Genome-Wide DNA Polymorphism Analysis and Molecular Marker Development for the Setaria italica Variety “SSR41” and Positional Cloning of the Setaria White Leaf Sheath Gene SiWLS1

Genome-wide DNA polymorphism analysis and molecular marker development are important for forward genetics research and DNA marker-assisted breeding. As an ideal model system for Panicoideae grasses and an important minor crop in East Asia, foxtail millet (Setaria italica) has a high-quality reference genome as well as large mutant libraries based on the “Yugu1” variety. However, there is still a lack of genetic and mutation mapping tools available for forward genetics research on S. italica. Here, we screened another S. italica genotype, “SSR41”, which is morphologically similar to, and readily cross-pollinates with, “Yugu1”. High-throughput resequencing of “SSR41” identified 1,102,064 reliable single nucleotide polymorphisms (SNPs) and 196,782 insertions/deletions (InDels) between the two genotypes, indicating that these two genotypes have high genetic diversity. Of the 8,361 high-quality InDels longer than 20 bp that were developed as molecular markers, 180 were validated with 91.5% accuracy. We used “SSR41” and these developed molecular markers to map the white leaf sheath gene SiWLS1. Further analyses showed that SiWLS1 encodes a chloroplastlocalized protein that is involved in the regulation of chloroplast development in bundle sheath cells in the leaf sheath in S. italica and is related to sensitivity to heavy metals. Our study provides the methodology and an important resource for forward genetics research on Setaria

Architecture of Heptagonal Metallo-macrocycles via Embedding Metal Nodes Into Its Rigid Backbone

Metal-organic macrocycles have received increasing attention not only due to their versatile applications such as molecular recognition, compounds encapsulation, anti-bacteria and others, but also for their important role in the study of structure-property relationship at nano scale. However, most of the constructions utilize benzene ring as the backbone, which restricts the ligand arm angle in the range of 60, 120 and 180 degrees. Thus, the topologies of most metallo-macrocycles are limited as triangles and hexagons, and explorations of using other backbones with large angles and the construction of metallo-macrocycles with more than six edges are very rare. In this study, we present a novel strategy for self-assembly two giant heptagonal metallo-macrocycles with an inner diameter of 5 nm, by embedding metal nodes into the ligand backbone and regulating the ligand arm angle. By complexing with metal ions, the angle between two arms at the 4,4” position of the central terpyridine (tpy) was extended, resulting in ring expansion of the metallo-macrocycle. This approach enabled the construction of giant and more complex metallo- macrocycles that could not be achieved with traditional benzene ring backbones. The characterization of complex molecules often requires the use of multiple techniques, such as multi-dimensional and multinuclear NMR and multidimensional mass spectrometry analysis. Here, we also utilized transmission electron microscopy (TEM) and ultra-high vacuum (∼E-10 torr) low-temperature (∼77 K) scanning tunneling microscopy (UHV-LT-STM) to characterize complex supramolecules. The resulting metallo-macrocycles formed hierarchical self-assembled nanotube structures at larger densities, which is observed by TEM, while UHV-LT-STM was used for direct visualization of individual complex supramolecules deposited on an Au(111) substrate. Our findings indicate that UHV-LT-STM is an effective methodology for characterizing supramolecules at a single molecule level, providing more details of the molecular structure that is difficult to resolve by the resolution of TEM.https://digitalcommons.odu.edu/gradposters2023_sciences/1005/thumbnail.jp

Slurry rheology of limestone and its effects on wet ultra-fine grinding

This thesis investigates rheology of limestone slurries and its effects on wet ultra-fine grinding in order to reduce energy cost and increase the throughput and the product fineness. The influences of solids concentration, molecular weight of a dispersant, particle size and distribution, and temperature on the rheological behaviours of limestone slurries have been investigated with rotational and cone-plate viscometers. The results reveal that when the solids concentration of a limestone slurry ( 75 wt.% or 52.63 vol.%). At a certain shear rate, the apparent viscosity and the relative viscosity of the slurry increase exponentially with the solids concentration. The extrapolated Bingham yield stress increases in a power- law form with increasing solids concentration when the solids concentration of the slurry is larger than 70 wt.% (i.e., 46.36 vol.%). The maximum packing solids fraction attainable is predicted as 64.6 vol.% at the certain limestone-water suspension system. Besides, the smaller the particle size, the more evident the pseudoplastic property of limestone slurry are with a larger yield stress and a larger apparent viscosity at a given shear rate. Furthermore, the apparent viscosity and the extrapolated Bingham decrease with increasing temperature in a range of 20 to 40 oC. Also, wet ultra-fine grinding of a limestone powder ( 83 vol.%). For a certain level of bead load, an optimal solids concentration exists for more effective grinding. The influence of feed temperature studied on wet ultra-fine grinding of the limestone is insignificant. Besides, the higher the bead load, the better the cumulative energy efficiency, the higher the milling rate, the larger the specific surface area of the product and the smaller the median size at the same specific energy consumption. In wet ultra-fine grinding of the limestone slurry with a given additive amount of a dispersant (i.e., Dispersant S40), the slurry from an initial feed to a final FP slurry (a discharge slurry where the grinding operation is automatically terminated by a safety control device due to poor slurry flowability) is transformed through different rheological behaviours due to the size reduction with a prolonged grinding time. For a given solids concentration of a limestone slurry ( 0.991) to the experimental results regardless of whatever grinding conditions.Godkänd; 2005; 20070103 (haneit

Slurry rheology of industrial minerals and its effects on wet ultra-fine grinding

This thesis investigates slurry rheology of industrial minerals (limestone and quartzite) and its effects on wet ultra-fine grinding in order to reduce energy cost, increase the throughput as well as the product fineness. The influences of solid concentration, molecular weight of a dispersant, and particle size and distribution on the rheological behaviour of original limestone slurries have been investigated. The results reveal that when the solid concentration of a limestone slurry (< 100 ¦Ìm) is increased from 60 wt.% (35.71 vol.%) to 78.5 wt.% (57.49 vol.%), the rheological behaviour of the slurry is transformed from a weakly dilatant or Newtonian characteristic to a pseudoplastic one with a yield stress, which is in combination with a thixotropic property at a higher solid concentration (i.e., ¡Ý 75 wt.% or 52.63 vol.%). At a certain shear rate, the apparent viscosity and the relative viscosity of the slurry both increase exponentially with solid concentration. The extrapolated Casson yield stress increases in a power-law form with increasing solid concentration when the solid concentration is larger than 70 wt.% (i.e., 46.36 vol.%). The maximum attainable packing solid fraction ( m) is predicted as 64.6 vol.% at the limestone-water suspension. A polymeric dispersant named Dispersant S40 with a molecular weight of 5,500 Da appears most efficient for the reduction of the apparent viscosity of limestone slurry. The smaller the particle size and the narrower the size distribution, the more evident the pseudoplastic behaviour of limestone slurry is with a higher yield stress and a larger apparent viscosity at a given shear rate in the range 12 - 1200 s-1. However, a sufficient addition dosage of Dispersant S40 significantly decreases or even eliminates the rheological differences of limestone slurries (apparent viscosity and extrapolated yield stress) resulting from differences in particle size and distribution. Wet ultra-fine grinding of a limestone material (< 100 ¦Ìm) has been investigated in a stirred media mill with respect to the effect of slurry rheology. The results obtained by varying operation parameters (i.e., molecular weight of a dispersant, solid concentration, addition dosage, addition method and bead load) are evaluated in terms of energy efficiency and the fineness. Dispersant S40 gives the superior results compared to the other dispersants (i.e., BCX-476 and BCX-552). For a certain level of bead load, an optimal solid concentration exists for more effective grinding. At 0.1 wt. % of addition dosage of Dispersant S40 or more (¡Ü 0.6 wt.%), a smaller addition amount of Dispersant S40 leads to a higher energy efficiency and a smaller median size at a lower level of specific energy input. However, the excessive amount of the dispersant causes the grinding less efficient. This can be avoided by either the multi-point addition of the dispersant or a higher bead load (¡Ý 83 vol. %). The role of slurry rheology in stirred media milling of quartzite has also been performed by varying important grinding parameters such as media bead density, addition of chemicals, solid concentration, stirrer rotational speed as well as the combined effect of these factors. Media bead density has an evident but complex effect on stirred milling performance, depending on stirrer rotational speed and solid concentration. Addition of Dispersant S40 or a lower solid concentration results in better grinding performance (i.e., a higher energy efficiency and a smaller median size) due to maintenance of lower viscosities at shear rates investigated during grinding. Stirrer rotational speed interacts with solid concentration. For a given solid concentration, an optimal stirrer speed exists. The observed phenomena can be explained by the effect of slurry rheology on the stress intensity of individual grinding bead. The flowability of ground limestone slurries during grinding has been monitored and characterized. The rheological behaviour of ground limestone slurries varies with grinding from a starting dilatant flowability to a resultant pseudoplastic one with an evident Casson yield stress in combination with a thixotropic character. The appearance of pseudoplastic flowability with a thixotropy is related to the fineness of a ground product and its specific surface area, which are both correlated to solid concentration and the addition amount of Dispersant S40. However, the rheological characterization of time-dependent fluids is dependent upon the instruments used and operating conditions. In addition, an empirical particle size-energy model provides a good fit to the wet ultra-fine grinding results for both limestone and quartzite under the experimental conditions investigated.Godkänd; 2007; 20071126 (ysko

Influence of slurry rheology on stirred media milling of quartzite

The role of slurry rheology in stirred media milling of quartzite has been investigated by varying important grinding parameters such as media bead density and size, addition of chemicals, solids concentration, stirrer rotational speed as well as the combined effect of these factors. Media bead density has an evident but complex effect on stirred milling performance, depending on stirrer rotational speed and solids concentration. The effect of media bead size on the ultra-fine grinding of quartzite is relevant to the feed size. Optimal ratio of media bead size to the median size of a feed is between 150 and 200. The combined effect of grinding bead size and stirrer speed or solids concentration is insignificant. The addition of Dispersant S40 or a lower solids concentration results in better grinding performance (i.e., a higher energy efficiency and a smaller median size) due to the maintenance of lower viscosities at shear rates investigated during grinding. Stirrer rotational speed interacts with solids concentration. For a given solids concentration, an optimal stirrer speed exists. The observed phenomena can be explained by the interaction of slurry rheology and the stress intensity of individual grinding bead. In addition, an empirical particle size-energy model provides a good fit (R2 > 0.904) to the grinding results under the experimental conditions investigated. Furthermore, the wear of grinding media beads is involved. ZrO2 beads have a lowest wear rate whereas the wear of SiO2 beads is most serious. The wear rate of Al2O3 beads is related to bead size

Rheological behaviors in wet ultrafine grinding of limestone

Effect of Dispersant S40. Figure 6 shows the effect of the additive dosage of a sodium polyacrylate called Dispersant S40 on the flowability of original limestone slurry at 75% (by weight) solids concentration. The slurry with less than 0.01% (by weight) Dispersant S40 shows a pseudoplastic characteristic with a yield stress and possesses a higher apparent viscosity than that without the dispersant at a given shear rate

Slurry rheology in wet ultra-fine grinding of industrial minerals: A review

Wet ultrafine grinding has been increasingly used for production of ultrafine powders in various industries. It has been known that slurry rheology significantly influences the grindability of industrial minerals in wet ultrafine grinding. This review represents some previous work with respect to slurry rheology in ultrafine grinding. In this review, some methods for the characterization of the slurry rheology and some empirical equations modelling rheological behaviours of slurries were presented. The semiempirical model incorporating slurry rheology, solids concentration, particle size and slurry temperature was described. In addition, on-line measurement for the slurry rheology control was also discussed. In the case of ultrafine grinding, various parameters (such as solid concentration, particle size and distribution, particle shape, temperature, rotation and pH, use of dispersants), which affect the slurry rheology, have been described. It was revealed that the optimization of the rheological behaviours of slurry in ultrafine grinding could increase throughput, energy efficiency and product fineness as well. It is suggested to further study the mechanisms of slurry rheology in the presence of chemical dispersants in wet ultrafine grinding. It is desired to develop a model, which can represent a relation among slurry rheology, comminution parameters, amount of dispersant, energy efficiency and particle size characterization