Payload drones are often limited more by frame weight than by motor power. This work aims to design, optimize, and validate a flat octocopter frame with eight independently driven rotors arranged symmetrically on separate arms. The drone frame design in SOLIDWORKS uses Finite Element Analysis (FEA) and topology optimization to remove material from low-stress regions while keeping the main load paths intact. The final design cuts the frame mass by 37.3% compared to the baseline model and reduces the 3D printing time by about five hours using a Creality K1C printer with Polylactic Acid (PLA) filament. These changes increase the available thrust-to-weight margin for payload without exceeding the allowable stress or deformation limits of the material. The electronic components also identified compatible flight controllers, ESCs, motors, and radio systems to show that the proposed frame can be integrated into a complete multirotor platform. Overall, this work demonstrates a practical approach to designing lighter octocopter frames that are easier to 3D print and can be used more effectively for delivery and inspection missions.
This study presents a comprehensive projection of China’s forest product yield dynamics (encompassing commodity timber and logs) through 2100, employing an innovative integration of machine learning and economic modeling. We developed a hybrid analytical framework combining random forest algorithms with Cobb-Douglas production functions to assess multi-dimensional drivers, including climatic variables, socio-economic indicators, and demographic trends. Our multi-model validation demonstrated strong predictive performance (R2 are 0.86 and 0.92), particularly in quantifying climate-production interactions, with sensitivity analysis identifying surface downward shortwave radiation (RSDS), population density (POP), and mean annual temperature (MAT) as dominant predictors explaining 68% of yield variance. Future yields exhibited significant spatial and temporal variations under different SSP scenarios, especially under SSP126, where yields were more stable, and under SSP245 and SSP370, where yields showed a moderate increasing trend. The SSP585 shows higher fluctuations and a decreasing trend in yields due to climate change. Geospatial modeling uncovered critical regional disparities, suggesting potential production migration from traditional southern bases to north-eastern/northwestern frontiers under climate stress. The southern subtropical belt emerged as particularly vulnerable to thermal extremes and precipitation variability, while northern regions demonstrated greater climate resilience but require substantial silvicultural adaptation. These results provide a scientific basis for developing more precise forest management policies and sustainable development strategies to help meet the challenges posed by future demand for forest products and climate change.
Investigations into the photoinduced reactions of deoxyribonucleic acid (DNA) bases are important for human health. Herein, we have synthesized colloidal CdS nanoparticles by a method reported in the literature. The mean particle diameter of the semiconductor was about 55 nm. The colloidal CdS particles were used as a photocatalyst to investigate the organic transformation of guanine (2-amino-6-oxopurine). The products of the semiconductor-induced reaction were analyzed by liquid chromatography-mass chromatography (LC-MS) measurements. The solitary product of the photocatalytic reaction of guanine was revealed as 2,5-diamino-4H-imidazol-4-one. The likely reaction pathway for the formation of the product has been presented. To our understanding, the present work is the first account on the mechanistic aspects of the semiconductor-induced photocatalytic reaction of guanine.
A2B2O7 complex oxides have a great potential to be used in high-temperature catalytic processes. Herein, a series of A2B2O7 (A = La, Nd, Sm, Gd, Er, Yb; B = Ti, Sn, Zr, Ce) compounds with all four kinds of typical sub-crystalline phases were synthesized to study their bulk and surface properties. FTIR spectroscopy was adopted as a novel method in this study to identify distinctively these phases. Whereas, it cannot be used to distinguish the subtle structure difference between disordered and ordered pyrochlores, nor that between the disordered defect fluorite and the rare earth. To discriminate these exquisite phase differences, XPS spectra must be supplementarily used. Specifically, it was discovered that the coordination numbers of the A- and B-site cations are the key factor affecting their binding energies. Furthermore, the electronegativity of the A- and B-site elements significantly influences the binding energy of surface lattice oxygen, reflecting their electrophilic and nucleophilic properties, which can thus be used to effectively identify the sub-crystalline phase. The oxygen vacancy concentration of different sub-crystalline phases is the primary factor controlling the amount of surface chemisorbed oxygen species on A2B2O7 compounds, with superoxide anions (O2−) identified as the major species.
Refractory high-entropy alloys (RHEAs) show promising properties for applications as structural materials in high-temperature applications, such as high solidus temperature and high strength. Improving their density, oxidation resistance, and room temperature ductility are still the aims of research in alloy development. In this study, Al-rich diffusion coatings by pack cementation are developed for three different alloys in the system Al-Cr-Mo-Ta-Ti in order to improve their high-temperature oxidation resistance. Equimolar AlCrMoTaTi, Al-rich Al3CrMoTaTi, and Ti-rich AlCrMoTaTi3 are synthesized by vacuum arc melting with subsequent milling to powder, consolidation to bulk material by field-assisted sintering technology/spark plasma sintering (FAST/SPS), and homogenization heat treatment. The applied aluminizing coatings are investigated by gravimetry, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Experimental analyses are supplemented by CALPHAD simulations. Compact, uniform, and adhesive Al-rich diffusion coatings are produced on all three substrate RHEAs and exhibit single-layered D022 Al3(Cr,Mo,Ta,Ti) intermetallic compound analogous to Al3Ti in the binary Al-Ti system. Isothermal oxidation at 1000 °C for 48 h in ambient air results in the formation of 1–2 µm thin protective single-layered alumina scale—in contrast to multi-layered oxide scales in uncoated condition—and mass gains as low as binary Al3Ti and Ni-based superalloys.
