Dual Propulsion Research Articles

Thrombin and NIR dual-responsive system driven by heat-gas for thrombus targeted therapy

Drug thrombolysis is the main means of clinical treatment for thrombotic-related diseases. However, serious bleeding complications caused by low drug delivery efficiency and secondary vascular embolism usually lead to unsatisfactory therapeutic effects. Herein, we constructed a thrombin and near-infrared (NIR) dual-responsive drug-loaded intelligent system to solve the above problems. The CREKA-modified polydopamine (PDA) nanoparticles (NPs) were crosslinked by thrombin-responsive peptide (Pep), to obtain Pep-PPC nanocarriers with special mesoporous nanostructures. Subsequently, NO donor BNN6 and thrombolytic drug UK were loaded on the surface and into the mesoporous of Pep-PPC, to get the multifunctional Pep-NO@PPC/UK. In vitro and in vivo results proved that Pep-NO@PPC/UK could effectively recognize and aggregate at the thrombus site via CREKA-mediated active targeting. Then local abundant thrombin cleaved the nanoplatform to release UK. Meanwhile, PDA converted NIR light into heat and synchronously triggered NO release. This transformed the DDS into a “heat-gas” dual propulsion nanomotor in situ, driving deep penetration of UK in thrombus tissue. Under the combined action of UK and PTT, arterial thrombosis rapidly dissolved with relatively low bleeding risk. More importantly, NO generated in situ could prevent re-embolism of blood vessels at the thrombolytic site by inhibiting activated platelet aggregation, ultimately improving vascular reperfusion rate through a combination of attack and defense mode.

Nano/Micromotors for Cancer Diagnosis and Therapy: Innovative Designs to Improve Biocompatibility.

Nano/micromotors are artificial robots at the nano/microscale that are capable of transforming energy into mechanical movement. In cancer diagnosis or therapy, such "tiny robots" show great promise for targeted drug delivery, cell removal/killing, and even related biomarker sensing. Yet biocompatibility is still the most critical challenge that restricts such techniques from transitioning from the laboratory to clinical applications. In this review, we emphasize the biocompatibility aspect of nano/micromotors to show the great efforts made by researchers to promote their clinical application, mainly including non-toxic fuel propulsion (inorganic catalysts, enzyme, etc.), bio-hybrid designs, ultrasound propulsion, light-triggered propulsion, magnetic propulsion, dual propulsion, and, in particular, the cooperative swarm-based strategy for increasing therapeutic effects. Future challenges in translating nano/micromotors into real applications and the potential directions for increasing biocompatibility are also described.

Simulation of Energy Dissipation in BLDC Motor and Analysis of Speed-Acoustic Characteristics

The hybrid electric vehicle combines dual propulsion systems: one employs the traditional internal combustion engine, while the other utilizes a PMDC or BLDC motor. Generally, BLDC motors exhibit an efficiency of 85% to 90%. Conversely, the PMDC motor inherently achieves an efficiency of 88% under optimal running conditions. Moreover, improving the efficiency of both motors is impeded by their design constraints. Power losses in these motors primarily stem from factors such as heat generation in the rotor (I²R losses), bearing friction, vibrations, and noise. This paper aims to investigate energy loss in a 4 kW BLDC motor manufactured by Bosch, attributable to speed-induced acoustic noise effects. Harmonic analysis of the phase current reveals the presence of odd-order harmonics, specifically those below the 11th order, resulting in current ripples. These dominant harmonic frequencies interact, ultimately generating noise and consuming a certain amount of power. These predominant frequencies correlate with fundamental electrical parameters: current frequency (Hz), RMS current (A), and threshold (%r), all associated with the motor's input power source. The 'K' factor, a parameter dependent on these three electrical factors, is calculated to determine harmonic stability. Variations in stable speeds (ranging from 1280 to 7500 RPM) are used to record 'K' factor readings. Based on IEEE Standard 85-1980 guidelines, motors are classified as either acceptable (OK) or not acceptable (not OK) according to their harmonic stability 'K' factor. Readings for each speed step are captured at a specific predominant frequency, facilitating subsequent comparisons. To validate the experimental findings, MATLAB/Simulink and a Fluke scope meter are employed to conduct power analyses for each motor, thus assessing energy loss attributed to noise. The waveform of the phase current proves instrumental in quantifying energy consumption in the BLDC motor. Notably, higher-frequency noise waves with shorter wavelengths entail greater energy consumption. Evaluating energy loss significantly contributes to the analysis of BLDC motor speed acoustics, serving to inform the design of energy-efficient hybrid electric vehicle models powered by BLDC motors, which are intended for customer service.

Back-Transition Control With Large Deceleration for a Dual Propulsion VTOL UAV Based on Its Maneuverability

This letter analyzes the maneuverability of a fixed-wing hybrid Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicle (UAV), and proposes a control strategy for back-transitions from fixed-wing mode to rotary-wing mode based on it. Longitudinal aerodynamic forces and moment are modeled to derive a dynamic model of the UAV, and the translational and rotational accelerations that can be generated for the UAV are examined based on the model. To achieve a back-transition with the largest deceleration while maintaining level flight, we search for the best choice of pitch angle and thrust forces for each forward speed by numerical optimization. Flight experiments demonstrate that it is possible to perform a horizontal back-transition while generating a large deceleration with the chosen pitch angles.

Dual‐Propelled Sporopollenin‐Exine‐Capsule Micromotors for Near‐Infrared Light Triggered Degradation of Organic Pollutants

AbstractTowards on‐site degradation of organic pollutants, dual‐propelled sporopollenin‐exine‐capsule (SEC) micromotors loaded with horseradish peroxidase (HRP) have been developed. The magnetic propulsion of SEC micromotors enables them to follow predesignated paths to arrive the pollution site, while the chemical propulsion on the site accelerates the degradation process taking advantage of the fluid mixing effect induced by their movement and bubble generation. Near‐infrared (NIR) light is employed to trigger the rupture of the magnetic polydopamine (PDA) outer coating and release the platinum‐coated SECs loaded with HRP enzyme. The dual propulsion system combined with the biocompatible nature of the components paves the way for on‐site bioremediation of organic pollutants.

Effects of preparation on catalytic, magnetic and hybrid micromotors on their functional features and application in gastric cancer biomarker detection

Artificial micromotors evolve to improve multitasking performance in different research areas, and different power sources are combined to give rise to hybrid micromotors. Such combinations can alter physical features and influence movement aspects that until now have not been taken into account. Here, we comparatively studied how physical features of magnetic (erGO/Ni), catalytic (erGO/Pt), or dual propulsion (erGO/Pt-Ni and its inverted form erGO/Ni-Pt) micromotors can influence direction and speed. The results showed that erGO/Pt and erGO/Ni microtubes presented different growth modes dependent on experimental conditions. For the hybrid form, similar features were observed but thicker and shorter than their individual versions. The catalytic motion comparison demonstrated that the main movement pattern was circular, and erGO/Pt micromotors were faster than the hybrid form, reaching speeds up to 360 μm s−1. The addition of a third material decreased significantly the speed especially when nickel was in the last layer, demonstrating that the order in which metallic elements are deposited is relevant and influences the speed. The erGO/Pt microtubes were selected to detect Reprimo, a gastric cancer biomarker. The detection assay (static or catalytic conditions) relies on the turn-off/turn-on fluorescence recovery due to the hybridization process between the Reprimo probe tagged with a fluorescein amidine dye and target biomarker Reprimo ssDNA, followed by its detachment from microtube. The catalytic detection results have shown to possess great selectivity as well as good reproducibility and can become a promising strategy for qualitative or quantitative detection of Reprimo or other circulant cancer biomarkers based on DNA.

Shafting alignment based on hydrodynamics simulation under larger rudder corner conditions

With the rudder angles getting larger and larger, the moment and force on propeller shafts, which are caused by complex flowing field, become more and more. They influence the shafting alignment greatly. Stress analysis of propeller shafts has been done under increasing rudder corner conditions with complex hydrodynamics simulation for a great domestic liquified natural gas (LNG) vessel, which is with dual propulsion systems. The improved three-moment equation is adopted in the process of dual propulsive shafting alignment. The calculated results show that the propeller hydrodynamic characteristics, which affect dual propulsive shafting alignment greatly, must be considered under large rudder angle conditions. Shafting accidents of Korean LNG vessels are interpreted reasonably. At the same time, salutary lessons and references are afforded to the marine multi-propulsion shafting alignment in the future.