphometric range. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparative study of differently treated animal bones for Co(2+) removal.

PubMed

Dimović, S; Smiciklas, I; Plećas, I; Antonović, D; Mitrić, M

2009-05-15

The objective of the present study was the evaluation of differently treated bovine bones for Co(2+) removal from aqueous media. Powdered bones (B), as well as samples prepared by H(2)O(2) oxidation (BH(2)O(2)) and annealing at 400-1000 degrees C (B400-B1000), were tested as sorbent materials. A combination of XRD, FTIR spectroscopies, DTA/TGA analyses, specific surface area (S(p)) and point of zero charge (pH(PZC)) measurements was utilized for physicochemical characterization of sorbents. Sorption of Co(2+) was studied in batch conditions as a function of pH, contact time and Co(2+) concentration. Initial pH values in the range 4-8 were found optimal for sorption experiments. Equilibrium time of 24h was required in all investigated systems. The maximum sorption capacities differ significantly from 0.078 to 0.495mmol/g, whereas the affinity towards Co(2+) decreased in the order: B400>BH(2)O(2)>B600>B>B800>B1000. The pseudo-second-order model and Langmuir theoretical equation were used for fitting the kinetic and equilibrium data, respectively. Ion-exchange with Ca(2+) and specific cation sorption were identified as main removal mechanisms. The amounts of Co(2+) desorbed from loaded bone sorbents increased with the decrease of pH as well as with the increase of Ca(2+) concentration. Heating at 400 degrees C was found to be an optimal treatment for the production of the Co(2+) removal agent.

Modeling of thermal storage systems in MILP distributed energy resource models

DOE PAGES

Steen, David; Stadler, Michael; Cardoso, Gonçalo; ...

2014-08-04

Thermal energy storage (TES) and distributed generation technologies, such as combined heat and power (CHP) or photovoltaics (PV), can be used to reduce energy costs and decrease CO 2 emissions from buildings by shifting energy consumption to times with less emissions and/or lower energy prices. To determine the feasibility of investing in TES in combination with other distributed energy resources (DER), mixed integer linear programming (MILP) can be used. Such a MILP model is the well-established Distributed Energy Resources Customer Adoption Model (DER-CAM); however, it currently uses only a simplified TES model to guarantee linearity and short run-times. Loss calculationsmore » are based only on the energy contained in the storage. This paper presents a new DER-CAM TES model that allows improved tracking of losses based on ambient and storage temperatures, and compares results with the previous version. A multi-layer TES model is introduced that retains linearity and avoids creating an endogenous optimization problem. The improved model increases the accuracy of the estimated storage losses and enables use of heat pumps for low temperature storage charging. Ultimately,results indicate that the previous model overestimates the attractiveness of TES investments for cases without possibility to invest in heat pumps and underestimates it for some locations when heat pumps are allowed. Despite a variation in optimal technology selection between the two models, the objective function value stays quite stable, illustrating the complexity of optimal DER sizing problems in buildings and microgrids.« less

Membrane Process to Capture CO{sub 2} from Coal-Fired Power Plant Flue Gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merkel, Tim; Wei, Xiaotong; Firat, Bilgen

2012-03-31

This final report describes work conducted for the U.S. Department of Energy National Energy Technology Laboratory (DOE NETL) on development of an efficient membrane process to capture carbon dioxide (CO{sub 2}) from power plant flue gas (award number DE-NT0005312). The primary goal of this research program was to demonstrate, in a field test, the ability of a membrane process to capture up to 90% of CO{sub 2} in coal-fired flue gas, and to evaluate the potential of a full-scale version of the process to perform this separation with less than a 35% increase in the levelized cost of electricity (LCOE).more » Membrane Technology and Research (MTR) conducted this project in collaboration with Arizona Public Services (APS), who hosted a membrane field test at their Cholla coal-fired power plant, and the Electric Power Research Institute (EPRI) and WorleyParsons (WP), who performed a comparative cost analysis of the proposed membrane CO{sub 2} capture process. The work conducted for this project included membrane and module development, slipstream testing of commercial-sized modules with natural gas and coal-fired flue gas, process design optimization, and a detailed systems and cost analysis of a membrane retrofit to a commercial power plant. The Polaris? membrane developed over a number of years by MTR represents a step-change improvement in CO{sub 2} permeance compared to previous commercial CO{sub 2}-selective membranes. During this project, membrane optimization work resulted in a further doubling of the CO{sub 2} permeance of Polaris membrane while maintaining the CO{sub 2}/N{sub 2} selectivity. This is an important accomplishment because increased CO{sub 2} permeance directly impacts the membrane skid cost and footprint: a doubling of CO{sub 2} permeance halves the skid cost and footprint. In addition to providing high CO{sub 2} permeance, flue gas CO{sub 2} capture membranes must be stable in the presence of contaminants including SO{sub 2}. Laboratory tests showed no degradation in Polaris membrane performance during two months of continuous operation in a simulated flue gas environment containing up to 1,000 ppm SO{sub 2}. A successful slipstream field test at the APS Cholla power plant was conducted with commercialsize Polaris modules during this project. This field test is the first demonstration of stable performance by commercial-sized membrane modules treating actual coal-fired power plant flue gas. Process design studies show that selective recycle of CO{sub 2} using a countercurrent membrane module with air as a sweep stream can double the concentration of CO{sub 2} in coal flue gas with little energy input. This pre-concentration of CO{sub 2} by the sweep membrane reduces the minimum energy of CO{sub 2} separation in the capture unit by up to 40% for coal flue gas. Variations of this design may be even more promising for CO{sub 2} capture from NGCC flue gas, in which the CO{sub 2} concentration can be increased from 4% to 20% by selective sweep recycle. EPRI and WP conducted a systems and cost analysis of a base case MTR membrane CO{sub 2} capture system retrofitted to the AEP Conesville Unit 5 boiler. Some of the key findings from this study and a sensitivity analysis performed by MTR include: The MTR membrane process can capture 90% of the CO{sub 2} in coal flue gas and produce high-purity CO{sub 2} (>99%) ready for sequestration. CO{sub 2} recycle to the boiler appears feasible with minimal impact on boiler performance; however, further study by a boiler OEM is recommended. For a membrane process built today using a combination of slight feed compression, permeate vacuum, and current compression equipment costs, the membrane capture process can be competitive with the base case MEA process at 90% CO{sub 2} capture from a coal-fired power plant. The incremental LCOE for the base case membrane process is about equal to that of a base case MEA process, within the uncertainty in the analysis. With advanced membranes (5,000 gpu for CO{sub 2} and 50 for CO{sub 2}/N{sub 2}), operating with no feed compression and low-cost CO{sub 2} compression equipment, an incremental LCOE of $33/MWh at 90% capture can be achieved (40% lower than the advanced MEA case). Even with lower cost compression, it appears unlikely that a membrane process using high feed compression (>5 bar) can be competitive with amine absorption, due to the capital cost and energy consumption of this equipment. Similarly, low vacuum pressure (<0.2 bar) cannot be used due to poor efficiency and high cost of this equipment. High membrane permeance is important to reduce the capital cost and footprint of the membrane unit. CO{sub 2}/N{sub 2} selectivity is less important because it is too costly to generate a pressure ratio where high selectivity can be useful. A potential cost ?sweet spot? exists for use of membrane-based technology, if 50-70% CO{sub 2} capture is acceptable. There is a minimum in the cost of CO{sub 2} avoided/ton that membranes can deliver at 60% CO{sub 2} capture, which is 20% lower than the cost at 90% capture. Membranes operating with no feed compression are best suited for lower capture rates. Currently, it appears that the biggest hurdle to use of membranes for post-combustion CO{sub 2} capture is compression equipment cost. An alternative approach is to use sweep membranes in parallel with another CO{sub 2} capture technology that does not require feed compression or vacuum equipment. Hybrid designs that utilize sweep membranes for selective CO{sub 2} recycle show potential to significantly reduce the minimum energy of CO{sub 2} separation.« less

Simulation and Optimization Methods for Assessing the Impact of Aviation Operations on the Environment

NASA Technical Reports Server (NTRS)

Sridhar, Banavar; Chen, Neil; Ng, Hok K.

2010-01-01

There is increased awareness of anthropogenic factors affecting climate change and urgency to slow the negative impact. Greenhouse gases, oxides of Nitrogen and contrails resulting from aviation affect the climate in different and uncertain ways. This paper develops a flexible simulation and optimization software architecture to study the trade-offs involved in reducing emissions. The software environment is used to conduct analysis of two approaches for avoiding contrails using the concepts of contrail frequency index and optimal avoidance trajectories.

A Workflow for Subsurface Pressure Control in Geological CO2 Storage: Optimization of Brine Extraction

NASA Astrophysics Data System (ADS)

Birkholzer, J. T.; Gonzalez-Nicolas, A.; Cihan, A.

2017-12-01

Industrial-scale injection of CO2 into the subsurface increases the fluid pressure in the reservoir, sometimes to the point that the resulting stress increases must be properly controlled to prevent potential damaging impacts such as fault activation, leakage through abandoned wells, or caprock fracturing. Brine extraction is one approach for managing formation pressure, effective stress, and plume movement in response to CO2 injection. However, the management of the extracted brine adds cost to the carbon capture and sequestration operations; therefore optimizing (minimizing) the extraction volume of brine is of great importance. In this study, we apply an adaptive management approach that optimizes extraction rates of brine for pressure control in an integrated optimization framework involving site monitoring, model calibration, and optimization. We investigate the optimization performance as affected by initial site characterization data and introduction of newly acquired data during the injection phase. More accurate initial reservoir characterization data reduce the risk of pressure buildup damage with better estimations of initial extraction rates, which results in better control of pressure during the overall injection time periods. Results also show that low frequencies of model calibration and optimization with the new data, especially at early injection periods, may lead to optimization problems, either that pressure buildup constraints are violated or excessively high extraction rates are proposed. These optimization problems can be eliminated if more frequent data collection and model calibration are conducted, especially at early injection time periods. Approaches such as adaptive pressure management may constitute an effective tool to manage pressure buildup under uncertain and unknown reservoir conditions by minimizing the brine extraction volumes while not exceeding critical pressure buildups of the reservoir.

Optimized adhesives for strong, lightweight, damage-resistant, nanocomposite materials: new insights from natural materials

NASA Astrophysics Data System (ADS)

Hansma, P. K.; Turner, P. J.; Ruoff, R. S.

2007-01-01

From our investigations of natural composite materials such as abalone shell and bone we have learned the following. (1) Nature is frugal with resources: it uses just a few per cent glue, by weight, to glue together composite materials. (2) Nature does not avoid voids. (3) Nature makes optimized glues with sacrificial bonds and hidden length. We discuss how optimized adhesives combined with high specific stiffness/strength structures such as carbon nanotubes or graphene sheets could yield remarkably strong, lightweight, and damage-resistant materials.

Rising CO2 widens the transpiration-photosynthesis optimality space

NASA Astrophysics Data System (ADS)

de Boer, Hugo J.; Eppinga, Maarten B.; Dekker, Stefan C.

2016-04-01

Stomatal conductance (gs) and photosynthetic biochemistry, typically expressed by the temperature-adjusted maximum rates of carboxylation (V cmax) and electron transport (Jmax), are key traits in land ecosystem models. Contrary to the many approaches available for simulating gs responses, the biochemical parameters V cmax and Jmax are often treated as static traits in ecosystem models. However, observational evidence indicates that V cmax and Jmax respond to persistent changes in atmospheric CO2. Hence, ecosystem models may be improved by incorporating coordinated responses of photosynthetic biochemistry and gs to atmospheric CO2. Recently, Prentice et al. (2014) proposed an optimality framework (referred to as the Prentice framework from here on) to predict relationships between V cmax and gs based on Fick's law, Rubisco-limited photosynthesis and the carbon costs of transpiration and photosynthesis. Here we show that this framework is, in principle, suited to predict CO2-induced changes in the V cmax -gs relationships. The framework predicts an increase in the V cmax:gs-ratio with higher atmospheric CO2, whereby the slope of this relationship is determined by the carbon costs of transpiration and photosynthesis. For our empirical analyses we consider that the carbon cost of transpiration is positively related to the plant's Huber value (sapwood area/leaf area), while the carbon cost of photosynthesis is positively related to the maintenance cost of the photosynthetic proteins. We empirically tested the predicted effect of CO2 on the V cmax:gs-ratio in two genotypes of Solanum dulcamara (bittersweet) that were grown from seeds to maturity under 200, 400 and 800 ppm CO2 in walk-in growth chambers with tight control on light, temperature and humidity. Seeds of the two Solanum genotypes were obtained from two distinct natural populations; one adapted to well-drained sandy soil (the 'dry' genotype) and one adapted to poorly-drained clayey soil (the 'wet' genotype). Measurements of gs and V cmax were obtained with a portable photosynthesis system. Our empirical results support the prediction that the V cmax:gs-ratio increases with higher CO2 in both Solanum genotypes. The 'dry' genotype revealed a significantly higher Huber value and lower V cmax than the 'wet' genotype at each CO2 growth level. Moreover, we found that the down-regulation of V cmax under higher CO2 was stronger in the 'dry' genotype than in the 'wet' genotype, whereas no change in the Huber value was observed between CO2 levels. Consistent with the theoretical trade-off between the resulting costs of transpiration and photosynthesis, we found that the CO2-induced increase in the V cmax:gs-ratio was stronger in the 'wet' genotype than in the 'dry' genotype. Given the divergence of V cmax:gs relationships observed, we conclude that rising atmospheric CO2 may widen the V cmax - gs optimality space available for plants to achieve an optimal trade-off between photosynthesis and transpiration. References Prentice, I. C., Dong, N., Gleason, S. M., Maire, V. and Wright, I. J.: Balancing the costs of carbon gain and water transport: testing a new theoretical framework for plant functional ecology, Ecol. Lett., 17(1), 82-91, 2014.

Measurement of CO 2, CO, SO 2, and NO emissions from coal-based thermal power plants in India

NASA Astrophysics Data System (ADS)

Chakraborty, N.; Mukherjee, I.; Santra, A. K.; Chowdhury, S.; Chakraborty, S.; Bhattacharya, S.; Mitra, A. P.; Sharma, C.

Measurements of CO 2 (direct GHG) and CO, SO 2, NO (indirect GHGs) were conducted on-line at some of the coal-based thermal power plants in India. The objective of the study was three-fold: to quantify the measured emissions in terms of emission coefficient per kg of coal and per kWh of electricity, to calculate the total possible emission from Indian thermal power plants, and subsequently to compare them with some previous studies. Instrument IMR 2800P Flue Gas Analyzer was used on-line to measure the emission rates of CO 2, CO, SO 2, and NO at 11 numbers of generating units of different ratings. Certain quality assurance (QA) and quality control (QC) techniques were also adopted to gather the data so as to avoid any ambiguity in subsequent data interpretation. For the betterment of data interpretation, the requisite statistical parameters (standard deviation and arithmetic mean) for the measured emissions have been also calculated. The emission coefficients determined for CO 2, CO, SO 2, and NO have been compared with their corresponding values as obtained in the studies conducted by other groups. The total emissions of CO 2, CO, SO 2, and NO calculated on the basis of the emission coefficients for the year 2003-2004 have been found to be 465.667, 1.583, 4.058, and 1.129 Tg, respectively.

Systems Analysis of Physical Absorption of CO2 in Ionic Liquids for Pre-Combustion Carbon Capture.

PubMed

Zhai, Haibo; Rubin, Edward S

2018-04-17

This study develops an integrated technical and economic modeling framework to investigate the feasibility of ionic liquids (ILs) for precombustion carbon capture. The IL 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide is modeled as a potential physical solvent for CO 2 capture at integrated gasification combined cycle (IGCC) power plants. The analysis reveals that the energy penalty of the IL-based capture system comes mainly from the process and product streams compression and solvent pumping, while the major capital cost components are the compressors and absorbers. On the basis of the plant-level analysis, the cost of CO 2 avoided by the IL-based capture and storage system is estimated to be $63 per tonne of CO 2 . Technical and economic comparisons between IL- and Selexol-based capture systems at the plant level show that an IL-based system could be a feasible option for CO 2 capture. Improving the CO 2 solubility of ILs can simplify the capture process configuration and lower the process energy and cost penalties to further enhance the viability of this technology.

Error Analysis and Selection of Optimal Excitation Parameters for the Sensing of CO2 and O2 from Space for ASCENDS Applications

NASA Technical Reports Server (NTRS)

Pliutau, Denis; Prasad, Narasimha S.

2012-01-01

Simulation studies to optimize sensing of CO2 and O2 from space are described. Uncertainties in line-by-line calculations unaccounted for in previous studies identified. Multivariate methods are employed for measurement wavelengths selection. The Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) recommended by NRC Decadal Survey has a stringent accuracy requirements of 0.5% or better in XCO2 retrievals. NASA LaRC and its partners are investigating the use of the 1.57 m band of CO2 and the 1.26-1.27 m band of oxygen for XCO2 measurements. As part of these efforts, we are carrying out simulation studies using a lidar modeling framework being developed at NASA LaRC to predict the performance of our proposed ASCENDS mission implementation [1]. Our study is aimed at predicting the sources and magnitudes of errors anticipated in XCO2 retrievals for further error minimization through the selection of optimum excitation parameters and development of better retrieval methods.

Bringing High-Rate, CO2-Based Microbial Electrosynthesis Closer to Practical Implementation through Improved Electrode Design and Operating Conditions.

PubMed

Jourdin, Ludovic; Freguia, Stefano; Flexer, Victoria; Keller, Jurg

2016-02-16

The enhancement of microbial electrosynthesis (MES) of acetate from CO2 to performance levels that could potentially support practical implementations of the technology must go through the optimization of key design and operating conditions. We report that higher proton availability drastically increases the acetate production rate, with pH 5.2 found to be optimal, which will likely suppress methanogenic activity without inhibitor addition. Applied cathode potential as low as -1.1 V versus SHE still achieved 99% of electron recovery in the form of acetate at a current density of around -200 A m(-2). These current densities are leading to an exceptional acetate production rate of up to 1330 g m(-2) day(-1) at pH 6.7. Using highly open macroporous reticulated vitreous carbon electrodes with macropore sizes of about 0.6 mm in diameter was found to be optimal for achieving a good balance between total surface area available for biofilm formation and effective mass transfer between the bulk liquid and the electrode and biofilm surface. Furthermore, we also successfully demonstrated the use of a synthetic biogas mixture as carbon dioxide source, yielding similarly high MES performance as pure CO2. This would allow this process to be used effectively for both biogas quality improvement and conversion of the available CO2 to acetate.

Emission Inventory of Halogenated greenhouse gases in China during 1980-2050

NASA Astrophysics Data System (ADS)

Fang, X.; Velders, G. J. M.; Ravishankara, A. R.; Molina, M.; Su, S.; Zhang, J.; Zhou, X.; Hu, J.; Prinn, R. G.

2015-12-01

China is currently the largest producer and consumer of ozone-depleting substances (ODSs) which are regulated by the Montreal Protocol (MP). Many ODSs are also powerful greenhouse gases (GHGs). The Multilateral Fund has subsidized ~1 billion US dollars for the ODS phase out in China, and thus the return on this investment is of great interest. This study gives a comprehensive emission inventory in China from 1980 to 2013 of halocarbons including ODSs and their alternatives, the hydrofluorocarbons (HFCs) that are also greenhouse gases. We then project these emissions up to 2050 according to the MP and several policy options. Total emissions of ODS and HFCs were estimated to be ~500 CO2-eq Tg/yr in 2013 which are equivalent to ~5% of total GHG emissions in China including fossil fuel CO2 emissions. Our estimate shows that China has succeeded in substantially reducing CFC-11-equivalent emissions (to protect the ozone layer), and CO2-equivalent emissions (to protect climate) of ODSs since the mid-1990s when their phase out started in China in compliance with the MP. Furthermore, the avoided CO2-eq emissions due to compliance with the MP are even greater compared to the reduced emissions, for example net cumulative avoided emissions during 19 year period between 1995-2013 are comparable to the current one year CO2 emissions from fossil fuels in China. We find that HFC CO2-eq emissions increased rapidly in last decade, which make up ~2% in 2005 to ~20% of total halocarbon CO2-eq emissions in 2013. Under a baseline scenario in which HFCs are used as alternatives in the ongoing phase out of HCFCs in China, emissions of HFCs are predicted to be important components of both China's and global future GHG emissions. However, potential exists for minimizing China's HFC emissions under mitigation scenarios. Our conclusions about China's past and future ODS and HFC emission trajectories are likely to apply to other developing countries, with important implications for mitigating global GHG emissions.

Modeling and optimal design of CO2 Direct Air Capture systems in large arrays

NASA Astrophysics Data System (ADS)

Sadri Irani, Samaneh; Luzzatto-Fegiz, Paolo

2017-11-01

As noted by the 2014 IPCC report, while the rise in atmospheric CO2 would be slowed by emissions reductions, removing atmospheric CO2 is an important part of possible paths to climate stabilization. Direct Air Capture of CO2 with chemicals (DAC) is one of several proposed carbon capture technologies. There is an ongoing debate on whether DAC is an economically viable approach to alleviate climate change. In addition, like all air capture strategies, DAC is strongly constrained by the net-carbon problem, namely the need to control CO2 emissions associated with the capture process (for example, if DAC not powered by renewables). Research to date has focused on the chemistry and economics of individual DAC devices. However, the fluid mechanics of their large-scale deployment has not been examined in the literature, to the best of our knowledge. In this presentation, we develop a model for flow through an array of DAC devices, varying their lateral extent and their separation. We build on a recent theory of canopy flows, introducing terms for CO2 entrainment into the array boundary layer, and transport into the farm. In addition, we examine the possibility of driving flow passively by wind, thereby reducing energy consumption. The optimal operational design is established considering the total cost, drag force, energy consumption and total CO2 capture.

A Dynamic Programming Model for Optimizing Frequency of Time-Lapse Seismic Monitoring in Geological CO2 Storage

NASA Astrophysics Data System (ADS)

Bhattacharjya, D.; Mukerji, T.; Mascarenhas, O.; Weyant, J.

2005-12-01

Designing a cost-effective and reliable monitoring program is crucial to the success of any geological CO2 storage project. Effective design entails determining both, the optimal measurement modality, as well as the frequency of monitoring the site. Time-lapse seismic provides the best spatial coverage and resolution for reservoir monitoring. Initial results from Sleipner (Norway) have demonstrated effective monitoring of CO2 plume movement. However, time-lapse seismic is an expensive monitoring technique especially over the long term life of a storage project and should be used judiciously. We present a mathematical model based on dynamic programming that can be used to estimate site-specific optimal frequency of time-lapse surveys. The dynamics of the CO2 sequestration process are simplified and modeled as a four state Markov process with transition probabilities. The states are M: injected CO2 safely migrating within the target zone; L: leakage from the target zone to the adjacent geosphere; R: safe migration after recovery from leakage state; and S: seepage from geosphere to the biosphere. The states are observed only when a monitoring survey is performed. We assume that the system may go to state S only from state L. We also assume that once observed to be in state L, remedial measures are always taken to bring it back to state R. Remediation benefits are captured by calculating the expected penalty if CO2 seeped into the biosphere. There is a trade-off between the conflicting objectives of minimum discounted costs of performing the next time-lapse survey and minimum risk of seepage and its associated costly consequences. A survey performed earlier would spot the leakage earlier. Remediation methods would have been utilized earlier, resulting in savings in costs attributed to excessive seepage. On the other hand, there are also costs for the survey and remedial measures. The problem is solved numerically using Bellman's optimality principal of dynamic programming to optimize over the entire finite time horizon. We use a Monte Carlo approach to explore trade-offs between survey costs, remediation costs, and survey frequency and to analyze the sensitivity to leakage probabilities, and carbon tax. The model can be useful in determining a monitoring regime appropriate to a specific site's risk and set of remediation options, rather than a generic one based on a maximum downside risk threshold for CO2 storage as a whole. This may have implications on the overall costs associated with deploying Carbon capture and storage on a large scale.

The economics of leaf-gas exchange in a fluctuating environment and their upscaling to the canopy-level using turbulent transport theories

NASA Astrophysics Data System (ADS)

Katul, G. G.; Palmroth, S.; Manzoni, S.; Oren, R.

2012-12-01

Global climate models predict decreases in leaf stomatal conductance (gs) and transpiration due to increases in atmospheric CO2. The consequences of these reductions are increases in soil moisture availability and continental scale run-off at decadal time-scales. Thus, a theory explaining the differential sensitivity of stomata to changing atmospheric CO2 and other environmental conditions such as soil moisture at the ecosystem scale must be identified. Here, these responses are investigated using an optimality theory applied to stomatal conductance. An analytical model for gs is first proposed based on (a) Fickian mass transfer of CO2 and H2O through stomata; (b) a biochemical photosynthesis model that relates intercellular CO2 to net photosynthesis; and (c) a stomatal model based on optimization for maximizing carbon gains when water losses represent a cost. The optimization theory produced three gas exchange responses that are consistent with observations across a wide-range of species: (1) the sensitivity of gs to vapour pressure deficit (D) is similar to that obtained from a previous synthesis of more than 40 species, (2) the theory is consistent with the onset of an apparent 'feed-forward' mechanism in gs, and (3) the emergent non-linear relationship between the ratio of intercellular to atmospheric CO2 (ci/ca) and D agrees with the results available on this response. A simplified version of this leaf-scale approach recovers the linear relationship between stomatal conductance and leaf-photosynthesis employed in numerous climate models that currently use a variant on the 'Ball-Berry' or the 'Leuning' approaches provided the marginal water use efficiency increases linearly with atmospheric CO2. The model is then up-scaled to the canopy-level using novel theories about the structure of turbulence inside vegetation. This up-scaling proved to be effective in resolving the complex (and two-way) interactions between leaves and their immediate micro-climate. Extensions of this optimality approach to drought and salt-stressed cases are briefly presented.

An anti-herbivore defense mutualism under elevated CO2 levels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marks, S.; Lincoln, D.E.

Previous studies have shown that insects typically consume more when fed leaf tissue grown under CO2 enrichment, but with few negative effects on growth. On the other hand, Lepidopteran larvae fed tissue infected with Balansiae fungal endophytes (which produce toxic alkaloids) typically eat less but suffer negative effects on growth and survival. This study was carried out to see how these two factors would interact to affect consumption and growth of Fall Armyworm larvae (Spodoptera frugiperda). Infected and uninfected ramets of a single genotype of tall fescue (Festuca arundinacea) were grown under CO2 concentrations of 400 and 700 ul/L. Larvaemore » had increased relative growth in the high CO2 treatment, but decreased growth when fed infected tissue. Relative consumption of leaf tissue was greater in the high CO2 treatment, but was not effected by infection. CO2 level, infection, and their interaction all significantly reduced the efficiency of conversion of food ingested (ECI). It appears that tall fescue may not be as well defended against herbivores under CO2 enrichment, although insects may still avoid and be negatively effected by endophyte infected plants.« less

Optimization of permanent magnetic properties in melt spun Co{sub 82−x}Hf{sub 12+x}B{sub 6} (x = 0–4) nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, H. W.; Liao, M. C.; Shih, C. W.

2015-05-07

Magnetic properties of melt spun Co{sub 82−x}Hf{sub 12+x}B{sub 6} ribbons made with various wheel speeds have been studied. The ribbons with x = 0–1 are not easy to crystallize and thus display soft magnetic behavior even at wheel speed of 10 m/s. In contrast, the ribbons with x = 1.5–4 at optimized wheel speed exhibit good permanent magnetic properties of B{sub r} = 0.41–0.59 T, {sub i}H{sub c} = 120–400 kA/m, and (BH){sub max} = 10.6–48.1 kJ/m{sup 3}. The optimal magnetic properties of B{sub r} = 0.59 T, {sub i}H{sub c} = 384 kA/m, and (BH){sub max} = 48.1 kJ/m{sup 3} are achieved for Co{sub 80}Hf{sub 14}B{sub 6} ribbons at wheel speed of 30 m/s. X-ray diffraction, thermo-magnetic analysis, and transmission electron microscopy resultsmore » show that good hard magnetic properties of Co{sub 82−x}Hf{sub 12+x}B{sub 6} ribbons (x = 2–4) are originated from the Co{sub 11}Hf{sub 2} phase well coupled with the Co phase. The change of magnetic properties for Co{sub 82−x}Hf{sub 12+x}B{sub 6} ribbons spun at various wheel speeds is correlated to microstructure and phase constitution. The strong exchange-coupling effect between magnetic grains for the ribbons with x = 2–3 at wheel speed = 30 m/s leads to remarkable permanent magnetic properties. The presented results suggest that the optimized Co{sub 82−x}Hf{sub 12+x}B{sub 6} (x = 2–3) ribbons are much suitable than others (x = 0–1.5 and 4) for making rare earth and Pt-free magnets.« less

Years of Life Lost (YLL) in Colombia 1998-2011: Overall and Avoidable Causes of Death Analysis

PubMed Central

Castillo-Rodríguez, Liliana; Díaz-Jiménez, Diana; Castañeda-Orjuela, Carlos; De la Hoz-Restrepo, Fernando

2015-01-01

Objective Estimate the Years of Life Lost (YLL) for overall and avoidable causes of death (CoD) in Colombia for the period 1998-2011. Methods From the reported deaths to the Colombian mortality database during 1998-2011, we classified deaths from avoidable causes. With the reference life table of the Global Burden of Disease (GBD) 2010 study, we estimated the overall YLL and YLL due to avoidable causes. Calculations were performed with the difference between life expectancy and the age of death. Results are reported by group of cause of death, events, sex, year and department. Comparative analysis between number of deaths and YLL was carried out. Results A total of 83,856,080 YLL were calculated in Colombia during period 1998-2011, 75.9% of them due to avoidable CoD. The year 2000 reported the highest number of missed YLL by both overall and avoidable CoD. The departments with the highest YLL rates were Caquetá, Guaviare, Arauca, Meta, and Risaralda. In men, intentional injuries and cardiovascular and circulatory diseases had the higher losses, while in women YLL were mainly due to cardiovascular and circulatory diseases. Conclusions The public health priorities should focus on preventing the loss of YLL due to premature death and differentiated interventions by sex. PMID:25942009

The Feasibility of Avoiding Future Climate Impacts: Results from the AVOID Programmes

NASA Astrophysics Data System (ADS)

Lowe, J. A.; Warren, R.; Arnell, N.; Buckle, S.

2014-12-01

The AVOID programme and its successor, AVOID2, have focused on answering three core questions: how do we characterise potentially dangerous climate change and impacts, which emissions pathways can avoid at least some of these impacts, and how feasible are the future reductions needed to significantly deviate from a business-as-usual future emissions pathway. The first AVOID project succeeded in providing the UK Government with evidence to inform its position on climate change. A key part of the work involved developing a range of global emissions pathways and estimating and understanding the corresponding global impacts. This made use of a combination of complex general circulation models, simple climate models, pattern-scaling and state-of-the art impacts models. The results characterise the range of avoidable impacts across the globe in several key sectors including river and coastal flooding, cooling and heating energy demand, crop productivity and aspects of biodiversity. The avoided impacts between a scenario compatible with a 4ºC global warming and one with a 2ºC global warming were found to be highly sector dependent and avoided fractions typically ranged between 20% and 70%. A further key aspect was characterising the magnitude of the uncertainty involved, which is found to be very large in some impact sectors although the avoided fraction appears a more robust metric. The AVOID2 programme began in 2014 and will provide results in the run up to the Paris CoP in 2015. This includes new post-IPCC 5th assessment evidence to inform the long-term climate goal, a more comprehensive assessment of the uncertainty ranges of feasible emission pathways compatible with the long-term goal and enhanced estimates of global impacts using the latest generation of impact models and scenarios.

Mechanisms of Host Receptor Adaptation by Severe Acute Respiratory Syndrome Coronavirus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Kailang; Peng, Guiqing; Wilken, Matthew

The severe acute respiratory syndrome coronavirus (SARS-CoV) from palm civets has twice evolved the capacity to infect humans by gaining binding affinity for human receptor angiotensin-converting enzyme 2 (ACE2). Numerous mutations have been identified in the receptor-binding domain (RBD) of different SARS-CoV strains isolated from humans or civets. Why these mutations were naturally selected or how SARS-CoV evolved to adapt to different host receptors has been poorly understood, presenting evolutionary and epidemic conundrums. In this study, we investigated the impact of these mutations on receptor recognition, an important determinant of SARS-CoV infection and pathogenesis. Using a combination of biochemical, functional,more » and crystallographic approaches, we elucidated the molecular and structural mechanisms of each of these naturally selected RBD mutations. These mutations either strengthen favorable interactions or reduce unfavorable interactions with two virus-binding hot spots on ACE2, and by doing so, they enhance viral interactions with either human (hACE2) or civet (cACE2) ACE2. Therefore, these mutations were viral adaptations to either hACE2 or cACE2. To corroborate the above analysis, we designed and characterized two optimized RBDs. The human-optimized RBD contains all of the hACE2-adapted residues (Phe-442, Phe-472, Asn-479, Asp-480, and Thr-487) and possesses exceptionally high affinity for hACE2 but relative low affinity for cACE2. The civet-optimized RBD contains all of the cACE2-adapted residues (Tyr-442, Pro-472, Arg-479, Gly-480, and Thr-487) and possesses exceptionally high affinity for cACE2 and also substantial affinity for hACE2. These results not only illustrate the detailed mechanisms of host receptor adaptation by SARS-CoV but also provide a molecular and structural basis for tracking future SARS-CoV evolution in animals.« less

Mechanisms of Host Receptor Adaptation by Severe Acute Respiratory Syndrome Coronavirus*

PubMed Central

Wu, Kailang; Peng, Guiqing; Wilken, Matthew; Geraghty, Robert J.; Li, Fang

2012-01-01

The severe acute respiratory syndrome coronavirus (SARS-CoV) from palm civets has twice evolved the capacity to infect humans by gaining binding affinity for human receptor angiotensin-converting enzyme 2 (ACE2). Numerous mutations have been identified in the receptor-binding domain (RBD) of different SARS-CoV strains isolated from humans or civets. Why these mutations were naturally selected or how SARS-CoV evolved to adapt to different host receptors has been poorly understood, presenting evolutionary and epidemic conundrums. In this study, we investigated the impact of these mutations on receptor recognition, an important determinant of SARS-CoV infection and pathogenesis. Using a combination of biochemical, functional, and crystallographic approaches, we elucidated the molecular and structural mechanisms of each of these naturally selected RBD mutations. These mutations either strengthen favorable interactions or reduce unfavorable interactions with two virus-binding hot spots on ACE2, and by doing so, they enhance viral interactions with either human (hACE2) or civet (cACE2) ACE2. Therefore, these mutations were viral adaptations to either hACE2 or cACE2. To corroborate the above analysis, we designed and characterized two optimized RBDs. The human-optimized RBD contains all of the hACE2-adapted residues (Phe-442, Phe-472, Asn-479, Asp-480, and Thr-487) and possesses exceptionally high affinity for hACE2 but relative low affinity for cACE2. The civet-optimized RBD contains all of the cACE2-adapted residues (Tyr-442, Pro-472, Arg-479, Gly-480, and Thr-487) and possesses exceptionally high affinity for cACE2 and also substantial affinity for hACE2. These results not only illustrate the detailed mechanisms of host receptor adaptation by SARS-CoV but also provide a molecular and structural basis for tracking future SARS-CoV evolution in animals. PMID:22291007

Optimizing an experimental design for an electromagnetic experiment

NASA Astrophysics Data System (ADS)

Roux, Estelle; Garcia, Xavier

2013-04-01

Most of geophysical studies focus on data acquisition and analysis, but another aspect which is gaining importance is the discussion on acquisition of suitable datasets. This can be done through the design of an optimal experiment. Optimizing an experimental design implies a compromise between maximizing the information we get about the target and reducing the cost of the experiment, considering a wide range of constraints (logistical, financial, experimental …). We are currently developing a method to design an optimal controlled-source electromagnetic (CSEM) experiment to detect a potential CO2 reservoir and monitor this reservoir during and after CO2 injection. Our statistical algorithm combines the use of linearized inverse theory (to evaluate the quality of one given design via the objective function) and stochastic optimization methods like genetic algorithm (to examine a wide range of possible surveys). The particularity of our method is that it uses a multi-objective genetic algorithm that searches for designs that fit several objective functions simultaneously. One main advantage of this kind of technique to design an experiment is that it does not require the acquisition of any data and can thus be easily conducted before any geophysical survey. Our new experimental design algorithm has been tested with a realistic one-dimensional resistivity model of the Earth in the region of study (northern Spain CO2 sequestration test site). We show that a small number of well distributed observations have the potential to resolve the target. This simple test also points out the importance of a well chosen objective function. Finally, in the context of CO2 sequestration that motivates this study, we might be interested in maximizing the information we get about the reservoir layer. In that case, we show how the combination of two different objective functions considerably improve its resolution.

Using Combustion Tracers to Estimate Surface Black Carbon Distributions in WRF-Chem

NASA Astrophysics Data System (ADS)

Raman, A.; Arellano, A. F.

2015-12-01

Black Carbon (BC) emissions significantly affect the global and regional climate, air quality, and human health. However, BC observations are currently limited in space and time; leading to considerable uncertainties in the estimates of BC distribution from regional and global models. Here, we investigate the usefulness of carbon monoxide (CO) in quantifying BC across continental United States (CONUS). We use high resolution EPA AQS observations of CO and IMPROVE BC to estimate BC/CO ratios. We model the BC and CO distribution using the community Weather Research and Forecasting model with Chemistry (WRF-Chem). We configured WRF-Chem using MOZART chemistry, NEI 2005, MEGAN, and FINNv1.5 for anthropogenic, biogenic and fire emissions, respectively. In this work, we address the following three key questions: 1) What are the discrepancies in the estimates of BC and CO distributions across CONUS during summer and winter periods?, 2) How do BC/CO ratios change for different spatial and temporal regimes?, 3) Can we get better estimates of BC from WRF-Chem if we use BC/CO ratios along with optimizing CO concentrations? We compare ratios derived from the model and observations and develop characteristic ratios for several geographical and temporal regimes. We use an independent set of measurements of BC and CO to evaluate these ratios. Finally, we use a Bayesian synthesis inversion to optimize CO from WRF-Chem using regionally tagged CO tracers. We multiply the characteristic ratios we derived with the optimized CO to obtain BC distributions. Our initial results suggest that the maximum ratios of BC versus CO occur in the western US during the summer (average: 4 ng/m3/ppbv) and in the southeast during the winter (average: 5 ng/m3/ppbv). However, we find that these relationships vary in space and time and are highly dependent on fuel usage and meteorology. We find that optimizing CO using EPA-AQS provides improvements in BC but only over areas where BC/CO ratios are close to observed values.Black Carbon (BC) emissions significantly affect the global and regional climate, air quality, and human health. However, BC observations are currently limited in space and time; leading to considerable uncertainties in the estimates of BC distribution from regional and global models. Here, we investigate the usefulness of carbon monoxide (CO) in quantifying BC across continental United States (CONUS). We use high resolution EPA AQS observations of CO and IMPROVE BC to estimate BC/CO ratios. We model the BC and CO distribution using the community Weather Research and Forecasting model with Chemistry (WRF-Chem). We configured WRF-Chem using MOZART chemistry, NEI 2005, MEGAN, and FINNv1.5 for anthropogenic, biogenic and fire emissions, respectively. In this work, we address the following three key questions: 1) What are the discrepancies in the estimates of BC and CO distributions across CONUS during summer and winter periods?, 2) How do BC/CO ratios change for different spatial and temporal regimes?, 3) Can we get better estimates of BC from WRF-Chem if we use BC/CO ratios along with optimizing CO concentrations? We compare ratios derived from the model and observations and develop characteristic ratios for several geographical and temporal regimes. We use an independent set of measurements of BC and CO to evaluate these ratios. Finally, we use a Bayesian synthesis inversion to optimize CO from WRF-Chem using regionally tagged CO tracers. We multiply the characteristic ratios we derived with the optimized CO to obtain BC distributions. Our initial results suggest that the maximum ratios of BC versus CO occur in the western US during the summer (average: 4 ng/m3/ppbv) and in the southeast during the winter (average: 5 ng/m3/ppbv). However, we find that these relationships vary in space and time and are highly dependent on fuel usage and meteorology. We find that optimizing CO using EPA-AQS provides improvements in BC but only over areas where BC/CO ratios are close to observed values.

Minimization of thermal impact by application of electrode cooling in a co-linear PEF treatment chamber.

PubMed

Meneses, Nicolas; Jaeger, Henry; Knorr, Dietrich

2011-10-01

A co-linear pulsed electric field (PEF) treatment chamber was analyzed and optimized considering electrical process conditions, temperature, and retention of heat-sensitive compounds during a continuous PEF treatment of peach juice. The applicability of a jacket heat-exchanger device surrounding the ground electrode was studied in order to provide active cooling and to avoid temperature peaks within the treatment chamber thus reducing the total thermal load to which the product is exposed. Simulation of the PEF process was performed using a finite element method prior to experimental verification. Inactivation of polyphenoloxydase (PPO) and peroxidase (POD) as well as the degradation of ascorbic acid (AA) in peach juice was quantified and used as indirect indicators for the temperature distribution. Peaks of product temperature within the treatment chamber were reduced, that is, from 98 to 75 °C and retention of the indicators PPO, POD, and AA increased by more than 10% after application of the active electrode cooling device. Practical Application:  The co-linear PEF treatment chamber is widely used for continuous PEF treatment of liquid products and also suitable for industrial scale application; however, Joule heating in combination with nonuniform electric field distribution may lead to unwanted thermal effects. The proposed design showed potential to reduce the thermal load, to which the food is exposed, allowing the retention of heat-sensitive components. The design is applicable at laboratory or industrial scale to perform PEF trials avoiding temperature peaks, which is also the basis for obtaining inactivation kinetic models with minimized thermal impact on the kinetic variables. © 2011 Institute of Food Technologists®

What would it take to achieve the Paris temperature targets?

NASA Astrophysics Data System (ADS)

Sanderson, Benjamin M.; O'Neill, Brian C.; Tebaldi, Claudia

2016-07-01

The 2015 Paris Agreement aims to limit warming to 2 or 1.5°C above preindustrial level, although combined Intended Nationally Determined Contributions (INDCs) are likely insufficient to achieve these targets. We propose a set of idealized emission pathways consistent with the targets. If countries reduce emissions in line with their INDCs, the 2°C threshold could be avoided only if net zero greenhouse gas emissions (GHGEs) are achieved by 2085 and late century negative emissions are considerably in excess of those assumed in Representative Concentration Pathway (RCP) 2.6 (net -5 Gt CO2/yr, compared with -1.5 Gt CO2/yr in RCP2.6). More aggressive near-term reductions would allow 2°C to be avoided with less end-of-century carbon removal capacity. A 10% cut in GHGEs by 2030 (relative to 2015) could likely achieve 2°C with RCP2.6 level negative emissions. The 1.5°C target requires GHGEs to be reduced by almost a third by 2030 and net zero by 2050, while a 50 year overshoot of 1.5°C allows net zero GHGEs by 2060.

What would it take to achieve the Paris temperature targets?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanderson, Benjamin M.; O'Neill, Brian C.; Tebaldi, Claudia

Here, the 2015 Paris Agreement aims to limit warming to 2 or 1.5°C above preindustrial level, although combined Intended Nationally Determined Contributions (INDCs) are likely insufficient to achieve these targets. We propose a set of idealized emission pathways consistent with the targets. If countries reduce emissions in line with their INDCs, the 2°C threshold could be avoided only if net zero greenhouse gas emissions (GHGEs) are achieved by 2085 and late century negative emissions are considerably in excess of those assumed in Representative Concentration Pathway (RCP) 2.6 (net –5 Gt CO 2/yr, compared with –1.5 Gt CO 2/yr in RCP2.6).more » More aggressive near-term reductions would allow 2°C to be avoided with less end-of-century carbon removal capacity. A 10% cut in GHGEs by 2030 (relative to 2015) could likely achieve 2°C with RCP2.6 level negative emissions. The 1.5°C target requires GHGEs to be reduced by almost a third by 2030 and net zero by 2050, while a 50 year overshoot of 1.5°C allows net zero GHGEs by 2060.« less

What would it take to achieve the Paris temperature targets?

DOE PAGES

Sanderson, Benjamin M.; O'Neill, Brian C.; Tebaldi, Claudia

2016-06-27

Here, the 2015 Paris Agreement aims to limit warming to 2 or 1.5°C above preindustrial level, although combined Intended Nationally Determined Contributions (INDCs) are likely insufficient to achieve these targets. We propose a set of idealized emission pathways consistent with the targets. If countries reduce emissions in line with their INDCs, the 2°C threshold could be avoided only if net zero greenhouse gas emissions (GHGEs) are achieved by 2085 and late century negative emissions are considerably in excess of those assumed in Representative Concentration Pathway (RCP) 2.6 (net –5 Gt CO 2/yr, compared with –1.5 Gt CO 2/yr in RCP2.6).more » More aggressive near-term reductions would allow 2°C to be avoided with less end-of-century carbon removal capacity. A 10% cut in GHGEs by 2030 (relative to 2015) could likely achieve 2°C with RCP2.6 level negative emissions. The 1.5°C target requires GHGEs to be reduced by almost a third by 2030 and net zero by 2050, while a 50 year overshoot of 1.5°C allows net zero GHGEs by 2060.« less

Development of a Next-Generation Membrane-Integrated Adsorption Processor for CO2 Removal and Compression for Closed-Loop Air Revitalization Systems

NASA Technical Reports Server (NTRS)

Mulloth, Lila; LeVan, Douglas

2002-01-01

The current CO2 removal technology of NASA is very energy intensive and contains many non-optimized subsystems. This paper discusses the concept of a next-generation, membrane integrated, adsorption processor for CO2 removal nd compression in closed-loop air revitalization systems. This processor will use many times less power than NASA's current CO2 removal technology and will be capable of maintaining a lower CO2 concentration in the cabin than that can be achieved by the existing CO2 removal systems. The compact, consolidated, configuration of gas dryer, CO2 separator, and CO2 compressor will allow continuous recycling of humid air in the cabin and supply of compressed CO2 to the reduction unit for oxygen recovery. The device has potential application to the International Space Station and future, long duration, transit, and planetary missions.

Application of Statistical Design for the Production of Cellulase by Trichoderma reesei Using Mango Peel.

PubMed

Saravanan, P; Muthuvelayudham, R; Viruthagiri, T

2012-01-01

Optimization of the culture medium for cellulase production using Trichoderma reesei was carried out. The optimization of cellulase production using mango peel as substrate was performed with statistical methodology based on experimental designs. The screening of nine nutrients for their influence on cellulase production is achieved using Plackett-Burman design. Avicel, soybean cake flour, KH(2)PO(4), and CoCl(2)·6H(2)O were selected based on their positive influence on cellulase production. The composition of the selected components was optimized using Response Surface Methodology (RSM). The optimum conditions are as follows: Avicel: 25.30 g/L, Soybean cake flour: 23.53 g/L, KH(2)PO(4): 4.90 g/L, and CoCl(2)·6H(2)O: 0.95 g/L. These conditions are validated experimentally which revealed an enhanced Cellulase activity of 7.8 IU/mL.

An inverse radiation model for optical determination of temperature and species concentration: Development and validation

NASA Astrophysics Data System (ADS)

Ren, Tao; Modest, Michael F.; Fateev, Alexander; Clausen, Sønnik

2015-01-01

In this study, we present an inverse calculation model based on the Levenberg-Marquardt optimization method to reconstruct temperature and species concentration from measured line-of-sight spectral transmissivity data for homogeneous gaseous media. The high temperature gas property database HITEMP 2010 (Rothman et al. (2010) [1]), which contains line-by-line (LBL) information for several combustion gas species, such as CO2 and H2O, was used to predict gas spectral transmissivities. The model was validated by retrieving temperatures and species concentrations from experimental CO2 and H2O transmissivity measurements. Optimal wavenumber ranges for CO2 and H2O transmissivity measured across a wide range of temperatures and concentrations were determined according to the performance of inverse calculations. Results indicate that the inverse radiation model shows good feasibility for measurements of temperature and gas concentration.

Implementation and Optimization of miniGMG - a Compact Geometric Multigrid Benchmark

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Samuel; Kalamkar, Dhiraj; Singh, Amik

2012-12-01

Multigrid methods are widely used to accelerate the convergence of iterative solvers for linear systems used in a number of different application areas. In this report, we describe miniGMG, our compact geometric multigrid benchmark designed to proxy the multigrid solves found in AMR applications. We explore optimization techniques for geometric multigrid on existing and emerging multicore systems including the Opteron-based Cray XE6, Intel Sandy Bridge and Nehalem-based Infiniband clusters, as well as manycore-based architectures including NVIDIA's Fermi and Kepler GPUs and Intel's Knights Corner (KNC) co-processor. This report examines a variety of novel techniques including communication-aggregation, threaded wavefront-based DRAM communication-avoiding,more » dynamic threading decisions, SIMDization, and fusion of operators. We quantify performance through each phase of the V-cycle for both single-node and distributed-memory experiments and provide detailed analysis for each class of optimization. Results show our optimizations yield significant speedups across a variety of subdomain sizes while simultaneously demonstrating the potential of multi- and manycore processors to dramatically accelerate single-node performance. However, our analysis also indicates that improvements in networks and communication will be essential to reap the potential of manycore processors in large-scale multigrid calculations.« less

Temporally dependent pollinator competition and facilitation with mass flowering crops affects yield in co-blooming crops

PubMed Central

Grab, Heather; Blitzer, Eleanor J.; Danforth, Bryan; Loeb, Greg; Poveda, Katja

2017-01-01

One of the greatest challenges in sustainable agricultural production is managing ecosystem services, such as pollination, in ways that maximize crop yields. Most efforts to increase services by wild pollinators focus on management of natural habitats surrounding farms or non-crop habitats within farms. However, mass flowering crops create resource pulses that may be important determinants of pollinator dynamics. Mass bloom attracts pollinators and it is unclear how this affects the pollination and yields of other co-blooming crops. We investigated the effects of mass flowering apple on the pollinator community and yield of co-blooming strawberry on farms spanning a gradient in cover of apple orchards in the landscape. The effect of mass flowering apple on strawberry was dependent on the stage of apple bloom. During early and peak apple bloom, pollinator abundance and yield were reduced in landscapes with high cover of apple orchards. Following peak apple bloom, pollinator abundance was greater on farms with high apple cover and corresponded with increased yields on these farms. Spatial and temporal overlap between mass flowering and co-blooming crops alters the strength and direction of these dynamics and suggests that yields can be optimized by designing agricultural systems that avoid competition while maximizing facilitation. PMID:28345653

Employing CO2 as reaction medium for in-situ suppression of the formation of benzene derivatives and polycyclic aromatic hydrocarbons during pyrolysis of simulated municipal solid waste.

PubMed

Lee, Jechan; Choi, Dongho; Tsang, Yiu Fai; Oh, Jeong-Ik; Kwon, Eilhann E

2017-05-01

This study proposes a strategic principle to enhance the thermal efficiency of pyrolysis of municipal solid waste (MSW). An environmentally sound energy recovery platform was established by suppressing the formation of harmful organic compounds evolved from pyrolysis of MSW. Using CO 2 as reaction medium/feedstock, CO generation was enhanced through the following: 1) expediting the thermal cracking of volatile organic carbons (VOCs) evolved from the thermal degradation of the MSWs and 2) directly reacting VOCs with CO 2 . This particular influence of CO 2 on pyrolysis of the MSWs also led to the in-situ mitigation of harmful organic compounds (e.g., benzene derivatives and polycyclic aromatic hydrocarbons (PAHs)) considering that CO 2 acted as a carbon scavenger to block reaction pathways toward benzenes and PAHs in pyrolysis. To understand the fundamental influence of CO 2 , simulated MSWs (i.e., various ratios of biomass to polymer) were used to avoid any complexities arising from the heterogeneous matrix of MSW. All experimental findings in this study suggested the foreseeable environmental application of CO 2 to energy recovery from MSW together with disposal of MSW. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optimization behavior of brainstem respiratory neurons. A cerebral neural network model.

PubMed

Poon, C S

1991-01-01

A recent model of respiratory control suggested that the steady-state respiratory responses to CO2 and exercise may be governed by an optimal control law in the brainstem respiratory neurons. It was not certain, however, whether such complex optimization behavior could be accomplished by a realistic biological neural network. To test this hypothesis, we developed a hybrid computer-neural model in which the dynamics of the lung, brain and other tissue compartments were simulated on a digital computer. Mimicking the "controller" was a human subject who pedalled on a bicycle with varying speed (analog of ventilatory output) with a view to minimize an analog signal of the total cost of breathing (chemical and mechanical) which was computed interactively and displayed on an oscilloscope. In this manner, the visuomotor cortex served as a proxy (homolog) of the brainstem respiratory neurons in the model. Results in 4 subjects showed a linear steady-state ventilatory CO2 response to arterial PCO2 during simulated CO2 inhalation and a nearly isocapnic steady-state response during simulated exercise. Thus, neural optimization is a plausible mechanism for respiratory control during exercise and can be achieved by a neural network with cognitive computational ability without the need for an exercise stimulus.

CO and NO emissions from pellet stoves: an experimental study

NASA Astrophysics Data System (ADS)

Petrocelli, D.; Lezzi, A. M.

2014-04-01

This work presents a report on an experimental investigation on pellet stoves aimed to fully understand which parameters influence CO and NO emissions and how it is possible to find and choose the optimal point of working. Tests are performed on three pellet stoves varying heating power, combustion chamber size and burner pot geometry. After a brief review on the factors which influence the production of these pollutants, we present and discuss the results of experimental tests aimed to ascertain how the geometry of the combustion chamber and the distribution of primary and secondary air, can modify the quantity of CO and NO in the flue gas. Experimental tests show that production of CO is strongly affected by the excess air and by its distribution: in particular, it is critical an effective control of air distribution. In these devices a low-level of CO emissions does require a proper setup to operate in the optimal range of excess air that minimizes CO production. In order to simplify the optimization process, we propose the use of instantaneous data of CO and O2 concentration, instead of average values, because they allow a quick identification of the optimal point. It is shown that the optimal range of operation can be enlarged as a consequence of proper burner pot design. Finally, it is shown that NO emissions are not a critical issue, since they are well below threshold enforced by law, are not influenced by the distribution of air in the combustion chamber, and their behavior as a function of air excess is the same for all the geometries investigated here.

Optimizing and Quantifying CO 2 Storage Resource in Saline Formations and Hydrocarbon Reservoirs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bosshart, Nicholas W.; Ayash, Scott C.; Azzolina, Nicholas A.

In an effort to reduce carbon dioxide (CO 2) emissions from large stationary sources, carbon capture and storage (CCS) is being investigated as one approach. This work assesses CO 2 storage resource estimation methods for deep saline formations (DSFs) and hydrocarbon reservoirs undergoing CO 2 enhanced oil recovery (EOR). Project activities were conducted using geologic modeling and simulation to investigate CO 2 storage efficiency. CO 2 storage rates and efficiencies in DSFs classified by interpreted depositional environment were evaluated at the regional scale over a 100-year time frame. A focus was placed on developing results applicable to future widespread commercial-scalemore » CO 2 storage operations in which an array of injection wells may be used to optimize storage in saline formations. The results of this work suggest future investigations of prospective storage resource in closed or semiclosed formations need not have a detailed understanding of the depositional environment of the reservoir to generate meaningful estimates. However, the results of this work also illustrate the relative importance of depositional environment, formation depth, structural geometry, and boundary conditions on the rate of CO 2 storage in these types of systems. CO 2 EOR occupies an important place in the realm of geologic storage of CO 2, as it is likely to be the primary means of geologic CO 2 storage during the early stages of commercial implementation, given the lack of a national policy and the viability of the current business case. This work estimates CO 2 storage efficiency factors using a unique industry database of CO 2 EOR sites and 18 different reservoir simulation models capturing fluvial clastic and shallow shelf carbonate depositional environments for reservoir depths of 1219 and 2438 meters (4000 and 8000 feet) and 7.6-, 20-, and 64-meter (25-, 66,- and 209-foot) pay zones. The results of this work provide practical information that can be used to quantify CO 2 storage resource estimates in oil reservoirs during CO 2 EOR operations (as opposed to storage following depletion) and the uncertainty associated with those estimates.« less

Atmospheric carbon mineralization in an industrial-scale chrysotile mining waste pile.

PubMed

Nowamooz, Ali; Dupuis, J Christian; Beaudoin, Georges; Molson, John; Lemieux, Jean-Michel; Horswill, Micha; Fortier, Richard; Larachi, Faïçal; Maldague, Xavier; Constantin, Marc; Duchesne, Josee; Therrien, René

2018-06-12

Magnesium rich minerals that are abundant in ultramafic mining waste have the potential to be used as a safe and permanent sequestration solution for carbon dioxide (CO2). Our understanding of thermo-hydro-chemical regimes that govern this reaction at an industrial scale, however, has remained an important challenge to its widespread implementation. Through a year-long monitoring experiment performed at a 110Mt chrysotile waste pile, we have documented the existence of two distinct thermo-hydro-chemical regimes that control the ingress of CO2 and the subsequent mineral carbonation of the waste. The experimental results are supported by coupled free-air/porous media numerical flow and transport model that provides insights into optimization strategies to increase the efficiency of mineral sequestration at an industrial-scale. Although functioning passively under less than optimal conditions compared to lab-scale experiments, the 110Mt Thetford Mines pile is nevertheless estimated to be sequestering up to 100 tonnes of CO2 per year, with a potential total carbon capture capacity under optimal conditions of 3 Mt. Yearly, over 100 Mt of ultramafic mine waste suitable for mineral carbonation are generated by the global mining industry. Our results show that this waste material could become a safe and permanent carbon sink for diffuse sources of CO2.

co2amp: A software program for modeling the dynamics of ultrashort pulses in optical systems with CO 2 amplifiers

DOE PAGES

Polyanskiy, Mikhail N.

2015-01-01

We describe a computer code for simulating the amplification of ultrashort mid-infrared laser pulses in CO 2 amplifiers and their propagation through arbitrary optical systems. This code is based on a comprehensive model that includes an accurate consideration of the CO 2 active medium and a physical optics propagation algorithm, and takes into account the interaction of the laser pulse with the material of the optical elements. Finally, the application of the code for optimizing an isotopic regenerative amplifier is described.

System design and analysis of the trans-critical carbon-dioxide automotive air-conditioning system.

PubMed

Mu, Jing-Yang; Chen, Jiang-Ping; Chen, Zhi-Jiu

2003-01-01

As an environmentally harmless and feasible alternate refrigerant, CO2 has attracted worldwide attention, especially in the area of automobile air-conditioning (AAC). The thermal property of CO2 and its trans-critical refrigeration cycle is very different from that of the traditional CFC or HCFC system. The detailed process of CO2 system thermal cycle design and optimization is described in this paper. System prototype and performance test bench were developed to analyze the performance of the CO2 AAC system.

The role of optimality in characterizing CO2 seepage from geological carbon sequestration sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cortis, Andrea; Oldenburg, Curtis M.; Benson, Sally M.

Storage of large amounts of carbon dioxide (CO{sub 2}) in deep geological formations for greenhouse gas mitigation is gaining momentum and moving from its conceptual and testing stages towards widespread application. In this work we explore various optimization strategies for characterizing surface leakage (seepage) using near-surface measurement approaches such as accumulation chambers and eddy covariance towers. Seepage characterization objectives and limitations need to be defined carefully from the outset especially in light of large natural background variations that can mask seepage. The cost and sensitivity of seepage detection are related to four critical length scales pertaining to the size ofmore » the: (1) region that needs to be monitored; (2) footprint of the measurement approach, and (3) main seepage zone; and (4) region in which concentrations or fluxes are influenced by seepage. Seepage characterization objectives may include one or all of the tasks of detecting, locating, and quantifying seepage. Each of these tasks has its own optimal strategy. Detecting and locating seepage in a region in which there is no expected or preferred location for seepage nor existing evidence for seepage requires monitoring on a fixed grid, e.g., using eddy covariance towers. The fixed-grid approaches needed to detect seepage are expected to require large numbers of eddy covariance towers for large-scale geologic CO{sub 2} storage. Once seepage has been detected and roughly located, seepage zones and features can be optimally pinpointed through a dynamic search strategy, e.g., employing accumulation chambers and/or soil-gas sampling. Quantification of seepage rates can be done through measurements on a localized fixed grid once the seepage is pinpointed. Background measurements are essential for seepage detection in natural ecosystems. Artificial neural networks are considered as regression models useful for distinguishing natural system behavior from anomalous behavior suggestive of CO{sub 2} seepage without need for detailed understanding of natural system processes. Because of the local extrema in CO{sub 2} fluxes and concentrations in natural systems, simple steepest-descent algorithms are not effective and evolutionary computation algorithms are proposed as a paradigm for dynamic monitoring networks to pinpoint CO{sub 2} seepage areas.« less

Current and Future United States Light-Duty Vehicle Pathways: Cradle-to-Grave Lifecycle Greenhouse Gas Emissions and Economic Assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elgowainy, Amgad; Han, Jeongwoo; Ward, Jacob

This article presents a cradle-to-grave (C2G) assessment of greenhouse gas (GHG) emissions and costs for current (2015) and future (2025-2030) light-duty vehicles. The analysis addressed both fuel cycle and vehicle manufacturing cycle for the following vehicle types: gasoline and diesel internal combustion engine vehicles (ICEVs), flex fuel vehicles, compressed natural gas (CNG) vehicles, hybrid electric vehicles (HEVs), hydrogen fuel cell electric vehicles (FCEVs), battery electric vehicles (BEVs), and plug-in hybrid electric vehicles (PHEVs). Gasoline ICEVs using current technology have C2G emissions of ~450 gCO2e/mi (grams of carbon dioxide equivalents per mile), while C2G emissions from HEVs, PHEVs, H2 FCEVs, andmore » BEVs range from 300-350 gCO2e/mi. Future vehicle efficiency gains are expected to reduce emissions to ~350 gCO2/mi for ICEVs and ~250 gCO2e/mi for HEVs, PHEVs, FCEVs, and BEVs. Utilizing low-carbon fuel pathways yields GHG reductions more than double those achieved by vehicle efficiency gains alone. Levelized costs of driving (LCDs) are in the range $0.25-$1.00/mi depending on time frame and vehicle-fuel technology. In all cases, vehicle cost represents the major (60-90%) contribution to LCDs. Currently, HEV and PHEV petroleum-fueled vehicles provide the most attractive cost in terms of avoided carbon emissions, although they offer lower potential GHG reductions. The ranges of LCD and cost of avoided carbon are narrower for the future technology pathways, reflecting the expected economic competitiveness of these alternative vehicles and fuels.« less

Current and Future United States Light-Duty Vehicle Pathways: Cradle-to-Grave Lifecycle Greenhouse Gas Emissions and Economic Assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elgowainy, Amgad; Han, Jeongwoo; Ward, Jacob

This article presents a cradle-to-grave (C2G) assessment of greenhouse gas (GHG) emissions and costs for current (2015) and future (2025–2030) light-duty vehicles. The analysis addressed both fuel cycle and vehicle manufacturing cycle for the following vehicle types: gasoline and diesel internal combustion engine vehicles (ICEVs), flex fuel vehicles, compressed natural gas (CNG) vehicles, hybrid electric vehicles (HEVs), hydrogen fuel cell electric vehicles (FCEVs), battery electric vehicles (BEVs), and plug-in hybrid electric vehicles (PHEVs). Gasoline ICEVs using current technology have C2G emissions of ~450 gCO2e/mi (grams of carbon dioxide equivalents per mile), while C2G emissions from HEVs, PHEVs, H2 FCEVs, andmore » BEVs range from 300–350 gCO2e/mi. Future vehicle efficiency gains are expected to reduce emissions to ~350 gCO2/mi for ICEVs and ~250 gCO2e/mi for HEVs, PHEVs, FCEVs and BEVs. Utilizing low-carbon fuel pathways yields GHG reductions more than double those achieved by vehicle efficiency gains alone. Levelized costs of driving (LCDs) are in the range $0.25–$1.00/mi depending on timeframe and vehicle-fuel technology. In all cases, vehicle cost represents the major (60–90%) contribution to LCDs. Currently, HEV and PHEV petroleum-fueled vehicles provide the most attractive cost in terms of avoided carbon emissions, although they offer lower potential GHG reductions The ranges of LCD and cost of avoided carbon are narrower for the future technology pathways, reflecting the expected economic competitiveness of these alternative vehicles and fuels.« less

Current and Future United States Light-Duty Vehicle Pathways: Cradle-to-Grave Lifecycle Greenhouse Gas Emissions and Economic Assessment.

PubMed

Elgowainy, Amgad; Han, Jeongwoo; Ward, Jacob; Joseck, Fred; Gohlke, David; Lindauer, Alicia; Ramsden, Todd; Biddy, Mary; Alexander, Mark; Barnhart, Steven; Sutherland, Ian; Verduzco, Laura; Wallington, Timothy J

2018-02-20

This article presents a cradle-to-grave (C2G) assessment of greenhouse gas (GHG) emissions and costs for current (2015) and future (2025-2030) light-duty vehicles. The analysis addressed both fuel cycle and vehicle manufacturing cycle for the following vehicle types: gasoline and diesel internal combustion engine vehicles (ICEVs), flex fuel vehicles, compressed natural gas (CNG) vehicles, hybrid electric vehicles (HEVs), hydrogen fuel cell electric vehicles (FCEVs), battery electric vehicles (BEVs), and plug-in hybrid electric vehicles (PHEVs). Gasoline ICEVs using current technology have C2G emissions of ∼450 gCO 2 e/mi (grams of carbon dioxide equivalents per mile), while C2G emissions from HEVs, PHEVs, H 2 FCEVs, and BEVs range from 300-350 gCO 2 e/mi. Future vehicle efficiency gains are expected to reduce emissions to ∼350 gCO 2 /mi for ICEVs and ∼250 gCO 2e /mi for HEVs, PHEVs, FCEVs, and BEVs. Utilizing low-carbon fuel pathways yields GHG reductions more than double those achieved by vehicle efficiency gains alone. Levelized costs of driving (LCDs) are in the range $0.25-$1.00/mi depending on time frame and vehicle-fuel technology. In all cases, vehicle cost represents the major (60-90%) contribution to LCDs. Currently, HEV and PHEV petroleum-fueled vehicles provide the most attractive cost in terms of avoided carbon emissions, although they offer lower potential GHG reductions. The ranges of LCD and cost of avoided carbon are narrower for the future technology pathways, reflecting the expected economic competitiveness of these alternative vehicles and fuels.

Optimal function explains forest responses to global change

Treesearch

Roderick Dewar; Oskar Franklin; Annikki Makela; Ross E. McMurtrie; Harry T. Valentine

2009-01-01

Plant responses to global changes in carbon dioxide (CO2), nitrogen, and water availability are critical to future atmospheric CO2 concentrations, hydrology, and hence climate. Our understanding of those responses is incomplete, however. Multiple-resource manipulation experiments and empirical observations have revealed a...

A Circular Bioeconomy with Biobased Products from CO2 Sequestration.

PubMed

Venkata Mohan, S; Modestra, J Annie; Amulya, K; Butti, Sai Kishore; Velvizhi, G

2016-06-01

The unprecedented climate change influenced by elevated concentrations of CO2 has compelled the research world to focus on CO2 sequestration. Although existing natural and anthropogenic CO2 sinks have proven valuable, their ability to further assimilate CO2 is now questioned. Thus, we highlight here the importance of biological sequestration methods as alternate and viable routes for mitigating climate change while simultaneously synthesizing value-added products that could sustainably fuel the circular bioeconomy. Four conceptual models for CO2 biosequestration and the synthesis of biobased products, as well as an integrated CO2 biorefinery model, are proposed. Optimizing and implementing this biorefinery model might overcome the limitations of existing sequestration methods and could help realign the carbon balance. Copyright © 2016 Elsevier Ltd. All rights reserved.

Insight into the Li{sub 2}CO{sub 3}–K{sub 2}CO{sub 3} eutectic mixture from classical molecular dynamics: Thermodynamics, structure, and dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corradini, Dario; Vuilleumier, Rodolphe, E-mail: rodolphe.vuilleumier@ens.fr; Sorbonne Universités, UPMC Univ. Paris 06, PASTEUR, 75005 Paris

We use molecular dynamics simulations to study the thermodynamics, structure, and dynamics of the Li{sub 2}CO{sub 3}–K{sub 2}CO{sub 3} (62:38 mol. %) eutectic mixture. We present a new classical non-polarizable force field for this molten salt mixture, optimized using experimental and first principles molecular dynamics simulations data as reference. This simple force field allows efficient molecular simulations of phenomena at long time scales. We use this optimized force field to describe the behavior of the eutectic mixture in the 900–1100 K temperature range, at pressures between 0 and 5 GPa. After studying the equation of state in these thermodynamic conditions, wemore » present molecular insight into the structure and dynamics of the melt. In particular, we present an analysis of the temperature and pressure dependence of the eutectic mixture’s self-diffusion coefficients, viscosity, and ionic conductivity.« less

Four Bed Molecular Sieve - Exploration (4BMS-X) Virtual Heater Design and Optimization

NASA Technical Reports Server (NTRS)

Schunk, R. Gregory; Peters, Warren T.; Thomas, John T., Jr.

2017-01-01

A 4BMS-X (Four Bed Molecular Sieve - Exploration) design and heater optimization study for CO2 sorbent beds in proposed exploration system architectures is presented. The primary objectives of the study are to reduce heater power and thermal gradients within the CO2 sorbent beds while minimizing channeling effects. Some of the notable changes from the ISS (International Space Station) CDRA (Carbon Dioxide Removal Assembly) to the proposed exploration system architecture include cylindrical beds, alternate sorbents and an improved heater core. Results from both 2D and 3D sorbent bed thermal models with integrated heaters are presented. The 2D sorbent bed models are used to optimize heater power and fin geometry while the 3D models address end effects in the beds for more realistic thermal gradient and heater power predictions.

Determination of free CO2 in emergent groundwaters using a commercial beverage carbonation meter

NASA Astrophysics Data System (ADS)

Vesper, Dorothy J.; Edenborn, Harry M.

2012-05-01

SummaryDissolved CO2 in groundwater is frequently supersaturated relative to its equilibrium with atmospheric partial pressure and will degas when it is conveyed to the surface. Estimates of dissolved CO2 concentrations can vary widely between different hydrochemical facies because they have different sources of error (e.g., rapid degassing, low alkalinity, non-carbonate alkalinity). We sampled 60 natural spring and mine waters using a beverage industry carbonation meter, which measures dissolved CO2 based on temperature and pressure changes as the sample volume is expanded. Using a modified field protocol, the meter was found to be highly accurate in the range 0.2-35 mM CO2. The meter provided rapid, accurate and precise measurements of dissolved CO2 in natural waters for a range of hydrochemical facies. Dissolved CO2 concentrations measured in the field with the carbonation meter were similar to CO2 determined using the pH-alkalinity approach, but provided immediate results and avoided errors from alkalinity and pH determination. The portability and ease of use of the carbonation meter in the field made it well-suited to sampling in difficult terrain. The carbonation meter has proven useful in the study of aquatic systems where CO2 degassing drives geochemical changes that result in surficial mineral precipitation and deposition, such as tufa, travertine and mine drainage deposits.

Biomass-derived chemicals: synthesis of biodegradable surfactant ether molecules from hydroxymethylfurfural.

PubMed

Arias, Karen S; Climent, Maria J; Corma, Avelino; Iborra, Sara

2014-01-01

A new class of biodegradable anionic surfactants with structures based on 5-alkoxymethylfuroate was prepared starting from 5-hydroxymethylfurfural (HMF), through a one-pot-two-steps process which involves the selective etherification of HMF with fatty alcohols using heterogeneous solid acid, followed by a highly selective oxidation of the formyl group with a gold catalyst. The etherification step was optimized using aluminosilicates as acid catalysts with different pore topologies (H-Beta, HY, Mordenite, ZSM-5, ITQ-2, and MCM-41), different active sites (Bronsted or Lewis) and different adsorption properties. It was shown that highly hydrophobic defect-free H-Beta zeolites with Si/Al ratios higher than 25 are excellent acid catalysts to perform the selective etherification of HMF with fatty alcohols, avoiding the competitive self-etherification of HMF. Moreover, the 5-alkoxymethylfurfural derivatives obtained can be selectively oxidized to the corresponding furoic salts in excellent yield using Au/CeO2 as catalyst and air as oxidant, at moderated temperatures. Both H-Beta zeolite and Au/CeO2 could be reused several times without loss of activity. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Global cost estimates of reducing carbon emissions through avoided deforestation

PubMed Central

Kindermann, Georg; Obersteiner, Michael; Sohngen, Brent; Sathaye, Jayant; Andrasko, Kenneth; Rametsteiner, Ewald; Schlamadinger, Bernhard; Wunder, Sven; Beach, Robert

2008-01-01

Tropical deforestation is estimated to cause about one-quarter of anthropogenic carbon emissions, loss of biodiversity, and other environmental services. United Nations Framework Convention for Climate Change talks are now considering mechanisms for avoiding deforestation (AD), but the economic potential of AD has yet to be addressed. We use three economic models of global land use and management to analyze the potential contribution of AD activities to reduced greenhouse gas emissions. AD activities are found to be a competitive, low-cost abatement option. A program providing a 10% reduction in deforestation from 2005 to 2030 could provide 0.3–0.6 Gt (1 Gt = 1 × 105 g) CO2·yr−1 in emission reductions and would require $0.4 billion to $1.7 billion·yr−1 for 30 years. A 50% reduction in deforestation from 2005 to 2030 could provide 1.5–2.7 Gt CO2·yr−1 in emission reductions and would require $17.2 billion to $28.0 billion·yr−1. Finally, some caveats to the analysis that could increase costs of AD programs are described. PMID:18650377

Integration of CO2 Capture and Mineral Carbonation by Using Recyclable Ammonium Salts

PubMed Central

Wang, Xiaolong; Maroto-Valer, M Mercedes

2011-01-01

A new approach to capture and store CO2 by mineral carbonation using recyclable ammonium salts was studied. This process integrates CO2 capture with mineral carbonation by employing NH3, NH4HSO4, and NH4HCO3 in the capture, mineral dissolution, and carbonation steps, respectively. NH4HSO4 and NH3 can then be regenerated by thermal decomposition of (NH4)2SO4. The use of NH4HCO3 as the source of CO2 can avoid desorption and compression of CO2. The mass ratio of Mg/NH4HCO3/NH3 is the key factor controlling carbonation and the optimum ratio of 1:4:2 gives a conversion of Mg ions to hydromagnesite of 95.5 %. Thermogravimetric analysis studies indicated that the regeneration efficiency of NH4HSO4 and NH3 in this process is 95 %. The mass balance of the process shows that about 2.63 tonnes of serpentine, 0.12 tonnes of NH4HSO4, 7.48 tonnes of NH4HCO3, and 0.04 tonnes of NH3 are required to sequester 1 tonne of CO2 as hydromagnesite. PMID:21732542

CarbonTracker-Lagrange: A Framework for Greenhouse Gas Flux Estimation at Regional to Continental Scales

NASA Astrophysics Data System (ADS)

Andrews, A. E.

2016-12-01

CarbonTracker-Lagrange (CT-L) is a flexible modeling framework developed to take advantage of newly available atmospheric data for CO2 and other long-lived gases such as CH4 and N2O. The North American atmospheric CO2 measurement network has grown from three sites in 2004 to >100 sites in 2015. The US network includes tall tower, mountaintop, surface, and aircraft sites in the NOAA Global Greenhouse Gas Reference Network along with sites maintained by university, government and private sector researchers. The Canadian network is operated by Environment and Climate Change Canada. This unprecedented dataset can provide spatially and temporally resolved CO2 emissions and uptake flux estimates and quantitative information about drivers of variability, such as drought and temperature. CT-L is a platform for systematic comparison of data assimilation techniques and evaluation of assumed prior, model and observation errors. A novel feature of CT-L is the optimization of boundary values along with surface fluxes, leveraging vertically resolved data available from NOAA's aircraft sampling program. CT-L uses observation footprints (influence functions) from the Weather Research and Forecasting/Stochastic Time-Inverted Lagrangian Transport (WRF-STILT) modeling system to relate atmospheric measurements to upwind fluxes and boundary values. Footprints are pre-computed and the optimization algorithms are efficient, so many variants of the calculation can be performed. Fluxes are adjusted using Bayesian or Geostatistical methods to provide optimal agreement with observations. Satellite measurements of CO2 and CH4 from GOSAT are available starting in July 2009 and from OCO-2 since September 2014. With support from the NASA Carbon Monitoring System, we are developing flux estimation strategies that use remote sensing and in situ data together, including geostatistical inversions using satellite retrievals of solar-induced chlorophyll fluorescence. CT-L enables quantitative investigation of what new measurements would best complement the existing carbon observing system. We are also working to implement multi-species inversions for CO2 flux estimation using CO2 data along with CO, δ13CO2, COS and radiocarbon observations and for CH4 flux estimation using data for various hydrocarbons.

Avoiding hypoglycaemia: a new target of care for elderly diabetic patients.

PubMed

Wong, C W

2015-10-01

Optimising glycaemic control to prevent diabetes-associated complications has received much attention. The associated risk of iatrogenic hypoglycaemia, however, is inevitable and can have a significant impact on health. The prevalence of iatrogenic hypoglycaemia tends to increase with advancing age. Elderly people are intrinsically prone to hypoglycaemia. Ageing attenuates the glucose counter-regulatory and symptomatic response to hypoglycaemia, particularly in the presence of a longer duration of diabetes. Multiple co-morbidities and polypharmacy correlated with advancing age also increase the hypoglycaemic risk. In addition to the acute adverse effects of hypoglycaemia, such as fall with injury, cardiovascular events and mortality, a hypoglycaemic episode can have long-term consequences. Repeated episodes may have a significant psychological impact and are also a risk factor for dementia. Because of the heterogeneous health status of the elderly, not all will benefit from optimal glycaemic control. Setting an individual glycaemic target and formulating a management plan that takes account of the patient's circumstances combined with balancing the benefit and risk of diabetes intervention to avoid hypoglycaemia is a more practical approach to the management of elderly diabetic patients.

Environmental CO2 inhibits Caenorhabditis elegans egg-laying by modulating olfactory neurons and evokes widespread changes in neural activity

PubMed Central

Fenk, Lorenz A.; de Bono, Mario

2015-01-01

Carbon dioxide (CO2) gradients are ubiquitous and provide animals with information about their environment, such as the potential presence of prey or predators. The nematode Caenorhabditis elegans avoids elevated CO2, and previous work identified three neuron pairs called “BAG,” “AFD,” and “ASE” that respond to CO2 stimuli. Using in vivo Ca2+ imaging and behavioral analysis, we show that C. elegans can detect CO2 independently of these sensory pathways. Many of the C. elegans sensory neurons we examined, including the AWC olfactory neurons, the ASJ and ASK gustatory neurons, and the ASH and ADL nociceptors, respond to a rise in CO2 with a rise in Ca2+. In contrast, glial sheath cells harboring the sensory endings of C. elegans’ major chemosensory neurons exhibit strong and sustained decreases in Ca2+ in response to high CO2. Some of these CO2 responses appear to be cell intrinsic. Worms therefore may couple detection of CO2 to that of other cues at the earliest stages of sensory processing. We show that C. elegans persistently suppresses oviposition at high CO2. Hermaphrodite-specific neurons (HSNs), the executive neurons driving egg-laying, are tonically inhibited when CO2 is elevated. CO2 modulates the egg-laying system partly through the AWC olfactory neurons: High CO2 tonically activates AWC by a cGMP-dependent mechanism, and AWC output inhibits the HSNs. Our work shows that CO2 is a more complex sensory cue for C. elegans than previously thought, both in terms of behavior and neural circuitry. PMID:26100886

First Principles Study on the CO Oxidation on Mn-Embedded Divacancy Graphene

PubMed Central

Jiang, Quanguo; Zhang, Jianfeng; Ao, Zhimin; Huang, Huajie; He, Haiyan; Wu, Yuping

2018-01-01

The CO oxidation mechanism on graphene with divacancy (DG) embedded with transition metal from Sc to Zn has been studied by using first principles calculations. The results indicate that O2 molecule is preferentially adsorbed on Sc, Ti, V, Cr, Mn, and Fe-DG, which can avoid the CO poisoning problem that many catalysts facing and is beneficial to the CO oxidation progress. Further study indicates that Mn-DG shows the best catalytic properties for CO oxidation with consideration of both Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) oxidation mechanisms. Along the ER mechanism, the reaction energy barrier for the first step (CO free + O2 pre-adsorbed → OOCO) is 0.96 eV. Along the LH mechanism, the energy barrier for the rate limiting step (CO adsorbed + O2 adsorbed → OOCO) is only 0.41 eV, indicating that the CO oxidation on Mn-DG will occur along LH mechanism. The Hirshfeld charge distributions of O2 and CO molecules is tuned by the embedded Mn atom, and the charge transfer from the embedded Mn atom to the adsorbed molecules plays an important role for the CO oxidation. The result shows that the Mn-embedded divacancy graphene is a noble-metal free and efficient catalyst for CO oxidation at low temperature.

Looking to nature for solutions

NASA Astrophysics Data System (ADS)

Turner, Will R.

2018-01-01

Completely stopping fossil fuel use may not be enough to avoid dangerous climate change. Recent research on the mitigation potential of conservation, restoration, and improved land management demonstrates that natural solutions can reduce emissions and remove atmospheric CO2 while safeguarding food security and biodiversity.

Incorporation of Alkylamine into Metal-Organic Frameworks through a Brønsted Acid-Base Reaction for CO2 Capture.

PubMed

Li, Hao; Wang, Kecheng; Feng, Dawei; Chen, Ying-Pin; Verdegaal, Wolfgang; Zhou, Hong-Cai

2016-10-06

The escalating atmospheric CO 2 concentration is one of the most urgent environmental concerns of our age. To effectively capture CO 2 , various materials have been studied. Among them, alkylamine-modified metal-organic frameworks (MOFs) are considered to be promising candidates. In most cases, alkylamine molecules are integrated into MOFs through the coordination bonds formed between open metal sites (OMSs) and amine groups. Thus, the alkylamine density, as well as the corresponding CO 2 uptake in MOFs, are severely restricted by the density of OMSs. To overcome this limit, other approaches to incorporating alkylamine into MOFs are highly desired. We have developed a new method based on Brønsted acid-base reaction to tether alkylamines into Cr-MIL-101-SO 3 H for CO 2 capture. A systematic optimization of the amine tethering process was also conducted to maximize the CO 2 uptake of the modified MOF. Under the optimal amine tethering condition, the obtained tris(2-aminoethyl)amine-functionalized Cr-MIL-101-SO 3 H (Cr-MIL-101-SO 3 H-TAEA) has a cyclic CO 2 uptake of 2.28 mmol g -1 at 150 mbar and 40 °C, and 1.12 mmol g -1 at 0.4 mbar and 20 °C. The low-cost starting materials and simple synthetic procedure for the preparation of Cr-MIL-101-SO 3 H-TAEA suggest that it has the potential for large-scale production and practical applications. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evolutionary dynamics of adult stem cells: comparison of random and immortal-strand segregation mechanisms.

PubMed

Tannenbaum, Emmanuel; Sherley, James L; Shakhnovich, Eugene I

2005-04-01

This paper develops a point-mutation model describing the evolutionary dynamics of a population of adult stem cells. Such a model may prove useful for quantitative studies of tissue aging and the emergence of cancer. We consider two modes of chromosome segregation: (1) random segregation, where the daughter chromosomes of a given parent chromosome segregate randomly into the stem cell and its differentiating sister cell and (2) "immortal DNA strand" co-segregation, for which the stem cell retains the daughter chromosomes with the oldest parent strands. Immortal strand co-segregation is a mechanism, originally proposed by [Cairns Nature (London) 255, 197 (1975)], by which stem cells preserve the integrity of their genomes. For random segregation, we develop an ordered strand pair formulation of the dynamics, analogous to the ordered strand pair formalism developed for quasispecies dynamics involving semiconservative replication with imperfect lesion repair (in this context, lesion repair is taken to mean repair of postreplication base-pair mismatches). Interestingly, a similar formulation is possible with immortal strand co-segregation, despite the fact that this segregation mechanism is age dependent. From our model we are able to mathematically show that, when lesion repair is imperfect, then immortal strand co-segregation leads to better preservation of the stem cell lineage than random chromosome segregation. Furthermore, our model allows us to estimate the optimal lesion repair efficiency for preserving an adult stem cell population for a given period of time. For human stem cells, we obtain that mispaired bases still present after replication and cell division should be left untouched, to avoid potentially fixing a mutation in both DNA strands.

Evolutionary dynamics of adult stem cells: Comparison of random and immortal-strand segregation mechanisms

NASA Astrophysics Data System (ADS)

Tannenbaum, Emmanuel; Sherley, James L.; Shakhnovich, Eugene I.

2005-04-01

This paper develops a point-mutation model describing the evolutionary dynamics of a population of adult stem cells. Such a model may prove useful for quantitative studies of tissue aging and the emergence of cancer. We consider two modes of chromosome segregation: (1) random segregation, where the daughter chromosomes of a given parent chromosome segregate randomly into the stem cell and its differentiating sister cell and (2) “immortal DNA strand” co-segregation, for which the stem cell retains the daughter chromosomes with the oldest parent strands. Immortal strand co-segregation is a mechanism, originally proposed by [Cairns Nature (London) 255, 197 (1975)], by which stem cells preserve the integrity of their genomes. For random segregation, we develop an ordered strand pair formulation of the dynamics, analogous to the ordered strand pair formalism developed for quasispecies dynamics involving semiconservative replication with imperfect lesion repair (in this context, lesion repair is taken to mean repair of postreplication base-pair mismatches). Interestingly, a similar formulation is possible with immortal strand co-segregation, despite the fact that this segregation mechanism is age dependent. From our model we are able to mathematically show that, when lesion repair is imperfect, then immortal strand co-segregation leads to better preservation of the stem cell lineage than random chromosome segregation. Furthermore, our model allows us to estimate the optimal lesion repair efficiency for preserving an adult stem cell population for a given period of time. For human stem cells, we obtain that mispaired bases still present after replication and cell division should be left untouched, to avoid potentially fixing a mutation in both DNA strands.

Nanostructural origin of semiconductivity and large magnetoresistance in epitaxial NiCo2O4/Al2O3 thin films

NASA Astrophysics Data System (ADS)

Zhen, Congmian; Zhang, XiaoZhe; Wei, Wengang; Guo, Wenzhe; Pant, Ankit; Xu, Xiaoshan; Shen, Jian; Ma, Li; Hou, Denglu

2018-04-01

Despite low resistivity (~1 mΩ cm), metallic electrical transport has not been commonly observed in inverse spinel NiCo2O4, except in certain epitaxial thin films. Previous studies have stressed the effect of valence mixing and the degree of spinel inversion on the electrical conduction of NiCo2O4 films. In this work, we studied the effect of nanostructural disorder by comparing the NiCo2O4 epitaxial films grown on MgAl2O4 (1 1 1) and on Al2O3 (0 0 1) substrates. Although the optimal growth conditions are similar for the NiCo2O4 (1 1 1)/MgAl2O4 (1 1 1) and the NiCo2O4 (1 1 1)/Al2O3 (0 0 1) films, they show metallic and semiconducting electrical transport, respectively. Post-growth annealing decreases the resistivity of NiCo2O4 (1 1 1)/Al2O3 (0 0 1) films, but the annealed films are still semiconducting. While the semiconductivity and the large magnetoresistance in NiCo2O4 (1 1 1)/Al2O3 (0 0 1) films cannot be accounted for in terms of non-optimal valence mixing and spinel inversion, the presence of anti-phase boundaries between nano-sized crystallites, generated by the structural mismatch between NiCo2O4 and Al2O3, may explain all the experimental observations in this work. These results reveal nanostructural disorder as being another key factor for controlling the electrical transport of NiCo2O4, with potentially large magnetoresistance for spintronics applications.

Optimizing emissions targets for residential recycling programmes: Why 'more' is not necessarily better with respect to diversion.

PubMed

Lakhan, Calvin

2016-11-01

This study highlights the economic and environmental challenges of recycling in Ontario, specifically examining the effect of attempting to increase the emissions target for the province's household recycling programme. The findings from the cost model analysis found that Ontario's Blue Box programme reduces overall carbon emissions by approximately 1.8 million tonnes every year. This study also found that targeting specific materials for recovery could result in a scenario where the province could improve both overall diversion and emissions offsets while reducing material management costs. Under our modelled scenario, as the tonnes of greenhouse gases (GHGs) avoided increases, the system cost per tonne of GHG avoided initial declines. However, after avoiding 2.05 million tonnes of GHGs, the system cost/tonne GHG avoided increases. To achieve an emissions target in excess of 2.05 million tonnes, the province will have to start recycling higher cost non-core materials (composite materials, other plastics, etc.). © The Author(s) 2016.

Complexes in the Photocatalytic Reaction of CO2 and H2O: Theoretical Studies

PubMed Central

Luo, Dongmei; Zhang, Ning; Hong, Sanguo; Wu, Huanwen; Liu, Zhihua

2010-01-01

Complexes (H2O/CO2, e–(H2O/CO2) and h+–(H2O/CO2)) in the reaction system of CO2 photoreduction with H2O were researched by B3LYP and MP2 methods along with natural bond orbital (NBO) analysis. Geometries of these complexes were optimized and frequencies analysis performed. H2O/CO2 captured photo-induced electron and hole produced e–(H2O/CO2) and h+–(H2O/CO2), respectively. The results revealed that CO2 and H2O molecules could be activated by the photo-induced electrons and holes, and each of these complexes possessed two isomers. Due to the effect of photo-induced electrons, the bond length of C=O and H-O were lengthened, while H-O bonds were shortened, influenced by holes. The infrared (IR) adsorption frequencies of these complexes were different from that of CO2 and H2O, which might be attributed to the synergistic effect and which could not be captured experimentally. PMID:21152274

2D MOF Nanoflake-Assembled Spherical Microstructures for Enhanced Supercapacitor and Electrocatalysis Performances

NASA Astrophysics Data System (ADS)

Xia, Huicong; Zhang, Jianan; Yang, Zhao; Guo, Shiyu; Guo, Shihui; Xu, Qun

2017-10-01

Metal-organic frameworks (MOFs) are of great interest as potential electrochemically active materials. However, few studies have been conducted into understanding whether control of the shape and components of MOFs can optimize their electrochemical performances due to the rational realization of their shapes. Component control of MOFs remains a significant challenge. Herein, we demonstrate a solvothermal method to realize nanostructure engineering of 2D nanoflake MOFs. The hollow structures with Ni/Co- and Ni-MOF (denoted as Ni/Co-MOF nanoflakes and Ni-MOF nanoflakes) were assembled for their electrochemical performance optimizations in supercapacitors and in the oxygen reduction reaction (ORR). As a result, the Ni/Co-MOF nanoflakes exhibited remarkably enhanced performance with a specific capacitance of 530.4 F g-1 at 0.5 A g-1 in 1 M LiOH aqueous solution, much higher than that of Ni-MOF (306.8 F g-1) and ZIF-67 (168.3 F g-1), a good rate capability, and a robust cycling performance with no capacity fading after 2000 cycles. Ni/Co-MOF nanoflakes also showed improved electrocatalytic performance for the ORR compared to Ni-MOF and ZIF-67. The present work highlights the significant role of tuning 2D nanoflake ensembles of Ni/Co-MOF in accelerating electron and charge transportation for optimizing energy storage and conversion devices. [Figure not available: see fulltext.

Novel CO 2 Foam Concepts and Injection Schemes for Improving CO 2 Sweep Efficiency in Sandstone and Carbonate Hydrocarbon Formations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Quoc; Hirasaki, George; Johnston, Keith

2015-02-05

We explored cationic, nonionic and zwitterionic surfactants to identify candidates that have the potential to satisfy all the key requirements for CO 2 foams in EOR. We have examined the formation, texture, rheology and stability of CO 2 foams as a function of the surfactant structure and formulation variables including temperature, pressure, water/CO 2 ratio, surfactant concentration, salinity and concentration of oil. Furthermore, the partitioning of surfactants between oil and water as well as CO 2 and water was examined in conjunction with adsorption measurements on limestone by the Hirasaki lab to develop strategies to optimize the transport of surfactantsmore » in reservoirs.« less

Photosynthetic conversion of CO2 to farnesyl diphosphate-derived phytochemicals (amorpha-4,11-diene and squalene) by engineered cyanobacteria.

PubMed

Choi, Sun Young; Lee, Hyun Jeong; Choi, Jaeyeon; Kim, Jiye; Sim, Sang Jun; Um, Youngsoon; Kim, Yunje; Lee, Taek Soon; Keasling, Jay D; Woo, Han Min

2016-01-01

Metabolic engineering of cyanobacteria has enabled photosynthetic conversion of CO2 to value-added chemicals as bio-solar cell factories. However, the production levels of isoprenoids in engineered cyanobacteria were quite low, compared to other microbial hosts. Therefore, modular optimization of multiple gene expressions for metabolic engineering of cyanobacteria is required for the production of farnesyl diphosphate-derived isoprenoids from CO2. Here, we engineered Synechococcus elongatus PCC 7942 with modular metabolic pathways consisting of the methylerythritol phosphate pathway enzymes and the amorphadiene synthase for production of amorpha-4,11-diene, resulting in significantly increased levels (23-fold) of amorpha-4,11-diene (19.8 mg/L) in the best strain relative to a parental strain. Replacing amorphadiene synthase with squalene synthase led to the synthesis of a high amount of squalene (4.98 mg/L/OD730). Overexpression of farnesyl diphosphate synthase is the most critical factor for the significant production, whereas overexpression of 1-deoxy-d-xylulose 5-phosphate reductase is detrimental to the cell growth and the production. Additionally, the cyanobacterial growth inhibition was alleviated by expressing a terpene synthase in S. elongatus PCC 7942 strain with the optimized MEP pathway only (SeHL33). This is the first demonstration of photosynthetic production of amorpha-4,11-diene from CO2 in cyanobacteria and production of squalene in S. elongatus PCC 7942. Our optimized modular OverMEP strain (SeHL33) with either co-expression of ADS or SQS demonstrated the highest production levels of amorpha-4,11-diene and squalene, which could expand the list of farnesyl diphosphate-derived isoprenoids from CO2 as bio-solar cell factories.

Optimizing feeding composition and carbon-nitrogen ratios for improved methane yield during anaerobic co-digestion of dairy, chicken manure and wheat straw.

PubMed

Wang, Xiaojiao; Yang, Gaihe; Feng, Yongzhong; Ren, Guangxin; Han, Xinhui

2012-09-01

This study investigated the possibilities of improving methane yield from anaerobic digestion of multi-component substrates, using a mixture of dairy manure (DM), chicken manure (CM) and wheat straw (WS), based on optimized feeding composition and the C/N ratio. Co-digestion of DM, CM and WS performed better in methane potential than individual digestion. A larger synergetic effect in co-digestion of DM, CM and WS was found than in mixtures of single manures with WS. As the C/N ratio increased, methane potential initially increased and then declined. C/N ratios of 25:1 and 30:1 had better digestion performance with stable pH and low concentrations of total ammonium nitrogen and free NH(3). Maximum methane potential was achieved with DM/CM of 40.3:59.7 and a C/N ratio of 27.2:1 after optimization using response surface methodology. The results suggested that better performance of anaerobic co-digestion can be fulfilled by optimizing feeding composition and the C/N ratio. Copyright © 2012 Elsevier Ltd. All rights reserved.

[Effect of CO2 laser on prostheses used in middle ear surgery].

PubMed

Szymański, Marcin

2005-01-01

The use of CO2 laser is advocated in primary and revision stapes surgery. The aim of the study was to assess the effect of CO2 laser on stapes prostheses. CO2 laser was applied on several types of stapes prostheses and PORPs, with power settings suggested by the manufacturer (continuous wave, 2 W and 6 W; 0,05 s). Application of the laser on stainless steel or titanium prosthesis did not exert any effect on the structure of the prosthesis. The use of the laser on the Teflon piston caused superficial burning with power 2 W, and melting and holes in the piston with power settings at 6W. Similar plastipore prostheses were melting. Hydroxyapatite PORP shattered after application of the laser energy. Teflon and hydroxyapatite prostheses are easily damaged by the laser energy, therefore applying a laser on them should be avoided. CO2 laser can be used on stainless steel and titanium prostheses without risk of damaging them. However the possibility of transmission of heat to the vestibule has to be taken into consideration.

Feedforward Inhibition and Synaptic Scaling – Two Sides of the Same Coin?

PubMed Central

Lücke, Jörg

2012-01-01

Feedforward inhibition and synaptic scaling are important adaptive processes that control the total input a neuron can receive from its afferents. While often studied in isolation, the two have been reported to co-occur in various brain regions. The functional implications of their interactions remain unclear, however. Based on a probabilistic modeling approach, we show here that fast feedforward inhibition and synaptic scaling interact synergistically during unsupervised learning. In technical terms, we model the input to a neural circuit using a normalized mixture model with Poisson noise. We demonstrate analytically and numerically that, in the presence of lateral inhibition introducing competition between different neurons, Hebbian plasticity and synaptic scaling approximate the optimal maximum likelihood solutions for this model. Our results suggest that, beyond its conventional use as a mechanism to remove undesired pattern variations, input normalization can make typical neural interaction and learning rules optimal on the stimulus subspace defined through feedforward inhibition. Furthermore, learning within this subspace is more efficient in practice, as it helps avoid locally optimal solutions. Our results suggest a close connection between feedforward inhibition and synaptic scaling which may have important functional implications for general cortical processing. PMID:22457610

Feedforward inhibition and synaptic scaling--two sides of the same coin?

PubMed

Keck, Christian; Savin, Cristina; Lücke, Jörg

2012-01-01

Feedforward inhibition and synaptic scaling are important adaptive processes that control the total input a neuron can receive from its afferents. While often studied in isolation, the two have been reported to co-occur in various brain regions. The functional implications of their interactions remain unclear, however. Based on a probabilistic modeling approach, we show here that fast feedforward inhibition and synaptic scaling interact synergistically during unsupervised learning. In technical terms, we model the input to a neural circuit using a normalized mixture model with Poisson noise. We demonstrate analytically and numerically that, in the presence of lateral inhibition introducing competition between different neurons, Hebbian plasticity and synaptic scaling approximate the optimal maximum likelihood solutions for this model. Our results suggest that, beyond its conventional use as a mechanism to remove undesired pattern variations, input normalization can make typical neural interaction and learning rules optimal on the stimulus subspace defined through feedforward inhibition. Furthermore, learning within this subspace is more efficient in practice, as it helps avoid locally optimal solutions. Our results suggest a close connection between feedforward inhibition and synaptic scaling which may have important functional implications for general cortical processing.

Carbon dioxide sensing in the social context: Leaf-cutting ants prefer elevated CO2 levels to tend their brood.

PubMed

Römer, Daniela; Bollazzi, Martin; Roces, Flavio

2018-07-01

Social insects show temperature and humidity preferences inside their nests to successfully rear brood. In underground nests, ants also encounter rising CO 2 concentrations with increasing depth. It is an open question whether they use CO 2 as a cue to decide where to place and tend the brood. Leaf-cutting ants do show CO 2 preferences for the culturing of their symbiotic fungus. We evaluated their CO 2 choices for brood placement in laboratory experiments. Workers of Acromyrmex lundii in the process of relocating brood were offered a binary choice consisting of two interconnected chambers with different CO 2 concentrations. Values ranged from atmospheric to high concentrations of 4% CO 2 . The CO 2 preferences shown by workers for themselves and for brood placement were assessed by quantifying the number of workers and relocated brood in each chamber. Ants showed clear CO 2 preferences for brood placement. They avoided atmospheric levels, 1% and 4% CO 2 , and showed a preference for levels of 3%. This is the first report of CO 2 preferences for the maintenance of brood in social insects. The observed preferences for brood location were independent of the workers' own CO 2 preferences, since they showed no clear-cut pattern. Workers' CO 2 preferences for brood maintenance were slightly higher than those reported for fungus culturing, although brood is reared in the same chambers as the fungus in leaf-cutting ant nests. Workers' choices for brood placement in natural nests are likely the result of competing preferences for other environmental factors more crucial for brood survival, aside from those for CO 2 . Copyright © 2018 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ray, Jaideep; Lee, Jina; Lefantzi, Sophia

The estimation of fossil-fuel CO2 emissions (ffCO2) from limited ground-based and satellite measurements of CO2 concentrations will form a key component of the monitoring of treaties aimed at the abatement of greenhouse gas emissions. To that end, we construct a multiresolution spatial parametrization for fossil-fuel CO2 emissions (ffCO2), to be used in atmospheric inversions. Such a parametrization does not currently exist. The parametrization uses wavelets to accurately capture the multiscale, nonstationary nature of ffCO2 emissions and employs proxies of human habitation, e.g., images of lights at night and maps of built-up areas to reduce the dimensionality of the multiresolution parametrization.more » The parametrization is used in a synthetic data inversion to test its suitability for use in atmospheric inverse problem. This linear inverse problem is predicated on observations of ffCO2 concentrations collected at measurement towers. We adapt a convex optimization technique, commonly used in the reconstruction of compressively sensed images, to perform sparse reconstruction of the time-variant ffCO2 emission field. We also borrow concepts from compressive sensing to impose boundary conditions i.e., to limit ffCO2 emissions within an irregularly shaped region (the United States, in our case). We find that the optimization algorithm performs a data-driven sparsification of the spatial parametrization and retains only of those wavelets whose weights could be estimated from the observations. Further, our method for the imposition of boundary conditions leads to a 10computational saving over conventional means of doing so. We conclude with a discussion of the accuracy of the estimated emissions and the suitability of the spatial parametrization for use in inverse problems with a significant degree of regularization.« less

Study of structural phase transformation and hysteresis behavior of inverse-spinel α-ferrite nanoparticles synthesized by co-precipitation method

NASA Astrophysics Data System (ADS)

Dabagh, Shadab; Chaudhary, Kashif; Haider, Zuhaib; Ali, Jalil

2018-03-01

Substitution of cobalt (Co2+) ions in cobalt ferrite (CoFe2O4) with copper (Cu2+) and aluminum (Al3+) ions allows variations in their electric and magnetic properties which can be optimized for specific applications. In this article, synthesis of inverse-spinel Co1-xCuxFe2-xAlxO4 (0.0 ≤ x ≤ 0.8) nanoparticles by substituting Cu2+ and Al3+ ions in CoFe2O4 via co-precipitation method is reported. By controlling copper and aluminum (Cu-Al) substituent ratio, the magnetic moment and coercivity of synthesized cobalt ferrite nanoparticles is optimized. The role of substituents on the structure, particle size, morphology, and magnetic properties of nano-crystalline ferrite is investigated. The Co1-xCuxFe2-xAlxO4 (0.0 ≤ x≤ 0.8) nanoparticles with crystallite size in the range of 23.1-26.5 nm are observed, 26.5 nm for x = 0.0-23.1 nm for x = 0.8. The inverse-spinel structure of synthesized Co1-xCuxFe2-xAlxO4 (0.0 ≤ x ≤ 0.8) nano-particles is confirmed by characteristic vibrational bands at tetrahedral and octahedral sites using Fourier transform infrared spectroscopy. A decreases in coercive field and magnetic moment is observed as Cu-Al contents are increased (x = 0.0-0.8). The positive anisotropy of synthesized particles Co1-xCuxFe2-xAlxO4 (0.0 ≤ x ≤ 0.8) is obtained in the range 1.96 × 105 J/m3 for x = 0.0 to 0.29 × 105 J/m3 for x = 0.8.

Improvements of the Penalty Avoiding Rational Policy Making Algorithm and an Application to the Othello Game

NASA Astrophysics Data System (ADS)

Miyazaki, Kazuteru; Tsuboi, Sougo; Kobayashi, Shigenobu

The purpose of reinforcement learning is to learn an optimal policy in general. However, in 2-players games such as the othello game, it is important to acquire a penalty avoiding policy. In this paper, we focus on formation of a penalty avoiding policy based on the Penalty Avoiding Rational Policy Making algorithm [Miyazaki 01]. In applying it to large-scale problems, we are confronted with the curse of dimensionality. We introduce several ideas and heuristics to overcome the combinational explosion in large-scale problems. First, we propose an algorithm to save the memory by calculation of state transition. Second, we describe how to restrict exploration by two type knowledge; KIFU database and evaluation funcion. We show that our learning player can always defeat against the well-known othello game program KITTY.

Off-shore enhanced oil recovery in the north sea: matching CO_2 demand and supply given uncertain market conditions

NASA Astrophysics Data System (ADS)

Compernolle, Tine; Welkenhuysen, Kris; Huisman, Kuno; Piessens, Kris; Kort, Peter

2015-04-01

Introduction CO2 enhanced oil recovery (CO2-EOR) entails the injection of CO2 in mature oil fields in order to mobilize the oil. In particular, the injected CO2 reduces the oil's viscosity and acts as a propellant, resulting in an increased oil extraction rate (Leach et al., 2011). Given uncertainty in both oil price and CO2 price under the EU ETS system, aim of this study is to analyze under which economic conditions a CO2 exchange can be established between a CO2 supplier (an electricity producer for whom CO2 is a by-product) and a CO2 user (an offshore oil company that exploits oil fields in the North Sea and needs CO2 for enhanced oil recovery). Methodology A techno-economic simulation tool, PSS IV, was developed to provide investment decision support on integrated CO2-EOR projects (Welkenhuysen et al., 2014). Until now, a fixed onshore supply of CO2 was presumed. An economic optimization model is now developed for both the CO2 producer and the CO2 user. Because net present value and discounted cash flow methods are inadequate to deal with issues like uncertainty and the irreversibility of an investment decision, the real options theory is applied (Dixit and Pindyck, 1994). The way in which cooperation between the companies can take place, will be studied using game theoretical concepts (Lukas and Welling, 2014). Economic and technical data on CO2 capture are available from the PSS database (Piessens et al., 2012). Data on EOR performance, CO2 requirements and various costs are taken from literature (BERR, 2007; Klokk et al., 2010; Pershad et al., 2012). Results/Findings It will be shown what the impact of price uncertainty is on the investment decision of the electricity producer to capture and sell CO2, and on the decision of the oil producer to make the necessary investments to inject CO2 for enhanced oil recovery. Based on these results, it will be determined under which economic conditions a CO2 exchange and transport can take place. Furthermore, also the role of the ETS system will be discussed. In an initial stage, only the CO2-price and oil price market uncertainties are considered. In a further stage, uncertainties from the supply side (technology) and EOR (geological) will be added. References BERR. 2007. Development of a CO2 transport and storage network in the North Sea: report to the North Sea Basin Task Force. Dixit A, Pindyck R (1994). Investment under Uncertainty. In, Princeton University Press. Klokk Ø, Schreiner PF, Pagès-Bernaus A, Tomasgard A (2010). Optimizing a CO2 value chain for the Norwegian Continental Shelf. Energy Policy 38(11): 6604-6614 Leach A, Mason CF, Veld Kvt (2011). Co-optimization of enhanced oil recovery and carbon sequestration. Resource Energy Econ 33(4): 893-912 Lukas E, Welling A (2014). Timing and eco(nomic) efficiency of climate-friendly investments in supply chains. Eur J Oper Res 233(2): 448-457 Pershad, H., Durusut, E., Crerar, A., Black, D., Mackay, E. & Oldern, P., 2012. Economic Impacts of CO2-enhanced oil recovery for Scotland, Final report for Scottish Enterprise. Element energy, London. Piessens, K., Welkenhuysen K., Laenen, B., Ferket, H., Nijs, W., Duerinck, J., Cochez, E., Mathieu, Ph., Valentiny, D., Baele, J.-M., Dupont, N. & Hendriks, Ch., 2012. Policy Support System for Carbon Capture and Storage and Collaboration between Belgium-the Netherlands "PSS-CCS", Final report. Belgian Science Policy Office, Research Programme Science for a Sustainable Development contracts SD/CP/04a,b & SD/CP/803, 335p. Welkenhuysen, K., Compernolle, T., Piessens, K., Ramírez, A., Rupert, J. & Swennen, R., 2014. Geological uncertainty and investment risk in CO2-enhanced oil recovery. 12th International Conference on Greenhouse Gas Control Technologies (GHGT-12), Austin, Texas, 05-09/10/2014.

Determination of Montelukast in Plasma Using β - Cyclodextrins Coated on CoFe2O4 Magnetic Nanoparticles in Luminol-H2O2 Chemiluminescence System Optimized by Doehlert Design.

PubMed

Samadi-Maybodi, Abdolraouf; Bakhtiar, Alireza; Fatemi, Mohammad Hossein

2016-05-01

A novel chemiluminescence method using β - cyclodextrins coated on CoFe2O4 magnetic nanoparticles is proposed for the chemiluminometric determination of montelukast in plasma. The effect of coated β - cyclodexterinon CoFe2O4 magnetic nanoparticles in the chemiluminescence of luminol-H2O2 system was investigated. It was found that β - cyclodexterin coated on CoFe2O4 magnetic nanoparticles could greatly enhance the chemiluminescence of the luminol-H2O2 system. Doehlert design was applied in order to optimize the number of experiments to be carried out to ascertain the possible interactions between the parameters and their effects on the chemiluminescence emission intensity. This design was selected because the levels of each variable may vary in a very efficient way with few experiments. Doehlert design and response surface methodology have been employed for optimization pH and concentrations of the components. Results showed under the optimized experimental conditions, the relative CL intensity (ΔI) is increased linearly in the concentration range of 0.003-0.586 μgml(-1) of montelukast with limit of detection (LOD) 1.09 × 10(-4) μgml(-1) at S/N ratio of 3, limit of quantitative (LOQ) 3.59 × 10(-4) μgml(-1) and the relative standard deviation 2.63 %. The method has been successfully applied to the determination of montelukast in plasma of human body. Results specified that relative chemiluminescence intensity (ΔI) has good proportional with the montelukast concentration with R(2) = 0.99979. The test of the recovery efficiency for known amounts of montelukast was also performed, the recoveries range obtained from 98.2 to 103.3 %, with RSDs of <4 % indicated that the proposed method was reliable.

Conceptual Design Optimization of an Augmented Stability Aircraft Incorporating Dynamic Response Performance Constraints

NASA Technical Reports Server (NTRS)

Welstead, Jason

2014-01-01

This research focused on incorporating stability and control into a multidisciplinary de- sign optimization on a Boeing 737-class advanced concept called the D8.2b. A new method of evaluating the aircraft handling performance using quantitative evaluation of the sys- tem to disturbances, including perturbations, continuous turbulence, and discrete gusts, is presented. A multidisciplinary design optimization was performed using the D8.2b transport air- craft concept. The con guration was optimized for minimum fuel burn using a design range of 3,000 nautical miles. Optimization cases were run using xed tail volume coecients, static trim constraints, and static trim and dynamic response constraints. A Cessna 182T model was used to test the various dynamic analysis components, ensuring the analysis was behaving as expected. Results of the optimizations show that including stability and con- trol in the design process drastically alters the optimal design, indicating that stability and control should be included in conceptual design to avoid system level penalties later in the design process.

Optimization of CO2 adsorption capacity and cyclical adsorption/desorption on tetraethylenepentamine-supported surface-modified hydrotalcite.

PubMed

Thouchprasitchai, Nutthavich; Pintuyothin, Nuthapol; Pongstabodee, Sangobtip

2018-03-01

The objective of this research was to investigate CO 2 adsorption capacity of tetraethylenepentamine-functionalized basic-modified calcined hydrotalcite (TEPA/b-cHT) sorbents at atmospheric pressure formed under varying TEPA loading levels, temperatures, sorbent weight to total gaseous flow rate (W/F) ratios and CO 2 concentrations in the influent gas. The TEPA/b-cHT sorbents were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), thermal gravimetric analysis (TGA), Brunauer-Emmet-Teller (BET) analysis of nitrogen (N 2 ) adsorption/desorption and carbon-hydrogen-nitrogen (CHN) elemental analysis. Moreover, a full 2 4 factorial design with three central points at a 95% confidence interval was used to screen important factor(s) on the CO 2 adsorption capacity. It revealed that 85.0% variation in the capacity came from the influence of four main factors and the 15.0% one was from their interactions. A face-centered central composite design response surface method (FCCCD-RSM) was then employed to optimize the condition, the maximal capacity of 5.5-6.1mmol/g was achieved when operating with a TEPA loading level of 39%-49% (W/W), temperature of 76-90°C, W/F ratio of 1.7-2.60(g·sec)/cm 3 and CO 2 concentration of 27%-41% (V/V). The model fitted sufficiently the experimental data with an error range of ±1.5%. From cyclical adsorption/desorption and selectivity at the optimal condition, the 40%TEPA/b-cHT still expressed its effective performance after eight cycles. Copyright © 2017. Published by Elsevier B.V.

The effect of atmospheric carbon dioxide concentrations on the performance of the mangrove Avicennia germinans over a range of salinities.

PubMed

Reef, Ruth; Winter, Klaus; Morales, Jorge; Adame, Maria Fernanda; Reef, Dana L; Lovelock, Catherine E

2015-07-01

By increasing water use efficiency and carbon assimilation, increasing atmospheric CO2 concentrations could potentially improve plant productivity and growth at high salinities. To assess the effect of elevated CO2 on the salinity response of a woody halophyte, we grew seedlings of the mangrove Avicennia germinans under a combination of five salinity treatments [from 5 to 65 parts per thousand (ppt)] and three CO2 concentrations (280, 400 and 800 ppm). We measured survivorship, growth rate, photosynthetic gas exchange, root architecture and foliar nutrient and ion concentrations. The salinity optima for growth shifted higher with increasing concentrations of CO2 , from 0 ppt at 280 ppm to 35 ppt at 800 ppm. At optimal salinity conditions, carbon assimilation rates were significantly higher under elevated CO2 concentrations. However, at salinities above the salinity optima, salinity had an expected negative effect on mangrove growth and carbon assimilation, which was not alleviated by elevated CO2 , despite a significant improvement in photosynthetic water use efficiency. This is likely due to non-stomatal limitations to growth at high salinities, as indicated by our measurements of foliar ion concentrations that show a displacement of K(+) by Na(+) at elevated salinities that is not affected by CO2 . The observed shift in the optimal salinity for growth with increasing CO2 concentrations changes the fundamental niche of this species and could have significant effects on future mangrove distribution patterns and interspecific interactions. © 2014 Scandinavian Plant Physiology Society.

Supercritical CO2 foamed polycaprolactone scaffolds for controlled delivery of 5-fluorouracil, nicotinamide and triflusal.

PubMed

Salerno, Aurelio; Saurina, Javier; Domingo, Concepción

2015-12-30

The manufacture of porous polycaprolactone (PCL) scaffolds containing three different drugs, namely 5-fluorouracil, nicotinamide and triflusal, was investigated in this work with the aim of obtaining bioactive systems with controlled drug delivery capabilities. The scaffolds were prepared by means of a supercritical CO2 (scCO2) foaming technique by optimizing the drug loading process. This was achieved by dissolving the drugs in organic solvents miscible with scCO2 and by mixing these drug/solvent solutions with PCL powder. The as prepared mixtures were further compressed to eliminate air bubbles and finally processed by the scCO2 foaming technique. ScCO2 saturation and foaming conditions were optimized to create the porosity within the samples and to allow for the concomitant removal of the organic solvents. Physical and chemical properties of porous scaffolds, as well as drug content and delivery profiles, were studied by HPLC. The results of this study demonstrated that the composition of the starting PCL/drug/solvent mixtures affected polymer crystallization, scaffold morphology and pore structure features. Furthermore, it was found that drug loading efficiency depended on both initial solution composition and drug solubility in scCO2. Nevertheless, in the case of highly scCO2-soluble drugs, such as triflusal, loading efficiency was improved by adding a proper amount of free drug inside of the pressure vessel. The drug delivery study indicated that release profiles depended mainly upon scaffolds composition and pore structure features. Copyright © 2015 Elsevier B.V. All rights reserved.

Electrochemical CO2 and O2 separation for crew and plant environments

NASA Technical Reports Server (NTRS)

Lee, M. G.; Grigger, David J.; Foerg, Sandra L.

1992-01-01

The study describes a closed ecosystem concept that includes electrochemical CO2 and O2 separators and a moisture condenser/separator for maintaining CO2, O2, and humidity levels in the crew and plant habitats at their respective optimal conditions. The key processes of this concept are aqueous electrolyte-based electrochemical CO2 and O2 separations. The principles and cell characteristics of these electrochemical gas separation processes are described. Also presented are descriptions of test hardware and the test results of the Electrochemical CO2 Separator (ECS) and the Electrochemical O2 Separator (EOS), and the combination of the ECS and the EOS. The test results proved that the ECS and EOS processes for the combined concept are viable.

C3 and C4 biomass allocation responses to elevated CO2 and nitrogen: contrasting resource capture strategies

USGS Publications Warehouse

White, K.P.; Langley, J.A.; Cahoon, D.R.; Megonigal, J.P.

2012-01-01

Plants alter biomass allocation to optimize resource capture. Plant strategy for resource capture may have important implications in intertidal marshes, where soil nitrogen (N) levels and atmospheric carbon dioxide (CO2) are changing. We conducted a factorial manipulation of atmospheric CO2 (ambient and ambient + 340 ppm) and soil N (ambient and ambient + 25 g m-2 year-1) in an intertidal marsh composed of common North Atlantic C3 and C4 species. Estimation of C3 stem turnover was used to adjust aboveground C3 productivity, and fine root productivity was partitioned into C3-C4 functional groups by isotopic analysis. The results suggest that the plants follow resource capture theory. The C3 species increased aboveground productivity under the added N and elevated CO2 treatment (P 2 alone. C3 fine root production decreased with added N (P 2 (P = 0.0481). The C4 species increased growth under high N availability both above- and belowground, but that stimulation was diminished under elevated CO2. The results suggest that the marsh vegetation allocates biomass according to resource capture at the individual plant level rather than for optimal ecosystem viability in regards to biomass influence over the processes that maintain soil surface elevation in equilibrium with sea level.

Optimal clinical time for reliable measurement of transcutaneous CO2 with ear probes: counterbalancing overshoot and the vasodilatation effect.

PubMed

Domingo, Christian; Canturri, Elisa; Moreno, Amalia; Espuelas, Humildad; Vigil, Laura; Luján, Manel

2010-01-01

To determine the optimal clinical reading time for the transcutaneous measurement of oxygen saturation (SpO(2)) and transcutaneous CO(2) (TcPCO(2)) in awake spontaneously breathing individuals, considering the overshoot phenomenon (transient overestimation of arterial PaCO(2)). EXPERIMENTAL SECTION: Observational study of 91 (75 men) individuals undergoing forced spirometry, measurement of SpO(2) and TcPCO(2) with the SenTec monitor every two minutes until minute 20 and arterial blood gas (ABG) analysis. Overshoot severity: (a) mild (0.1-1.9 mm Hg); (b) moderate (2-4.9 mm Hg); (c) severe: (>5 mm Hg). The mean difference was calculated for SpO(2) and TcPCO(2) and arterial values of PaCO(2) and SpO(2). The intraclass correlation coefficient (ICC) between monitor readings and blood values was calculated as a measure of agreement. The mean age was 63.1 ± 11.8 years. Spirometric values: FVC: 75.4 ± 6.2%; FEV(1): 72.9 ± 23.9%; FEV(1)/FVC: 70 ± 15.5%. ABG: PaO(2): 82.6 ± 13.2; PaCO(2): 39.9.1 ± 4.8 mmHg; SaO(2): 95.3 ± 4.4%. Overshoot analysis: overshoot was mild in 33 (36.3%) patients, moderate in 20 (22%) and severe in nine (10%); no overshoot was observed in 29 (31%) patients. The lowest mean differences between arterial blood gas and TcPCO(2) was -0.57 mmHg at minute 10, although the highest ICC was obtained at minutes 12 and 14 (>0.8). The overshoot lost its influence after minute 12. For SpO(2), measurements were reliable at minute 2. The optimal clinical reading measurement recommended for the ear lobe TcPCO(2) measurement ranges between minute 12 and 14. The SpO(2) measurement can be performed at minute 2.

Optimal Clinical Time for Reliable Measurement of Transcutaneous CO2 with Ear Probes: Counterbalancing Overshoot and the Vasodilatation Effect

PubMed Central

Domingo, Christian; Canturri, Elisa; Moreno, Amalia; Espuelas, Humildad; Vigil, Laura; Luján, Manel

2010-01-01

OBJECTIVES: To determine the optimal clinical reading time for the transcutaneous measurement of oxygen saturation (SpO2) and transcutaneous CO2 (TcPCO2) in awake spontaneously breathing individuals, considering the overshoot phenomenon (transient overestimation of arterial PaCO2). EXPERIMENTAL SECTION: Observational study of 91 (75 men) individuals undergoing forced spirometry, measurement of SpO2 and TcPCO2 with the SenTec monitor every two minutes until minute 20 and arterial blood gas (ABG) analysis. Overshoot severity: (a) mild (0.1–1.9 mm Hg); (b) moderate (2–4.9 mm Hg); (c) severe: (>5 mm Hg). The mean difference was calculated for SpO2 and TcPCO2 and arterial values of PaCO2 and SpO2. The intraclass correlation coefficient (ICC) between monitor readings and blood values was calculated as a measure of agreement. RESULTS: The mean age was 63.1 ± 11.8 years. Spirometric values: FVC: 75.4 ± 6.2%; FEV1: 72.9 ± 23.9%; FEV1/FVC: 70 ± 15.5%. ABG: PaO2: 82.6 ± 13.2; PaCO2: 39.9.1 ± 4.8 mmHg; SaO2: 95.3 ± 4.4%. Overshoot analysis: overshoot was mild in 33 (36.3%) patients, moderate in 20 (22%) and severe in nine (10%); no overshoot was observed in 29 (31%) patients. The lowest mean differences between arterial blood gas and TcPCO2 was −0.57 mmHg at minute 10, although the highest ICC was obtained at minutes 12 and 14 (>0.8). The overshoot lost its influence after minute 12. For SpO2, measurements were reliable at minute 2. CONCLUSIONS: The optimal clinical reading measurement recommended for the ear lobe TcPCO2 measurement ranges between minute 12 and 14. The SpO2 measurement can be performed at minute 2. PMID:22315552

[Orthogonal experiment using SFE-CO2 in extraction of essential oil from fresh Houttuynia cordata and analysis of essential oil by GC-MS].

PubMed

Meng, Jiang; Dong, Xiao-ping; Zhou, Yi-sheng; Jiang, Zhi-hong; Leung, Kelvin Sze-Yin; Zhao, Zhong-zhen

2007-02-01

To optimize the extraction procedure of essential oil from H. cordata using the SFE-CO2 and analyze the chemical composition of the essential oil. The extraction procedure of essential oil from fresh H. cordata was optimized with the orthogonal experiment. Essential oil of fresh H. cordata was analysed by GC-MS. The optimize preparative procedure was as follow: essential oil of H. cordata was extracted at a temperature of 35 degrees C, pressure of 15,000 kPa for 20 min. 38 chemical components were identified and the relative contents were quantified. The optimum preparative procedure is reliable and can guarantee the quality of essential oil.

[Study on new extraction technology of astragaloside IV].

PubMed

Sun, Haiyan; Guan, Su; Huang, Min

2005-08-01

To explore the possibility and the optimal extraction technology of astragaloside IV by SFE-CO2. According the content of astragaloside IV, the optimum extraction technology parameters such as extraction temperature, pressure, extraction time, velocity of fluid and co-solvent were investigated and the result was compared with that of water extraction. The optimum technical parameters were as follows: Extracting pressure 40 Mpa, temperature 45 degrees C, extracting time 2h, co-solvent was 95% ethanol and its dosage was 4ml/g, the ratio of CO2 fluid was 10 kg/kg x h. Extraction technology of astragaloside IV by SFE-CO2 is reliable, stable.

Heterologous production of an energy-conserving carbon monoxide dehydrogenase complex in the hyperthermophile Pyrococcus furiosus

DOE PAGES

Schut, Gerrit J.; Lipscomb, Gina L.; Nguyen, Diep M. N.; ...

2016-01-29

In this study, carbon monoxide (CO) is an important intermediate in anaerobic carbon fixation pathways in acetogenesis and methanogenesis. In addition, some anaerobes can utilize CO as an energy source. In the hyperthermophilic archaeon Thermococcus onnurineus, which grows optimally at 80°C, CO oxidation and energy conservation is accomplished by a respiratory complex encoded by a 16-gene cluster containing a CO dehydrogenase, a membrane-bound [NiFe]-hydrogenase and a Na +/H + antiporter module. This complex oxidizes CO, evolves CO 2 and H 2, and generates a Na+ motive force that is used to conserve energy by a Na+-dependent ATP synthase. Herein wemore » used a bacterial artificial chromosome to insert the 13.2 kb gene cluster encoding the CO-oxidizing respiratory complex of T. onnurineus into the genome of the heterotrophic archaeon, Pyrococcus furiosus, which grows optimally at 100° C. P. furiosus is normally unable to utilize CO, however, the recombinant strain readily oxidized CO and generated H 2 at 80° C. Moreover, CO also served as an energy source and allowed the P. furiosus strain to grow with a limiting concentration of sugar or with peptides as the carbon source. Moreover, CO oxidation by P. furiosus was also coupled to the re-utilization, presumably for biosynthesis, of acetate generated by fermentation. The functional transfer of CO utilization between Thermococcus and Pyrococcus species demonstrated herein is representative of the horizontal gene transfer of an environmentally relevant metabolic capability. The transfer of CO utilizing, hydrogen-producing genetic modules also has applications for biohydrogen production and a CO-based industrial platform for various thermophilic organisms.« less

[Optimization of supercritical fluid extraction of bioactive components in Ligusticum chuanxiong by orthogonal array design].

PubMed

Hu, Li-Cui; Wu, Xun; Yang, Xue-Dong

2013-10-01

With the yields of ferulic acid, coniferylferulate, Z-ligustilide, senkyunolide A, butylidenephthalide, butylphthalide, senkyunolide I, senkyunolide H, riligustilide, levistolide A, and total pharmacologically active ingredient as evaluation indexes, the extraction of Ligusticum chuanxiong by supercritical fluid technology was investigated through an orthogonal experiment L9 (3(4)). Four factors, namely temperature, pressure, flow rate of carbon dioxide, co-solvent concentration of the supercritical fluid, were investigated and optimized. Under the optimized conditions, namely 65 degrees C of temperature, 35 MPa of pressure, 1 L x min(-1) of CO2 flow rate, 8% of co-solvent concetration, supercritical fluid extraction could achieve a better yield than the conventional reflux extraction using methanol. And the supercritical fluid extraction process was validated to be stable and reliable.

Elevated CO2 stimulates marsh elevation gain, counterbalancing sea-level rise

USGS Publications Warehouse

Langley, J.A.; McKee, K.L.; Cahoon, D.R.; Cherry, J.A.; Megonigala, J.P.

2009-01-01

Tidal wetlands experiencing increased rates of sea-level rise (SLR) must increase rates of soil elevation gain to avoid permanent conversion to open water. The maximal rate of SLR that these ecosystems can tolerate depends partly on mineral sediment deposition, but the accumulation of organic matter is equally important for many wetlands. Plant productivity drives organic matter dynamics and is sensitive to global change factors, such as rising atmospheric CO2 concentration. It remains unknown how global change will influence organic mechanisms that determine future tidal wetland viability. Here, we present experimental evidence that plant response to elevated atmospheric [CO2] stimulates biogenic mechanisms of elevation gain in a brackish marsh. Elevated CO2 (ambient + 340 ppm) accelerated soil elevation gain by 3.9 mm yr−1in this 2-year field study, an effect mediated by stimulation of below-ground plant productivity. Further, a companion greenhouse experiment revealed that the CO2 effect was enhanced under salinity and flooding conditions likely to accompany future SLR. Our results indicate that by stimulating biogenic contributions to marsh elevation, increases in the greenhouse gas, CO2, may paradoxically aid some coastal wetlands in counterbalancing rising seas.

Elevated CO2 stimulates marsh elevation gain, counterbalancing sea-level rise.

PubMed

Langley, J Adam; McKee, Karen L; Cahoon, Donald R; Cherry, Julia A; Megonigal, J Patrick

2009-04-14

Tidal wetlands experiencing increased rates of sea-level rise (SLR) must increase rates of soil elevation gain to avoid permanent conversion to open water. The maximal rate of SLR that these ecosystems can tolerate depends partly on mineral sediment deposition, but the accumulation of organic matter is equally important for many wetlands. Plant productivity drives organic matter dynamics and is sensitive to global change factors, such as rising atmospheric CO(2) concentration. It remains unknown how global change will influence organic mechanisms that determine future tidal wetland viability. Here, we present experimental evidence that plant response to elevated atmospheric [CO(2)] stimulates biogenic mechanisms of elevation gain in a brackish marsh. Elevated CO(2) (ambient + 340 ppm) accelerated soil elevation gain by 3.9 mm yr(-1) in this 2-year field study, an effect mediated by stimulation of below-ground plant productivity. Further, a companion greenhouse experiment revealed that the CO(2) effect was enhanced under salinity and flooding conditions likely to accompany future SLR. Our results indicate that by stimulating biogenic contributions to marsh elevation, increases in the greenhouse gas, CO(2), may paradoxically aid some coastal wetlands in counterbalancing rising seas.

Elevated CO2 stimulates marsh elevation gain, counterbalancing sea-level rise

PubMed Central

Langley, J. Adam; McKee, Karen L.; Cahoon, Donald R.; Cherry, Julia A.; Megonigal, J. Patrick

2009-01-01

Tidal wetlands experiencing increased rates of sea-level rise (SLR) must increase rates of soil elevation gain to avoid permanent conversion to open water. The maximal rate of SLR that these ecosystems can tolerate depends partly on mineral sediment deposition, but the accumulation of organic matter is equally important for many wetlands. Plant productivity drives organic matter dynamics and is sensitive to global change factors, such as rising atmospheric CO2 concentration. It remains unknown how global change will influence organic mechanisms that determine future tidal wetland viability. Here, we present experimental evidence that plant response to elevated atmospheric [CO2] stimulates biogenic mechanisms of elevation gain in a brackish marsh. Elevated CO2 (ambient + 340 ppm) accelerated soil elevation gain by 3.9 mm yr−1 in this 2-year field study, an effect mediated by stimulation of below-ground plant productivity. Further, a companion greenhouse experiment revealed that the CO2 effect was enhanced under salinity and flooding conditions likely to accompany future SLR. Our results indicate that by stimulating biogenic contributions to marsh elevation, increases in the greenhouse gas, CO2, may paradoxically aid some coastal wetlands in counterbalancing rising seas. PMID:19325121

Formulation and characterization of ORMOSIL particles loaded with budesonide for local colonic delivery.

PubMed

Petrovska-Jovanovska, Vesna; Geskovski, Nikola; Crcarevska, Maja Simonoska; Memed, Oya; Petruševski, Gjorgji; Chachorovska, Marina; Petrusevska, Marija; Poceva-Panovska, Ana; Mladenovska, Kristina; Ugarkovic, Sonja; Glavas-Dodov, Marija

2015-04-30

In this study, hybrid silica xerogel particles were developed as carriers of budesonide (BDS) for efficient local treatment of inflammatory bowel diseases (IBD). Organically modified silica particles (ORMOSILs) were prepared by co-condensation of 3-aminopropyltriethoxysilane (APTES) and tetraethyl orthosilicate (TEOS) by an ambient temperature acid catalysed sol-gel process followed by spray-drying. Formulation for preparation of BDS-loaded particles was optimized and their physicochemical parameters and drug release profiles were evaluated in vitro. Optimal formulation had a small particle size (mean diameter of 1.45±0.02μm) with unimodal narrow size distribution and high encapsulation efficiency (98.0 ± 1.85%). Due to the positive surface charge originated from amino group of APTES, ORMOSILs showed excessive mucoadhesiveness in comparison to native TEOS particles. The drug release decreased with increasing pH from 2.0 to 7.4. In order to avoid undesirable erroneous performance in the upper GI tract, particles were additionally coated with Eudragit(®) FS 30D, as a barrier to the drug release at pH range from 2.0 to 7.0. After Eudragit(®) FS 30D coating, the release of BDS in acidic media was sustained, while no significant differences in drug release were observed at pH 7.4. In conclusion, pH-responsive ORMOSILs showed great potential for efficient BDS delivery to the colon region. Copyright © 2015 Elsevier B.V. All rights reserved.

A nonlinear model predictive control formulation for obstacle avoidance in high-speed autonomous ground vehicles in unstructured environments

NASA Astrophysics Data System (ADS)

Liu, Jiechao; Jayakumar, Paramsothy; Stein, Jeffrey L.; Ersal, Tulga

2018-06-01

This paper presents a nonlinear model predictive control (MPC) formulation for obstacle avoidance in high-speed, large-size autono-mous ground vehicles (AGVs) with high centre of gravity (CoG) that operate in unstructured environments, such as military vehicles. The term 'unstructured' in this context denotes that there are no lanes or traffic rules to follow. Existing MPC formulations for passenger vehicles in structured environments do not readily apply to this context. Thus, a new nonlinear MPC formulation is developed to navigate an AGV from its initial position to a target position at high-speed safely. First, a new cost function formulation is used that aims to find the shortest path to the target position, since no reference trajectory exists in unstructured environments. Second, a region partitioning approach is used in conjunction with a multi-phase optimal control formulation to accommodate the complicated forms the obstacle-free region can assume due to the presence of multiple obstacles in the prediction horizon in an unstructured environment. Third, the no-wheel-lift-off condition, which is the major dynamical safety concern for high-speed, high-CoG AGVs, is ensured by limiting the steering angle within a range obtained offline using a 14 degrees-of-freedom vehicle dynamics model. Thus, a safe, high-speed navigation is enabled in an unstructured environment. Simulations of an AGV approaching multiple obstacles are provided to demonstrate the effectiveness of the algorithm.

Molecular simulation of CH4/CO2/H2O competitive adsorption on low rank coal vitrinite.

PubMed

Yu, Song; Bo, Jiang; Wu, Li

2017-07-21

The competitive adsorptions of CH 4 /CO 2 /H 2 O on coal vitrinite (DV-8, C 214 H 180 O 24 N 2 ) were computed based on density function theory (DFT) and grand canonical Monte Carlo (GCMC). The adsorption process reaches the saturation state after adsorbing 17 CH 4 s, 22 CO 2 s, and 35 H 2 Os per C 214 H 180 O 24 N 2 respectively. The optimal configurations of CH 4 -vitrinite, CO 2 -vitrinite, and H 2 O-vitrinite respectively manifest as aromatic 1 /T 2 /rT 3 (1 adsorption location, 2 adsorption sites and T here represents sites above the carbon atom and the heteroatom, 3 adsorption orientation and rT here means the orientations of three hydrogen atoms pointing to vitrinite), aromatic/T/v (v represents the orientations perpendicular to the plane of vitrinite), and aromatic/rV/T (rV represents an oxygen atom pointing to the vitrinite surface). The GCMC results show that high temperature is not conducive to the vitrinite's adsorption of adsorbates and the adsorption capacity order is H 2 O > CO 2 > CH 4 (263-363 K) in the one-component, binary, and ternary adsorbate systems. The optimal configurations of vitrinite are similar to graphite/graphene, while ΔE is significantly lower than graphite/graphene. Simulation data are in good agreement with the experimental results.

Climate-society feedbacks and the avoidance of dangerous climate change

NASA Astrophysics Data System (ADS)

Jarvis, A. J.; Leedal, D. T.; Hewitt, C. N.

2012-09-01

The growth in anthropogenic CO2 emissions experienced since the onset of the Industrial Revolution is the most important disturbance operating on the Earth's climate system. To avoid dangerous climate change, future greenhouse-gas emissions will have to deviate from business-as-usual trajectories. This implies that feedback links need to exist between climate change and societal actions. Here, we show that, consciously or otherwise, these feedbacks can be represented by linking global mean temperature change to the growth dynamics of CO2 emissions. We show that the global growth of new renewable sources of energy post-1990 represents a climate-society feedback of ~0.25%yr-1 per degree increase in global mean temperature. We also show that to fulfil the outcomes negotiated in Durban in 2011, society will have to become ~ 50 times more responsive to global mean temperature change than it has been since 1990. If global energy use continues to grow as it has done historically then this would result in amplification of the long-term endogenous rate of decarbonization from -0.6%yr-1 to ~-13%yr-1. It is apparent that modest levels of feedback sensitivity pay large dividends in avoiding climate change but that the marginal return on this effort diminishes rapidly as the required feedback strength increases.

Loss of Bone Mineral Density Associated with Age in Male Rats Fed on Sunflower Oil Is Avoided by Virgin Olive Oil Intake or Coenzyme Q Supplementation

PubMed Central

Ochoa, Julio J.; Llamas-Elvira, José M.; López-Frías, Magdalena

2017-01-01

The role of dietary fat unsaturation and the supplementation of coenzyme Q have been evaluated in relation to bone health. Male Wistar rats were maintained for 6 or 24 months on two diets varying in the fat source, namely virgin olive oil, rich in monounsaturated fatty acids, or sunflower oil, rich in n-6 polyunsaturated fatty acids. Both dietary fats were supplemented or not with coenzyme Q10 (CoQ10). Bone mineral density (BMD) was evaluated in the femur. Serum levels of osteocalcin, osteopontin, receptor activator of nuclear factor κB ligand (RANKL), osteoprotegerin (OPG), adrenocorticotropin (ACTH) and parathyroid hormone (PTH), as well as urinary F2-isoprostanes were measured. Aged animals fed on virgin olive oil showed higher BMD than those fed on sunflower oil. In addition, CoQ10 prevented the age-related decline in BMD in animals fed on sunflower oil. Urinary F2-isoprostanes analysis showed that sunflower oil led to the highest oxidative status in old animals, which was avoided by supplementation with CoQ10. In conclusion, lifelong feeding on virgin olive oil or the supplementation of sunflower oil on CoQ10 prevented, at least in part mediated by a low oxidative stress status, the age-related decrease in BMD found in sunflower oil fed animals. PMID:28661441

Design of experiment analysis of CO2 dielectric barrier discharge conditions on CO production

NASA Astrophysics Data System (ADS)

Becker, Markus; Ponduri, Srinath; Engeln, Richard; van de Sanden, Richard; Loffhagen, Detlef

2016-09-01

Dielectric barrier discharges (DBD) are frequently used for the generation of CO from CO2 which is of particular interest for syngas production. It has been found by means of fluid modelling in that the CO2 conversion frequency in a CO2 DBD depends linearly on the specific energy input (SEI) while the energy efficiency of CO production is only weakly dependent on the SEI. Here, the same numerical model as in is applied to study systematically the influence of gas pressure, applied voltage amplitude and frequency on the CO2 conversion frequency and the energy efficiency of CO production based on a 2-level 3-factor full factorial experimental design. It is found that the operating conditions of the CO2 DBD for CO production can be chosen to either have an optimal throughput or a better energy efficiency. This work was partly supported by the German Research Foundation within the Collaborative Research Centre Transregio 24.

Optimism, Symptom Distress, Illness Appraisal, and Coping in Patients With Advanced-Stage Cancer Diagnoses Undergoing Chemotherapy Treatment.

PubMed

Sumpio, Catherine; Jeon, Sangchoon; Northouse, Laurel L; Knobf, M Tish

2017-05-01

To explore the relationships between optimism, self-efficacy, symptom distress, treatment complexity, illness appraisal, coping, and mood disturbance in patients with advanced-stage cancer.
. Cross-sectional study.
. Smilow Cancer Hospital at Yale New Haven in Connecticut, an outpatient comprehensive cancer center.
. A convenience sample of 121 adult patients with stages III-IV cancer undergoing active chemotherapy.
. Participants completed common self-report questionnaires to measure variables. Treatment hours and visits were calculated from data retrieved from medical record review. Mediation and path analysis were conducted to identify direct and indirect pathways from the significant antecedent variables to mood disturbance.
. Dispositional optimism, self-efficacy, social support, treatment complexity, symptom distress, illness appraisal, coping, and mood disturbance.
. Greater optimism and self-efficacy were associated with less negative illness appraisal, less avoidant coping, and decreased mood disturbance. Conversely, greater symptom distress was associated with greater negative illness appraisal, greater avoidant coping, and greater mood disturbance. In the final model, optimism and symptom distress had direct and indirect effects on mood disturbance. Indirect effects were partially mediated by illness appraisal.
. Mood disturbance resulted from an interaction of disease stressors, personal resources, and cognitive appraisal of illness. Avoidant coping was associated with greater disturbed mood, but neither avoidant nor active coping had a significant effect on mood in the multivariate model. 
. Illness appraisal, coping style, and symptom distress are important targets for intervention. Optimism is a beneficial trait and should be included, along with coping style, in comprehensive nursing assessments of patients with cancer.

Highly Efficient Carbon Dioxide Hydrogenation to Methanol Catalyzed by Zigzag Platinum-Cobalt Nanowires.

PubMed

Bai, Shuxing; Shao, Qi; Feng, Yonggang; Bu, Lingzheng; Huang, Xiaoqing

2017-06-01

Carbon dioxide (CO 2 ) hydrogenation is an effective strategy for CO 2 utilization, while unsatisfied conversion efficiencies remain great challenges. It is reported herein that zigzag Pt-Co nanowires (NWs) with Pt-rich surfaces and abundant steps/edges can perform as highly active and stable CO 2 hydrogenation catalysts. It is found that tuning the Pt/Co ratio of the Pt-Co NWs, solvents, and catalyst supports could well optimize the CO 2 hydrogenation to methanol (CH 3 OH) with the Pt 4 Co NWs/C exhibiting the best performance, outperforming all the previous catalysts. They are also very durable with limited activity decays after six catalytic cycles. The diffuse reflectance infrared Fourier transform spectroscopy result of CO 2 adsorption shows that the Pt 4 Co NWs/C undergoes the adsorption/activation of CO 2 by forming appropriate carboxylate intermediates, and thus enhancing the CH 3 OH production. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Triacetic acid lactone production from Saccharomyces cerevisiae

USDA-ARS?s Scientific Manuscript database

Triacetic acid lactone (TAL) is a potential platform chemical produced from acetyl-CoA and malonyl-CoA by the Gerbera hybrida 2-pyrone synthase (2PS) gene. Studies are ongoing to optimize production, purification, and chemical modification of TAL, which can be used to create the commercial chemicals...

Optimal recovery of regional carbon dioxide surface fluxes by data assimilation of anthropogenic and biogenic tracers

NASA Astrophysics Data System (ADS)

Campbell, Elliott

Measurements of atmospheric carbon dioxide (CO2) have led to an understanding of the past and present CO2 trends at global scales. However, many of the processes that underlie the CO 2 fluxes are highly uncertain, especially at smaller spatial scales in the terrestrial biosphere. Our abilities to forecast climate change and manage the carbon cycle are reliant on an understanding of these underlying processes. In this dissertation, new steps were taken to understand the biogenic and anthropogenic processes based on analysis with an atmospheric transport model and simultaneous measurements of CO2 and other trace gases. The biogenic processes were addressed by developing an approach for quantifying photosynthesis and respiration surface fluxes using observations of CO 2 and carbonyl sulfide (COS). There is currently no reliable method for separating the influence of these gross biosphere fluxes on atmospheric CO2 concentrations. First, the plant sink for COS was quantified as a function of the CO2 photosynthesis uptake using the STEM transport model and measurements of COS and CO2 from the INTEX-NA campaign. Next, the STEM inversion model was modified for the simultaneous optimization of fluxes using COS and CO2 measurements and using only CO 2 measurements. The CO2-only inversion was found to be process blind, while the simultaneous COS/CO2 inversion was found to provide a unique estimate of the respiration and photosynthesis component fluxes. Further validation should be pursued with independent observations. The approach presented here is the first application of COS measurements for inferring information about the carbon cycle. Anthropogenic emissions were addressed by improving the estimate of the fossil fuel component of observed CO2 by using observed carbon monoxide (CO). Recent applications of the CO approach were based on simple approximations of non-fossil fuel influences on the measured CO such as sources from oxidation of volatile organic carbon species, sinks from oxidation of CO, and sources from forest fires. A revised CO method was developed using STEM simulations of atmospheric reactions and tracers of different combustion sources. Applications of the revised method to the NASA INTEX-NA measurements showed large differences with conventional methods. Application to the INTEX-B measurements resulted in partitioning of continental and offshore oil rig sources around Mexico.

Area 2. Use Of Engineered Nanoparticle-Stabilized CO 2 Foams To Improve Volumetric Sweep Of CO 2 EOR Processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiCarlo, David; Huh, Chun; Johnston, Keith P.

2015-01-31

The goal of this project was to develop a new CO 2 injection enhanced oil recovery (CO 2-EOR) process using engineered nanoparticles with optimized surface coatings that has better volumetric sweep efficiency and a wider application range than conventional CO 2-EOR processes. The main objectives of this project were to (1) identify the characteristics of the optimal nanoparticles that generate extremely stable CO 2 foams in situ in reservoir regions without oil; (2) develop a novel method of mobility control using “self-guiding” foams with smart nanoparticles; and (3) extend the applicability of the new method to reservoirs having a widemore » range of salinity, temperatures, and heterogeneity. Concurrent with our experimental effort to understand the foam generation and transport processes and foam-induced mobility reduction, we also developed mathematical models to explain the underlying processes and mechanisms that govern the fate of nanoparticle-stabilized CO 2 foams in porous media and applied these models to (1) simulate the results of foam generation and transport experiments conducted in beadpack and sandstone core systems, (2) analyze CO 2 injection data received from a field operator, and (3) aid with the design of a foam injection pilot test. Our simulator is applicable to near-injection well field-scale foam injection problems and accounts for the effects due to layered heterogeneity in permeability field, foam stabilizing agents effects, oil presence, and shear-thinning on the generation and transport of nanoparticle-stabilized C/W foams. This report presents the details of our experimental and numerical modeling work and outlines the highlights of our findings.« less

Integrated, Geothermal-CO2 Storage: An Adaptable, Hybrid, Multi-Stage, Energy-Recovery Approach to Reduce Carbon Intensity and Environmental Risk

NASA Astrophysics Data System (ADS)

Buscheck, T. A.; Chen, M.; Lu, C.; Sun, Y.; Hao, Y.; Elliot, T. R.; Celia, M. A.; Bielicki, J. M.

2012-12-01

The challenges of mitigating climate change and generating sustainable renewable energy are inseparable and can be addressed by synergistic integration of geothermal energy production with secure geologic CO2 storage (GCS). Pressure buildup can be a limiting factor for GCS and geothermal reservoir operations, due to a number of concerns, including the potential for CO2 leakage and induced seismicity, while pressure depletion can limit geothermal energy recovery. Water-use demands can also be a limiting factor for GCS and geothermal operations, particularly where water resources are already scarce. Economic optimization of geothermal-GCS involves trade-offs of various benefits and risks, along with their associated costs: (1) heat extraction per ton of delivered CO2, (2) permanent CO2 storage, (3) energy recovery per unit well (and working-fluid recirculation) costs, and (4) economic lifetime of a project. We analyze a hybrid, multi-stage approach using both formation brine and injected CO2 as working fluids to attempt to optimize the benefits of sustainable energy production and permanent CO2 storage, while conserving water resources and minimizing environmental risks. We consider a range of well-field patterns and operational schemes. Initially, the fluid production is entirely brine. After CO2 breakthrough, the fraction of CO2 in production, which is called the CO2 "cut", increases with time. Thus, brine is the predominant working fluid for early time, with the contribution of CO2 to heat extraction increasing with CO2 cut (and time). We find that smaller well spacing between CO2 injectors and producers favors earlier CO2 breakthrough and a more rapid rise in CO2 cut, which increases the contribution of recirculated CO2, thereby improving the heat extraction per ton of delivered CO2. On the other hand, larger well spacing increases permanent CO2 storage, energy production per unit well cost, while reducing the thermal drawdown rate, which extends the economic lifetime of a project. For the range of cases considered, we were never able to eliminate the co-production of brine; thus, brine management is likely to be important for reservoir operations, whether or not brine is considered as a candidate working fluid. Future work will address site-specific reservoir conditions and infrastructure factors, such as proximity to potential CO2 sources. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Thermal effects on geologic carbon storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vilarrasa, Victor; Rutqvist, Jonny

One of the most promising ways to significantly reduce greenhouse gases emissions, while carbon-free energy sources are developed, is Carbon Capture and Storage (CCS). Non-isothermal effects play a major role in all stages of CCS. In this paper, we review the literature on thermal effects related to CCS, which is receiving an increasing interest as a result of the awareness that the comprehension of non-isothermal processes is crucial for a successful deployment of CCS projects. We start by reviewing CO 2 transport, which connects the regions where CO 2 is captured with suitable geostorage sites. The optimal conditions for COmore » 2 transport, both onshore (through pipelines) and offshore (through pipelines or ships), are such that CO 2 stays in liquid state. To minimize costs, CO 2 should ideally be injected at the wellhead in similar pressure and temperature conditions as it is delivered by transport. To optimize the injection conditions, coupled wellbore and reservoir simulators that solve the strongly non-linear problem of CO 2 pressure, temperature and density within the wellbore and non-isothermal two-phase flow within the storage formation have been developed. CO 2 in its way down the injection well heats up due to compression and friction at a lower rate than the geothermal gradient, and thus, reaches the storage formation at a lower temperature than that of the rock. Inside the storage formation, CO 2 injection induces temperature changes due to the advection of the cool injected CO 2, the Joule-Thomson cooling effect, endothermic water vaporization and exothermic CO 2 dissolution. These thermal effects lead to thermo-hydro-mechanical-chemical coupled processes with non-trivial interpretations. These coupled processes also play a relevant role in “Utilization” options that may provide an added value to the injected CO 2 , such as Enhanced Oil Recovery (EOR), Enhanced Coal Bed Methane (ECBM) and geothermal energy extraction combined with CO 2 storage. If the injected CO 2 leaks through faults, the caprock or wellbores, strong cooling will occur due to the expansion of CO 2 as pressure decreases with depth. Finally, we conclude by identifying research gaps and challenges of thermal effects related to CCS.« less

Thermal effects on geologic carbon storage

DOE PAGES

Vilarrasa, Victor; Rutqvist, Jonny

2016-12-27

One of the most promising ways to significantly reduce greenhouse gases emissions, while carbon-free energy sources are developed, is Carbon Capture and Storage (CCS). Non-isothermal effects play a major role in all stages of CCS. In this paper, we review the literature on thermal effects related to CCS, which is receiving an increasing interest as a result of the awareness that the comprehension of non-isothermal processes is crucial for a successful deployment of CCS projects. We start by reviewing CO 2 transport, which connects the regions where CO 2 is captured with suitable geostorage sites. The optimal conditions for COmore » 2 transport, both onshore (through pipelines) and offshore (through pipelines or ships), are such that CO 2 stays in liquid state. To minimize costs, CO 2 should ideally be injected at the wellhead in similar pressure and temperature conditions as it is delivered by transport. To optimize the injection conditions, coupled wellbore and reservoir simulators that solve the strongly non-linear problem of CO 2 pressure, temperature and density within the wellbore and non-isothermal two-phase flow within the storage formation have been developed. CO 2 in its way down the injection well heats up due to compression and friction at a lower rate than the geothermal gradient, and thus, reaches the storage formation at a lower temperature than that of the rock. Inside the storage formation, CO 2 injection induces temperature changes due to the advection of the cool injected CO 2, the Joule-Thomson cooling effect, endothermic water vaporization and exothermic CO 2 dissolution. These thermal effects lead to thermo-hydro-mechanical-chemical coupled processes with non-trivial interpretations. These coupled processes also play a relevant role in “Utilization” options that may provide an added value to the injected CO 2 , such as Enhanced Oil Recovery (EOR), Enhanced Coal Bed Methane (ECBM) and geothermal energy extraction combined with CO 2 storage. If the injected CO 2 leaks through faults, the caprock or wellbores, strong cooling will occur due to the expansion of CO 2 as pressure decreases with depth. Finally, we conclude by identifying research gaps and challenges of thermal effects related to CCS.« less

Bladder welding in rats using controlled temperature CO2 laser system.

PubMed

Lobik, L; Ravid, A; Nissenkorn, I; Kariv, N; Bernheim, J; Katzir, A

1999-05-01

Laser tissue welding has potential advantages over conventional suture closure of surgical wounds. It is a noncontact technique that introduces no foreign body and limits the possibility of infections and complications. The closure could be immediately watertight and the procedure may be less traumatic, faster and easier. In spite of these positives laser welding has not yet been approved for wide use. The problem in the clinical implementation of this technique arises from the difficulty in defining the conditions under which a highly reliable weld is formed. We have assumed that the successful welding of tissues depends on the ability to monitor and control the surface temperature during the procedure, thereby avoiding underheating or overheating. The purpose of this work was to develop a laser system for reliable welding of urinary tract tissues under good temperature control. We have developed a "smart" laser system that is capable of a dual role: transmitting CO2 laser power for tissue heating, and noncontact (radiometric) temperature monitoring and control. Bladder opening (cystotomy) was performed in 38 rats. Thirty-three animals underwent laser welding. In 5 rats (control group) the bladder wound was closed with one layer of continuous 6-0 dexon sutures. Reliable welding was obtained when the surface temperature was kept at 71 + 5C. Quality of weld was controlled immediately after operation. The rats were sacrificed on days 2, 10 and 30 for histological study. Bladder closure using the laser welding system was successful in 31/33 (94%) animals. Histological examination revealed an excellent welding and healing of the tissue. Efficiency of laser welding of urinary bladder in rats was confirmed by high survival rate and quality of scar that was demonstrated by clinical and histological examinations. In the future, optimal laser welding conditions will be studied in larger animals, using CO2 lasers and other lasers, with deeper radiation penetration into tissues.

Systematic Optimization of Battery Materials: Key Parameter Optimization for the Scalable Synthesis of Uniform, High-Energy, and High Stability LiNi0.6Mn0.2Co0.2O2 Cathode Material for Lithium-Ion Batteries.

PubMed

Ren, Dong; Shen, Yun; Yang, Yao; Shen, Luxi; Levin, Barnaby D A; Yu, Yingchao; Muller, David A; Abruña, Héctor D

2017-10-18

Ni-rich LiNi x Mn y Co 1-x-y O 2 (x > 0.5) (NMC) materials have attracted a great deal of interest as promising cathode candidates for Li-ion batteries due to their low cost and high energy density. However, several issues, including sensitivity to moisture, difficulty in reproducibly preparing well-controlled morphology particles and, poor cyclability, have hindered their large scale deployment; especially for electric vehicle (EV) applications. In this work, we have developed a uniform, highly stable, high-energy density, Ni-rich LiNi 0.6 Mn 0.2 Co 0.2 O 2 cathode material by systematically optimizing synthesis parameters, including pH, stirring rate, and calcination temperature. The particles exhibit a spherical morphology and uniform size distribution, with a well-defined structure and homogeneous transition-metal distribution, owing to the well-controlled synthesis parameters. The material exhibited superior electrochemical properties, when compared to a commercial sample, with an initial discharge capacity of 205 mAh/g at 0.1 C. It also exhibited a remarkable rate capability with discharge capacities of 157 mAh/g and 137 mAh/g at 10 and 20 C, respectively, as well as high tolerance to air and moisture. In order to demonstrate incorporation into a commercial scale EV, a large-scale 4.7 Ah LiNi 0.6 Mn 0.2 Co 0.2 O 2 Al-full pouch cell with a high cathode loading of 21.6 mg/cm 2 , paired with a graphite anode, was fabricated. It exhibited exceptional cyclability with a capacity retention of 96% after 500 cycles at room temperature. This material, which was obtained by a fully optimized scalable synthesis, delivered combined performance metrics that are among the best for NMC materials reported to date.

Estimating the CO2 mitigation potential of horizontal Ground Source Heat Pumps in the UK

NASA Astrophysics Data System (ADS)

Garcia-Gonzalez, R.; Verhoef, A.; Vidale, P. L.; Gan, G.; Chong, A.; Clark, D.

2012-04-01

By 2020, the UK will need to generate 15% of its energy from renewables to meet our contribution to the EU renewable energy target. Heating and cooling systems of buildings account for 30%-50% of the global energy consumption; thus, alternative low-carbon technologies such as horizontal Ground Couple Heat Pumps (GCHPs) can contribute to the reduction of anthropogenic CO2 emissions. Horizontal GCHPs currently represent a small fraction of the total energy generation in the UK. However, the fact that semi-detached and detached dwellings represent approximately 40% of the total housing stocks in the UK could make the widespread implementation of this technology particularly attractive in the UK and so could significantly increase its renewable energy generation potential. Using a simulation model, we analysed the dynamic interactions between the environment, the horizontal GCHP heat exchanger and typical UK dwellings, as well as their combined effect on heat pump performance and CO2 mitigation potential. For this purpose, a land surface model (JULES, Joint UK Land Environment Simulator), which calculates coupled soil heat and water fluxes, was combined with a heat extraction model. The analyses took into account the spatio-temporal variability of soil properties (thermal and hydraulic) and meteorological variables, as well as different horizontal GCHP configurations and a variety of building loads and heat demands. Sensitivity tests were performed for four sites in the UK with different climate and soil properties. Our results show that an installation depth of 1.0m would give us higher heat extractions rates, however it would be preferable to install the pipes slightly deeper to avoid the seasonal influence of variable meteorological conditions. A value of 1.5m for the spacing between coils (S) for a slinky configuration type is recommended to avoid thermal disturbances between neighbouring coils. We also found that for larger values of the spacing between the coils (S > 2), a slinky coil diameter (D) of 0.8m might be a better choice in terms of heat extraction rate. The fluid temperature of the pipe had a direct effect on the heat extraction rates of the system. The coefficient of performance of a heat pump did not remain constant and depended on the operating conditions and outdoor temperatures. The outcomes of this study will allow us to give recommendations to installers and relevant government bodies concerning the optimal configuration of future installations of horizontal GCHPs at UK developments. Finally, long-term simulations with the coupled JULES-GCHP model, using high resolution (1 km) meteorological (historical and projected data), soil physical and land cover data over the entire UK-domain, will allow us to explore the effect that global warming will have on future surface and soil temperatures, as well as soil moisture contents, and therefore its impact on the energy demand of the buildings and the CO2 mitigation potential of this type of renewable energy.

Two Hop Adaptive Vector Based Quality Forwarding for Void Hole Avoidance in Underwater WSNs

PubMed Central

Javaid, Nadeem; Ahmed, Farwa; Wadud, Zahid; Alrajeh, Nabil; Alabed, Mohamad Souheil; Ilahi, Manzoor

2017-01-01

Underwater wireless sensor networks (UWSNs) facilitate a wide range of aquatic applications in various domains. However, the harsh underwater environment poses challenges like low bandwidth, long propagation delay, high bit error rate, high deployment cost, irregular topological structure, etc. Node mobility and the uneven distribution of sensor nodes create void holes in UWSNs. Void hole creation has become a critical issue in UWSNs, as it severely affects the network performance. Avoiding void hole creation benefits better coverage over an area, less energy consumption in the network and high throughput. For this purpose, minimization of void hole probability particularly in local sparse regions is focused on in this paper. The two-hop adaptive hop by hop vector-based forwarding (2hop-AHH-VBF) protocol aims to avoid the void hole with the help of two-hop neighbor node information. The other protocol, quality forwarding adaptive hop by hop vector-based forwarding (QF-AHH-VBF), selects an optimal forwarder based on the composite priority function. QF-AHH-VBF improves network good-put because of optimal forwarder selection. QF-AHH-VBF aims to reduce void hole probability by optimally selecting next hop forwarders. To attain better network performance, mathematical problem formulation based on linear programming is performed. Simulation results show that by opting these mechanisms, significant reduction in end-to-end delay and better throughput are achieved in the network. PMID:28763014

Two Hop Adaptive Vector Based Quality Forwarding for Void Hole Avoidance in Underwater WSNs.

PubMed

Javaid, Nadeem; Ahmed, Farwa; Wadud, Zahid; Alrajeh, Nabil; Alabed, Mohamad Souheil; Ilahi, Manzoor

2017-08-01

Underwater wireless sensor networks (UWSNs) facilitate a wide range of aquatic applications in various domains. However, the harsh underwater environment poses challenges like low bandwidth, long propagation delay, high bit error rate, high deployment cost, irregular topological structure, etc. Node mobility and the uneven distribution of sensor nodes create void holes in UWSNs. Void hole creation has become a critical issue in UWSNs, as it severely affects the network performance. Avoiding void hole creation benefits better coverage over an area, less energy consumption in the network and high throughput. For this purpose, minimization of void hole probability particularly in local sparse regions is focused on in this paper. The two-hop adaptive hop by hop vector-based forwarding (2hop-AHH-VBF) protocol aims to avoid the void hole with the help of two-hop neighbor node information. The other protocol, quality forwarding adaptive hop by hop vector-based forwarding (QF-AHH-VBF), selects an optimal forwarder based on the composite priority function. QF-AHH-VBF improves network good-put because of optimal forwarder selection. QF-AHH-VBF aims to reduce void hole probability by optimally selecting next hop forwarders. To attain better network performance, mathematical problem formulation based on linear programming is performed. Simulation results show that by opting these mechanisms, significant reduction in end-to-end delay and better throughput are achieved in the network.

High-Power DFB Diode Laser-Based CO-QEPAS Sensor: Optimization and Performance.

PubMed

Ma, Yufei; Tong, Yao; He, Ying; Yu, Xin; Tittel, Frank K

2018-01-04

A highly sensitive carbon monoxide (CO) trace gas sensor based on quartz-enhanced photoacoustic spectroscopy (QEPAS) was demonstrated. A high-power distributed feedback (DFB), continuous wave (CW) 2.33 μm diode laser with an 8.8 mW output power was used as the QEPAS excitation source. By optimizing the modulation depth and adding an optimum micro-resonator, compared to a bare quartz tuning fork (QTF), a 10-fold enhancement of the CO-QEPAS signal amplitude was achieved. When water vapor acting as a vibrational transfer catalyst was added to the target gas, the signal was further increased by a factor of ~7. A minimum detection limit (MDL) of 11.2 ppm and a calculated normalized noise equivalent absorption (NNEA) coefficient of 1.8 × 10 -5 cm -1 W/√Hz were obtained for the reported CO-QEPAS sensor.

High-Power DFB Diode Laser-Based CO-QEPAS Sensor: Optimization and Performance

PubMed Central

Ma, Yufei; Tong, Yao; He, Ying; Yu, Xin

2018-01-01

A highly sensitive carbon monoxide (CO) trace gas sensor based on quartz-enhanced photoacoustic spectroscopy (QEPAS) was demonstrated. A high-power distributed feedback (DFB), continuous wave (CW) 2.33 μm diode laser with an 8.8 mW output power was used as the QEPAS excitation source. By optimizing the modulation depth and adding an optimum micro-resonator, compared to a bare quartz tuning fork (QTF), a 10-fold enhancement of the CO-QEPAS signal amplitude was achieved. When water vapor acting as a vibrational transfer catalyst was added to the target gas, the signal was further increased by a factor of ~7. A minimum detection limit (MDL) of 11.2 ppm and a calculated normalized noise equivalent absorption (NNEA) coefficient of 1.8 × 10−5 cm−1W/√Hz were obtained for the reported CO-QEPAS sensor. PMID:29300310

First Novozym 435 lipase-catalyzed Morita-Baylis-Hillman reaction in the presence of amides.

PubMed

Tian, Xuemei; Zhang, Suoqin; Zheng, Liangyu

2016-03-01

The first Novozym 435 lipase-catalyzed Morita-Baylis-Hillman (MBH) reaction with amides as co-catalyst was realized. Results showed that neither Novozym 435 nor amide can independently catalyze the reaction. This co-catalytic system that used a catalytic amount of Novozym 435 with a corresponding amount of amide was established and optimized. The MBH reaction strongly depended on the structure of aldehyde substrate, amide co-catalyst, and reaction additives. The optimized reaction yield (43.4%) was achieved in the Novozym 435-catalyzed MBH reaction of 2, 4-dinitrobenzaldehyde and cyclohexenone with isonicotinamide as co-catalyst and β-cyclodextrin as additive only in 2 days. Although enantioselectivity of Novozym 435 was not found, the results were still significant because an MBH reaction using lipase as biocatalyst was realized for the first time. Copyright © 2015 Elsevier Inc. All rights reserved.

SP70-alpha-benzoin oxime chelating resin for preconcentration-separation of Pb(II), Cd(II), Co(II) and Cr(III) in environmental samples.

PubMed

Narin, Ibrahim; Surme, Yavuz; Bercin, Erdogan; Soylak, Mustafa

2007-06-25

In the presented work, alpha-benzoin oxime immobilized SP70 chelating resin was synthesized for separation and preconcentration of Pb(II), Cd(II), Co(II) and Cr(III). The optimization procedure for analytical parameters including pH, eluent type, flow rate, etc. was examined in order to gain quantitative recoveries of analyte ions. The effects of foreign ions on the recoveries of studied metal ions were also investigated. The detection limits (3sigma) were found to be 16.0, 4.2, 1.3, 2.4microgL(-1) for Pb, Cd, Co and Cr, respectively. The preconcentration factor was 75 for Pb, 100 for Cd, Co and Cr. The optimized method was validated with certified reference materials and successfully applied to the waters, crops and pharmaceutical samples with good results (recoveries greater than 95%, R.S.D. lower than 10%).

Predicting the ultimate potential of natural gas SOFC power cycles with CO2 capture - Part B: Applications

NASA Astrophysics Data System (ADS)

Campanari, Stefano; Mastropasqua, Luca; Gazzani, Matteo; Chiesa, Paolo; Romano, Matteo C.

2016-09-01

An important advantage of solid oxide fuel cells (SOFC) as future systems for large scale power generation is the possibility of being efficiently integrated with processes for CO2 capture. Focusing on natural gas power generation, Part A of this work assessed the performances of advanced pressurised and atmospheric plant configurations (SOFC + GT and SOFC + ST, with fuel cell integration within a gas turbine or a steam turbine cycle) without CO2 separation. This Part B paper investigates such kind of power cycles when applied to CO2 capture, proposing two ultra-high efficiency plant configurations based on advanced intermediate-temperature SOFCs with internal reforming and low temperature CO2 separation process. The power plants are simulated at the 100 MW scale with a set of realistic assumptions about FC performances, main components and auxiliaries, and show the capability of exceeding 70% LHV efficiency with high CO2 capture (above 80%) and a low specific primary energy consumption for the CO2 avoided (1.1-2.4 MJ kg-1). Detailed results are presented in terms of energy and material balances, and a sensitivity analysis of plant performance is developed vs. FC voltage and fuel utilisation to investigate possible long-term improvements. Options for further improvement of the CO2 capture efficiency are also addressed.

Esophageal incisions repair by CO2 laser soldering.

PubMed

Nageris, Ben I; Zilker, Zeev; Zilker, Maya; Kariv, Noam; Feinmesser, Rafael; Katzir, Abraham

2004-12-01

This study evaluated the feasibility of fiberoptic CO2 laser soldering for the repair of esophageal injuries under tight temperature feedback control in an animal model. Healing was compared to conventional suture closure. A CO2 soldering system equipped with infrared transmitting silver halide fibers was used. The soldered tissue temperature was monitored continuously, and laser power was adjusted to provide constant temperature. The procedure was done with 50% bovine serum albumin solder. Longitudinal incisions measuring 8 to 10 mm were made under general anesthesia in the cervical esophagus of 25 rats. Twenty rats (group I) underwent laser tissue bonding; 8 of which were tested in a preliminary study to determine optimal laser parameters. In the remaining 5 rats (group II, controls), closure was performed with 1 layer of 6/0 Vicryl sutures. The rats were sacrificed 2, 3, 4, and 6 weeks postoperatively, and the esophagus was examined histologically. Optimal temperature was found to be 65 to 70 degrees C and optimal exposure time, 150 to 200 seconds. Laser soldering was successful in 9 of the 12 rats (75%) treated under optimal settings; suturing was successful in 4 of the 5 control rats (80%). There were no significant differences between the groups in healing or complication rates. These results indicate that the CO2 laser soldering technique is a valid option for the correction of esophageal tears or incisions in rats. The confirmation and extension of these findings in further studies with larger animals may ultimately lead to the routine in vivo use of temperature-controlled laser repair for the esophagus and other organs. This method lends itself to endoscopic bonding of tissues.

Non elective re-admissions to an acute hospital in people with diabetes: Causes and the potential for avoidance. The WICKED project.

PubMed

Gillani, Syed M R; Aziz, Umaira; Blundell, David; Singh, Baldev M

2015-10-01

Managing people with diabetes is a health priority worldwide. Cost benefit attempts at avoiding non elective admissions (NEA) have had some success. To develop an NEA avoidance service, we audited multiple NEA in those with diabetes. All people with diabetes who had ≥3 NEA to our hospital over 12 months were identified (n=418); 104 (1 in 4) patients were randomly selected and retrospective data collected in 98 subjects on their index (latest, 3rd) admission. Of 98 subjects (50 males, 60 Caucasians, 86 type 2 diabetes, aged 69±16 years).Conditions contributing to admission included: Significant co-morbidities in 95 patients (≥2 in 57, ≥4 in 24). Only 14 admission were directly due to diabetes: hypoglycaemia (5); hyperglycaemia (6); DKA (2), Infected foot ulcer (1).97 admissions were justified at the time of presentation. However whilst 78 were unavoidable, 19 were deemed avoidable amongst whom 10 were diabetes related. The majority of re-admissions were due to multi-morbidity and were often non-diabetes related. The concept of avoidability must be distinguished from point justification at the time of acute need. This would allow the prospective identification of high risk patients and requires an integrated working process to avoid NEA. Copyright © 2015 Primary Care Diabetes Europe. Published by Elsevier Ltd. All rights reserved.

CO2 hydrate formation and dissociation in cooled porous media: a potential technology for CO2 capture and storage.

PubMed

Yang, Mingjun; Song, Yongchen; Jiang, Lanlan; Zhu, Ningjun; Liu, Yu; Zhao, Yuechao; Dou, Binlin; Li, Qingping

2013-09-03

The purpose of this study was to investigate the hydrate formation and dissociation with CO2 flowing through cooled porous media at different flow rates, pressures, temperatures, and flow directions. CO2 hydrate saturation was quantified using the mean intensity of water. The experimental results showed that the hydrate block appeared frequently, and it could be avoided by stopping CO2 flooding early. Hydrate formed rapidly as the temperature was set to 274.15 or 275.15 K, but the hydrate formation delayed when it was 276.15 K. The flow rate was an important parameter for hydrate formation; a too high or too low rate was not suitable for CO2 hydration formation. A low operating pressure was also unacceptable. The gravity made hydrate form easily in the vertically upward flow direction. The pore water of the second cycle converted to hydrate more completely than that of the first cycle, which was a proof of the hydrate "memory effect". When the pressure was equal to atmospheric pressure, hydrate did not dissociate rapidly and abundantly, and a long time or reduplicate depressurization should be used in industrial application.

Process Optimization Assessment: Fort Leonard Wood, MO and Fort Carson, CO

DTIC Science & Technology

2003-11-01

IUJ US Army Corps of Engineers, Engineer Research and Development Center Process Optimization Assessment Fort Leonard Wood, MO and Fort Carson, CO... Optimization Assessment: Fort Leonard Wood, MO and Fort Carson, CO Mike C.J. Lin and John Vavrin Construction Engineering Research Laboratory PO Box 9005...work performed a Process Optimization Assessment (POA) on behalf of Fort Leonard Wood, MO and Fort Carson, CO to identify process, energy, and

Carbon source-sink limitations differ between two species with contrasting growth strategies.

PubMed

Burnett, Angela C; Rogers, Alistair; Rees, Mark; Osborne, Colin P

2016-11-01

Understanding how carbon source and sink strengths limit plant growth is a critical knowledge gap that hinders efforts to maximize crop yield. We investigated how differences in growth rate arise from source-sink limitations, using a model system comparing a fast-growing domesticated annual barley (Hordeum vulgare cv. NFC Tipple) with a slow-growing wild perennial relative (Hordeum bulbosum). Source strength was manipulated by growing plants at sub-ambient and elevated CO 2 concentrations ([CO 2 ]). Limitations on vegetative growth imposed by source and sink were diagnosed by measuring relative growth rate, developmental plasticity, photosynthesis and major carbon and nitrogen metabolite pools. Growth was sink limited in the annual but source limited in the perennial. RGR and carbon acquisition were higher in the annual, but photosynthesis responded weakly to elevated [CO 2 ] indicating that source strength was near maximal at current [CO 2 ]. In contrast, photosynthetic rate and sink development responded strongly to elevated [CO 2 ] in the perennial, indicating significant source limitation. Sink limitation was avoided in the perennial by high sink plasticity: a marked increase in tillering and root:shoot ratio at elevated [CO 2 ], and lower non-structural carbohydrate accumulation. Alleviating sink limitation during vegetative development could be important for maximizing growth of elite cereals under future elevated [CO 2 ]. © 2016 John Wiley & Sons Ltd.

Highly Active and Selective Hydrogenation of CO2 to Ethanol by Ordered Pd-Cu Nanoparticles.

PubMed

Bai, Shuxing; Shao, Qi; Wang, Pengtang; Dai, Qiguang; Wang, Xingyi; Huang, Xiaoqing

2017-05-24

Carbon dioxide (CO 2 ) hydrogenation to ethanol (C 2 H 5 OH) is considered a promising way for CO 2 conversion and utilization, whereas desirable conversion efficiency remains a challenge. Herein, highly active, selective and stable CO 2 hydrogenation to C 2 H 5 OH was enabled by highly ordered Pd-Cu nanoparticles (NPs). By tuning the composition of the Pd-Cu NPs and catalyst supports, the efficiency of CO 2 hydrogenation to C 2 H 5 OH was well optimized with Pd 2 Cu NPs/P25 exhibiting high selectivity to C 2 H 5 OH of up to 92.0% and the highest turnover frequency of 359.0 h -1 . Diffuse reflectance infrared Fourier transform spectroscopy results revealed the high C 2 H 5 OH production and selectivity of Pd 2 Cu NPs/P25 can be ascribed to boosting *CO (adsorption CO) hydrogenation to *HCO, the rate-determining step for the CO 2 hydrogenation to C 2 H 5 OH.

[Intraoperative monitoring in artificial respiration of premature and newborn infants. I. Monitoring of respiratory parameters and alveolar ventilation].

PubMed

Lenz, G; Heipertz, W; Leidig, E; Madee, S

1986-06-01

Monitoring of ventilation serves to ensure adequate alveolar ventilation and arterial oxygenation, and to avoid pulmonary damage due to mechanical ventilation. Basic clinical monitoring, i.e., inspection, auscultation (including precordial or oesophageal stethoscope) and monitoring of heart rate and blood pressure, is mandatory. Mechanical ventilation is monitored by ventilation pressures (peak pressure, plateau pressure and endexpiratory pressure), ventilation volumes (measured at the in/expiratory valve of the respirator and by hot-wire anemometry at the tube connector), ventilation rate, and inspiratory oxygen concentration (FiO2). Alveolar ventilation should be continuously and indirectly recorded by capnometry (pECO2) and by measurement of transcutaneous pCO2 (tcpCO2), whereas oxygenation is determined via measurement of transcutaneous pO2 (tcpO2). Invasive monitoring of gas exchange is essential in prolonged or intrathoracic interventions as well as in neonates with cardiopulmonary problems. paCO2 may be estimated by capillary or venous blood gas analysis; arterial blood gas analysis is required for exact determination of paCO2 as well as arteriocutaneous pCO2 (atcDCO2) and arterio-end-expiratory (aEDCO2) gradients.

Fast 2D FWI on a multi and many-cores workstation.

NASA Astrophysics Data System (ADS)

Thierry, Philippe; Donno, Daniela; Noble, Mark

2014-05-01

Following the introduction of x86 co-processors (Xeon Phi) and the performance increase of standard 2-socket workstations using the latest 12 cores E5-v2 x86-64 CPU, we present here a MPI + OpenMP implementation of an acoustic 2D FWI (full waveform inversion) code which simultaneously runs on the CPUs and on the co-processors installed in a workstation. The main advantage of running a 2D FWI on a workstation is to be able to quickly evaluate new features such as more complicated wave equations, new cost functions, finite-difference stencils or boundary conditions. Since the co-processor is made of 61 in-order x86 cores, each of them having up to 4 threads, this many-core can be seen as a shared memory SMP (symmetric multiprocessing) machine with its own IP address. Depending on the vendor, a single workstation can handle several co-processors making the workstation as a personal cluster under the desk. The original Fortran 90 CPU version of the 2D FWI code is just recompiled to get a Xeon Phi x86 binary. This multi and many-core configuration uses standard compilers and associated MPI as well as math libraries under Linux; therefore, the cost of code development remains constant, while improving computation time. We choose to implement the code with the so-called symmetric mode to fully use the capacity of the workstation, but we also evaluate the scalability of the code in native mode (i.e running only on the co-processor) thanks to the Linux ssh and NFS capabilities. Usual care of optimization and SIMD vectorization is used to ensure optimal performances, and to analyze the application performances and bottlenecks on both platforms. The 2D FWI implementation uses finite-difference time-domain forward modeling and a quasi-Newton (with L-BFGS algorithm) optimization scheme for the model parameters update. Parallelization is achieved through standard MPI shot gathers distribution and OpenMP for domain decomposition within the co-processor. Taking advantage of the 16 GB of memory available on the co-processor we are able to keep wavefields in memory to achieve the gradient computation by cross-correlation of forward and back-propagated wavefields needed by our time-domain FWI scheme, without heavy traffic on the i/o subsystem and PCIe bus. In this presentation we will also review some simple methodologies to determine performance expectation compared to real performances in order to get optimization effort estimation before starting any huge modification or rewriting of research codes. The key message is the ease of use and development of this hybrid configuration to reach not the absolute peak performance value but the optimal one that ensures the best balance between geophysical and computer developments.

Performance evaluation of a slow-release packing material-embedded functional microorganisms for biofiltration.

PubMed

Zhu, Rencheng; Li, Shunyi; Wu, Zhenjun; Dumont, Éric

2017-04-01

A composite packing material (CM-5) was prepared in this study, mainly consisting of compost with functional microorganisms, calcium carbonate (CaCO 3 ), perlite, cement and plant fiber. To get stronger compressive strength, mass ratios of these components were optimized based on single factor experiments, and finally adding amounts of perlite, cement, plant fiber, CaCO 3 , compost and binder at 18%, 18%, 7%, 13%, 17% and 27%, respectively. According to the optimum proportion, CM-5 was extruded in cylindrical shape (12 mm in diameter and 20 mm in length) with a bulk density of 470 kg m -3 , a moisture retention capacity of 49% and the microbial counts of × 10 5 CFU g -1 of packing material. The cumulative release rates of total organic carbon (TOC) and total nitrogen (TN) from CM-5 were 3.1% and 6.5%, respectively, after 19 times extraction in distilled water. To evaluate the H 2 S removal capacity, CM-5 was compared with an organic (corncob) and an inorganic (ceramsite) packing material in three biofilters. The results showed that CM-5 had higher H 2 S removal capacity compared with corncob and ceramsite. CM-5 could avoid the large fluctuation of pH value and pressure drop during the operation. The maximum H 2 S removal capacity of CM-5 was 12.9 g m -3  h -1 and the removal efficiency could maintain over 95.4% when the inlet H 2 S loading rate was lower than 11.3 g m -3  h -1 without any addition of nutrients and pH buffer substances. Besides, only 2-3 days were needed for the recovery of biofiltration performance after about two weeks of idle period.

Supercritical Carbon Dioxide Extraction of Flavonoids from Pomelo (Citrus grandis (L.) Osbeck) Peel and Their Antioxidant Activity

PubMed Central

He, Jin-Zhe; Shao, Ping; Liu, Jian-Hua; Ru, Qiao-Mei

2012-01-01

Supercritical carbon dioxide (SC-CO2) extraction of flavonoids from pomelo (Citrus grandis (L.) Osbeck) peel and their antioxidant activity were investigated. Box-Behnken design combined with response surface methodology was employed to maximize the extraction yield of flavonoids. Correlation analysis of the mathematical-regression model indicated that a quadratic polynomial model could be used to optimize the SC-CO2 extraction of flavonoids. The optimal conditions for obtaining the highest extraction yield of flavonoids from pomelo peel were a temperature of 80 °C, a pressure of 39 MPa and a static extraction time of 49 min in the presence of 85% ethanol as modifier. Under these conditions, the experimental yield was 2.37%, which matched positively with the value predicted by the model. Furthermore, flavonoids obtained by SC-CO2 extraction showed a higher scavenging activity on hydroxyl, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radicals than those obtained by conventional solvent extraction (CSE). Therefore, SC-CO2 extraction can be considered as a suitable technique for the obtainment of flavonoids from pomelo peel. PMID:23202938

Healthy young adults implement distinctive avoidance strategies while walking and circumventing virtual human vs. non-human obstacles in a virtual environment.

PubMed

Souza Silva, Wagner; Aravind, Gayatri; Sangani, Samir; Lamontagne, Anouk

2018-03-01

This study examines how three types of obstacles (cylinder, virtual human and virtual human with footstep sounds) affect circumvention strategies of healthy young adults. Sixteen participants aged 25.2 ± 2.5 years (mean ± 1SD) were tested while walking overground and viewing a virtual room through a helmet mounted display. As participants walked towards a stationary target in the far space, they avoided an obstacle (cylinder or virtual human) approaching either from the right (+40°), left (-40°) or head-on (0°). Obstacle avoidance strategies were characterized using the position and orientation of the head. Repeated mixed model analysis showed smaller minimal distances (p = 0.007) while avoiding virtual humans as compared to cylinders. Footstep sounds added to virtual humans did not modify (p = 0.2) minimal distances compared to when no sound was provided. Onset times of avoidance strategies were similar across conditions (p = 0.06). Results indicate that the nature of the obstacle (human-like vs. non-human object) matters and can modify avoidance strategies. Smaller obstacle clearances in response to virtual humans may reflect the use of a less conservative avoidance strategy, due to a resemblance of obstacles to pedestrians and a recall of strategies used in daily locomotion. The lack of influence of footstep sounds supports the fact that obstacle avoidance primarily relies on visual cues and the principle of 'inverse effectiveness' whereby multisensory neurons' response to multimodal stimuli becomes weaker when the unimodal sensory stimulus (vision) is strong. Present findings should be taken into consideration to optimize the ecological validity of VR-based obstacle avoidance paradigms used in research and rehabilitation. Copyright © 2018 Elsevier B.V. All rights reserved.

CO(2) incorporation in hydroxide and hydroperoxide containing water clusters--a unifying mechanism for hydrolysis and protolysis.

PubMed

Ryding, Mauritz J; Uggerud, Einar

2014-05-28

The reactions of CO2 with anionic water clusters containing hydroxide, OH(-)(H2O)n, and hydroperoxide, HO2(-)(H2O)n, have been studied in the isolated state using a mass spectrometric technique. The OH(-)(H2O)n clusters were found to react faster for n = 2,3, while for n >3 the HO2(-)(H2O)n clusters are more reactive. Insights from quantum chemical calculations revealed a common mechanism in which the decisive bicarbonate-forming step starts from a pre-reaction complex where OH(-) and CO2 are separated by one water molecule. Proton transfer from the water molecule to OH(-) then effectively moves the hydroxide ion motif next to the CO2 molecule. A new covalent bond is formed between CO2 and the emerging OH(-) in concert with the proton transfer. For larger clusters, successive proton transfers from H2O molecules to neighbouring OH(-) are required to effectively bring about the formation of the pre-reaction complex, upon which bicarbonate formation is accomplished according to the concerted mechanism. In this manner, a general mechanism is suggested, also applicable to bulk water and thereby to CO2 uptake in oceans. Furthermore, this mechanism avoids the intermediate H2CO3 by combining the CO2 hydrolysis step and the protolysis step into one. The general mechanistic picture is consistent with low enthalpy barriers and that the limiting factors are largely of entropic nature.

Microscopic, Transport and Thermodynamic properties of Ca10(Pt3As8)((Fe1-xTMx)2As2)5 (TM=Co, Ni) single crystals

NASA Astrophysics Data System (ADS)

Jiang, Shan; Ni, Ni

2015-03-01

Here we report detailed microscopic, transport and thermodynamic measurements on two series of high quality single crystals Ca10(Pt3As8)((Fe1-xTMx)2As2)5 (TM=Co, Ni). With electron doping on Fe sites, the structural/magnetic phase transitions in the parent compound were suppressed at a rate of roughly -7K per 0.01Co doping and -9K per 0.01Ni doping. Superconductivity emerges in the region of 0 . 048 < x < 0 . 20 for Co doping with optimal Tc of 13.5K (x = 0 . 11) while it occurs in the region of 0 . 035 < x < 0 . 11 for Ni doping with optimal Tc of 9.6K (x = 0 . 064). No coexistence of AFM and SC is observed, which is different from the well-studied 122 Fe-pnictides but reminiscent the one of La1111. The comparison of the effect between Co- and Ni- doping on 10-3-8 shows that rigid band approximation is likely working for these two dopants in this superconducting family.

A terrestrial biosphere model optimized to atmospheric CO2 concentration and above ground woody biomass

NASA Astrophysics Data System (ADS)

Saito, M.; Ito, A.; Maksyutov, S. S.

2013-12-01

This study documents an optimization of a prognostic biosphere model (VISIT; Vegetation Integrative Similator for Trace gases) to observations of atmospheric CO2 concentration and above ground woody biomass by using a Bayesian inversion method combined with an atmospheric tracer transport model (NIES-TM; National Institute for Environmental Studies / Frontier Research Center for Global Change (NIES/FRCGC) off-line global atmospheric tracer transport model). The assimilated observations include 74 station records of surface atmospheric CO2 concentration and aggregated grid data sets of above ground woody biomass (AGB) and net primary productivity (NPP) over the globe. Both the biosphere model and the atmospheric transport model are used at a horizontal resolution of 2.5 deg x 2.5 deg grid with temporal resolutions of a day and an hour, respectively. The atmospheric transport model simulates atmospheric CO2 concentration with nine vertical levels using daily net ecosystem CO2 exchange rate (NEE) from the biosphere model, oceanic CO2 flux, and fossil fuel emission inventory. The models are driven by meteorological data from JRA-25 (Japanese 25-year ReAnalysis) and JCDAS (JMA Climate Data Assimilation System). Statistically optimum physiological parameters in the biosphere model are found by iterative minimization of the corresponding Bayesian cost function. We select thirteen physiological parameter with high sensitivity to NEE, NPP, and AGB for the minimization. Given the optimized physiological parameters, the model shows error reductions in seasonal variation of the CO2 concentrations especially in the northern hemisphere due to abundant observation stations, while errors remain at a few stations that are located in coastal coastal area and stations in the southern hemisphere. The model also produces moderate estimates of the mean magnitudes and probability distributions in AGB and NPP for each biome. However, the model fails in the simulation of the terrestrial vegetation compositions in some grids. These misfits are assumed to derive from simplified representation in the biosphere model without the impact of land use change and dire disturbance and the seasonal variability in the physiological parameters.

AOM optimization with ultra stable high power CO2 lasers for fast laser engraving

NASA Astrophysics Data System (ADS)

Bohrer, Markus

2015-05-01

A new ultra stable CO2 laser in carbon fibre resonator technology with an average power of more than 600W has been developed especially as basis for the use with AOMs. Stability of linear polarisation and beam pointing stability are important issues as well as appropriate shaping of the incident beam. AOMs are tested close to the laser-induced damage threshold with pulses on demand close to one megahertz. Transversal and rotational optimization of the AOMs benefits from the parallel-kinematic principle of a hexapod used for this research.

Synthesis and magnetic properties of cobalt-iron/cobalt-ferrite soft/hard magnetic core/shell nanowires

NASA Astrophysics Data System (ADS)

Leandro Londoño-Calderón, César; Moscoso-Londoño, Oscar; Muraca, Diego; Arzuza, Luis; Carvalho, Peterson; Pirota, Kleber Roberto; Knobel, Marcelo; Pampillo, Laura Gabriela; Martínez-García, Ricardo

2017-06-01

A straightforward method for the synthesis of CoFe2.7/CoFe2O4 core/shell nanowires is described. The proposed method starts with a conventional pulsed electrodeposition procedure on alumina nanoporous template. The obtained CoFe2.7 nanowires are released from the template and allowed to oxidize at room conditions over several weeks. The effects of partial oxidation on the structural and magnetic properties were studied by x-ray spectrometry, magnetometry, and scanning and transmission electron microscopy. The results indicate that the final nanowires are composed of 5 nm iron-cobalt alloy nanoparticles. Releasing the nanowires at room conditions promoted surface oxidation of the nanoparticles and created a CoFe2O4 shell spinel-like structure. The shell avoids internal oxidation and promotes the formation of bi-magnetic soft/hard magnetic core/shell nanowires. The magnetic properties of both the initial single-phase CoFe2.7 nanowires and the final core/shell nanowires, reveal that the changes in the properties from the array are due to the oxidation more than effects associated with released processes (disorder and agglomeration).

Synthesis and magnetic properties of cobalt-iron/cobalt-ferrite soft/hard magnetic core/shell nanowires.

PubMed

Londoño-Calderón, César Leandro; Moscoso-Londoño, Oscar; Muraca, Diego; Arzuza, Luis; Carvalho, Peterson; Pirota, Kleber Roberto; Knobel, Marcelo; Pampillo, Laura Gabriela; Martínez-García, Ricardo

2017-06-16

A straightforward method for the synthesis of CoFe 2.7 /CoFe 2 O 4 core/shell nanowires is described. The proposed method starts with a conventional pulsed electrodeposition procedure on alumina nanoporous template. The obtained CoFe 2.7 nanowires are released from the template and allowed to oxidize at room conditions over several weeks. The effects of partial oxidation on the structural and magnetic properties were studied by x-ray spectrometry, magnetometry, and scanning and transmission electron microscopy. The results indicate that the final nanowires are composed of 5 nm iron-cobalt alloy nanoparticles. Releasing the nanowires at room conditions promoted surface oxidation of the nanoparticles and created a CoFe 2 O 4 shell spinel-like structure. The shell avoids internal oxidation and promotes the formation of bi-magnetic soft/hard magnetic core/shell nanowires. The magnetic properties of both the initial single-phase CoFe 2.7 nanowires and the final core/shell nanowires, reveal that the changes in the properties from the array are due to the oxidation more than effects associated with released processes (disorder and agglomeration).

Evaluation of the impact of H2O, O2, and SO2 on postcombustion CO2 capture in metal-organic frameworks.

PubMed

Yu, Jiamei; Ma, Yuguang; Balbuena, Perla B

2012-05-29

Molecular modeling methods are used to estimate the influence of impurity species: water, O(2), and SO(2) in flue gas mixtures present in postcombustion CO(2) capture using a metal organic framework, HKUST-1, as a model sorbent material. Coordinated and uncoordinated water effects on CO(2) capture are analyzed. Increase of CO(2) adsorption is observed for both cases, which can be attributed to the enhanced binding energy between CO(2) and HKUST-1 due to the introduction of a small amount of water. Density functional theory calculations indicate that the binding energy between CO(2) and HKUST-1 with coordinated water is ~1 kcal/mol higher than that without coordinated water. It is found that the improvement of CO(2)/N(2) selectivity induced by coordinated water may mainly be attributed to the increased CO(2) adsorption on the hydrated HKUST-1. On the other hand, the enhanced selectivity induced by uncoordinated water in the flue gas mixture can be explained on the basis of the competition of adsorption sites between water and CO(2) (N(2)). At low pressures, a significant CO(2)/N(2) selectivity increase is due to the increase of CO(2) adsorption and decrease of N(2) adsorption as a consequence of competition of adsorption sites between water and N(2). However, with more water molecules adsorbed at higher pressures, the competition between water and CO(2) leads to the decrease of CO(2) adsorption capacity. Therefore, high pressure operation should be avoided in HKUST-1 sorbents for CO(2) capture. In addition, the effects of O(2) and SO(2) on CO(2) capture in HKUST-1 are investigated: The CO(2)/N(2) selectivity does not change much even with relatively high concentrations of O(2) in the flue gas (up to 8%). A slightly lower CO(2)/N(2) selectivity of a CO(2)/N(2)/H(2)O/SO(2) mixture is observed compared with that in a CO(2)/N(2)/H(2)O mixture, especially at high pressures, due to the strong SO(2) binding with HKUST-1.

An Improved Simulated Annealing Technique for Enhanced Mobility in Smart Cities

PubMed Central

Amer, Hayder; Salman, Naveed; Hawes, Matthew; Chaqfeh, Moumena; Mihaylova, Lyudmila; Mayfield, Martin

2016-01-01

Vehicular traffic congestion is a significant problem that arises in many cities. This is due to the increasing number of vehicles that are driving on city roads of limited capacity. The vehicular congestion significantly impacts travel distance, travel time, fuel consumption and air pollution. Avoidance of traffic congestion and providing drivers with optimal paths are not trivial tasks. The key contribution of this work consists of the developed approach for dynamic calculation of optimal traffic routes. Two attributes (the average travel speed of the traffic and the roads’ length) are utilized by the proposed method to find the optimal paths. The average travel speed values can be obtained from the sensors deployed in smart cities and communicated to vehicles via the Internet of Vehicles and roadside communication units. The performance of the proposed algorithm is compared to three other algorithms: the simulated annealing weighted sum, the simulated annealing technique for order preference by similarity to the ideal solution and the Dijkstra algorithm. The weighted sum and technique for order preference by similarity to the ideal solution methods are used to formulate different attributes in the simulated annealing cost function. According to the Sheffield scenario, simulation results show that the improved simulated annealing technique for order preference by similarity to the ideal solution method improves the traffic performance in the presence of congestion by an overall average of 19.22% in terms of travel time, fuel consumption and CO2 emissions as compared to other algorithms; also, similar performance patterns were achieved for the Birmingham test scenario. PMID:27376289

Semi-continuous anaerobic co-digestion of cow manure and steam-exploded Salix with recirculation of liquid digestate.

PubMed

Estevez, Maria M; Sapci, Zehra; Linjordet, Roar; Schnürer, Anna; Morken, John

2014-04-01

The effects of recirculating the liquid fraction of the digestate during mesophilic anaerobic co-digestion of steam-exploded Salix and cow manure were investigated in laboratory-scale continuously stirred tank reactors. An average organic loading rate of 2.6 g VS L(-1) d(-1) and a hydraulic retention time (HRT) of 30 days were employed. Co-digestion of Salix and manure gave better methane yields than digestion of manure alone. Also, a 16% increase in the methane yield was achieved when digestate was recirculated and used instead of water to dilute the feedstock (1:1 dilution ratio). The reactor in which the larger fraction of digestate was recirculated (1:3 dilution ratio) gave the highest methane yields. Ammonia and volatile fatty acids did not reach inhibitory levels, and some potentially inhibitory compounds released during steam explosion (i.e., furfural and 5-hydroxy methyl furfural) were only detected at trace levels throughout the entire study period. However, accumulation of solids, which was more pronounced in the recycling reactors, led to decreased methane yields in those systems after three HRTs. Refraining from the use of fresh water to dilute biomass with a high-solids content and obtaining a final digestate with increased dry matter content might offer important economic benefits in full-scale processes. To ensure long-term stability in such an approach, it would be necessary to optimize separation of the fraction of digestate to be recirculated and also perform proper monitoring to avoid accumulation of solids. Copyright © 2014 Elsevier Ltd. All rights reserved.

Assessment of CO2 Storage Potential in Naturally Fractured Reservoirs With Dual-Porosity Models

NASA Astrophysics Data System (ADS)

March, Rafael; Doster, Florian; Geiger, Sebastian

2018-03-01

Naturally Fractured Reservoirs (NFR's) have received little attention as potential CO2 storage sites. Two main facts deter from storage projects in fractured reservoirs: (1) CO2 tends to be nonwetting in target formations and capillary forces will keep CO2 in the fractures, which typically have low pore volume; and (2) the high conductivity of the fractures may lead to increased spatial spreading of the CO2 plume. Numerical simulations are a powerful tool to understand the physics behind brine-CO2 flow in NFR's. Dual-porosity models are typically used to simulate multiphase flow in fractured formations. However, existing dual-porosity models are based on crude approximations of the matrix-fracture fluid transfer processes and often fail to capture the dynamics of fluid exchange accurately. Therefore, more accurate transfer functions are needed in order to evaluate the CO2 transfer to the matrix. This work presents an assessment of CO2 storage potential in NFR's using dual-porosity models. We investigate the impact of a system of fractures on storage in a saline aquifer, by analyzing the time scales of brine drainage by CO2 in the matrix blocks and the maximum CO2 that can be stored in the rock matrix. A new model to estimate drainage time scales is developed and used in a transfer function for dual-porosity simulations. We then analyze how injection rates should be limited in order to avoid early spill of CO2 (lost control of the plume) on a conceptual anticline model. Numerical simulations on the anticline show that naturally fractured reservoirs may be used to store CO2.

Continuous N-alkylation reactions of amino alcohols using γ-Al2O3 and supercritical CO2: unexpected formation of cyclic ureas and urethanes by reaction with CO2.

PubMed

Streng, Emilia S; Lee, Darren S; George, Michael W; Poliakoff, Martyn

2017-01-01

The use of γ-Al 2 O 3 as a heterogeneous catalyst in scCO 2 has been successfully applied to the amination of alcohols for the synthesis of N -alkylated heterocycles. The optimal reaction conditions (temperature and substrate flow rate) were determined using an automated self-optimising reactor, resulting in moderate to high yields of the target products. Carrying out the reaction in scCO 2 was shown to be beneficial, as higher yields were obtained in the presence of CO 2 than in its absence. A surprising discovery is that, in addition to cyclic amines, cyclic ureas and urethanes could be synthesised by incorporation of CO 2 from the supercritical solvent into the product.

The reduction of atmospheric emissions after the implementation of first Polish nuclear power plant

NASA Astrophysics Data System (ADS)

Cholewiński, Maciej

2018-04-01

In this work the environmental benefits in the atmospheric emissions after the implementation of 3,000 MW nuclear power plants were assessed and presented. To determine the quantity of avoided emissions of CO2, NOx, SO2 and Hg compounds, harmonised stoichiometric combustion model dedicated to solid fuel fired power plant was created. To increase the credibility of the studies, future strict emission standards (Directive 2010/75/EU, BAT documents for LCP) were included as well. In conducted studies, representative samples of 3 different Polish solid fuels were examined (by comprehensive proximate and ultimate analysis) and used in assessment. It was proven that by the replacement of thermal solid fuel power plant by nuclear unit (with annual production rate of 22.4 TWh net) up to 16.4 million tonnes of lignite, 8.9 million tonnes of hard coal or 13.1 million tonnes of solid biomass can be saved. Further, for the case of lignite, the emission, at least, of 21.29 million tonnes of CO2 (6.9% of all Polish emission in 2015), 1,610 tonnes of dust (0.4%), 16,102 tonnes of NOx (2.2%), 16,102 tonnes of SO2 (2.0%) and 564 kg of mercury (5.9%) can be avoided. For selected hard coal, calculated emission savings were equal to 17.60 million tonnes of CO2 (5.7%), 1,357 tonnes of dust (0.4%), 13,566 tonnes of NOx (1.9%), 13,566 tonnes of SO2 (1.7%), 271 kg of mercury (2.9%), and for biomass - equal to 20.04 million tonnes of CO2 (6.5%), 1,471 tonnes of dust (0.4%), 14,712 tonnes of NOx (2.0%), 14,712 tonnes of SO2 (1.8%) and 294 kg of mercury (3.1%).

Influence of headspace flushing on methane production in Biochemical Methane Potential (BMP) tests.

PubMed

Koch, Konrad; Bajón Fernández, Yadira; Drewes, Jörg E

2015-06-01

The influence of headspace flushing on the specific methane (CH4) production of blank samples with just inoculum in Biochemical Methane Potential (BMP) tests was studied. The three most common ways were applied: flushing with nitrogen (N2) gas, flushing with a mixture of N2 and CO2 (80/20 v/v), and no flushing. The results revealed that removing the oxygen is crucial to avoid aerobic respiration, which caused both hindered activity of methanogens and loss of methane potential. Furthermore it was demonstrated that 20% of CO2 in the flush gas increased significantly the methane production by over 20% compared to the flushing with pure N2. In order to mimic the same headspace conditions as in full-scale treatment plants, using a flush gas with a similar CO2 concentration as the expected biogas is suggested. Copyright © 2015 Elsevier Ltd. All rights reserved.

A Full-Featured User Friendly CO 2-EOR and Sequestration Planning Software

DOE Office of Scientific and Technical Information (OSTI.GOV)

Savage, Bill

A Full-Featured, User Friendly CO 2-EOR and Sequestration Planning Software This project addressed the development of an integrated software solution that includes a graphical user interface, numerical simulation, visualization tools and optimization processes for reservoir simulation modeling of CO 2-EOR. The objective was to assist the industry in the development of domestic energy resources by expanding the application of CO 2-EOR technologies, and ultimately to maximize the CO 2} sequestration capacity of the U.S. The software resulted in a field-ready application for the industry to address the current CO 2-EOR technologies. The software has been made available to the publicmore » without restrictions and with user friendly operating documentation and tutorials. The software (executable only) can be downloaded from NITEC’s website at www.nitecllc.com. This integrated solution enables the design, optimization and operation of CO 2-EOR processes for small and mid-sized operators, who currently cannot afford the expensive, time intensive solutions that the major oil companies enjoy. Based on one estimate, small oil fields comprise 30% of the of total economic resource potential for the application of CO 2-EOR processes in the U.S. This corresponds to 21.7 billion barrels of incremental, technically recoverable oil using the current “best practices”, and 31.9 billion barrels using “next-generation” CO 2-EOR techniques. The project included a Case Study of a prospective CO 2-EOR candidate field in Wyoming by a small independent, Linc Energy Petroleum Wyoming, Inc. NITEC LLC has an established track record of developing innovative and user friendly software. The Principle Investigator is an experienced manager and engineer with expertise in software development, numerical techniques, and GUI applications. Unique, presently-proprietary NITEC technologies have been integrated into this application to further its ease of use and technical functionality.« less

Optimally Stopped Optimization

NASA Astrophysics Data System (ADS)

Vinci, Walter; Lidar, Daniel A.

2016-11-01

We combine the fields of heuristic optimization and optimal stopping. We propose a strategy for benchmarking randomized optimization algorithms that minimizes the expected total cost for obtaining a good solution with an optimal number of calls to the solver. To do so, rather than letting the objective function alone define a cost to be minimized, we introduce a further cost-per-call of the algorithm. We show that this problem can be formulated using optimal stopping theory. The expected cost is a flexible figure of merit for benchmarking probabilistic solvers that can be computed when the optimal solution is not known and that avoids the biases and arbitrariness that affect other measures. The optimal stopping formulation of benchmarking directly leads to a real-time optimal-utilization strategy for probabilistic optimizers with practical impact. We apply our formulation to benchmark simulated annealing on a class of maximum-2-satisfiability (MAX2SAT) problems. We also compare the performance of a D-Wave 2X quantum annealer to the Hamze-Freitas-Selby (HFS) solver, a specialized classical heuristic algorithm designed for low-tree-width graphs. On a set of frustrated-loop instances with planted solutions defined on up to N =1098 variables, the D-Wave device is 2 orders of magnitude faster than the HFS solver, and, modulo known caveats related to suboptimal annealing times, exhibits identical scaling with problem size.

Post-traumatic stress avoidance is attenuated by corticosterone and associated with brain levels of steroid receptor co-activator-1 in rats.

PubMed

Whitaker, Annie M; Farooq, Muhammad A; Edwards, Scott; Gilpin, Nicholas W

2016-01-01

Individuals with post-traumatic stress disorder (PTSD) avoid trauma-related stimuli and exhibit blunted hypothalamic-pituitary-adrenal (HPA) axis activation at the time of stress. Our rodent model of stress mimics the avoidance symptom cluster of PTSD. Rats are classified as "Avoiders" or "Non-Avoiders" post-stress based on the avoidance of a predator-odor paired context. Previously, we found Avoiders exhibit an attenuated HPA stress response to predator odor. We hypothesized that corticosterone administration before stress would reduce the magnitude and incidence of stress-paired context avoidance. Furthermore, we also predicted that Avoiders would exhibit altered expression of glucocorticoid receptor (GR) signaling machinery elements, including steroid receptor co-activator (SRC)-1. Male Wistar rats (n = 16) were pretreated with corticosterone (25 mg/kg) or saline and exposed to predator-odor stress paired with a context and tested for avoidance 24 h later. A second group of corticosterone-naïve rats (n = 24) were stressed (or not), indexed for avoidance 24 h later, and killed 48 h post-odor exposure to measure phosphorylated GR, FKBP51 and SRC-1 levels in the paraventricular nucleus (PVN), central amygdala (CeA) and ventral hippocampus (VH), all brain sites that highly express GRs and regulate HPA function. Corticosterone pretreatment reduced the magnitude and incidence of avoidance. In Avoiders, predator-odor exposure led to lower SRC-1 expression in the PVN and CeA, and higher SRC-1 expression in the VH. SRC-1 expression in PVN, CeA and VH was predicted by prior avoidance behavior. Hence, a blunted HPA stress response may contribute to stress-induced neuroadaptations in central SRC-1 levels and behavioral dysfunction in Avoider rats.

Application of Statistical Design for the Production of Cellulase by Trichoderma reesei Using Mango Peel

PubMed Central

Saravanan, P.; Muthuvelayudham, R.; Viruthagiri, T.

2012-01-01

Optimization of the culture medium for cellulase production using Trichoderma reesei was carried out. The optimization of cellulase production using mango peel as substrate was performed with statistical methodology based on experimental designs. The screening of nine nutrients for their influence on cellulase production is achieved using Plackett-Burman design. Avicel, soybean cake flour, KH2PO4, and CoCl2 ·6H2O were selected based on their positive influence on cellulase production. The composition of the selected components was optimized using Response Surface Methodology (RSM). The optimum conditions are as follows: Avicel: 25.30 g/L, Soybean cake flour: 23.53 g/L, KH2PO4: 4.90 g/L, and CoCl2 ·6H2O: 0.95 g/L. These conditions are validated experimentally which revealed an enhanced Cellulase activity of 7.8 IU/mL. PMID:23304453

Robust Airfoil Optimization to Achieve Consistent Drag Reduction Over a Mach Range

NASA Technical Reports Server (NTRS)

Li, Wu; Huyse, Luc; Padula, Sharon; Bushnell, Dennis M. (Technical Monitor)

2001-01-01

We prove mathematically that in order to avoid point-optimization at the sampled design points for multipoint airfoil optimization, the number of design points must be greater than the number of free-design variables. To overcome point-optimization at the sampled design points, a robust airfoil optimization method (called the profile optimization method) is developed and analyzed. This optimization method aims at a consistent drag reduction over a given Mach range and has three advantages: (a) it prevents severe degradation in the off-design performance by using a smart descent direction in each optimization iteration, (b) there is no random airfoil shape distortion for any iterate it generates, and (c) it allows a designer to make a trade-off between a truly optimized airfoil and the amount of computing time consumed. For illustration purposes, we use the profile optimization method to solve a lift-constrained drag minimization problem for 2-D airfoil in Euler flow with 20 free-design variables. A comparison with other airfoil optimization methods is also included.

Windshear detection and avoidance - Airborne systems perspective

NASA Technical Reports Server (NTRS)

Bowles, Roland L.; Targ, Russell

1988-01-01

The generalized windshear hazard index presently defined is derived from aircraft-position wind data and remotely sensed data obtained along the extended flight path by such candidate sensor technologies as microwave Doppler radar, Doppler lidar, and IR radiometry. Attention is given here to the results of a comparative evaluation of CO2 and Ho:YAG lidar sensor-employing windshear-detection systems, over a range 1-3 km ahead of the aircraft (corresponding to 15-45 sec of warning time). While the technology for a 10.6-micron CO2 lidar system is available, an optimum 2-micron REE laser crystal-based system remains to be developed.

Discovery, Synthesis, And Structure-Based Optimization of a Series of N-(tert-Butyl)-2-(N-arylamido)-2-(pyridin-3-yl) Acetamides (ML188) as Potent Noncovalent Small Molecule Inhibitors of the Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) 3CL Protease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobs, Jon; Grum-Tokars, Valerie; Zhou, Ya

A high-throughput screen of the NIH molecular libraries sample collection and subsequent optimization of a lead dipeptide-like series of severe acute respiratory syndrome (SARS) main protease (3CLpro) inhibitors led to the identification of probe compound ML188 (16-(R), (R)-N-(4-(tert-butyl)phenyl)-N-(2-(tert-butylamino)-2-oxo-1-(pyridin-3-yl)ethyl)furan-2-carboxamide, Pubchem CID: 46897844). But, unlike the majority of reported coronavirus 3CLpro inhibitors that act via covalent modification of the enzyme, 16-(R) is a noncovalent SARS-CoV 3CLpro inhibitor with moderate MW and good enzyme and antiviral inhibitory activity. A multicomponent Ugi reaction was utilized to rapidly explore structure–activity relationships within S1', S1, and S2enzyme binding pockets. Moreover, the X-ray structure of SARS-CoV 3CLpromore » bound with 16-(R) was instrumental in guiding subsequent rounds of chemistry optimization. 16-(R) provides an excellent starting point for the further design and refinement of 3CLpro inhibitors that act by a noncovalent mechanism of action.« less

Method of controlling injection of oxygen into hydrogen-rich fuel cell feed stream

DOEpatents

Meltser, Mark Alexander; Gutowski, Stanley; Weisbrod, Kirk

2001-01-01

A method of operating a H.sub.2 --O.sub.2 fuel cell fueled by hydrogen-rich fuel stream containing CO. The CO content is reduced to acceptable levels by injecting oxygen into the fuel gas stream. The amount of oxygen injected is controlled in relation to the CO content of the fuel gas, by a control strategy that involves (a) determining the CO content of the fuel stream at a first injection rate, (b) increasing the O.sub.2 injection rate, (c) determining the CO content of the stream at the higher injection rate, (d) further increasing the O.sub.2 injection rate if the second measured CO content is lower than the first measured CO content or reducing the O.sub.2 injection rate if the second measured CO content is greater than the first measured CO content, and (e) repeating steps a-d as needed to optimize CO consumption and minimize H.sub.2 consumption.

Response of Integrated CO 2 Capture and Storage Systems in Saline Aquifers and Fractured Shale Formations to Changes in CO 2 Capture Costs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Langenfeld, Julie K.; Bielicki, Jeffrey M.; Tao, Zhiyuan

Fractured shale formations are new potential target reservoirs for CO 2 capture and storage (CCS) and provide several potential advantages over storage in saline aquifers in terms of storage capacity, leakage risk, and cost savings from brownfield development. Here, we used a geospatial-optimization, engineering-economic model to investigate the sensitivity of integrated CCS networks in Ohio, Pennsylvania, and West Virginia to reductions in CO 2 capture costs. The resulting reductions in CO 2 capture costs were based on hypothetical cases where technological innovation reduced CO 2 capture costs. There were also small differences in the spatial organization of the CCS deploymentmore » when the capture costs were reduced. We also found that the percent reduction in average cost of CCS systems became smaller as the CO 2 capture costs were decreased.« less

Response of Integrated CO 2 Capture and Storage Systems in Saline Aquifers and Fractured Shale Formations to Changes in CO 2 Capture Costs

DOE PAGES

Langenfeld, Julie K.; Bielicki, Jeffrey M.; Tao, Zhiyuan; ...

2017-08-18

Fractured shale formations are new potential target reservoirs for CO 2 capture and storage (CCS) and provide several potential advantages over storage in saline aquifers in terms of storage capacity, leakage risk, and cost savings from brownfield development. Here, we used a geospatial-optimization, engineering-economic model to investigate the sensitivity of integrated CCS networks in Ohio, Pennsylvania, and West Virginia to reductions in CO 2 capture costs. The resulting reductions in CO 2 capture costs were based on hypothetical cases where technological innovation reduced CO 2 capture costs. There were also small differences in the spatial organization of the CCS deploymentmore » when the capture costs were reduced. We also found that the percent reduction in average cost of CCS systems became smaller as the CO 2 capture costs were decreased.« less

Growth and chemical responses to CO{sub 2} enrichment - Virginia pine (Pinus virginiana Mill.)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luxmoore, R.J.; Norby, R.J.; Neill, E.G.O.

1985-03-01

Global atmospheric CO{sub 2} concentrations have been increasing over the past several decades and are projected to continue increasing for several more decades. Because of the fundamental role of CO{sub 2} in the physiology of all green plants, changes in plant growth and productivity are expected. There is ample experimental evidence illustrating an increase in photosynthesis and growth with increasing CO{sub 2} concentrations. However, much of this evidence is based on short term results and optimal growth and nutrient conditions. Kramer raised the question of whether plants growing in natural environments, which are probably more often limited by water ormore » nutrient (especially nitrogen) deficiencies than by low CO{sub 2}, will respond to rising atmospheric CO{sub 2} concentrations. This package covers one segment of the research performed to determine whether the proposed mechanism occurs with elevated CO{sub 2} concentrations.« less

Visible light activity of Ag-loaded and guanidine nitrate-doped nano-TiO2: Degradation of dichlorophenol and antibacterial properties

EPA Science Inventory

To utilize visible light, co-doped nano-TiO2 was prepared via “one pot” synthesis using mild reaction conditions and benign precursors. Synthesis was optimized using an appropriate experimental design taking into account silver content and calcination temperature. The optimized ...

The growth response of Alternanthera philoxeroides in a simulated post-combustion emission with ultrahigh [CO2] and acidic pollutants.

PubMed

Xu, Cheng-Yuan; Griffin, Kevin L; Blazier, John C; Craig, Elizabeth C; Gilbert, Dominique S; Sritrairat, Sanpisa; Anderson, O Roger; Castaldi, Marco J; Beaumont, Larry

2009-07-01

Although post-combustion emissions from power plants are a major source of air pollution, they contain excess CO2 that could be used to fertilize commercial greenhouses and stimulate plant growth. We addressed the combined effects of ultrahigh [CO2] and acidic pollutants in flue gas on the growth of Alternanthera philoxeroides. When acidic pollutants were excluded, the biomass yield of A. philoxeroides saturated near 2000 micromol mol(-1) [CO2] with doubled biomass accumulation relative to the ambient control. The growth enhancement was maintained at 5000 micromol mol(-1) [CO2], but declined when [CO2] rose above 1%, in association with a strong photosynthetic inhibition. Although acidic components (SO2 and NO2) significantly offset the CO2 enhancement, the aboveground yield increased considerably when the concentration of pollutants was moderate (200 times dilution). Our results indicate that using excess CO2 from the power plant emissions to optimize growth in commercial green house could be viable.

Alkaline modified oil shale fly ash: optimal synthesis conditions and preliminary tests on CO2 adsorption.

PubMed

Reinik, Janek; Heinmaa, Ivo; Kirso, Uuve; Kallaste, Toivo; Ritamäki, Johannes; Boström, Dan; Pongrácz, Eva; Huuhtanen, Mika; Larsson, William; Keiski, Riitta; Kordás, Krisztián; Mikkola, Jyri-Pekka

2011-11-30

Environmentally friendly product, calcium-silica-aluminum hydrate, was synthesized from oil shale fly ash, which is rendered so far partly as an industrial waste. Reaction conditions were: temperature 130 and 160°C, NaOH concentrations 1, 3, 5 and 8M and synthesis time 24h. Optimal conditions were found to be 5M at 130°C at given parameter range. Original and activated ash samples were characterized by XRD, XRF, SEM, EFTEM, (29)Si MAS-NMR, BET and TGA. Semi-quantitative XRD and MAS-NMR showed that mainly tobermorites and katoite are formed during alkaline hydrothermal treatment. Physical adsorption of CO(2) on the surface of the original and activated ash samples was measured with thermo-gravimetric analysis. TGA showed that the physical adsorption of CO(2) on the oil shale fly ash sample increases from 0.06 to 3-4 mass% after alkaline hydrothermal activation with NaOH. The activated product has a potential to be used in industrial processes for physical adsorption of CO(2) emissions. Copyright © 2011 Elsevier B.V. All rights reserved.

Evaluation of food waste disposal options by LCC analysis from the perspective of global warming: Jungnang case, South Korea.

PubMed

Kim, Mi-Hyung; Song, Yul-Eum; Song, Han-Byul; Kim, Jung-Wk; Hwang, Sun-Jin

2011-01-01

The costs associated with eight food waste disposal options, dry feeding, wet feeding, composting, anaerobic digestion, co-digestion with sewage sludge, food waste disposer, incineration, and landfilling, were evaluated in the perspective of global warming and energy and/or resource recovery. An expanded system boundary was employed to compare by-products. Life cycle cost was analyzed through the entire disposal process, which included discharge, separate collection, transportation, treatment, and final disposal stages, all of which were included in the system boundary. Costs and benefits were estimated by an avoided impact. Environmental benefits of each system per 1 tonne of food waste management were estimated using carbon prices resulting from CO(2) reduction by avoided impact, as well as the prices of by-products such as animal feed, compost, and electricity. We found that the cost of landfilling was the lowest, followed by co-digestion. The benefits of wet feeding systems were the highest and landfilling the lowest. Copyright © 2011 Elsevier Ltd. All rights reserved.

A synthetic pathway for the fixation of carbon dioxide in vitro.

PubMed

Schwander, Thomas; Schada von Borzyskowski, Lennart; Burgener, Simon; Cortina, Niña Socorro; Erb, Tobias J

2016-11-18

Carbon dioxide (CO 2 ) is an important carbon feedstock for a future green economy. This requires the development of efficient strategies for its conversion into multicarbon compounds. We describe a synthetic cycle for the continuous fixation of CO 2 in vitro. The crotonyl-coenzyme A (CoA)/ethylmalonyl-CoA/hydroxybutyryl-CoA (CETCH) cycle is a reaction network of 17 enzymes that converts CO 2 into organic molecules at a rate of 5 nanomoles of CO 2 per minute per milligram of protein. The CETCH cycle was drafted by metabolic retrosynthesis, established with enzymes originating from nine different organisms of all three domains of life, and optimized in several rounds by enzyme engineering and metabolic proofreading. The CETCH cycle adds a seventh, synthetic alternative to the six naturally evolved CO 2 fixation pathways, thereby opening the way for in vitro and in vivo applications. Copyright © 2016, American Association for the Advancement of Science.

DIDO Optimization of a Lunar Landing Trajectory with Respect to Autonomous Landing Hazard Avoidance Technology

DTIC Science & Technology

2009-09-01

22 b. Hazard Detection and Avoidance ( HDA )...............................22 c. Hazard Relative Navigation (HRN...Navigation (HRN) and Hazard Detection and Avoidance ( HDA ). In addition to the TRN and HDA sensors used during these phases, which will be discussed...and Avoidance ( HDA ) During the HAD phase, the expected landing site is examined and evaluated, and a new site may be selected. Using the HDA

PdCo nanoparticles supported on carbon fibers derived from cotton: Maximum utilization of Pd atoms for efficient reduction of nitroarenes.

PubMed

Yang, Jin; Wang, Wei David; Dong, Zhengping

2018-08-15

In the present work, a facile and environment-friendly route is illustrated for the efficient fabrication of highly dispersed PdCo nanoparticles (NPs) by modified cotton-derived carbon fibers (PdCo/CCF). Firstly, commercial cotton was impregnated with CoCl 2 , followed by pyrolysis under high calcination temperature to obtain the Co NPs modified CCF sample (Co/CCF). Secondly, Co/CCF was treated with Pd(AcO) 2 aqueous solution, wherein, through a spontaneous replacement reaction process, Pd 2+ is reduced to metallic Pd and mostly covered on the surface of the Co NPs. Thus, the PdCo/CCF catalyst was obtained avoiding the use of toxic reductants like NaBH 4 , NH 2 NH 2 and HCHO. The PdCo/CCF catalyst exhibits excellent catalytic activity and recyclability for the reduction of 4-nitrophenol and other nitroarenes compared with Pd/CCF, PdCo NPs and many other noble metals based catalysts. The reasons could be attributed to the uniformly dispersed and accessible PdCo NPs on the surface of the CCF, and the Pd atoms deposited on the Co NPs surface that makes the Pd active sites available for optimum use. The PdCo/CCF catalyst also exhibits potential application for catalytic reduction of nitroarenes in a fixed bed reactor under mild reaction conditions. Furthermore, the PdCo/CCF catalyst can be magnetically recycled and reused for at least ten cycles without either losing catalytic activity or leaching of Pd active sites, thereby confirming its superior stability. Copyright © 2018 Elsevier Inc. All rights reserved.

Sensitivity Analysis for CO2 Retrieval using GOSAT-2 FTS-2 Simulator

NASA Astrophysics Data System (ADS)

Kamei, Akihide; Yoshida, Yukio; Dupuy, Eric; Yokota, Yasuhiro; Hiraki, Kaduo; Matsunaga, Tsuneo

2015-04-01

The Greenhouse Gases Observing Satellite (GOSAT), launched in 2009, is the world's first satellite dedicated to global greenhouse gases observation. GOSAT-2, the successor mission to GOSAT, is scheduled for launch in early 2018. The Fourier Transform Spectrometer-2 (FTS-2) is the primary sensor onboard GOSAT-2. It observes infrared light reflected and emitted from the Earth's surface and atmosphere. The FTS-2 obtains high resolution spectra using three bands in the near to short-wavelength infrared (SWIR) region and two bands in the thermal infrared (TIR) region. Column amounts and vertical profiles of carbon dioxide (CO2) and methane (CH4) are retrieved from the radiance spectra obtained with the SWIR and TIR bands, respectively. Further, compared to the FTS onboard the GOSAT, the FTS-2 has several improvements: 1) added spectral coverage in the SWIR region for carbon monoxide (CO) retrieval, 2) increased signal-to-noise ratio (SNR) for all bands, 3) extended range of along-track pointing angles for sunglint observations, 4) intelligent pointing to avoid cloud contamination. Since 2012, we have been developing a simulator software to simulate the spectral radiance data that will be acquired by the GOSAT-2 FTS-2. The purpose of the GOSAT-2 FTS-2 simulator is to analyze/optimize data with respect to the sensor specification, the parameters for Level 1 processing, and the improvement of the Level 2 algorithms. The GOSAT-2 FTS-2 simulator includes the six components: 1) overall control, 2) sensor carrying platform, 3) spectral radiance calculation, 4) Fourier Transform module, 5) Level 1B (L1B) processing, and 6) L1B data output. It has been installed on the GOSAT Research Computation Facility (GOSAT RCF), which is a high-performance and energy-efficient supercomputer. More realistic and faster simulations have been made possible by the improvement of the details of sensor characteristics, the sophistication of the data processing and algorithms, the addition of the various observing modes including calibration observation, the use of surface and atmospheric ancillary data for radiative transfer calculation, and the speed-up and parallelization of the radiative transfer code. We will summarize the current status and the future plans in the development of the GOSAT-2 FTS-2 simulator. We will also demonstrate the reproduction of GOSAT FTS L1B data and present the sensitivity analysis relating to the engineering parameters, the aerosols and clouds, and so on, on the Level 1 processing for CO2 retrieval using latest version of the GOSAT-2 FTS-2 simulator.

Conservation agricultural management to sequester soil organic carbon

USDA-ARS?s Scientific Manuscript database

Storing carbon (C) in soil as organic matter is not only a viable strategy to sequester CO2 from the atmosphere, but is vital for improving the quality, fertility, and functioning of soil. This presentation describes relevant management approaches to avoid land degradation and foster soil organic C ...

A Molecular Identification Device for Individual Sub-Micron Aerosols: Feasibility Study.

DTIC Science & Technology

1980-05-01

effort devoted to co- alignment could have been entirely avoided by two simple incisions else- where in the hermetic chamber (which incisions could...The spectrograph was c-’prised of the following elements: 1) quartz plano -convex collimating lens, 2) transmission grating (which was transparent

The Role of Optimality in Characterizing CO2 Seepage from Geological Carbon Sequestration Sites

NASA Astrophysics Data System (ADS)

Cortis, A.; Oldenburg, C. M.; Benson, S. M.

2007-12-01

Storage of large amounts of carbon dioxide (CO2) in deep geological formations for greenhouse-gas mitigation is gaining momentum and moving from its conceptual and testing stages towards widespread application. In this talk we explore various optimization strategies for characterizing surface leakage (seepage) using near-surface measurement approaches such as accumulation chambers and eddy covariance towers. Seepage characterization objectives and limitations need to be defined carefully from the outset especially in light of large natural background variations that can mask seepage. The cost and sensitivity of seepage detection are related to four critical length scales pertaining to the size of the: (1) region that needs to be monitored; (2) footprint of the measurement approach; (3) main seepage zone; and (4) region in which concentrations or fluxes are influenced by seepage. Seepage characterization objectives may include one or all of the tasks of detecting, locating, and quantifying seepage. Each of these tasks has its own optimal strategy. Detecting and locating seepage in a region in which there is no expected or preferred location for seepage nor existing evidence for seepage requires monitoring on a fixed grid, e.g., using eddy covariance towers. The fixed-grid approaches needed to detect seepage are expected to require large numbers of eddy covariance towers for large-scale geologic CO2 storage. Once seepage has been detected and roughly located, seepage zones and features can be optimally pinpointed through a dynamic search strategy, e.g., employing accumulation chambers and/or soil-gas sampling. Quantification of seepage rates can be done through measurements on a localized fixed grid once the seepage is pinpointed. Background measurements are essential for seepage detection in natural ecosystems. Artificial neural networks are considered as regression models useful for distinguishing natural system behavior from anomalous behavior suggestive of CO2 seepage without need for detailed understanding of natural system processes. Because of the local extrema in CO2 fluxes and concentrations in natural systems, simple steepest-descent algorithms are not effective and evolutionary computation algorithms are proposed as a paradigm for dynamic monitoring networks to pinpoint CO2 seepage areas. This work was carried out within the ZERT project, funded by the Assistant Secretary for Fossil Energy, Office of Sequestration, Hydrogen, and Clean Coal Fuels, National Energy Technology Laboratory, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Quantifying CO2 Emissions from Individual Power Plants using OCO-2 Observations

NASA Astrophysics Data System (ADS)

Nassar, R.; Hill, T. G.; McLinden, C. A.; Wunch, D.; Jones, D. B. A.; Crisp, D.

2017-12-01

In order to better manage anthropogenic CO2 emissions, improved methods of quantifying emissions are needed at all spatial scales from the national level down to the facility level. Although the Orbiting Carbon Observatory 2 (OCO-2) satellite was not designed for monitoring power plant emissions, we show that in select cases, CO2 observations from OCO-2 can be used to quantify daily CO2 emissions from individual mid- to large-sized coal power plants by fitting the data to plume model simulations. Emission estimates for US power plants are within 1-13% of reported daily emission values enabling application of the approach to international sites that lack detailed emission information. These results affirm that a constellation of future CO2 imaging satellites, optimized for point sources, could be used for the Monitoring, Reporting and Verification (MRV) of CO2 emissions from individual power plants to support the implementation of climate policies.