3,163 research outputs found
白金微粒/Ru錯合物/高分子薄磨修飾電極之製備及其電催化應用
No full text[[abstract]]Membrane-metal modified cells are usually applied to the field of membrane cells, such as fuel cells, light cells… etc. Some hydrogen evolution catalysts, for example Pt metal, are used as the cathodes in these cells. Therefore, in this research, we try to dose a series of Ru complexes into the intervals between the cathode and the thin film electrode to improve the hydrogen evolution efficiency of the membrane-metal modified cells.
Ru complex (chosen from Ru(bpy)2phenNH2, Ru(dmb)2 phenNH2, Ru(tmb)2phenNH2, Ru(bpy)2Cl2, Ru(dmb)2Cl2, Ru(tmb)2Cl2) doped Nafion solution was drop-coated onto glassy carbon (GC) electrode and formed a thin film after drying. Then, the GC electrode was immersed into H2PtCl6 solution, and the Pt/Ru complex/polymer modified electrode was obtained by reducing Pt with a DPTB method. Different amount of Pt was electroplated on the GC electrode even at the same conditions (the same potential, the same time interval) when different consistency or kinds of Ru complexes were used, suggesting the influence of the ligands on the red-ox property of Ru complexes. The effective surface area (estimated by CV method) of Pt in the modified electrode is also varied with different species of Ru complexes, which in turn affect on the efficiency of hydrogen evolution.
Furthermore, from the information obtained by SEM and EDS, the alignment and the density of Pt particles growing on the GC electrode are figured out. From the fluorescence lifetime and luminescence spectra, a good electron-transfer is considered to have occurred between D series Ru complexes and Pt modified electrode that explained why a high hydrogen evolution efficiency has been obtained. The modified electrodes are still stable one month after fabricated and their hydrogen evolution efficiency was as good as a newly prepared one.
Evaluating drought tolerance of southern highbush and rabbiteye blueberries
No full textDrought is one of the most detrimental natural causes leading to yield loss in crops across
the globe. With increasing severity and frequency of drought events, it is imperative to identify
and breed for cultivars that can withstand periods of water deficit. In blueberry (Vaccinium sp.),
drought is especially adverse due to a shallow root system which lacks root hairs. The purpose of
this study was to identify common responses of blueberry to drought in addition to finding
cultivars with superior traits in response to water deficit. In the southeastern United States, both
rabbiteye (Vaccinium virgatum) and southern highbush (Vaccinium corymbosum L. interspecific
hybrids) blueberries are commonly cultivated due to their low chill requirements. Previous
studies have highlighted on the ability of the rabbiteye ecotype to withstand several abiotic
stresses including drought, while southern highbush is more well-known for its superior berry
quality.
In order to examine the effects of drought on both southern highbush and rabbiteye
blueberries, seven cultivars were chosen for evaluation: Misty, Star, Suziblue (SHB), Brightwell,
Vernon, Powderblue, and Climax (RE). Four-year-old plants of all seven cultivars were
subjected to a drought period of 36-days in the spring of 2023 at EV Smith Research Station in
Tallassee, AL. Throughout the drought, plants were monitored for overall plant health,
physiological activity, yield, and fruit quality.
Drought stress was found to significantly decrease photosynthesis, stomatal conductance,
electron transport rate, leaf relative water content, specific leaf area, chlorophyll content, Jmax,
yield, average berry weight, and malic acid content of berries. Alternatively, water stress was
found to significantly increase Brix, polyphenol, and berry firmness. Star and Misty were
identified as the most drought tolerant cultivars based on high yield and average berry weight in addition to high levels of gas exchange under drought stress. Alternatively, Powderblue, Vernon,
and Suziblue were found to be the most susceptible to drought. Brightwell was found to have
intermediate tolerance in comparison to other cultivars. In the future, it would be valuable to
study post-drought root morphology in addition to studying genetic factors that may play a role
in blueberry drought toleranc
High-throughput phenotyping applications in control and outdoor environments for stress tolerance analysis of kale and blueberries production
No full textAbiotic stressors such as drought and salinity significantly impact plant growth, development, and productivity. Traditional phenotyping methods for assessing plant responses to these stressors are labor-intensive, time-consuming, and unsuitable for large-scale plant populations. This thesis explores the application of advanced high-throughput phenotyping techniques by utilizing cutting-edge imaging technologies combined with machine learning and deep learning models to assess plant stress tolerance and predict physiological traits. These application-driven approaches provide scalable, non-destructive, and precise phenotyping capabilities, improving resource management and accelerating breeding programs for stress-resilient crops. To evaluate salt stress tolerance in kale plants, a high-throughput phenotyping system utilizing RGB imaging was developed. This system automated the extraction of morphological traits, such as canopy area and axes lengths, using YOLOv8 instance segmentation models trained on images from GoPro and Raspberry Pi cameras. Results showed that the model achieved mAP values between 0.897–0.952, and plants with split-root systems demonstrated superior growth under high salt stress compared to single-root systems. An ARIMA model was also used to forecast plant growth, achieving low MAPE values, providing growers with a new method to optimize resource allocation in controlled environments. Assessing drought stress in blueberries is crucial for supporting breeding programs aimed at developing drought-tolerant varieties. To facilitate laborious and time consumption task, a custom hyperspectral imaging platform was designed to capture high-resolution spectral data. A Transformer-based model, LWC-former, was introduced to predict leaf water content (LWC) by transforming spectral reflectance into patch representations, effectively addressing multicollinearity issues in hyperspectral data. The results showed that our model achieved a coefficient of determination (R²) of 0.81 on the test dataset. The performance of the proposed model was also compared with a multilayer perceptron (MLP), partial least squares regression (PLSR), support vector regression (SVR), and random forest (RF), achieving R² values of 0.71, 0.47, and 0.58, respectively. The results demonstrated that LWC-former outperformed other deep learning and statistical-based models, demonstrating its effectiveness for large-scale drought tolerance phenotyping. To obtain more comprehensive insights into plant responses under drought stress, it is critical to predict additional physiological traits beyond LWC. To this end, a Graph Convolutional Network (GCN)-based model, Plant-GCN, was developed to predict multiple physiological traits of blueberries along with LWC, such as stomatal conductance (gs), electron transport rate (ETR), photosystem II efficiency (φPSII), and photosynthesis (A) using hyperspectral imaging data. The GCN model transformed spectral data into a graph-based representation, capturing complex spectral interactions among plants. The model achieved R² values ranging from 0.89 to 0.94 for different traits and consistently outperformed other statistical and deep learning-based models, demonstrating its ability to accurately and efficiently predict a wide range of physiological traits under drought stress conditions. This unified approach provides a more complete picture of plant responses, offering a scalable solution for phenotyping and improving drought resilience strategies
Photophysical Characterization of Ru Nanoclusters on Nanostructured TiO<sub>2</sub> by Time-Resolved Photoluminescence Spectroscopy
No full textDespite the promising performance of Ru nanoparticles or nanoclusters on nanostructured TiO2 in photocatalytic and photothermal reactions, a mechanistic understanding of the photophysics is limited. The aim of this study is to uncover the nature of light-induced processes in Ru/TiO2 and the role of UV versus visible excitation by time-resolved photoluminescence (PL) spectroscopy. The PL at a 267 nm excitation is predominantly due to TiO2, with a minor contribution of the Ru nanoclusters. Relative to TiO2, the PL of Ru/TiO2 following a 267 nm excitation is significantly blue-shifted, and the bathochromic shift with time is smaller. We show by global analysis of the spectrotemporal PL behavior that for both TiO2 and Ru/TiO2 the bathochromic shift with time is likely caused by the diffusion of electrons from the TiO2 bulk toward the surface. During this directional motion, electrons may recombine (non)radiatively with relatively immobile hole polarons, causing the PL spectrum to red-shift with time following excitation. The blue-shifted PL spectra and smaller bathochromic shift with time for Ru/TiO2 relative to TiO2 indicate surface PL quenching, likely due to charge transfer from the TiO2 surface into the Ru nanoclusters. When deposited on SiO2 and excited at 532 nm, Ru shows a strong emission. The PL of Ru when deposited on TiO2 is completely quenched, demonstrating interfacial charge separation following photoexcitation of the Ru nanoclusters with a close to unity quantum yield. The nature of the charge-transfer phenomena is discussed, and the obtained insights indicate that Ru nanoclusters should be deposited on semiconducting supports to enable highly effective photo(thermal)catalysis.QN/Afdelingsburea
Mitigating Salinity Stress in Red Kale (Brassica napus L. var. Pabularia ‘KX-1’) Through Split-root: Implications for Brackish Water Aquaponics
No full textBrackish water aquaponics is a promising approach to expand the scope of aquaculture-hydroponics integration. However, progress on brackish water aquaponics is limited due to low salinity tolerance of most high-value vegetable crops. Salinity can significantly affect plant growth by reducing plant height, decreasing leaf number and leaf size, leading to early leaf senescence, and decreasing biomass accumulation in salt-sensitive plant species. Additionally, salinity can negatively impact plant physiological performance, resulting in reduced stomatal conductance, lower CO2 assimilation, reduced photosynthetic activity, and ultimately lower plant productivity. To address this limitation in brackish water aquaponics systems, two studies were conducted to investigate the effectiveness of split-root system in deep-water culture (DWC) hydroponics system to mitigate salinity effects on red kale (Brassica napus L. var. pabularia). The focus of the first study was to evaluate the effect of increasing salinity levels (0, 3, 6, and 9 g L-1 or ppt) on red kale growth and physiology in whole-root and split-root systems. Results indicated that red kale plants grown in split-root system had a higher growth index than whole-root system when compared to the control treatment (0 ppt) in each condition. Stomatal conductance was similar in split-root system with increasing salinity level but was greatly decreased in the whole-root system as salinity level increased.
The second study evaluated the effect of brackish water aquaculture effluents on the growth and physiology of red kale in two split-root systems: homogeneous and heterogeneous. In homogeneous split-root system, both parts of the plant root system received the same treatment, while in the heterogeneous system, one part was treated and the other exposed to clear water. Treatments included hydroponic solution containing 0 ppt salinity, saltwater-based hydroponics at 11 ppt, and shrimp effluents at 14 ppt. Significant interactions were found between split-root systems (conditions) and treatments in kale growth traits including height, leaf number, size index, and shoot fresh and dry weights. The heterogeneous split-root system showed positive effects on mitigating salinity stress on red kale growth, compared to the homogeneous split-root system. Plants treated with shrimp effluents showed lower stress levels, evidenced by improved leaf stomatal conductance compared to saltwater-based hydroponic in split-root system.
The split-root system demonstrated in this thesis under the DWC system offers a practical solution to mitigate salinity effects on high-value vegetable crops cultivated with brackish water aquaculture effluents. Further research can explore and refine split-root systems for commercial application in brackish water aquaponics systems
THEORETICAL AND EMPIRICAL EVALUATION OF EFFICIENCY OF MARKER-ASSISTED SEEDLING SELECTION IN ROSACEAE TREE FRUIT BREEDING
No full textThesis (Ph.D.), Horticulture, Washington State UniversityMost rosaceous tree fruit have long juvenility and large plant sizes, which makes traditional seedling selection (TSS), relying on phenotypic evaluation alone, time-consuming and expensive. Marker-assisted seedling selection (MASS) uses DNA markers to provide an early DNA-based evaluation of genetic potential of seedlings. A major challenge in conducting MASS for rosaceous tree fruit is a lack of knowledge of estimating relative efficiency of various MASS strategies compared to TSS. To overcome this challenge and help facilitate successful MASS in rosaceous tree fruit, this study evaluates key elements of MASS efficiency both theoretically and empirically.
This study provides an assessment of the current applications, challenges, and perspectives of MASS in Rosaceae tree fruit breeding, investigates genetic gain from alternative seedling selection strategies through analytical derivation and stochastic simulation modelling, provides software tools to estimate the cost of using MASS, and evaluates the efficiency of applying a DNA test for apple acidity, crispness, and firmness in an apple seedling population.
Theoretical evaluation of genetic gain suggests that marker-based strategies tends to achieve higher genetic gain than TSS for a trait where the proportion of genotypic variance explained by marker information is greater than the broad-sense heritability. The cost modeling pipeline and decision support tool provide a solution to streamlining cost estimation for complex MASS schemes. Empirical analysis shows applying DNA tests for apple acidity, crispness, and firmness in an apple seedling population achieved similar genetic gain and up to 13% cost savings compared to TSS, if genotyping costs are under $2 per sample. Results from this study provide rosaceous tree fruit breeders, for the first time, both guidance and tools for designing efficient MASS schemes.Horticulture, Washington State Universit
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A mechanistic view of shoot vigor in grapevines xylem anatomy, hydraulics, and reproductive growth
No full textIdentifying the distribution, causal pathogens, and potential solutions for managing Botryosphaeria stem blight disease of blueberry in Alabama
No full textIn response to the surging global demand for nutritious foods, blueberry production has doubled in the last decade. However, sustainability of blueberry production is challenged by diseases such as Botryosphaeria stem blight, which is caused by fungi in the Botryosphaeriaceae family. Botryosphaeria stem blight can lead to rapid leaf wilting, chlorosis, reddening, and distinct stem discoloration, often resulting in significant yield loss. Management options are largely limited to cultural practices due to the limited success of chemical controls. Currently, no blueberry cultivar is known to have sufficient and lasting resistance to Botryosphaeria stem blight. The identification of resistant genotypes is hindered by knowledge gaps in isolates’ identity and virulence, as well as non-standardized screening protocols. To address these challenges, this study surveyed blueberry stem blight pathogens in Alabama and surrounding regions to evaluate the distribution and identity of the causal pathogens. A total of 47 symptomatic blueberry samples were collected from Alabama, Georgia, and Mississippi between 2021 and 2022. Phylogenetic analysis based on three genomic regions revealed that species in the Botryosphaeriaceae were encountered on 36% of disease samples, followed by other families such as Sporocadaceae (13%) and Diaporthaceae (11%). Within Botryosphaeriaceae, Neofusicoccum and Lasiodiplodia are the most common genera. Virulence testing using attached-stem assay showed that isolates of Neofusicoccum species caused longest lesion length four weeks after inoculation. Inoculating four blueberry cultivars ‘Star’, ‘Legacy’, ‘Miss Alice’, and ‘Vernon’ with Neofusicoccum parvum and Neofusicoccum sp. confirmed virulence of the isolates and revealed significant difference in lesion length due to treatment and cultivar, but no treatment x cultivar interaction (P < 0.05) was detected. Based on our findings, eighteen blueberry cultivars are currently being screened with the same two species. We hope to uncover sources of resistance to Botryosphaeria stem blight from this larger-scale screening and contribute to sustainable blueberry production
RU LOCAL Foods Initiative: Bringing the Farm to the Community through Local Advertising
No full textThe goal of the RU LOCAL group is to promote the purchasing of local foods through advertising at local grocery storesFall 201
Asymmetric Cyanation of α-Ketimino Ester Derivatives with Chiral Ru-Li Combined Catalysts
No full textAsymmetric cyanation of alpha-ketimino esters catalyzed by combined systems of amino acid/BINAP derivative/Ru-(II) complexes and lithium compounds was examined. The use of an appropriate combination of amino acid and BINAP ligands achieved high enantioselectivity for a variety of alpha-alkynyl (Val/XylBINAP/Ru), alpha-alkenyl (Val/TolBINAP/Ru), and alpha-aryl imino esters (Val/XylBINAP/Ru) as well as an isatin-derived cyclic imino amide (t-Leu/BINAP/Ru) to afford the alpha-cyano-alpha-amino esters and the amide with an alpha-nitrogen-substituted quaternary chiral center with up to 98% ee
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