Theoretical Analysis and Experimental Study on Breakaway Torque of Large-diameter Magnetic Liquid Seal at Low Temperature

The existing researches of the magnetic liquid rotation seal have been mainly oriented to the seal at normal temperature and the seal with the smaller shaft diameter less than 100 mm. However, the large-diameter magnetic liquid rotation seal at low temperature has not been reported both in theory and in application up to now. A key factor restricting the application of the large-diameter magnetic liquid rotation seal at low temperature is the high breakaway torque. In this paper, the factors that influence the breakaway torque including the number of seal stages, the injected quantity of magnetic liquid and the standing time at normal temperature are studied. Two kinds of magnetic liquid with variable content of large particles are prepared first, and a seal feedthrough with 140 mm shaft diameter is used in the experiments. All experiments are carried out in a low temperature chamber with a temperature range from 200℃ to -100℃. Different numbers of seal stages are tested under the same condition to study the relation between the breakaway torque and the number of seal stages. Variable quantity of magnetic liquid is injected in the seal gap to get the relation curve of the breakaway torque and the injecting quantity of magnetic liquid. In the experiment for studying the relation between the breakaway torque and the standing time at the normal temperature, the seal feedtrough is laid at normal temperature for different period of time before it is put in the low temperature chamber. The experimental results show that the breakaway torque is proportional to the number of seal stages, the injected quantity of magnetic liquid and the standing time at the normal temperature. Meanwhile, the experimental results are analyzed and the torque formula of magnetic liquid rotation seal at low temperature is deduced from the Navier-Stokes equation on the base of the model of magnetic liquid rotation seal. The presented research can make wider application of the magnetic liquid seal in general. And the large-diameter magnetic liquid rotation seal at low temperature designed by using present research results are to be used in some special fields, such as the military field, etc.

Experimental study on freezing of liquids under static magnetic field

Freezing processes of several liquids under static magnetic field(SMF) less than 50 mT were investigated. Central temperature of liquid samples held in glass test tubes immersed in a liquid bath was measured and collected. Nucleation temperature and phase transition time were obtained from freezing curves. Normality tests were performed for nucleation temperature of these liquids with/without magnetic field and normality distributions were justified. Analysis of variances was carried out for nucleation temperature of these liquids with magnetic field flux density as the influencing factor. Results showed that no significant difference was found for deionized water with or without SMF. However, differences exist in 0.9% NaCl solution and 5% ethylene glycol solution with and without SMF. Nucleation temperature of 0.9% NaCl with SMF is lower than that without SMF, while its phase transition time is shorter than that without SMF. Nucleation temperature of 5% ethylene glycol with SMF is higher than that without SMF, while its phase transition time is not modified with SMF.

Experimental Investigation on Finishing Technology by Magnetostrictive Ultrasonic Vibration of Magnetic Liquid

Magnetic liquid can produce alternative internal pressure under the alternative high-frequency gradient magnetic field.Because it has higher bulk modulus,the internal pressure results in its volume change.Using piezoelectric transducers,the ultrasonic wave generated by the vibration of magnetic liquids can be detected,which shows that the magnetic liquids have the magnetostrictive effect and can generate the ultrasonic vibration under the alternative magnetic gradient field.Some nonmagnetic abrasives and rust-proofing agents can be mixed into the magnetic liquids,under the alternative magnetic field,the abrasives held by magnetic liquids grind the surface of the workpieces,and thus,the finishing for the surface with complex shape,mold cavity and inner wall of tiny tubes can be realized.

MHD Stability Analysis and Flow Controls of Liquid Metal Free Surface Film Flows as Fusion Reactor PFCs

Numerical and experimental investigation results on the magnetohydrodynamics（MHD） film flows along flat and curved bottom surfaces are summarized in this study. A simplified modeling has been developed to study the liquid metal MHD film state, which has been validated by the existing experimental results. Numerical results on how the inlet velocity（V）, the chute width（W） and the inlet film thickness（d0） affect the MHD film flow state are obtained. MHD stability analysis results are also provided in this study. The results show that strong magnetic fields make the stable V decrease several times compared to the case with no magnetic field,especially small radial magnetic fields（Bn） will have a significant impact on the MHD film flow state. Based on the above numerical and MHD stability analysis results flow control methods are proposed for flat and curved MHD film flows. For curved film flow we firstly proposed a new multi-layers MHD film flow system with a solid metal mesh to get the stable MHD film flows along the curved bottom surface. Experiments on flat and curved MHD film flows are also carried out and some firstly observed results are achieved.

Magneto and Electro-Optic Intensity Modulator Based on Liquid Crystal and Magnetic Fluid Filled Photonic Crystal Fiber

We propose a novel light intensity modulator based on magnetic fluid and liquid crystal（LC） filled photonic crystal fibers（PCFs）. The influences of electric and magnetic fields on the transmission intensity are theoretically and experimentally analyzed and investigated. Both the electric and magnetic fields can manipulate the molecular arrangement of LC to array a certain angle without changing the refractive index of the LC. Therefore, light loss in the PCF varies with the electric and magnetic fields whereas the peak wavelengths remain constant. The experimental results show that the transmission intensity decreases with the increase of the electric and magnetic fields. The cut-off electric field is 0.899 V/um at 20 Hz and the cut-off magnetic field is 195 m T. This simple and compacted optical modulator will have a great prospect in sensing applications.

Unambiguously Resolving the Potential Neutrino Magnetic Moment Signal at Large Liquid Scintillator Detectors

Non-vanishing electromagnetic properties of neutrinos have been predicted by many theories beyond the Standard Model, and an enhanced neutrino magnetic moment can have profound implications for fundamental physics. The XENON1T experiment recently detected an excess of electron recoil events in the 1–7 keV energy range, which can be compatible with solar neutrino magnetic moment interaction at a most probable value of μ_(v) = 2.1 × 10^(-11)μ_(B).However, tritium backgrounds or solar axion interaction in this energy window are equally plausible causes.Upcoming multi-tonne noble liquid detectors will test these scenarios more in depth, but will continue to face similar ambiguity. We report a unique capability of future large liquid scintillator detectors to help resolve the potential neutrino magnetic moment scenario. With O(100) kton·year exposure of liquid scintillator to solar neutrinos, a sensitivity of μ_(v) < 10^(-11)μ_(B) can be reached at an energy threshold greater than 40 keV, where no tritium or solar axion events but only neutrino magnetic moment signal is still present.

Oriented magnetic liquid metal-filled interlocked bilayer films as multifunctional smart electromagnetic devices

Smart electromagnetic functional devices prepared based on electromagnetic wave responsive materials will provide more convenience for human life in the future.Here,we prepare oriented magnetic liquid metal droplet-filled polydimethylsiloxane films with micropillar array patterned surfaces,and further assemble them into bilayer films with interlocked structures.Once compressed,the increase in conductivity of the film due to the tunneling effect between microarrays and the elongation of liquid metal droplets leads to a rapid increase in electromagnetic interference shielding performance.Accordingly,a tunable electromagnetic interference shielding material with high sensitivity and wide control range is obtained,which has potential applications in electromagnetic wave control systems and intelligent electromagnetic protection systems.Meanwhile,we assemble a strain sensor and a magnetic sensor,which can precisely sense pressure and magnetic field according to changes in electromagnetic signal and electrical signal,respectively.

Characterization of Phase Transition in Heisenberg Fluids from Density Functional Theory

The phase transition of Heisenberg fluid has been investigated with the density functional theory in mean-field approximation （MF）. The matrix of the second derivatives of the grand canonical potential Ω with respect to the particle density fluctuations and the magnetization fluctuations has been investigated and diagonalized. The smallest eigenvalue being 0 signalizes the phase instability and the related eigenvector characterizes this phase transition. We find a Curie line where the order parameter is pure magnetization and a spinodal where the order parameter is a mixture of particle density and magnetization. Along the spinodal, the character of phase instability changes continuously from predominant condensation to predominant ferromagnetic phase transition with the decrease of total density. The spinodal meets the Curie line at the critical endpoint with the reduced density p＊=pσ3=0.224 and the reduced temperature T＊ =kT/ε=1.87 （σ is the diameter of Heisenberg hard sphere and e is the coupling constant）.

Magnetically rotational reactor for absorbing benzene emissions by ionic liquids

A magnetically rotational reactor （MRR） has been developed and used in absorbing benzene emissions. The MRR has a permanent magnet core and uses magnetic ionic liquid [bmim]FeCl4 as absorbent. Benzene emissions were carried by N2 into the MRR and were absorbed by the magnetic ionic liquid. The rotation of the permanent magnet core provided impetus for the agitation of the magnetic ionic liquid, enhancing mass transfer and making benzene better dispersed in the absorbent. 0.68 g benzene emissions could be absorbed by a gram of [bmim]FeCl4, 0.27 and 0.40 g/g higher than that by [bmim]PF6 and [bmim]BF4, respectively. The absorption rate increased with increasing rotation rate of the permanent magnet.

Effects of magnetic ionic liquid as a lubricant on the friction and wear behavior of a steel-steel sliding contact under elevated temperatures

A magnetic ionic liquid(abridged as MIL)[C_(6)mim]_(5)[Dy(SCN)_(8)]was prepared and used as the magnetic lubricant of a steel-steel sliding pair.The tribological properties of the as-prepared MIL were evaluated with a commercially obtained magnetic fluid lubricant(abridged as MF;the mixture of dioctyl sebacate and Fe_(3)O_(4),denoted as DIOS-Fe_3O_4)as a control.The lubrication mechanisms of the two types of magnetic lubricants were discussed in relation to worn surface analyses by SEM-EDS,XPS,and profilometry,as well as measurement of the electric contact resistance of the rubbed steel surfaces.The results revealed that the MIL exhibits better friction-reducing and antiwear performances than the as-received MF under varying test temperatures and loads.This is because the MIL participates in tribochemical reactions during the sliding process,and forms a boundary lubrication film composed of Dy_(2)O_(3),FeS,FeSO_(4),nitrogen-containing organics,and thioether on the rubbed disk surface,thereby reducing the friction and wear of the frictional pair.However,the MF is unable to form a lubricating film on the surface of the rubbed steel at 25°C,though it can form a boundary film consisting of Fe_(3)O_(4) and a small amount of organics under high temperature.Furthermore,the excessive Fe_(3)O_(4) particulates that accumulate in the sliding zone may lead to enhanced abrasive wear of the sliding pair.

Tunable LCST-type phase behavior of [FeCl4]--based ionic liquids in water

In this work, 16 kinds of [FeCl4]--based magnetic ionic liquids （ILs） with different cation structures have been designed and synthesized, and their structures are characterized by IR and Raman spectroscopy. Then the lower critical solution temperature （LCST）-type phase behavior of these magnetic ILs in water is investigated as a function of concentration. It is shown that cat- ion structure, alkyl chain length and molar ratio of FeCl3/chloride IL have a significant influence on the LCST of the mixtures. The phase separation temperature can be tuned efficiently by these factors. Meanwhile, the LCST-type phase separation pro- cess is also investigated by dynamic light scattering. The results support the mechanism that the hydrogen bonds of the [Fefl4]- anion with water have been gradually disrupted to form ILs aggregates with increasing temperature. In addition, the stability of the ILs in water is also examined in some details. These LCST-type phase separation systems may have potential applications in extraction and separation techniques at room temperature.

Liquid metal spiral coil enabled soft electromagnetic actuator

Soft robot is a kind of machine form with flexible deformation capability. Making flexible actuators has recently become a hot research topic in the field. In this study, we demonstrated the facile fabrication of a soft electromagnetic actuator using liquid metal coil of Ga-In alloys, and designed several illustrative mechanical devices, such as jellyfish like robot, soft fishtail and flexible manipulator. Measurements of the liquid metal coil's electrical properties confirmed that the liquid metal coil was mechanically stable under 48% uniaxial strains. Furthermore, the resistance of the liquid metal coil is stable under 60° bending deformation. Tests on the liquid metal coil's driving properties confirmed that the liquid metal coil(55 mm×55 mm×1 mm) could reach the maximum displacement amplitude of 21.5 mm with the current of 0.48 A. It was shown that the electromagnetic interaction between the magnet and the liquid metal coil enables the coil as a highly efficient actuator. The mechanisms lying behind were interpreted and future applications of such system were discussed.

Noise suppression for the detection laser of a nuclear magnetic resonance gyroscope based on a liquid crystal variable retarder

Nuclear magnetic resonance gyroscopes （NMRGs） are a kind of rotation-speed sensor that senses the angular velocity by measuring a frequency shift in the Larmor pre- cession of the nuclear spin in a constant magnetic field.

Hard-magnetic liquid metal droplets with excellent magnetic field dependent mobility and elasticity

Magnetic liquid metal droplets(MLMDs)have been proven to be very important in many fields such as flexible electronics and soft robotics.Usually,soft magnetic particles such as nickel(Ni)and iron(Fe)are mixed or suspended into the liquid metal to obtain soft MLMDs(S-LMDs),which can be easily manipulated under the magnetic field due to the favorable deformability and flexibility.In addition,hard magnetic particles such as neodymium iron boron(Nd Fe B)with a high residual magnetization can also be dispersed into the liquid metal and the hard MLMDs(H-LMDs)become more compact due to the interaction between internal particles induced by remanence.This work reports a kind of H-LMDs with high surface tension,high flexibility and mechanical robustness,whose electrical conductivity and strength are better than the S-LMDs.Under the magnetic field,the H-LMDs have a faster response time(0.58 s)and a larger actuating velocity(4.45 cm/s)than the S-LMDs.Moreover,the H-LMDs show excellent magnetic controllability,good elasticity and favorable mobility,as demonstrated by magnetically actuated locomotion,bounce tests and rolling angle measurements.Finally,the droplets can be further applied in wheeldriven motors and micro-valve switches,which demonstrates their high application potential in robotic manipulation and microfluidic devices.

Effects of medium fluid cavitation on fluctuation characteristics of magnetic fluid seal interface in agricultural centrifugal pump

The fluctuation law of magnetic fluid seal interface of an agricultural centrifugal pump is theoretically unknown;the pressure and velocity fluctuations are crucial factors that cause interface fluctuation.In this study,the pressure and velocity fluctuations of the sealing interface on an agricultural centrifugal pump during cavitation were investigated based on the methods of Ansys CFX numerical calculation and experimental verification.The results demonstrated that at the same flow rate,the pressure fluctuation amplitude of the sealing interface decreased gradually from the shaft surface to the bottom of the polar tooth.At different flow rates,the amplitude of the pressure fluctuation decreased with an increase in the flow rate.The cavitation of the medium aggravated the impact and water hammer of the liquid,leading to the occurrence of the jitter phenomenon in the sealing interface to accelerate the fluctuation frequency of the axial velocity of the sealing liquid,which accelerated the emulsification of the magnetic fluid.This law can provide a reference for the design of magnetic fluid sealing devices for agricultural centrifugal pumps.

Identification of Biomarkers for Endometriosis Using Clinical Proteomics

Background：We investigated possible biomarkers for endometriosis （EM） using the ClinProt technique and proteomics methods.Methods：We enrolled 50 patients with EM,34 with benign ovarian neoplasms and 40 healthy volunteers in this study.Serum proteomic spectra were generated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MS） combined with weak cationic exchange （WCX） magnetic beads.Possible biomarkers were analyzed by a random and repeat pattern model-validation method that we designed,and ClinProtools software,results were refined using online liquid chromatography-tandem MS.Results：We found a cluster of 5 peptides （4210,5264,2660,5635,and 5904 Da）,using 3 peptides （4210,5904,2660 Da） to discriminate EM patients from healthy volunteers,with 96.67％ sensitivity and 100％ specificity.We selected 4210 and 5904 m/z,which differed most between patients with EM and controls,and identified them as fragments of ATP1B4,and the fibrinogen alpha （FGA） isoform 1/2 of the FGA chain precursor,respectively.Conclusions：ClinProt can identify EM biomarkers,which-most notably-distinguish even early-stage or minimal disease.We found 5 stable peaks at 4210,5264,2660,5635,and 5904 Da as potential EM biomarkers,the strongest of which were associated with ATP1B4 （4210 Da） and FGA （5904 Da）; this indicates that ATP1B4 and FGA are associated with EM pathogenesis.

Metal-organic framework derived magnetic nanoporous carbon as an adsorbent for the magnetic solid-phase extraction of chlorophenols from mushroom sample

In this work, a metal-organic framework derived nanoporous carbon （MOF-5-C） was fabricated and modified with Fe3O4 magnetic nanoparticles. The resulting magnetic MOF-5-derived porous carbon （Fe304@MOF-5-C） was then used for the magnetic solid-phase extraction of chlorophenols （CPs） from mushroom samples prior to high performance liquid chromatography-ultraviolet detection. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and N2 adsorption were used to characterize the adsorbent. After experimental optimization, the amount of the adsorbent was chosen as 8.0 mg, extraction time as 10 min, sample volume as 50 mL, desorption solvent as 0.4 mL （0.2 mL × 2） of alkaline methanol, and sample pH as 6. Under the above optimized conditions, good linearity for the analytes was obtained in the range of 0.8-100.0 ng g 1 with the correlation coefficients between 0.9923 and 0.9963. The limits of detection （SIN= 3） were in the range of 0.25-0.30 ng g-1, and the relative standard deviations were below 6.8%. The result showed that the Fe304@MOF-5-C has an excellent adsorption capacity for the analytes.

Local heat transfer properties in co- and counter-current G-L-S magnetically stabilized fluidized beds

Heat transfer coefficients were measured by immersed probes in co- and counter-current G-L-S magnetically stabilized fluidized beds （MSFBs） using air, water and nickel-alloy particles as the gas, liquid and solid phases. Influences of major factors, including magnetic field intensity, superficial gas and liquid velocities, liquid viscosity and surface tension, on heat-transfer properties were studied experimentally, indicating that both co- and counter-current G-L-S MSFB can provide relatively uniform radial distribution of heat transfer coefficients under appropriate operation conditions, thus controlling operation temperature for highly exothermic multi-phase reaction systems. Two correlations were provided to estimate accurately heat transfer properties in both co- and counter-current G-L-S MSFB systems, with an average error of less than 10%.