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- 摘要
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- 实验方案
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Structure and binding efficiency relations of QB site inhibitors of photosynthetic reaction centres*
摘要： Many herbicides employed in agriculture and also some antibiotics bind to a specific site of the reaction centre protein (RC) blocking the photosynthetic electron transport. Crystal structures showed that all these compounds bind at the secondary ubiquinone (QB) site albeit to slightly different places. Different herbicide molecules have different binding affinities (evaluated as inhibition constants, KI, and binding enthalpy values, ?Hbind). The action of inhibitors depends on the following parameters: (i) herbicide molecular structure; (ii) interactions between herbicide and quinone binding site; (iii) protein environment. In our investigations KI and ?Hbind were determined for several inhibitors. Bound herbicide structures were optimized and their intramolecular charge distributions were calculated. Experimental and calculated data were compared to those available from databank crystal structures. We can state that the herbicide inhibition efficiency depends on steric and electronic factors, i.e. geometry of binding with the protein and molecular charge distribution, respectively. Apolar bulky groups on N-7 atom of the inhibitor molecule (like t-buthyl in terbutryn) are preferable for establishing stronger interactions with QB site, while such substituents are not recommended on N-8. The N-4,7,8 nitrogen atoms maintain a larger electron density so that more effective H-bonds are formed between the inhibitor and the surrounding amino acids of the protein.
关键词： Herbicides,Bacterial reaction centers,Photosynthesis,Molecular modeling
更新于2025-09-23 15:22:29
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Realization of modified Luneburg lens antenna using quasi-conformal transformation optics and additive manufacturing
摘要： We demonstrate a new method for realizing modified Luneburg lens antennas with nearly continuously graded permittivity profiles in three-dimensions. The method used a quasi-conformal transformation optics (QCTO) approach to modify the geometry and permittivity of a spherical Luneburg lens to have a flat surface for convenient integration of antenna feeds. The modified lens was then fabricated using Fused Deposition Modeling (FDM) printing with an effective media approach that employs space-filling curves. The method was validated by designing and fabricating a modified Luneburg lens antenna designed to operate in the Ka-band. The antenna performance of the sample was measured experimentally and shown to compare well to predicted results using full wave simulations. The device was able to achieve a reasonably high degree of beam steering (ie, ?55° to +55°) over the entire Ka-band. We believe this new approach provides a cost-effective and scalable means of realizing practical passive beam steering lenses that operate over a broad range of frequencies.
关键词： additive manufacturing,beamscanning,beamforming,fused deposition modeling,Luneburg lens,transformation optics
更新于2025-09-23 15:22:29
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[IFIP Advances in Information and Communication Technology] Computer and Computing Technologies in Agriculture X Volume 509 (10th IFIP WG 5.14 International Conference, CCTA 2016, Dongying, China, October 19–21, 2016, Proceedings) || Modelling and Predicting of Soil Electrical Conductivity and PH from Semi-arid Grassland Using VIS-NIR Spectroscopy Technology
摘要： The electrical conductivity (EC) and pH value are key indicators for soil physical and chemical properties, which can re?ect the level of soil acid and alkali, furthermore, in?uence the vegetation growth. The spectroscopy technique can estimate and evaluate electrical conductivity and pH value rapidly and ef?ciently, which can provide useful information on the real-time soil management in the semi-arid rangeland or grassland. We picked the semi-arid grassland of northern China covering an area about 200 km2 as the target research area, given that it is highly sensitive to grazing and mining affect. Soil samples were collected from 72 sampling sites in this area, which covered grazing exclusion, over grazing and grassland restoration area. The SVC HR-1024 spectroradiometer was used to acquire soil spectrum. This study aims to indicate the spectral characteristic for soil EC and pH, and propose a predicting modeling method with optimal input spectral region and transformation by comparing the support vector machine (SVM) regression method and partial least squares (PLSR) regression modeling method. Our results showed that: (1) once EC value is larger than 0.10 ls/m, the soil spectral re?ectance decreases with increasing of EC value. The absorption depth, width and area at 1900 nm reduce with increasing of EC value as well; (2) There are positive correlation between EC, pH value and soil spectral re?ectance. The highest correlation coef?cient value of 0.7 between pH and re?ectance is recorded at visible region around 500 nm; (3) The SVM modeling method produce the higher prediction accuracy (RPD = 2.18, RMSE = 0.035, R2 = 0.78 for EC, RPD > 3, RMSE = 0.349, R2 = 0.91 for pH) rather than PLSR methods in soil EC and pH prediction. This study indicated that it was possible to use the spectroradiometer technology to predict EC and pH value for the soil from semi-arid grassland, which would provide the basis for soil acid and alkali detecting using hyper-spectral remote sensing technology.
关键词： Semi-arid grassland,Spectral modeling and predicting,Soil electrical conductivity and pH,Spectral characteristic
更新于2025-09-23 15:22:29
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Materials-Informatics-Assisted High-Yield Synthesis of 2D Nanomaterials through Exfoliation
摘要： A variety of inorganic and organic nanosheets with characteristic structures and properties can be synthesized through exfoliation of layered materials. However, in general, immense time and efforts are required for exploration of exfoliation conditions and characterization of nanosheets. In addition, it is challenging to improve the yield of nanosheets obtained through exfoliation. Here a materials-informatics-assisted high-yield synthesis of nanosheets is proposed, which does not require experience and intuition. Layered composites containing inorganic layers and interlayer organic guests are delaminated into nanosheets in a variety of dispersion media. First, an experimental screening is performed to find efficient exfoliation conditions and obtain a training dataset for the informatics approach. Sparse modeling is then used facilitating the extraction of important factors predicting the yield of nanosheets. High-yield (up to (cid:2)50%) synthesis of nanosheets is demonstrated in unknown systems in a minimum number of experiments. The yield is higher than those typically reported for layered materials. It is expected that the effective combination has potentials for not only discovery of compounds but also structure control of materials.
关键词： sparse modeling,layered materials,exfoliation,2D nanomaterials,materials informatics
更新于2025-09-23 15:22:29
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Transport models in disordered organic semiconductors and their application to the simulation of thin-film transistors
摘要： Relevant organic thin-film transistor (OTFT) simulation software must account for the main specificities of organic semiconductors (OSC) in term of free carriers’ density of states, transport mechanisms, and injection/collection properties from/to the device contacts. Among the parameters impacting the OTFT performance the carrier mobility is a key parameter. Usual methods to extract the mobility from current-voltage (I-V) measurements lead to obtained only an apparent, or effective, mobility. The value of the apparent mobility is different of the intrinsic channel organic semiconductor mobility. Despite this effective mobility actually determines most of a given device performance, therefore providing a very useful technology benchmark, it does not describe the intrinsic organic semiconductor material transport properties, and may even be misleading in the route to improve the OTFT fabrication process. To obtain a better understanding of the transport properties in OSCs using OTFT electrical characterization, implementing an appropriate physical mobility model in an OTFT I-V simulation software is a good way. The present paper gives a review of the carrier mobility models which can be implemented in OTFT simulation software. The review is restricted to the analytical and semi-analytical physical models taking into account the temperature, the carrier concentration and the electric field dependence of the carrier mobility in disordered OSCs.
关键词： mobility,transport,modeling,organic semiconductors,Organic thin-film transistor (OTFT)
更新于2025-09-23 15:22:29
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Barriers to and consequences of a solar-based energy transition in Greece
摘要： In Greece, the renewable energy potential and a low-quality building stock constitute the background of a possible low-carbon energy transition. This transition, however, faces significant uncertainties, ranging from long-term effects of the ongoing economic recession and technological lock-ins, to the stability of the regulatory framework and issues of public acceptance. Such uncertainties may eventually give rise to significant barriers to, as well as severe economic and social consequences of, the envisaged transition. Here, in a structured approach to eliciting the knowledge embedded in stakeholders, we identify such risks and explore their dynamics and role in a sustainable transition to a power system that is based on large-scale solar projects and prosuming in the residential sector. We then employ a modelling ensemble, consisting of a macroeconomic dynamic stochastic general equilibrium model and a business strategy assessment model, in order to quantify and evaluate the extent of the identified risks’ impact.
关键词： Modeling,Energy transitions,Fuzzy cognitive maps,Solar power,Greece,Self-consumption
更新于2025-09-23 15:22:29
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Mapping salt marsh soil properties using imaging spectroscopy
摘要： Tidal salt marshes sequester and store blue carbon at both short and long time scales. Marsh soils shape and maintain the ecosystem by supporting complex biogeochemical reactions, deposition of sediment, and accumulation of organic matter. In this study, we examined the potential of imaging spectroscopy techniques to indirectly quantify and map tidal marsh soil properties at a National Estuarine Research Reserve in Georgia, USA. A framework was developed to combine modern digital image processing techniques for marsh soil mapping, including object-based image analysis (OBIA), machine learning modeling, and ensemble analysis. We also evaluated the efficacy of airborne hyperspectral sensors in estimating marsh soil properties compared to spaceborne multispectral sensors, WorldView-2 and QuickBird. The pros and cons of object-based modeling and mapping were assessed and compared with traditional pixel-based mapping methods. The results showed that the designed framework was effective in quantifying and mapping three marsh soil properties using the composite reflectance from salt marsh environment: soil salinity, soil water content, and soil organic matter content. Multispectral sensors were successful in quantifying soil salinity and soil water content but failed to model soil organic matter. The study also demonstrated the value of minimum noise fraction transformation and ensemble analysis techniques for marsh soil mapping. The results suggest that imaging spectroscopy based modeling is a promising tool to quantify and map marsh soil properties at a local scale, and is a potential alternative to traditional soil data acquisition to support carbon cycle research and the conservation and restoration of tidal marshes.
关键词： Salt marsh,Object-based modeling,Soil properties,Imaging spectroscopy,Machine learning
更新于2025-09-23 15:22:29
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[IEEE 2018 North American Power Symposium (NAPS) - Fargo, ND, USA (2018.9.9-2018.9.11)] 2018 North American Power Symposium (NAPS) - Effect of Solar PV Penetration on Residential Energy Consumption Pattern
摘要： The residential rooftop solar penetration in the U.S. has increased rapidly over the past few years. This increase, if not properly accounted for, can lead to operational and reliability challenges for the electric power industry in the form of under-utilization of available energy, increase in costs, and reduction in environmental benefits, as demonstrated by the California Independent System Operator (CAISO) Duck Curve. The authors of this paper had previously developed a bottom-up approach for computing season-wise household-level residential energy consumption profiles using a synthetic population resource. In this paper, that model is enhanced to account for the effects that increasing percentages of rooftop solar penetration can have on the residential energy demand profiles of different regions. This information will be very useful to electric power utilities because it will help them efficiently manage the increasing numbers of residential rooftop solar installations in their supply areas.
关键词： rooftop solar photovoltaic (PV),synthetic population,residential energy consumption,Energy demand modeling,seasonal variation
更新于2025-09-23 15:22:29
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A D-band Multiplier-based OOK Transceiver with Supplementary Transistor Modeling in 65-nm Bulk CMOS Technology
摘要： A D-band on-off keying (OOK) transceiver chipset is fabricated in a 65-nm bulk CMOS technology as a low-cost and highly-integrative solution to short-distance wireless connectivity. Supplementary transistor modeling is performed for accurate circuit design at mm-wave frequencies. To overcome low transistor fmax and reduce DC power consumption, the transmitter employs a frequency-multiplier-based architecture with no power amplifier. The receiver adopts a non-coherent architecture consisting of a DC-coupled three-stage differential amplifier and an envelope detector. The OOK transmitter exhibits a measured output power of -9.8 dBm and on-off level difference of 13.2 dB at 134.1 GHz. The receiver shows a measured average responsivity of 4.1 kV/W and a noise equivalent power of 211.4 pW/Hz1/2 over all D-band frequencies. The DC power consumption of the transmitter and receiver are 76 mW and 32.5 mW, respectively. The transceiver is tested in both on-chip loopback and air-channel configurations, and demonstrates data transmission up to 10 Gbps and 2 Gbps at a distance of 0.03 m, respectively.
关键词： transceiver,transistor modeling,D-band,wireless communication,low-cost bulk CMOS,OOK
更新于2025-09-23 15:22:29
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[IEEE 2018 Wave Electronics and its Application in Information and Telecommunication Systems (WECONF) - Saint-Petersburg, Russia (2018.11.26-2018.11.30)] 2018 Wave Electronics and its Application in Information and Telecommunication Systems (WECONF) - Modeling Environment for Processing of Photos and Video Content Transmitting by Open Channels
摘要： The report describes the Graphical User Interface and Architecture of the Modeling Environment for photo and video images processing transmitted by open channels.
关键词： image processing,masking method,open networks,modeling environment
更新于2025-09-23 15:22:29