Scots pine stands biomass assessment using 3D data from unmanned aerial vehicle imagery in the Chernobyl Exclusion Zone.

Thirty-five years after the accident, large forest areas in the Chernobyl Exclusion Zone still contain huge amounts of radionuclides released from the Chernobyl Nuclear Power Plant Unit 4 in April 1986. An assessment of the radiological and radioecological consequences of persistent radioactive contamination and development of remediation strategies for Chernobyl forests imply acquiring comprehensive data on their contamination levels and dynamics of biomass inventories. The most accurate forest inventory data can be obtained in ground timber cruises. However, such cruises in radioactive contaminated forest ecosystems in the Chernobyl Exclusion Zone result in radiation exposures of the personnel involved, which means the need for development of the remote sensing methods. The purpose of this study is to analyze the applicability and limitations of the photogrammetric method for the remote large-scale monitoring of aboveground biomass inventories. Based on field measurements, we estimated the biomass inventories in 31 Scots pine stands including both artificial plantations and natural populations. The stands differed significantly in age (from a few years in natural populations to 115 years in the oldest plantation), productivity (from 0.4 to 19.8 kg m-2), mean height (from 4.1 to 36 m), and other parameters. Photogrammetric data were obtained from the same stands using unmanned aerial vehicle (UAV). These data were then processed using two approaches to derive the canopy height model (CHM) parameters which were tested for correlation with the aboveground biomass inventories. In the first approach, we found that the inventories correlated well with the mean value of CHM of the site (R2 = 0.79). In the second approach, the total aboveground biomass was approximated by a function of the average height of trees detected at the site and the total crown projection area (R2 = 0.78). Among other local parameters, the total crown projection area was identified as the major factor impacting the accuracy of the aboveground biomass inventory estimates from the UAV survey data in both approaches. In the dense stands with the high total crown projections areas (more than 0.90), the average relative deviations of the UAV-based aboveground biomass estimates from the results of the field measurements were close to 0, which means the adequate accuracy of the UAV surveys data for radioecological monitoring purposes. The relative deviations of the UAV-based estimates in both approaches increased in the stands consisting of separated groups of trees, which indicates potential limitation of the approaches and need for their further development.

Conformation-Based Design and Synthesis of Apratoxin A Mimetics Modified at the α,ß-Unsaturated Thiazoline Moiety.

We have demonstrated design, synthesis, and biological evaluation of apratoxin A mimetics. In the first generation, the moCys moiety was replaced with seven simple amino acids as their 3D structures can be similar to that of apratoxin A. Apratoxins M1-M7 were synthesized using solid-phase peptide synthesis and solution-phase macrolactamization. Apratoxin M7, which contains a piperidinecarboxylic acid moiety, exhibited potent cytotoxicity against HCT-116 cells. In the second generation, substitution of each amino acid residue in the tripeptide Tyr(Me)-MeAla-MeIle moiety in apratoxin M7 led to the development of the highly potent apratoxin M16 possessing biphenylalanine (Bph) instead of Tyr(Me), which exhibited an IC50 value of 1.1 nM against HCT-116 cells. Moreover, compared to apratoxin A, apratoxin M16 exhibited a similarly high level of growth inhibitory activity against various cancer cell lines. The results indicate that apratoxin M16 could be a potential candidate as an anticancer agent.