Development of a Method for Soil Tilth Quality Evaluation from Crumbling Roller Baskets Using Deep Machine Learning Models.

A combination tillage with disks, rippers, and roller baskets allows the loosening of compacted soils and the crumbling of soil clods. Statistical methods for evaluating the soil tilth quality of combination tillage are limited. Light Detection and Ranging (LiDAR) data and machine learning models (Random Forest (RF), Support Vector Machine (SVM), and Neural Network (NN)) are proposed to investigate roller basket pressure settings on soil tilth quality. Soil profiles were measured using LiDAR (stop and go and on-the-go) and RGB visual images from a Completely Randomized Design (CRD) tillage experiment on clay loam soil with treatments of roller basket down, roller basket up, and no-till in three replicates. Utilizing RF, SVM, and NN methods on the LiDAR data set identified median, mean, maximum, and standard deviation as the top features of importance variables that were statistically affected by the roller settings. Applying multivariate discriminatory analysis on the four statistical measures, three soil tilth classes were predicted with mean prediction rates of 77% (Roller-basket down), 64% (Roller-basket up), and 90% (No till). The LiDAR data analytics-inspired soil tilth classes correlated well with the RGB image discriminatory analysis. Soil tilth machine learning models were shown to be successful in classifying soil tilth with regard to onboard operator pressure control settings on the roller basket of the combination tillage implement.

C3-Selective Trifluoromethylthiolation and Difluoromethylthiolation of Pyridines and Pyridine Drugs via Dihydropyridine Intermediates.

Herein, we report a method for C3-selective C-H tri- and difluoromethylthiolation of pyridines. The method relies on borane-catalyzed pyridine hydroboration for generation of nucleophilic dihydropyridines; these intermediates react with trifluoromethylthio and difluoromethylthio electrophiles to form functionalized dihydropyridines, which then undergo oxidative aromatization. The method can be used for late-stage functionalization of pyridine drugs for the generation of new drug candidates.

Borane-Catalyzed C3-Alkylation of Pyridines with Imines, Aldehydes, or Ketones as Electrophiles.

Achieving C3-selective pyridine functionalization is a longstanding challenge in organic chemistry. The existing methods, including electrophilic aromatic substitution and C-H activation, often require harsh reaction conditions and excess pyridine and generate multiple regioisomers. Herein, we report a method for borane-catalyzed tandem reactions that result in exclusively C3-selective alkylation of pyridines. These tandem reactions consist of pyridine hydroboration, nucleophilic addition of the resulting dihydropyridine to an imine, an aldehyde, or a ketone, and subsequent oxidative aromatization. Because the pyridine is the limiting reactant and the reaction conditions are mild, this method constitutes a practical tool for late-stage functionalization of structurally complex pharmaceuticals bearing a pyridine moiety.

Infrared Thermography Measurement for Vibration-Based Structural Health Monitoring in Low-Visibility Harsh Environments.

In this study, infrared thermography is used for vibration-based structural health monitoring (SHM). Heat sources are employed as sensors. An acrylic frame structure was experimentally investigated using the heat sources as structural marker points to record the vibration response. The effectiveness of the infrared thermography measurement system was verified by comparing the results obtained using an infrared thermal imager with those obtained using accelerometers. The average error in natural frequency was between only 0.64% and 3.84%. To guarantee the applicability of the system, this study employed the mode shape curvature method to locate damage on a structure under harsh environments, for instance, in dark, hindered, and hazy conditions. Moreover, we propose the mode shape recombination method (MSRM) to realize large-scale structural measurement. The partial mode shapes of the 3D frame structure are combined using the MSRM to obtain the entire mode shape with a satisfactory model assurance criterion. Experimental results confirmed the feasibility of using heat sources as sensors and indicated that the proposed methods are suitable for overcoming the numerous inherent limitations associated with SHM in harsh or remote environments as well as the limitations associated with the SHM of large-scale structures.

Catalytic Intermolecular Coupling of Rhodacyclopentanones with Alcohols Enabled by Dual Directing Strategy.

A catalytic carbonylative ring-opening and functionalization reaction of poorly activated cyclopropanes has been developed. The key achievement of this work is the accomplishment of an unprecedented effective intermolecular trapping of the rhodacyclopentanone intermediate, which is derived from rhodium-mediated carbonylative insertion of poorly activated cyclopropanes, by an external reactant. The success of this development hinges upon the use of a dual directing strategy.