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Designing Coiled-Coil Peptide Materials for Biomedical Applications
No full textPeptide biomaterials have drawn great attention in recent decades owing to their tunability and biocompatibility. Coiled-coils specifically have become a well-studied scaffold with a clear sequence-to-structure relationship. As such, the Chmielewski lab has extensively studied peptide assemblies based on the GCN4 leucine zipper. First, we present the peptide TriCross,where nitrilotriacetic acid (NTA) and di-histidine ligands are installed at the N- and C-terminus, respectively, and a bipyridine ligand installed at a central, solvent exposed position. Through strategic placement of these metal-binding ligands, TriCross assembled into a three-dimensional (3D) mesh in the presence of zinc ions and dissembled following mild ethylenediaminetetraacetic acid (EDTA) treatment. These properties created a 3D network capable of encapsulating cells for extended periods of time (\u3e1 week) and releasing cells upon metal-chelation.Next, we describe a stabilized nanotube and enhanced crystal assembly through a heterocoiled-coil assembly. Nanotubes composed of the coiled-coil peptide TriNL that assembled likely through ionic interactions rapidly degraded in phosphate buffered saline (PBS). To improve stability, a peptide with metal-binding ligands, p2L, was introduced through thermal annealing of the two peptides. Low levels of p2L (up to 10:1 TriNL:p2L) retained nanotube morphology while simultaneously introducing NTA and di-histidine ligands. Upon addition of metal, metal-ligand interactions were established within the nanotube and increased stability of the material. Higher levels of p2L (2:1 TriNL:p2L) led to hexagonal crystals similar to p2L but now without the use of metal ions. These crystals expanded the scope of protein inclusion by removing the requirement for His-tags on proteins to be incorporated within the material.Finally, a self-replicating and self-assembling coiled-coil peptide is reported. The coiledcoil TriNL was cysteine modified (N20C) to create a peptide capable of native chemical ligation. At low concentrations, the N20C FLpeptide acted as a template for the cysteine and thioester fragments while high concentrations led to fibrillar structures. The size of the fibrils was controlled through the addition of preassembled seeds into the native chemical ligation system
Sources of Spatial Soil Variability and Weed Seedbank Data for Variable-Rate Applications of Residual Herbicides
No full textSoil residual herbicides are a vital component of the best management practices (BMPs), to provide early season weed control in most cropping systems. The availability of a biologically effective dose of a soil residual herbicide in the soil solution is dependent on several soil parameters including soil texture, organic matter (OM), and pH. Soil residual herbicides are currently applied as a uniform application rate over an individual field; yet soil properties can vary spatially within agricultural fields. Therefore, areas of the field are being over- and under-applied when using a uniform application rate. By integrating variable-rate (VR) technology with soil residual herbicides, the correct rate could be applied based on the intra-field soil variability. However, the extent of spatial soil variability within a field and the impact on herbicide application rates has not been well-characterized to inform whether soil residual herbicide applications should move towards variable rate applications. Therefore, the objectives of this research were to 1) determine the extent of intra-field variability of soil texture and organic matter in ten commercial Indiana fields, 2) quantify the reliability of five different combinations of spatial soil data sources, 3) determine the impact of soil sample intensity on map development and the classification accuracy for VR applications of soil residual herbicides, 4) quantify the impact of VR herbicide application on the total amount and spatial accuracy of herbicide applied according to product labels, and 5) determine if the intensive spatial characterization of soil properties is related to weed seedbank abundance and species richness to improve predictive weed management using soil residual herbicides.Commercial soil data was generated by intensively collecting 60 soil samples in a stratified random sampling pattern in 10 agricultural fields across Indiana. Analysis of this data from commercial fields confirmed inherent field variability that would benefit from multiple management zones according to the labeled rate structures of pendimethalin, s-metolachlor, and metribuzin. Therefore, further research was conducted to determine an accurate and reliable method to delineate the fields into management zones for variable-rate residual herbicide applications based on the spatial soil variability and herbicide labels.A modified Monte Carlo cross validation method was used to determine the best source of spatial soil data and sampling intensity for delineating management zones for variable-rate applications of pendimethalin, s- metolachlor, and metribuzin. These sources of spatial soil data included: Soil Survey Geographic database (SSURGO) data, intensive soil samples, electrical resistivity sensors, and implement mounted optical reflectance sensors using VNIR reflectance spectroscopy. The mean management zone classification accuracy for maps developed from soil samples with and without electrical conductivity were similar for 75% of all maps developed across each field, herbicide, and sampling intensity. The method of using soil sampling data combined with electrical conductivity (SSEC) maps was most frequently the top performing source of spatial soil data. The most reliable sampling intensity was one sample per hectare which resulted in lower root mean squared error (RMSE) OM values, higher management zone classification accuracy, and more reliable predictions for the number of management zones within each field.Using VR maps developed from SSEC with one sample per hectare sampling intensity, additional research was conducted to compare the amount of herbicide and field area that was over-or under-applied with a uniform application rate compared to a VR application for 10 corn and soybean residual herbicides. Although research from our previous study documented that spatial soil variability was extensive enough to require two or more management zones for all fields, the same labeled herbicide dose defined for multiple soil condition led to 20% of all maps not requiring a variable rate application (VRA). Additionally, no difference was shown in total amount applied of herbicide in an individual field between a variable and uniform application rate for all herbicides. Nonetheless, nearly half of all VR maps had 10% or more of the field area misapplied with a uniform application rate and justifies further research to determine if the proper placement of residual herbicide adds value through increased weed control in the field areas being under-applied.Similar to soil residual herbicides, weed seedbank abundance and species richness were impacted by the variable soil conditions present within the field area. The seedbanks favor establishment in areas of the field that promote vigorous germination, growth, and reproduction next to the competing crop. Therefore, soil sampling and weed seedbank greenhouse grow-outs were conducted in four fields to gain a better understanding in the relationship between the spatial soil and weed seedbank variability. All weed seedbank characteristics were shown to be spatially aggregated. Even though no individual or combination of soil parameters consistently explained the variability of weed seedbank abundance, species richness, or individual weed species across all four fields. However, clay content was the most persistent soil parameter to negatively impact (lower seedbank values) the soil weed seedbank
Improving Primary Care Provider Prediabetes Patient Education Through Use of an Education Tool
Get PDFCurrent research findings suggest that improving provider education and utilizing communication guidelines can positively impact patient outcomes. This study used a series of three surveys and a focus group to examine if primary care provider’s knowledge, confidence, and practice regarding prediabetes patient education can be improved by utilizing the Ready and Able prediabetes lifestyle modification education tool. Study results found that the Ready and Able conversation guide was well received, had a positive impact on providers knowledge and confidence, and addressed barriers to delivering patient education
Chile pepper variety evaluation and profitability analysis at three farms in Minnesota and Wisconsin, 2022
Get PDFLatino fresh market vegetable farmers in Minnesota and Wisconsin are interested in growing hot peppers for local markets, both for fresh and dried pepper sales. This variety trial is the third and final trial of a 3 year project. We trialed 14 varieties of peppers representing jalapeño, serrano, habanero, poblano, and “other” types. The varieties included the top varieties from 2020 and 2021, alongside new varieties. We measured yield, fruit size, and Scoville heat units. In addition to the variety trial, we conducted an enterprise analysis to determine the profitability of hot pepper production in the Upper Midwest
Particle Alignment Effects on Mechanical Properties of Cellulose Nanocrystal Thin Films
Get PDFCellulose nanocrystal (CNC) thin films are of increasing interest as sustainable materials due to their anisotropic mechanical properties. Previous computational work has shown that the fracture mechanisms of CNC films vary as a function of particle alignment with respect to the loading direction. However, it is challenging to experimentally measure the mechanical anisotropy of extremely thin CNC films due to their brittleness. Here, a new experimental approach was developed to identify the effect of CNC alignment on modulus while simultaneously observing the fracture mechanisms. In this method, uniaxial tensile strain is applied to a CNC film laminated on a silicone substrate with a mechanical stage mounted over a microscope. The modulus calculated by measuring the wavelength of wrinkles that formed perpendicular to the tensile strain direction at low strains during mechanical testing. The elastic modulus of CNC films decayed exponentially as the misalignment of particles to the loading direction increased. By carrying out coarse-grained modeling and comparing the misalignment angle with the crack opening direction beyond the fracture strains, fracture mechanism dependence on misalignment was observed
Neural Network Based Adaptive Fractional-Order Backstepping Control of Uncertain Quadrotors with Unknown Input Delays
Get PDFAdaptive control is essential and effective for reliable quadrotor operations in the presence of uncertain modeling parameters and unknown time-delayed inputs. This paper presents an original radial basis function neural network-based adaptive fractional-order backstepping controller (RBF-ADFOBC). The nonlinearity of the time-delayed inputs is eliminated by introducing an augmented state variable via Pade’s approximation method. For each subsystem in the quadrotor dynamics, a companioned second-order compensation system is developed. The candidate Lyapunov functions are then properly designed by incorporating the control errors, parameter uncertainties and estimation errors of the neural networks’ weight vectors. It is shown that the semi-globally uniformly ultimately boundedness of all the state variables and the estimation error of uncertain parameters can be guaranteed. In addition, the trajectory-tracking error of the state variables can be driven to an adjustable small neighborhood of origin by properly setting the selectable parameters. Numerical simulations reveal that the tracking performance of the proposed controller can be improved continuously as the fractional order increases to a specific positive value, and the controller with a negative order may demonstrate higher robustness to the modeling uncertainties. Favorably, the comparison to the other two previous controllers further reveals the superior tracking accuracy and robustness of the proposed RBF-ADFOBC controller
Unsorted Significance: Examining Potential Pathways to Extreme Political Beliefs and Communities on Reddit
Get PDFViolent political extremists often point to online communities as motivating their behavior. However, researchers studying online exposure to extremism through structural mechanisms such as algorithms have not found strong evidence of their influence. At the same time, models of offline radicalization processes emphasize the importance of personal motivations, such as desire for significance and community, but do not fully account for online contexts. The authors integrate these approaches, which are both interested in worsening political extremism, asking, (1) What are the pathways to extreme content and communities online? and (2) What are the perceptions of extremism in online communities? Through interviews with politically active Redditors, the authors identify three motivations for initial engagement with fringe political communities: political unsorting of the self, political exceptionalism, and virtuous participation. The authors argue these motivations are potentially important seeds of political extremism and discuss the implications for supporting healthy political discourse online
Non-polar Ether-based Electrolyte Solutions for Stable High-voltage Non-aqueous Lithium Metal Batteries
Get PDFThe electrochemical instability of ether-based electrolyte solutions hinders their practical applications in high-voltage Li metal batteries. To circumvent this issue, here, we propose a dilution strategy to lose the Li+/solvent interaction and use the dilute non-aqueous electrolyte solution in high-voltage lithium metal batteries. We demonstrate that in a non-polar dipropyl ether (DPE)-based electrolyte solution with lithium bis(fluorosulfonyl) imide salt, the decomposition order of solvated species can be adjusted to promote the Li+/salt-derived anion clusters decomposition over free ether solvent molecules. This selective mechanism favors the formation of a robust cathode electrolyte interphase (CEI) and a solvent-deficient electric double-layer structure at the positive electrode interface. When the DPE-based electrolyte is tested in combination with a Li metal negative electrode (50 μm thick) and a LiNi0.8Co0.1Mn0.1O2-based positive electrode (3.3 mAh/cm2) in pouch cell configuration at 25 °C, a specific discharge capacity retention of about 74% after 150 cycles (0.33 and 1 mA/cm2 charge and discharge, respectively) is obtained