Search Results (80)

Paddlewheel dirhodium complexes are cytotoxic compounds that are also used as catalysts and in the formation of Rh-based artificial metalloenzymes. Low-temperature structures of adducts formed by the model protein hen egg white lysozyme (HEWL) with dirhodium tetraacetate ([Rh₂(μ-O₂CCH₃)₄]) when crystals of the protein were treated with the metal compound at 20 °C demonstrated that [Rh₂(μ-O₂CCH₃)₄] in part breaks down upon reaction with HEWL; dimeric Rh-Rh units bind the side chains of Asp18 and the C-terminal carboxylate, and monometallic fragments coordinate the side chains of Arg14 and His15 in 20% ethylene glycol, 0.100 M sodium acetate at pH 4.5 and 0.600 M sodium nitrate, while dimeric Rh-Rh units bind the side chains of Asn93 and Lys96, the C-terminal carboxylate and Asp101, with monometallic fragments that bind the side chains of Lys33 and His15 in 0.010 M HEPES pH 7.5 and 2.00 M sodium formate. To verify whether the binding of this metallodrug to proteins also occurs at body temperature, crystals of HEWL were grown in 0.010 M HEPES pH 7.5 and 2.00 M sodium formate at 37 °C and soaked with [Rh₂(μ-O₂CCH₃)₄] at the same temperature. X-ray diffraction data collected on these crystals at 37 °C demonstrate that [Rh₂(μ-O₂CCH₃)₄] reacts with proteins at body temperature. The structures of the Rh/HEWL adduct formed at 20 °C (obtained from data collected at 100 K) and at 37 °C under the same experimental conditions are very similar, with metal binding sites that are conserved. However, metal-containing fragment occupancy is higher in the structure obtained at 37 °C, suggesting a role of temperature in defining the protein metalation process. Full article

At present, there is a lack of effective and usable machinery in the harvesting of aquatic vegetables. The harvesting of most aquatic vegetables such as Brasenia schreberi relies entirely on manual labor, resulting in a high labor demand and labor shortages, which restricts the industrial development of aquatic vegetables. To address this problem, an intelligent harvesting system for the aquatic vegetable Brasenia schreberi was developed in response to the challenging working conditions associated with harvesting it. The system is composed of a catamaran mobile platform, a picking device, and a harvesting manipulator control system. The mobile platform, driven by two paddle wheels, is equipped with a protective device to prevent vegetable stem entanglement, making it suitable for shallow pond aquatic vegetable environments. The self-designed picking device rapidly harvests vegetables through lateral clamping and cutting. The harvesting manipulator control system incorporates harvesting posture perception based on the YOLO-GS recognition algorithm and combines it with an improved RRT algorithm for robotic arm path planning. The experimental results indicate that the intelligent harvesting system is suitable for aquatic vegetable harvesting and the improved RRT algorithm surpasses the traditional one in terms of the planning time and path length. The vision-based positioning error was 4.80 mm, meeting harvesting accuracy requirements. In actual harvest experiments, the system showed an average success rate of 90.0%, with an average picking time of 5.229 s per leaf, thus proving its feasibility and effectiveness. Full article

Biological systems can adaptively navigate multi-terrain environments via morphological and behavioral flexibility. While robotic systems increasingly achieve locomotion versatility in one or two domains, integrating terrestrial, aquatic, and aerial mobility into a single platform remains an engineering challenge. This work tackles this by introducing a bipedal robot equipped with a reconfigurable locomotion framework, enabling seven adaptive policies: (1) thrust-assisted jumping, (2) legged crawling, (3) balanced wheeling, (4) tricycle wheeling, (5) paddling-based swimming, (6) air-propelled drifting, and (7) quadcopter flight. Field experiments and indoor statistical tests validated these capabilities. The robot achieved a 3.7-m vertical jump via thrust forces counteracting gravitational forces. A unified paddling mechanism enabled seamless transitions between crawling and swimming modes, allowing amphibious mobility in transitional environments such as riverbanks. The crawling mode demonstrated the traversal on uneven substrates (e.g., medium-density grassland, soft sand, and cobblestones) while generating sufficient push forces for object transport. In contrast, wheeling modes prioritize speed and efficiency on flat terrain. The aquatic locomotion was validated through trials in static water, an open river, and a narrow stream. The flight mode was investigated with the assistance of the jumping mechanism. By bridging terrestrial, aquatic, and aerial locomotion, this platform may have the potential for search-and-rescue and environmental monitoring applications. Full article

Armillaria root rot (ARR) is a fungal disease caused by Desarmillaria caespitosa and the leading cause of peach tree decline in the Southeastern U.S. It affects the roots and lower stems of trees, leading to the decay of the tree’s root system. Planting peach trees shallow on berms and excavating soil around the root collar after two years can extend the economic life of infected trees. However, berms pose operational challenges, including elevation changes, soil erosion from water flow, and herbicide and fertilizer runoff, thereby reducing orchard management efficiency. This study aimed to develop a tractor-mounted rotary tillage method to flatten the area between peach trees planted on berms, improving safety and reducing runoff. A custom paddle wheel attachment (20.3 cm height, 30.5 cm length) was retrofitted to an existing mechanical orchard weed management implement equipped with a hydraulic rotary head. A hydraulic flow meter, two pressure transducers, and an RTK-GPS receiver were integrated with a wireless data acquisition system to monitor the paddle wheel rotational speed and tractor ground speed during field trials. The effects of three paddle wheel speeds (132, 177, and 204 RPM) and three tractor ground speeds (1.65, 2.255, and 3.08 km/h) were evaluated in two orchards with Cecil sandy loam soil (bulk density: 1.93 g/cm³; slope: 2–6%). The paddle wheel speed had a greater influence on the torque and power requirements than the tractor ground speed. The combination of a 177 RPM paddle speed and 3 km/h tractor speed resulted in the smoothest soil surface with minimum torque demand, indicating this setting as optimal for flattening berms in similar soil conditions. Future research will include optimizing the paddle wheel structure and equipping the berm leveling machine with tree detection sensors to control the rotary head position. Full article

A ligand exchange reaction between [Ru₂(npc)₂(O₂CMe)₂] (1; npc = 1,8-naphthyridine-2-carboxylate) and trifluoroacetic acid yielded the diruthenium naphthyridine complex with two trifluoroacetate ligands, [Ru₂(npc)₂(O₂CCF₃)₂] (2), which was structurally characterized by electrospray ionization mass spectrometry, elemental analysis, infrared spectrum, and synchrotron single-crystal X-ray diffraction. The crystal structure of 2 adopts a paddlewheel-type structure in which two npc and two O₂CCF₃ ligands are coordinated in a cis-2:2 arrangement around the Ru₂ core. The temperature-dependent magnetic susceptibility measurements indicated that 2 has (i) an S = 1 spin state for the Ru₂⁴⁺ core and (ii) a large D value of 243 cm⁻¹; characteristic of paddlewheel-type Ru₂ complexes. The cyclic voltammetry measurements indicated that 2 exhibited one reversible oxidation wave (E_1/2 = 0.72 V vs. SCE) and two reduction waves (E_1/2 = −0.67 and −1.10 V vs. SCE); which were clearly positively shifted when compared with those of 1. Additionally, the absorption spectrum of 2 displayed intense absorption bands in the visible region; attributed to metal-to-ligand charge transfer from the Ru₂ core to the npc ligands; which were blue-shifted by approximately 70–100 nm when compared with those of 1. These distinct shifts in redox potentials and absorption bands originated from the strong electron-withdrawing effect of the O₂CCF₃ ligands in 2. Full article

In order to design antimicrobial species, a series of methacrylate (Macr) complexes, [Cu(HBzIm)₂(Macr)₂] (1), [Cu₂(HBzIm)₂(Macr)₄] (2), [Cu(2-MeBzIm)₂(Macr)₂] (3), [Cu₂(2-MeBzIm)₂(Macr)₄] (4), and [Cu(5,6-Me₂BzIm)₂(Macr)₂] (5) (HBzIm = benzimidazole, 2-MeBzIm = 2-methylbenzimidazole, and 5,6-Me₂BzIm = 5,6-dimethylbenzimidazole) were synthesized and characterized by several spectral techniques, as well as by single crystal X-ray diffraction. The mononuclear species exhibit a distorted octahedral stereochemistry, while the binuclear types, with a paddle-wheel structure, adopt a square pyramidal surrounding. The methacrylate acts either as a chelate or a bridge, while all benzimidazole derivatives are coordinated as unidentate. The supramolecular networks are developed by both intermolecular π–π stacking interactions and hydrogen bonds. The antimicrobial assays provided both complexes the ability to inhibit planktonic strain proliferation, as well as to adhere on inert substratum. All complexes exhibit a moderate antimicrobial activity, both in regards to standard and clinical isolate strains, the most active being compound 5 against Candida albicans, with a minimum inhibitory concentration (MIC) of 0.156 mg/mL. It is worth mentioning that complex 1 inhibited the microbial adhesion of the clinical Escherichia coli strain and complex 2 constrained that of the clinical C. albicans strain. Full article

The cultivation of Arthrospira platensis (Spirulina) is well-established in applied phycology, but the high cost of conventional media limits large-scale production. Anaerobically digested food effluent (ADFE), rich in nitrogen and phosphorus, offers a cost-effective alternative while mitigating environmental impacts. This study evaluated ADFE as a partial replacement for Zarrouk’s medium, with 37.5%, 50%, and 70% substitutions, the latter two added incrementally. Cultivation was conducted in paddlewheel-driven raceway ponds under outdoor conditions for 22 days during the Australian autumn. The highest biomass productivity (8.83 g m⁻² d⁻¹) was achieved with 70% ADFE, significantly outperforming Zarrouk’s medium (p < 0.05). Chlorophyll a content remained unaffected (p > 0.05), and ammonium (N-NH₄⁺) declined to near zero by day 9, indicating efficient nutrient uptake. These findings demonstrate that staged ADFE addition can successfully replace up to 70% of Zarrouk’s medium while maintaining robust A. platensis growth, highlighting its potential as a sustainable alternative for large-scale microalgal cultivation. Full article

Researchers are currently conducting several studies in the field of navigation systems and sensors. Even in the past, there was a lot of research regarding the field of velocity sensors for unmanned underwater vehicles (UUVs). UUVs have various services and significance in the military, scientific research, and many commercial applications due to their autonomy mechanism. So, it’s very crucial for the proper maintenance of the navigation system. Reliable navigation of unmanned underwater vehicles depends on the quality of their state determination. There are so many navigation systems available, like position determination, depth information, etc. Among them, velocity determination is now one of the most important navigational criteria for UUVs. The key source of navigational aids for different deep-sea research projects is water currents. These days, many different sensors are available to monitor the UUV’s velocity. In recent times, there have been five primary types of sensors utilized for UUV velocity forecasts. These include Doppler Velocity Logger sensors, paddlewheel sensors, optical sensors, electromagnetic sensors, and ultrasonic sensors. The most popular sensing sensor for estimating velocity at the moment is the Doppler Velocity Logger (DVL) sensor. DVL sensor is the most fully developed sensor for UUVs in recent years. In this work, we offer an overview of the field of navigation systems and sensors (especially velocity) developed for UUVs with respect to their use with tidal current sensing in the UUV setting, including their history, evolution, current research initiatives, and anticipated future. Full article

We synthesized four new copper(II) complexes with acetato and chlorido ligands and methylammonium (MA), dimethylammonium (DMA), and tetramethylammonium (TMA) counterions: (MA)₄[Cu₂Ac₄Cl₂]Cl₂·2H₂O (1), (DMA)₂[Cu₂Ac₄Cl₂] (2), (DMA)₄[Cu₂Ac₄Cl₂]Cl₂·2H₂O (3), and (TMA)₅[Cu₂Ac₄Cl]Cl₄·4H₂O (4). All compounds were characterized by single-crystal X-ray diffraction, magnetic measurements, FTIR spectroscopy, and thermogravimetric analysis. Complexes 1, 2, and 3 consist of a dinuclear coordination anion [Cu₂(Ac)₄Cl₂]²⁻ with bridging acetato ligands arranged in a paddle-wheel conformation and square-pyramidal coordination around Cu(II) atoms, while the coordination anion in compound 4 is a polymeric chain, parallel to the c axis, with Cu₂(Ac)₄ units connected through bridging chlorido ligands. Magnetic measurements carried out between 2 K and 300 K indicate strong antiferromagnetic interactions between Cu(II) ions. The effective magnetic moments range from $1.94 {\mu }_{\mathrm{B}}$ to $2.21 {\mu }_{\mathrm{B}}$, exceeding the spin-only value for Cu(II) ions (${\mu }_{\mathrm{e}\mathrm{f}\mathrm{f}}=1.73 {\mu }_{\mathrm{B}}$) and suggesting significant orbital contributions to the magnetic moment. Thermogravimetric analysis of all complexes showed a multistep decomposition behavior yielding elemental copper as the final product. Full article

A reaction between copper(II) nitrate and trans-1,4-cyclohexanedicarboxylic acid (H₂chdc) carried out under hydrothermal conditions led to a new metal-organic coordination polymer [Cu₂(Hchdc)₂(chdc)]_n. According to single-crystal XRD data, the compound is based on bi-nuclear paddlewheel-type carboxylate blocks that are joined with polymeric chains due to the (μ₃-κ¹:κ²) coordination of carboxylate groups. The chains are interconnected by chdc²⁻ bridging ligands into layers containing free COOH groups of terminal Hchdc⁻. The neighboring layers adopt a RCOOH···OOCR hydrogen bond-assisted arrangement into a dense-packed structure. Magnetization measurements showed the presence of a strong antiferromagnetic exchange interaction (J/k_B = −495 K) inside the bi-nuclear blocks. At the same time, no significant interaction was found between the {-Cu₂(OOCR)₄-} units in spite of their polymeric in-chain packing. Patterns of magnetic behavior of [Cu₂(Hchdc)₂(chdc)]_n were thoroughly analyzed and explained from a structural point of view. Full article

Metallodrugs are an important group of medicinal agents used for the treatment of various diseases ranging from cancers to viral, bacterial, and parasitic diseases. Their distinctive features include the availability of a metal centre, redox activity, as well as the ability to multitarget. Diruthenium paddlewheel complexes are an intensely developing group of metal scaffolds, which can securely coordinate bidentate xenobiotics and transport them to target tissues, releasing them by means of substitution reactions with biomolecular nucleophiles. It is of the utmost importance to gain a complete comprehension of which chemical reactions happen with them in physiological milieu to design novel drugs based on these bimetallic scaffolds. This review presents the data obtained in experiments and calculations, which clarify the chemistry these complexes undergo once administered in the proteic environment. This study demonstrates how diruthenium paddlewheel complexes may indeed embody a new paradigm in the design of metal-based drugs of dual-action by presenting and discussing the protein metalation by these complexes. Full article

This study aims to investigate the influence of wheel configurations on hydrodynamic resistance of an amphibious vessel through experiments and simulations. To evaluate the resistance performance associated with wheel attachments, three configurations were examined: vessel without attachments, with caterpillars, and with both caterpillars and shoe−paddles. A comprehensive series of computational fluid dynamics (CFD) simulations were conducted for these attachment types, complemented by experimental validations. The Volume-of-Fluid (VOF) model was employed in CFD simulations to capture the free surface movement, and the Dynamic Fluid–Body Interaction (DFBI) model was adopted to represent the two-degree-of-freedom motion of the vessel, specifically trim and sinkage. The total resistance derived from CFD simulations was calculated across a range of Froude numbers (Fns), including the design speed of the target vessel, and validated through model tests conducted in a wave basin equipped with a towing facility. The analysis indicated a general increase in resistance when attachments were added to the amphibious vessel. Remarkably, at the design speed (Fn = 0.27), the total resistance with both caterpillars and shoe−paddles exceeded that of the configuration without any attachments by more than 75.7%. These results provide crucial insights for the preliminary design stage of amphibious vessels, particularly those intended for marine debris collection in hard-to-reach areas. Full article

The present study focuses on the spin-dependent vibrational properties of HKUST-1, a metal–organic framework with potential applications in gas storage and separation. Employing density functional theory (DFT), we explore the consequences of spin couplings in the copper paddle wheels (as the secondary building units of HKUST-1) on the material’s vibrational properties. By systematically screening the impact of the spin state on the phonon bands and densities of states in the various frequency regions, we identify asymmetric -COO- stretching vibrations as being most affected by different types of magnetic couplings. Notably, we also show that the DFT-derived insights can be quantitatively reproduced employing suitably parametrized, state-of-the-art machine-learned classical potentials with root-mean-square deviations from the DFT results between 3 cm⁻¹ and 7 cm⁻¹. This demonstrates the potential of machine-learned classical force fields for predicting the spin-dependent properties of complex materials, even when explicitly considering spins only for the generation of the reference data used in the force-field parametrization process. Full article

Two new paddlewheel-type dirhodium (Rh₂) complex isomers, formulated as trans-2,2- and 3,1-forms of [Rh₂(bhp)₄] (bhp = 6-bromo-2-hydroxypyridinate), were obtained by the reaction of 6-bromo-2-hydroxypyridine with [Rh₂(O₂CCH₃)₄(H₂O)₂] and characterized by NMR, ESI-MS, and elemental analyses. Single crystal X-ray diffraction analyses clarified that the crystal structure of trans-2,2-form takes a conventional paddlewheel-type dimer structure with no axial coordination ligands, i.e., trans-2,2-[Rh₂(bhp)₄], whereas that of the 3,1-form changed significantly depending on the kinds of solvent used for crystallization processes; dimer-of-dimers-type tetrarhodium complex, i.e., 3,1-[Rh₂(bhp)₄]₂, and a conventional paddlewheel-type dimer complex with an axial DMF ligand, i.e., 3,1-[Rh₂(bhp)₄(DMF)], were observed. The 3,1-form showed unique absorption changes that were not observed in the trans-2,2-form; the trans-2,2-form showed an absorption band at approximately 780 nm both in the solid state and in solution (CH₂Cl₂ and DMF), whereas the 3,1-form showed a similar absorption band at 783 nm in CH₂Cl₂ solution, but their corresponding bands were blue-shifted in solid state (655 nm) and in DMF solution (608 nm). The molecular structures and the origin of their unique absorption properties of these Rh₂ complexes were investigated using density functional theory (DFT) and time-dependent DFT (TDDFT). Full article

Two ferrocenecarboxylate (fca)-bridged dirhodium (Rh₂) complexes, [Rh₂(fca)₄] (1) and [Rh₂(fca)(piv)₃] (2; piv = pivalate), were prepared through the carboxylate-exchange reactions of [Rh₂(O₂CCH₃)₄(H₂O)₂] and [Rh₂(piv)₄], respectively, with fcaH and characterized by ¹H NMR, ESI-TOF-MS, and elemental analyses. Single-crystal X-ray diffraction analyses of [Rh₂(fca)₄(MeOH)₂] (1(MeOH)₂) and [Rh₂(fca)(piv)₃(MeOH)₂] (2(MeOH)₂), which are recrystallized from MeOH-containing solutions of 1 and 2, revealed that (1) 1(MeOH)₂ and 2(MeOH)₂ possess homoleptic and heteroleptic paddlewheel-type dinuclear structures, respectively; (2) both complexes have a single Rh–Rh bond (2.3771(3) Å for 1(MeOH)₂, 2.3712(3) Å for 2(MeOH)₂); and (3) the cyclopentadienyl rings of the fca ligands in 1(MeOH)₂ adopt an eclipsed conformation, whereas those in 2(MeOH)₂ are approximately 12–14° rotated from the staggered conformation. Density functional theory (DFT) calculations revealed that (1) the electronic configurations of the Rh₂ core in 1(MeOH)₂ and 2(MeOH)₂ are π⁴σ²δ²π*²δ*²π*² and π⁴σ²δ²δ*²π*⁴, respectively; and (2) the occupied molecular orbitals (MOs) localized on the fca ligands are energetically degenerate and relatively more unstable than those on the Rh₂ cores. Absorption features and electrochemical properties of 1 and 2 were investigated in a 9:1 CHCl₃-MeOH solution and compared with those of fcaH and [Rh₂(piv)₄]. Through examining the obtained results in detail using time-dependent DFT (TDDFT) and unrestricted DFT, we found that 1 and 2 exhibit charge transfer excitations between the fca ligands and Rh₂ cores, and 1 shows electronic interactions between ferrocene units through the Rh₂ core in the electrochemical oxidation process. Full article