Search

Electric thrusters are considered to be the most promising propulsion system of choice for space gravitational wave detection. However, the requirement of high accuracy and drag-free control results in significant challenges in thrust measurements. To better understand the thrust noise characteristics, this work proposes a time-frequency-domain method for thrust noise analysis, i.e., a scalogram method attained through wavelet analysis. Unlike the conventional Fourier transform method, it can provide 3-D relationships for the time-frequency and thrust noise. A free-state thrust measurement experiment identified that the environmental temperature produces the dominant impact in the thrust noise. During a 70,000 s measurement, even without thruster operation, the thrust noise increased from 0.3 μN/Hz1/2 to 19 μN/Hz1/2 as the environmental temperature increased from −1 °C to 3 °C. The corresponding frequency of peak thrust noise for the entire period tends to be the same of 0.1 Hz. Additionally, a Hall thruster thrust measurement experiment was conducted to verify the method's time-varying analysis capability for thrust noise. The complete time-frequency thrust noise variation throughout the entire operating process of a Hall thruster was observed. The results at different stages of thruster operation indicate that thrust noise has the greatest influence 150–300 s after ignition. This is because the thrust stand will take hundreds of seconds to reach thermal equilibrium after ignition. Another finding during the Hall thruster operation is that the 0.1 Hz frequency corresponding to the peak thrust noise is highly consistent with the frequency of peak thrust noise in the free-state thrust experiment. This reveals the fact that the 0.1 Hz frequency should be the dominant frequency for thrust noise caused by temperature drift in our thrust measurement system.

Endoplasmic reticulum stress (ERS) plays a vital role in the pathogenesis of the alcoholic liver disease (ALD). Betulinic acid (BA) has been reported to be effective in the attenuation of ALD; however, its role in ERS and associated stress-signaling pathways remains elusive. Here, we found that the BA pretreatment significantly reduced the alcohol-induced liver injury by decreasing the activities of serum alanine aminotransferase and aspartate aminotransferase, alleviating fat deposition and rupturing the ER in hepatocytes. Moreover, the protective effect of BA on ALD was associated with the inhibition of reactive oxygen species accumulation and ERS, accompanied by the downregulation of glucose-regulated protein 78 (Grp78), Grp94, phosphorylation-inositol-requiring enzyme 1α (p-IRE1α), and phosphorylation-protein kinase R-like endoplasmic reticulum kinase (p-PERK), activating the transcription factor 6 (ATF6) and C/EBP homologous protein (CHOP). Moreover, the alcohol-induced hepatocyte apoptosis was reduced, along with the downregulation of the mitogen-activated protein kinase pathway, caspase-12, caspase-3, and caspase-7, following BA administration. Additionally, the BA-mediated mitigation of alcohol-induced liver injury and deactivation of the ER pathways were the same with 4-PBA, an inhibitor of ERS, indicating that the protective effect of BA on ALD may be regulated by ERS-associated pathways. Collectively, BA is a potentially desirable agent for the ALD, which may reduce hepatocyte apoptosis by suppressing excessive ERS in the liver.

One of the most important aspects of clinical acupuncture practice, like diabetic gastroparesis, is the selection of suitable acupoints. Furthermore, it is critical to examine the therapeutic impact differences between distal and local acupoints, as well as the prescription of their combination. In this study, diabetic gastroparesis rats were treated by needling Zhongwan (CV12) and Zusanli (ST36), and then used Single Photon Emission Computed Tomography-CT (SPECT-CT) technology to assess the effects of promoting gastric motility. In addition, morphological observation, immunohistochemical examination, and biomarker assays, such as determination of growth factor 1, motilin, and ghrelin contents in serum samples, were performed to better understand the impact of certain various acupuncture treatments. All of the therapies improved the symptoms of diabetic gastroparesis rats, according to the findings. Stimulating these acupoints, on the other hand, can have a different therapeutic effect. In addition, needling local and distal acupoints together can have an antagonistic or synergistic impact on specific physiological and biochemical indexes such as gastric motility, ghrelin, gastrin, and growth factor 1, among others. Our findings demonstrated the benefits of acupoints and acupuncture in the management of diabetic gastroparesis, as well as a new insight into acupuncture therapeutics.

High-temperature superconducting (HTS) tape stacks have broad applications in magnetic levitation because of the uniform induced current distribution, good heat dissipation, and preferable mechanical properties. Configuration of the stack is one of the primary factors on the uniformity and strength of the trapped magnetic field. In this paper, the levitation characteristics, which are levitation force, stiffness, and rotational friction of four different YBCO tape stack configurations, were compared. It is observed from the experiments that there is an obvious influence of stack configurations on the levitation characteristics. The levitation forces gradually improve with the increase of tape pieces. While the module No.2 is an inclined stack, the levitation force is related to the inclination angle. Most of the tape stack modules can give low loss rotation in levitation, and the magnitude of the friction coefficient is close to 10− 6. By the investigation of levitation characteristics, the tape stack has great potential for the bearing application.

Traditional photodynamic therapy (PDT) requires external light excitation to produce reactive oxygen species (ROSs) for the treatment of tumors. Due to problems of light penetration, traditional PDT is limited by the location and depth of the tumor. In this study, we rationally designed and constructed a novel strategy to amplify the therapeutic effect of PDT. We prepared a chlorin-lipid nanovesicle based on the conjugates of chlorin e6 (Ce 6) and phospholipids, with the surface conjugating the aptamer for lung cancer targeting, GLT21.T. 131I-labeled bovine serum albumin (131I-BSA) was loaded into the chlorin-lipid nanovesicle cavity (131I-BSA@LCN-Apt). 131I not only plays a role in radiotherapy, but its Cerenkov radiation (CR), as an internal light source, can also stimulate Ce6 to produce ROSs without external light excitation. The in vitro and in vivo therapeutic effects in subcutaneous lung tumor models and orthotopic lung tumor models indicated that 131I-BSA@LCN-Apt produced a powerful anti-tumor effect through synergistic radiotherapy and CR-PDT, which almost caused complete tumor growth regression. After treatment, the survival time of the mice was significantly prolonged. During the treatment, no obvious side effects were found by histopathology of important organs, hematology and biochemistry analysis except the decrease of the white blood cell count (WBC). The study provides a major tool for deep-seated tumors to obtain amplified therapeutic effects by synergistic radiotherapy and CR-PDT without the use of any external light source.

One of the praxeological problems of safe and sustainable air transport (airfreight transport/air cargo, and air passenger transport) is the prevention and management of risks by competent staff, with the support of modern information and communication technologies. This paper presents an educational information model and software for the airport network and information systems risk assessment, primarily intended for aviation education and training of professionals for ensuring safe and sustainable air transport. The solution to the problem is based on the application of the fuzzy logic method in the air transport environment. Based on a fuzzy expert model, the selected scenario, and the input data established separately for airport assets by a group of 23 experts from aviation practice and a university, the following three assessments of airport network information system assets were constructed: Asset A2 (meteorological information systems) has an insignificant risk with an estimated 0.1162, and assets A1 (air traffic control and management (ATM), navigational aids and approach) and A3 (runway monitoring system) received a low risk of airport network and information systems (NIS) security with ratings of 0.2623 and 0.2915, respectively. An airport NIS risk assessment was aggregated (0.2288), indicating a low degree of security risk to the airport&rsquo, s network and information systems. The aggregated risk assessment of airport NIS, including financial loss data, was calculated as 0.1438, representing a low degree of security risk to the airport&rsquo, s network and information systems. Scenarios for evaluating airport assets are changing for students during education. The results of the developed model and its software will be part of the Simulation Center of the Faculty of Aeronautics.

Induction coilgun can accelerate a high-temperature superconductor (HTS) projectile to higher velocity than a conventional projectile, because an HTS projectile can generate greater induced current by the premagnetized process and then obtain larger thrust in the launch process. In this paper, a numerical field model for the dynamic and electromagnetic characteristics of a single-stage induction coilgun is established, using the finite-element method. The electromagnetic force, muzzle velocity, and current density distribution of the aluminum projectile and the HTS projectile are studied, respectively. Then, the effect of magnetization on the characteristics of the HTS projectile during the launch process is considered. The result illustrates that magnetization brings a great improvement in the performance of the coilgun due to the higher induced current value in the HTS projectile. In addition, due to the limitation of the full magnetization state, the magnetization of the HTS projectile should be in a suitable range. The simulation work shows the potential of HTS projectile for future induction coilgun application.

The rapid development of industry results in large energy consumption and a negative impact on the environment. Pollution of the environment caused by conventional energy sources such as petrol leads to increased demand for propulsion systems with higher efficiency and capable of energy-saving and emission reduction. The usage of hybrid technology is expected to improve energy conversion efficiency, reduce energy consumption and environmental pollution. In this paper, the simulation platform for the hybrid unmanned aerial vehicle (UAV) has been built by establishing the subsystem models of the UAV power system. Under the two chosen working conditions, the conventional cruise flight mission and the terrain tracking mission, the power tracking control and Q-Learning method have been used to design the energy management controller for the hybrid UAV. The fuel consumption and pollutant emissions under each working condition were calculated. The results show that the hybrid system can improve the efficiency of the UAV system, reduce the fuel consumption of the UAV, and so reduce the emissions of CO2, NOx, and other pollutants. This contributes to improving of environmental quality, energy-saving, and emission reduction, thereby contributing to the sustainable development of aviation.

This work reports the synthesis, radiolabeling, and biological studies of 99m Tc-diethylene triamine pentaacetic acid (DTPA)-colchicine dimer in tumor-bearing mice. The novel colchicine dimer was successfully synthesized by conjugation of DTPA to 2 colchicine biomolecules. The ligand could be labeled by 99m Tc in high yield to get 99m Tc-DTPA-colchicine dimer, which was hydrophilic and stable at room temperature. Biodistribution and imaging studies in tumor-bearing mice showed that 99m Tc-DTPA-colchicine dimer accumulated in the tumor with improved uptake and retention. The results indicate the need for synthetic modification of the parent colchicine derivative and the 99m Tc-chelate with a view to improve the tumor-targeting efficacy and in vivo kinetic profiles.

The decarbonization of transport and heating will introduce uncertain smart appliance growth in the power system, which fundamentally challenges traditional network pricing. In this paper, a new long-term distribution network charging is proposed to accommodate uncertain load growth. Instead of using fixed a load growth rate (LGR), it adopts a fuzzy model, developed based on a set of projected deterministic LGRs and confidence levels. This fuzzy model is incorporated into the pricing model through $ {\alpha } $ -cut intervals. In order to improve computational efficiency, an analytical pricing approach is introduced. The vertex extension approach is used to build charge membership functions. Thereafter, a common defuzzification approach, center of gravity, is employed to defuzzify membership functions in order to generate deterministic charges. The new approach is benchmarked with two existing standard charging methods on a practical U.K. high-voltage distribution system. Results show that it is effective in capturing the uncertainty in load growth.

A wormlike micelle templated attachment growth approach for the preparation of mono- and bi-metallic nanochain networks is reported. Zwitterionic wormlike micelles with PtCl62− and PdCl42− counterions were fabricated for the first time as soft-templates. A possible soft-template assisted attachment-based growth mechanism for nanochain formation is proposed for the morphological replica process. The present strategy was further extended to synthesize alloyed noble-metal such as Pt–Au, Pd–Au, and Pt–Pd nanochain networks. The results presented may provide inspirations and strategies for the fabrication of noble metal nanostructures with adjustable structures and constituents through soft templated attachment growth.

Diethylenetriaminepentaacetic acid neolactosyl human serum albumin (DTPA-LSA) was prepared and labeled with technetium-99m. The labeling conditions of Tc-99m-DTPA-LSA were optimized, and lyophilized kit was developed for instant preparing of Tc-99m-DTPA-LSA. Tc-99m-DTPA-LSA showed high liver uptake in normal mice (> 96% ID/g at 5 min after injection), and it could be blocked significantly by pre-injecting free neogalactosylalbumin (NGA). Single photon emission computed tomography (SPECT) study was performed in normal Japanese White rabbits and SPECT images with high quality were obtained at 15, 30, 60, and 120 min after injection of the radiotracer. The promising biological properties of Tc-99m-DTPA-LSA combined with the development of reliable and instant lyophilized DTPA-LSA kit afford the opportunity of hepatic receptor imaging for routine clinical assessment of hepatic function. (c) 2012 Elsevier Ltd. All rights reserved.

Due to the zero gravity environment in space, the docking and assembling of space systems in orbit present many challenges, which are often overcome by approaches that depend on adapting interface structures and techniques. By using the trapped magnetic flux in high temperature superconductors (HTSs), the flux-pinned interaction between the HTS and the applied field provides a new, no-contacting interface method that can be used in the adapting approach. This paper presents a type of superconducting interface configuration consisting of bulk HTSs, actuation electromagnets and interfacing magnets. Unlike operations on the ground, the field cooling of the HTSs happens in orbit and the magnetic interactions in the superconducting interface are complicated. We carry out primary experiments using a magnet–superconductor pair to understand the magnetization and mechanical properties of the superconducting interface. The results show that the superconducting interface force properties are seriously affected by the magnetization process of the HTS. The magnet–superconductor pair shows different force properties on different values and directions of the supplied current in the actuation electromagnet. However, due to the weak actuation field, the flux-pinned force is slight and ineffectual for the self stability of the pair. However, depending on the combining interaction of the actuation electromagnet and the HTS with the interfacing magnet, the interface force between them shows lots of strong self-stable features along the axial direction. We also investigate a magnetization method with the multi-repeated static field. The flux-pinned force is largely increased and the self stability of the magnet–superconductor pair is added by the method. This is beneficial to the superconducting interface.

Three chemical modification methods of carboxymethylation, quaternization and hydroxypropylation were used to synthesize water-soluble chitosan derivatives. In order to study the feasibility of these chitosan derivatives as backbones of nuclear imaging agents, folic acid (FA) and Technetium-99m were introduced onto the water-soluble chitosan chains. The bifunctional chelating agent 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) was conjugated to the folate grafted chitosan derivatives for chelating with radionuclides such as (64)Cu and (68)Ga. The structures of these new ligands were characterized with multiple methods. The solubility and stability of the (99m)Tc-complexes were both favorable. Further study of their radiochemical and biological properties will be performed to evaluate the usefulness of these water-soluble chitosan derivatives for nuclear imaging agent design.

Rare-earth-based nanoparticles have attracted increasing attention for their unique optical and magnetic properties. However, their application in bioimaging has been limited to photoluminescence bioimaging and magnetic resonance imaging. To facilitate their use in other bioimaging techniques, we developed a simple, rapid, efficient and general synthesis strategy for (18)F-labeled rare-earth nanoparticles through a facile inorganic reaction between rare-earth cations and fluoride ions. The (18)F-labeling process based on rare-earth elements was achieved efficiently in water at room temperature with an (18)F-labeling yield of >90% and completed within 5 min, with only simple purification by aqueous washing and centrifugation, and without the use of organic agents. The effectiveness of (18)F-labeled rare-earth nanoparticles was further evaluated by positron emission tomography (PET) imaging of their in vivo distribution and application in lymph monitoring. In addition, this strategy is proposed for the creation of a dual-model bioimaging technique, combining upconversion luminescence bioimaging and PET imaging.

Compared to currently used chemical boosters or mechanical devices, electromagnetic catapults have special advantages on multiple acceleration profiles and highly variable velocity, which are attractive for launching unmanned air vehicles (UAVs) in several hundred kilogram range. A linear motor is usually designed as the thrust producer of the electromagnetic catapult. In this paper, we firstly give technical features of the catapult applied to the UAV of 200-kg class with an initial velocity of 30 m/s, and then make a comparison between linear synchronous motors (LSMs) and linear induction motors (LIMs). The LIM is selected and the initial characteristics (thrust, input power, efficiency, current and mass) of the LIM working under different voltages and frequencies are calculated by a T model equivalent circuit method. The calculation suggests that the LIM exhibits better properties when it works under the higher voltage or higher frequency. When superconducting wires are applied to primary coils to construct a superconducting LIM (SLIM), the motor characteristics are also calculated and discussed. The SLIM gives a favorable opportunity to reduce the input power and current. A finite element method (FEM) is employed to simulate static field distribution of the SLIM and give electromagnetic properties to verify the equivalent circuit method.

This study reports the synthesis and characterization of N-(3-(4-(2-methoxyphenyl)piperazin-1-yl)propyl-4-[(18)F]fluorobenzamide ([(18)F]MPP3F). The total reaction time for [(18)F]MPP3F, including final high-performance liquid chromatography purification, was about 3h. Typical decay-corrected radiochemical yield was 18.4+/-3.1%. The radiochemical purity was98%. Biodistribution in mice showed that [(18)F]MPP3F is a potential brain imaging agent for positron emission tomography. The brain uptake of [(18)F]MPP3F was 6.59+/-0.77% Injected Dose/g at 2 min post-injection time. A brain-to-blood ratio of 3.67 was reached at 15 min after injection.

In order to investigate the feasible application of a high-Tc superconducting (HTS) levitation system to a maglev train or a space vehicle launcher, we construct a demonstration maglev test vehicle consisting of two linear permanent magnets (PM) guideways and a test levitator with multi-block melt-processed YBaCuO superconductors. By using a vibration testing technique, we measure the dynamic force properties of the test vehicle in different field cooling (FC) and loading conditions. In both vertical and lateral vibration directions, resonance frequencies and related magnetic stiffness show large dependence on the FC height (FCH) and the load weight. The resonance frequencies increase as the FCH decreases or the load weight is reduced. The magnetic stiffness is also increased by using the low FCH or adding the load weight. It is shown that the dynamic properties of the HTS levitation system are closely related to the flux history in superconductors and the motion process of the system. Finally a low FC scheme and a preloading method are proposed to improve the stability of the HTS maglev vehicle.

In this paper, we present a simulation process of the melt-texture YBCO high-temperature superconductor (HTS) bulk levitated over the permanent-magnet (PM) guideway, and further experiment also been built to analyze the dynamic behavior of HTS. The relation between suspension force and amplitude of the levitation system under single-degree of freedom vibration environment was investigated, and stiffness was acquired based on the experiment. Besides, equation of motion of the suspension system was presented in this paper, and with an attempt to analyze and predict damping properties of HTS in given dynamic conditions. The obtained simulation results of the suspending motion behavior also prove that high damper on the levitation body could strengthen the levitation system's capacity of resisting the vibration impact.

In order to study the extraction pattern of protactinium in different types of extracting agents and compare the similarity of patterns of extraction with dubnium and thereby unraveling its chemistry, solvent extraction of protactinium(V) with methyl-iso-butyl carbinol (MIBC) and methyl-iso-butyl ketone (MIBK) was studied using 233Pa as a radiotracer. The extraction efficiencies of Pa were determined as a function of shaking time, concentrations of mineral acids, and extractant concentrations using the two extractants. The results show that MIBK is more suitable for the extraction of protactinium than MIBC in benzene. Furthermore, the effect of the F anion is also discussed.

Magnetic levitation technology, having the characteristics of low cost and high quality, has been considered a preferable option for the next generation of launcher systems. A world-wide research design on the conceptual level has been carried out on the highly reusable space transportation systems by applying magnetic levitation to the launch assistance. Recently, a research plan has been implemented in our laboratory by constructing a scale-model suspension system with high temperature superconductor (HTS henceforth) bulks over a 7 m Nd–Fe–B permanent-magnet (PM henceforth) track for the launch assistance. An experimental platform was built to investigate the dynamic responses of the PM–HTS interaction at different field-cooled positions. The critical frequencies and amplitudes which lead to the instability of levitation drift were investigated. The stiffness and the vibration damping were also discussed at the zero-field-cooled position.

Solvent extraction of protactinium with tri-iso-octyl-amine (TIOA) in xylene, benzene, carbon tetrachloride and chloroform from HCl, HF, HNO3, HClO4 and H2SO4 media was studied using 233Pa as a radiotracer. The extraction efficiencies of protactinium were determined as a function of shaking time, concentrations of mineral acids in aqueous phase, extractant concentrations and diluents in organic phase. The extraction mechanism was discussed. The results show that the extracted species in the organic phase is [(R3N−H)nPa(OH)xCl y 5−x−y ].

The goal of this study is to develop a novel 5-HT 1A receptor imaging agent. 4-[(2-methoxyphenyl)piperazin-1-yl]-dithioformate (MPPDTF) was labeled with 99m Tc-tricarbonyl core via dithioformate moiety in high yield (>96% by HPLC). 99m Tc(CO) 3 –MPPDTF is a neutral and lipophilic complex, which was confirmed by paper electrophoresis and octanol/water partition coefficient ( P =27.0±1.4, n =3), respectively. In vivo biodistribution indicated that this complex had moderate brain uptake (0.53±0.10% ID/g at 5 min and 0.42±0.02% ID/g at 120 min) and good retention (about 80% of the activity was retained in the brain at 120 min post-injection). Regional brain distribution study showed that hippocampus, where the 5-HT 1A receptor density is high, had the highest uptake (0.60±0.02% ID/g at 5 min p.i.) and the cerebellum, where the 5-HT 1A receptor density is low, had the lowest uptake (0.10±0.02% ID/g at 5 min p.i.). After blocking with 8-OH-DPAT, the hippocampus uptake was decreased obviously while the cerebellum uptake was increased slightly. This result indicates that 99m Tc(CO) 3 –MPPDTF complex has specific binding to 5-HT 1A receptor.

Various Maglev launch assist concepts were proposed in the world for the aim to find low-cost, safe, and reliable ways to get to space. Among them, high temperature superconducting (HTS) bulk magnetic levitation platform was considered as a better one for Maglev launch assist because of its inherent stability both in the vertical and lateral directions. As a primary work, a demo HTS Maglev launch assist test vehicle was designed and constructed in our laboratory. The system includes a vehicle body, permanent magnet guideway with the length of 7 m, the acceleration and braking parts. HTS bulks were located in LN2 vessels fixed below the vehicle body. The levitation force larger than 50 kg was provided by the interaction between HTS bulks and NdFeB guideway. The HTS bulk arrangement was optimized by measuring and comparing static and dynamic levitating characteristics of different HTS bulk units on NdFeB guideway. The acceleration part of the system was achieved by the linear motor. The braking was achieved by a set of spring buffer. The experimental investigation was carried out by the system, and some results were presented in the paper

The chlorambucil l-histidine conjugate was synthesized and radiolabeled with [(99m)Tc(CO)(3)](+) core to form the (99m)Tc(CO)(3)(His-CB) complex. The radiochemical purity of the complex was over 90%. It had good hydrophilicity and was stable at room temperature. The high initial tumor uptake with certain retention, fast clearance from background, good tumor/non-tumor ratios and satisfactory scintigraphic images highlighted the potential of (99m)Tc(CO)(3)(His-CB) as a tumor imaging agent.