scholarly journals Underlying mechanisms in microbial solar cells: how modeling can help

2020 ◽  
Vol 4 (12) ◽  
pp. 6004-6010
Author(s):  
Léna Beauzamy ◽  
Frédéric Lemaître ◽  
Julien Derr
Keyword(s):  
Solar Cells ◽  
Rate Constants ◽  
Underlying Mechanisms ◽  
Over Time

Using modeling we uncoupled and quantified the different rate constants implicated in microbial solar cells: mediator fluxes in and out of microbes, oxidation at the electrode, photo-reduction inside the microbe, and degradation over time.

The Importance of Variables and Parameters in Radiolytic Chemical Kinetics Modeling

1988 ◽  
Vol 127 ◽  
Author(s):  
M. G. Piepho ◽  
P. J. Turner ◽  
P. W. Reimus
Keyword(s):  
Chemical Kinetics ◽  
Rate Constants ◽  
Transient Species ◽  
Geologic Repository ◽  
Species Concentration ◽  
Waste Package ◽  
Long Term Performance ◽  
Term Performance ◽  
Over Time

ABSTRACTRadiolysis may significantly affect the long-term performance of nuclear waste packages in a geologic repository. Radiolysis of available moisture and air in an unsaturated or saturated environment will create transient species that can significantly change the pH and/or Eh of the available moisture. These changes can influence rates of containment corrosion, waste form dissolution, and radionuclide solubilities and transport.Many of the pertinent radiochemical reactions are not completely understood, and most of the associated rate constants are poorly characterized. To help identify the important radiochemical reactions, rate constants, species, and environmental conditions, an importance theory code, SWATS (Sensitivity With Adjoint Theory-Sparse version)-LOOPCHEM, has been developed for the radiolytic chemical kinetics model in the radiolysis code LOOPCHEM. The LOOPCHEM code calculates the concentrations of various species in a radiolytic field over time. The SWATS-LOOPCHEM code efficiently calculates: 1) the importance (relative to a defined response of interest) of each species concentration over time, 2) the sensitivity of each parameter of interest, and 3) the importance of each equation in the radiolysis model. The calculated results will be used to guide future experimental and modeling work for determining the importance of radiolysis on waste package performance. A demonstration (the importance of selected concentrations and the sensitivities of selected parameters) of the SWATS-LOOPCHEM code is provided for illustrative purposes, and no attempt is made at this time to interpret the results for waste package performance assessment purposes.

Measuring Displacement: Assessing Proxies for Involuntary Residential Mobility

2020 ◽  
Vol 19 (3) ◽  
pp. 573-592 ◽  
Author(s):  
H. Jacob Carlson
Keyword(s):  
New York ◽  
New York City ◽  
Residential Mobility ◽  
Population Approach ◽  
Individual Housing ◽  
Individual Mobility ◽  
Variable Displacement ◽  
Compositional Changes ◽  
Underlying Mechanisms ◽  
Over Time

Research has repeatedly found that displacement is not more likely in gentrifying neighborhoods. Since the dependent variable—displacement—is difficult to measure, researchers resort to a variety of proxy measures for it. I classify three types of proxies: a population approach that measures compositional changes in neighborhoods over time, an individual approach that measures individual housing mobility, and a motivational approach that traces both individual mobility as well as the reasons why a household moved to determine whether that move was involuntary. I examine the prevalence of these approaches across a sample of the literature. I then test the commensurability of the proxy measures with data from New York City by comparing the rank orderings of neighborhoods with the most and least displacement. I find widely different results across the approaches. I explain these results by examining the underlying mechanisms of displacement that are masked by the other approaches.

scholarly journals Episodic Bouts of Activity Accompany Recovery of Rhythmic Output By a Neuromodulator- and Activity-Deprived Adult Neural Network

2003 ◽  
Vol 90 (4) ◽  
pp. 2720-2730 ◽  
Author(s):  
Jason A. Luther ◽  
Alice A. Robie ◽  
John Yarotsky ◽  
Christopher Reina ◽  
Eve Marder ◽  
...  
Keyword(s):  
Neural Network ◽  
Neuronal Network ◽  
Recovery Process ◽  
Stomatogastric Ganglion ◽  
Cancer Borealis ◽  
Pyloric Network ◽  
Underlying Mechanisms ◽  
Over Time ◽  
Phase Relationships ◽  
Pyloric Rhythm

The pyloric rhythm of the stomatogastric ganglion of the crab, Cancer borealis, slows or stops when descending modulatory inputs are acutely removed. However, the rhythm spontaneously resumes after one or more days in the absence of neuromodulatory input. We recorded continuously for days to characterize quantitatively this recovery process. Activity bouts lasting 40–900 s began several hours after removal of neuromodulatory input and were followed by stable rhythm recovery after 1–4 days. Bout duration was not related to the intervals (0.3–800 min) between bouts. During an individual bout, the frequency rapidly increased and then decreased more slowly. Photoablation of back-filled neuromodulatory terminals in the stomatogastric ganglion (STG) neuropil had no effect on activity bouts or recovery, suggesting that these processes are intrinsic to the STG neuronal network. After removal of neuromodulatory input, the phase relationships of the components of the triphasic pyloric rhythm were altered, and then over time the phase relationships moved toward their control values. Although at low pyloric rhythm frequency the phase relationships among pyloric network neurons depended on frequency, the changes in frequency during recovery did not completely account for the change in phase seen after rhythm recovery. We suggest that activity bouts represent underlying mechanisms controlling the restructuring of the pyloric network to allow resumption of an appropriate output after removal of neuromodulatory input.

RELIABILITY STUDIES OF P3HT: PCBM ORGANIC SOLAR CELLS FABRICATED WITH CALCIUM–ALUMINUM AND LITHIUM FLUORIDE–ALUMINIUM CATHODES

2011 ◽  
Vol 10 (04n05) ◽  
pp. 803-807
Author(s):  
T. S. KRISHNAN ◽  
S. SUNDAR KUMAR IYER
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Continuous Illumination ◽  
Stress Tests ◽  
Ambient Conditions ◽  
Over Time

This work addresses the shelf life characteristics of P3HT: PCBM blend based organic solar cells (OSC) fabricated with Ca–Al and LiF–Al cathodes. Some of these devices are encapsulated in nitrogen ambient and some in room ambient. Device electrical characteristics are studied under both dark and light. In the analysis under dark ambient conditions, the degradation in peak dark current is monitored over time (in days) and an empirical model is postulated for the degradation based on statistical curve fitting techniques. In the analysis under light, degradation of parameters such as fill factor (FF), open circuit voltage (V oc ) and short circuit current density (J sc ) is monitored over time in these devices (for different cathodes and different ambients) and the results are analyzed and compared. Also, accelerated stress tests are conducted wherein the devices are subjected to continuous illumination for a period of 1.5 h under two different intensities (0.76 sun and 1 sun) and again, the results are analyzed and compared. A model is fitted to the observed degradation in normalized J sc and the degradation constants (k deg ) are obtained. It is seen that the devices fabricated with cathode as LiF–Al and being encapsulated in nitrogen ambient provide the best performance over time.

Designing of a Mobile Robot Using Photovoltaic Cells

2014 ◽  
Vol 678 ◽  
pp. 373-376
Author(s):  
Paul Ciprian Patic ◽  
Lucia Pascale ◽  
Marin Mâinea
Keyword(s):  
Solar Cells ◽  
Mobile Robot ◽  
Mobile Robots ◽  
Energy Management ◽  
Power Supply ◽  
Photovoltaic Cells ◽  
Control Techniques ◽  
Battery Technology ◽  
Supply Costs ◽  
Over Time

The robots operate in a specific environment, the characteristics of which may remain constant or variable over time. While battery technology is of great interest for mobile robots, but it is not reliable in the time, there are several strategies for the storage of energy, as well as strategies for harvesting energy from the environment in various ways and energy management using sophisticated control techniques to improve power supply costs. One of these strategies is to use solar energy to power mobile robots. The solar cells appearance is due to the need to supply power spacecraft since not require maintenance for a period of time.

Behavior of Cu(In,Ga)Se2 solar cells under light/damp heat over time

2004 ◽  
Vol 44 (2) ◽  
pp. 229-235 ◽  
Author(s):  
Takeshi Yanagisawa ◽  
Takeshi Kojima ◽  
Tadamasa Koyanagi
Keyword(s):  
Solar Cells ◽  
Over Time

scholarly journals Changes in pulmonary function and patient-reported outcomes during COVID-19 recovery: a longitudinal, prospective cohort study

2021 ◽  
pp. 00243-2021
Author(s):  
Aditi S. Shah ◽  
Min Hyung Ryu ◽  
Cameron J Hague ◽  
Darra T. Murphy ◽  
James C. Johnston ◽  
...  
Keyword(s):  
Pulmonary Function ◽  
Symptom Onset ◽  
Prospective Cohort ◽  
Pulmonary Function Tests ◽  
Patient Reported Outcome Measures ◽  
Patient Reported Outcome ◽  
Considerable Proportion ◽  
Patient Reported ◽  
Underlying Mechanisms ◽  
Over Time

ObjectivesTo compare respiratory and patient-reported outcome measures (PROMs) between 3 and 6 months after symptom onset and to identify features that predict these changes.MethodsThis is a consecutive prospective cohort of 73 patients who were hospitalised with COVID-19. We evaluated the changes in pulmonary function tests (PFTs) and PROMs between 3 and 6 months and then investigated the associations between outcomes (change in diffusing capacity for carbon monoxide of the lung (DLCO), dyspnea, and quality of life (QOL)) and clinical and radiological features.ResultsThere was improvement in forced vital capacity (FVC), total lung capacity (TLC), and DLCO between 3 and 6 months by 3.25%, 3.82% and 5.69% respectively; however, there was no difference in PROMs. Reticulation and total CT scores were associated with lower DLCO %-predicted at 6 months (coefficients; −8.7 and −5.3 respectively). The association between radiological scores and DLCO were modified by time, with the degree of association between ground glass and DLCO having decreased markedly over time. There was no association between other predictors and change in dyspnea or QOL over time.ConclusionsThere is improvement in pulmonary function measurements between 3 and 6 months after COVID-19 symptom onset; however, PROMs did not improve. A higher reticulation and total CT score are negatively associated with DLCO, but this association is attenuated over time. Lastly, there is a considerable proportion of patients with unexplained dyspnea at 6 months, motivating further research to identify the underlying mechanisms.

demand for producer goods (that is, implements, fertilisers, etc.) was largely left unsatisfied, a fact which eroded the peasants' productive basis. The exchange with the peasantry became conditioned by the following three interlocking phenomena: (1) the reduction in relative and in absolute terms of official marketing of crops as result of the rapid expansion of parallel markets; (2) the galloping inflation of prices in the parallel markets; and (3) the consequent rapid depreciation of the currency and the increased reluctance to accept the metical in exchange for sale of goods. Although the surface appearances of these phenomena were generally recog-nised, the explanation of the underlying mechanisms was by no means clear. The dominant explanation of the problem came from the ministry of internal commerce which was in its day-to-day operation more directly con-fronted with the problem. According to this view the nature of the problem was the withdrawal from the market by the peasantry since money no longer bought goods. Hence, the payment of rural wages and the buying of cash crops channelled a volume of money into the economy far in excess of available pro-ducer and consumer goods directed to the peasantry. Cash balances therefore accumulated over time and the stimulus to further production was blunted. The fact that the supply of commodities destined to be traded with the peasantry was, in terms of value, far in excess of the official marketing of crops was the often quoted proof that peasants simply ran down cash balances to buy goods and did not produce more for exchange. This view often overlooked the impact of the demand springing from the wage bill and, hence, directly equated the difference between the supply of goods to the peasantry and the goods obtained in return with the running down of cash balances accumulated by the peasantry. The problem therefore was seen as one of an excessive volume of money being held in the rural areas: peasants had too much money relative to the available supply of goods. Therefore, they withdrew from the market and preferred to buy up any supplies forthcoming with the money in hand rather than through production. Implicit in this view was a conception of a single circuit of exchange between the state sector and the peasantry in which the state buys with money either cash crops or labour power, and subsequently the peasantry buys consumer and producer commodities from the state sector (with or without the intermediation of private trade). If both parts do not balance in value, idle balances of money will build up in the hands of the peasantry and over time blunt the incentive of production. The preoccupation was thus with the stock of money in the hands of the peasantry (as a measure of frustrated demand) and little attention was paid to its velocity since it was implicitly assumed that these balances remained idle (stuck in the peasants' pockets). Therefore, concerning economic policy, a solution was sought in the direction of neutralising the interference of accumulated balances by linking sale and purchase together. Hence, commodities would be sold to the peasantry only in exchange for the purchase of cash crops. Similarly, state farms would guarantee a certain part of the wage in kind to assure the flow of labour.

2013 ◽  
pp. 206-207
Keyword(s):  
Rural Areas ◽  
The State ◽  
Rapid Expansion ◽  
State Sector ◽  
Cash Crops ◽  
The Difference ◽  
Underlying Mechanisms ◽  
Rural Wages ◽  
The Impact ◽  
Over Time

scholarly journals Dust deposition drives microbial metabolism in a remote, high-elevation catchment

The Holocene ◽  
2019 ◽  
Vol 30 (4) ◽  
pp. 589-596 ◽  
Author(s):  
Amy Bigelow ◽  
Natalie Mladenov ◽  
David Lipson ◽  
Mark Williams
Keyword(s):  
Organic Matter ◽  
Atmospheric Deposition ◽  
Rate Constants ◽  
Rocky Mountains ◽  
Microbial Metabolism ◽  
High Elevation ◽  
Dust Deposition ◽  
Fluorescence Excitation ◽  
Colorado Rocky Mountains ◽  
Over Time

In barren alpine catchments of the Colorado Rocky Mountains, microorganisms are typically carbon (C)-limited, and C-limitation can influence critical heterotrophic processes, such as denitrification. In these remote locations, organic matter deposited during dust intrusion events and other forms of aerosol deposition may be an important C source for heterotrophs; however, little is known regarding the biodegradability of atmospherically deposited organic matter. This study evaluated the extent to which organic matter in Holocene dust and other types of atmospheric deposition in the Colorado Rocky Mountains could support metabolic activity and be biodegraded by alpine bacteria. Microplate bioassays revealed that all atmospheric deposition samples were able to activate microbial metabolism. Decreases in dissolved organic carbon (DOC) concentrations over time in biodegradability incubations reflect the presence of two pools of dissolved organic matter (DOM), a rapidly decaying pool with rate constants in the range of 0.0130–0.039 d–1 and a slowly decaying pool with rate constants in the range of 0.0008–0.009 d–1. Changes in the fluorescence excitation-emission matrix of solutions evaluated over time indicated a transformation of organic matter by bacteria resulting in a more humic-like fluorescence signature. Fluorescence spectroscopic analyses, therefore, suggest that the degradation of non-fluorescent DOM in glutamate and dust-derived C sources by bacteria results in the production of fluorescent DOM.

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