108 research outputs found
A meta-analysis study of welfares of genetically modified crops
No full textDue to the controversial debates, skepticism and speculations around Genetic Modified (GM) crops, substantial research has been done on the allocation of welfare implications of GM crops. However, different procedures, various data sources and economic models are used to study commercialized GM crops around the world. Therefore mixed conclusions were conducted. Some papers mentioned benefits from farm producer side; some focused on research of willingness to pay among consumers; while others were asmore interested in market prospect. As a result, is has become difficult to effectively summarize the benefit of adopting GM crops and explain the large study-to-study variations of surplus estimation. This thesis presents a meta-analysis of 58 primary studies with a total of 119 GM crops evaluations, aiming to summarize previous studies on economic surplus of GM crops which are not conditional from a single research study and to identify the determinants of the farmer surplus, GM seed company surplus and consumer surplus of GM crops, from analysis and comparison those broad range data set. This thesis finds that GM seed companies and farmers gained different surplus based on geographic locations. On the other hand, research methods might affect farmer surplus estimation but not GM seed company surplus.M.S.Includes bibliographical referencesby Yuze Shan
Intimate Relationship Satisfaction as a Potential Moderator of the Longitudinal Association between Stress and Depression
Full text linkDepression is a highly prevalent psychiatric disorder and a major contributor to global disease burden. The quality of one’s relationship with their romantic partner (i.e., relationship satisfaction) is negatively associated with depression. However, there has been surprisingly little research conducted evaluating the degree to which relationship satisfaction buffers the impact of stress on depression. The current study evaluated the longitudinal associations between relationship satisfaction, stress, and depressive symptoms in the Americans’ Changing Lives survey, a large probability sample of American married adults (N = 1390). Results indicated that (a) relationship satisfaction was significantly and negatively correlated with depressive symptoms and stress was significantly and positively correlated with depressive symptoms in cross-sectional analyses, (b) relationship satisfaction and stress were each uniquely associated with residual change in depressive symptoms in longitudinal analyses, and (c) relationship satisfaction did not moderate the longitudinal association between stress and depression. Results suggest the examination of both relationship satisfaction and stress may provide a more comprehensive understanding of depression than an exclusive focus on either relationship satisfaction or stress.</p
Intimate Relationship Satisfaction as a Potential Moderator of the Longitudinal Association between Stress and Depression
Full text linkDepression is a highly prevalent psychiatric disorder and a major contributor to global disease burden. The quality of one’s relationship with their romantic partner (i.e., relationship satisfaction) is negatively associated with depression. However, there has been surprisingly little research conducted evaluating the degree to which relationship satisfaction buffers the impact of stress on depression. The current study evaluated the longitudinal associations between relationship satisfaction, stress, and depressive symptoms in the Americans’ Changing Lives survey, a large probability sample of American married adults (N = 1390). Results indicated that (a) relationship satisfaction was significantly and negatively correlated with depressive symptoms and stress was significantly and positively correlated with depressive symptoms in cross-sectional analyses, (b) relationship satisfaction and stress were each uniquely associated with residual change in depressive symptoms in longitudinal analyses, and (c) relationship satisfaction did not moderate the longitudinal association between stress and depression. Results suggest the examination of both relationship satisfaction and stress may provide a more comprehensive understanding of depression than an exclusive focus on either relationship satisfaction or stress.</p
Sensor Calibrations with the Improved Picodrift Interferometer
No full textTo meet the growing demand for high precision measurement equipment, sensors with sub-nanometer resolution are becoming readily available. Because of its high precision, traceability and ease of use, the interferometer stands out for high precision measurements. However, the laser beam of an interferometer can be influenced by temperature and pressure fluctuations. Compensation of this error is possible by sensing temperature and pressure fluctuations while performing interferometric measurements. Alternatively, a refractometer running parallel with the interferometer can be used to do the same compensation with a higher accuracy. Additionally, errors caused by external sources such as vibrations, can be compensated by adopting a highly symmetrical design. Picodrift interferometer was developed and upgraded at VSL (Dutch Metrology Institute) as a calibration facility for high-precision sensors. First, the improved design of the picodrift interferometer is evaluated, implemented and tested allowing for a controlled measurement environment and high stability. The design requirements are determined to reduce the uncertainty caused by temperature and pressure fluctuations to picometer level in one hour. Based on those requirements, a vacuum system is implemented and tested to reach a pressure level in the ultra-high vacuum regime. During the implementation, necessary experiments and tests are performed to find leakages and the reasons for an undesired beam drift related to the pressure change. Additionally, an active temperature control system with passive shield is installed. Also, various kinematic coupling mount systems are designed and manufactured to provide a good positioning stability even in a noisy environment caused by a turbo pump. As the number of the interferometer channels has been doubled to perform measurements in both vacuum and atmospheric conditions, a well planned alignment procedure is developed to align the more sophisticated optical path. To characterize the performance of the new interferometer, a dead path measurement is performed. Second, to take advantage of the high precision and traceability, the interferometer is expanded to work as a calibration facility for external sensors of different sizes. A stable symmetrical calibration setup is designed to fit in a limited space for external measurements while minimizing uncertainty caused by temperature fluctuation and misalignment. An alignment procedure for the setup is developed. Eventually an example calibration is performed. <br/
Fast-responsive capsule based on two soluble components for self-healing concrete
No full textDue to low activity or long mineralization time, traditional mineral agents for self-healing concrete generally need a long time to achieve a desired repair efficiency. Inspired by epoxy resin AB glue which can consolidate in a short time when mixing the two components together, a novel type of fast-responsive capsules based on two soluble components was designed for self-healing concrete. Component A (sodium carbonate) and component B (calcium acetate) were encapsulated in two different groups of capsules, respectively, coated with three layers consisting of epoxy resin and fine sands to achieve superior waterproof and alkali resistance properties. After rupture of the capsules, the rapid response with respect to core material dissolution and precipitation can be realized in presence of water, by which the cracks below 200 μm can be healed in 3 days. Super absorbent resin (SAP) embedded in the capsules could expand in contact with water, and further improve the self-healing efficiency of the capsules by blocking the crack.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Materials and Environmen
Study on the optimization of the number of entrances in automobile factory based on Queuing Theory
No full textEvolved structure of thiazolothiazole based small molecules towards enhanced efficiency in organic solar cells
No full textSmall molecule donors T0-T2 with thiazolothiazole as acceptor unit, triphenylamine as donor unit and thiophene with different number as bridge are synthesized. With increasing thiophene number and conjugation length, these molecules exhibit red-shifted absorption (300-600 nm), slightly up-shifted HOMO levels (-5.31 to -5.28 eV), slightly down-shifted LUMO levels (-2.64 to -2.75 eV), and reduced optical band gaps (2.55-2.11 eV). Solution processed organic solar cells based on T0-T2/PC71BM (1:4, w/w) after thermal annealing exhibit power conversion efficiency up to 2.19%, 3.73% and 4.05% under AM 1.5G illumination (100 mW/cm(2)), respectively. Effects of thermal annealing on morphology, charge transport and photovoltaic property of blend films are investigated. (C) 2012 Elsevier B.V. All rights reserved.Materials Science, MultidisciplinaryPhysics, AppliedSCI(E)EI24ARTICLE2599-6061
Oligomer Molecules for Efficient Organic Photovoltaics
No full textCONSPECTUS: Solar cells, a renewable, clean energy technology that efficiently converts sunlight into electricity, are a promising long-term solution for energy and environmental problems caused by a mass of production and the use of fossil fuels. Solution-processed organic solar cells (OSCs) have attracted much attention in the past few years because of several advantages, including "easy fabrication, low cost, lightweight, and flexibility. Now, OSCs exhibit power conversion efficiencies (PCEs) of over 10%. In the early stage of OSCs, vapor-deposited organic dye materials were first used in bilayer heterojunction devices in the 1980s, and then, solution-processed polymers were introduced in bulk heterojunction (BHJ) devices. Relative to polymers, vapor deposited small molecules offer potential advantages, such as a defined molecular structure, definite molecular weight, easy purification, mass-scale production, and good batch-to-batch reproducibility. However, the limited solubility and high crystallinity of vapor-deposited small molecules are unfavorable for use in solution-processed BHJ OSCs. Conversely, polymers have good solution-processing and film-forming properties and are easily processed into flexible devices, whereas their polydispersity of molecular weights and difficulty in purification results in batch to batch variation, which may hamper performance reproducibility and commercialization. Oligomer molecules (OMs) are monodisperse big molecules with intermediate molecular weights (generally in the thousands), and their sizes are between those of small molecules (generally with molecular weights <1000) and polymers (generally with molecular weights >10000). OMs not only overcome shortcomings of both vapor-deposited small molecules and solution processed polymers, but also combine their advantages, such as defined molecular structure, definite molecular weight, easy purification, mass-scale production, good batch-to -batch reproducibility, good solution processability, and film-forming properties. Therefore, OMs are a good choice for solution-processed reproducible OSCs toward scalable commercialized applications. Considerable efforts have been dedicated to developing new OM electron donors and electron acceptors for OSCs. So far, the highest PCEs of solution -processed OSCs based on OM donors and acceptors are 9-10% and 6-7%, respectively. OM materials have become promising alternatives to polymer and/or fullerene materials for efficient and stable OSCs. In this Account, we present a brief survey of the recent developments in solution-processable OM electron donors and acceptors and their application in OSCs. Rational design of OMs with star- and linear-shaped structures based on triphenylamine, benzodithiophene, and indacenodithiophene units and their impacts on device performance are discussed. Structure property relationships are also proposed. Furthermore, the remaining challenges and the key research directions in the near future are also addressed. In the next years, an interdisciplinary approach involving novel OM materials, especially electron acceptor materials, accurate morphology optimization, and advanced device technologies will probably bring high-efficiency and stable OSCs to final commercialization.973 Program [2013CB834702]; NSFC [91433114, 51261130582, 21025418, 21504058]SCI(E)[email protected]
Phosphonium Salt-Promoted C2–H Functionalization of Heterocyclic <i>N</i>‑Oxides
No full textWe report the development of a phosphonium salt as a
remarkable
activating agent that enables the direct conversion of C2–H
bonds of a variety of heterocyclic N-oxides into
C2–N, C2–O, or C2–S bonds with high efficiency.
The phosphonium salt was prepared on a >150 g scale in a single
step
and is tolerant of multiple functionalities
Feasibility of Offshore Co-culture of Abalone, Haliotis discus hannai Ino, and Sea Cucumber, Apostichopus japonicus, in a Temperate Zone
No full textFeasibility of offshore co-culture of abalone and sea cucumber was investigated in Northern China. Survival and growth of abalone, Haliotis discus hannai Ino, and sea cucumber, Apostichopus japonicus, co-cultured in abalone cages from suspended longlines, in the offshore area, were examined. Abalone and sea cucumbers were co-cultured at density ratios of both 3: 1 and 6: 1 for 1 yr. Abalone were fed with fresh kelp and no additional feed was given to sea cucumbers. Survival of abalone and sea cucumber was 100% for all treatments. Abalone and sea cucumber grew well; the body weight (BW) of abalone and sea cucumber was nearly doubled and had reached a commercial size. There were no significant differences in the growth rates for both abalone and sea cucumber between the two density treatments. The specific growth rate of BW of abalone (SGRbw) was highest in June, with a value of 0.536%/ d. Growth rate of sea cucumber (SGRsc) was highest in December, reached 1.84%/ d, with an annual average SGRsc of 0.182%/ d. Results suggested that the offshore co-culture of abalone and sea cucumber was feasible offshore. The co-culture of abalone with sea cucumbers may provide an additional valuable crop without additional financial input.Feasibility of offshore co-culture of abalone and sea cucumber was investigated in Northern China. Survival and growth of abalone, Haliotis discus hannai Ino, and sea cucumber, Apostichopus japonicus, co-cultured in abalone cages from suspended longlines, in the offshore area, were examined. Abalone and sea cucumbers were co-cultured at density ratios of both 3: 1 and 6: 1 for 1 yr. Abalone were fed with fresh kelp and no additional feed was given to sea cucumbers. Survival of abalone and sea cucumber was 100% for all treatments. Abalone and sea cucumber grew well; the body weight (BW) of abalone and sea cucumber was nearly doubled and had reached a commercial size. There were no significant differences in the growth rates for both abalone and sea cucumber between the two density treatments. The specific growth rate of BW of abalone (SGRbw) was highest in June, with a value of 0.536%/ d. Growth rate of sea cucumber (SGRsc) was highest in December, reached 1.84%/ d, with an annual average SGRsc of 0.182%/ d. Results suggested that the offshore co-culture of abalone and sea cucumber was feasible offshore. The co-culture of abalone with sea cucumbers may provide an additional valuable crop without additional financial input
- …
