High-speed Spinning Research Articles

CD-like全血分析芯片内压缩空气的定量泵送

To overcome the dependence of the plasma extraction on siphon hydrophilicity in a centrifugal microfluidic chip and to ensure long-term stability and reliability of the microfluidic chip, a compressed air reservoir connected to the blood separated reservoir was proposed to separate the blood in blood separated reservoir at high rotating speeds. Through lowering the spinning speed, the plasma in the separated reservoir was pumped toward the CD-like chip center to release the stored air pressure produced by the rotation at high spinning speeds. Based on the thermodynamics of the isothermal gas, the pneumatic pumping method was modeled, and the model was confirmed by analyzing pumping positions and air compression versus spinning speeds. By using the layered Polymethyl Methacrylate(PMMA)as materials, the centrifugal microfluidic chips for plasma extraction were fabricated with a CO2 laser process technique and the volume of compressed air and the blood position at siphon were tested at different rotational speeds. Experimental results demonstrate that the achieved volume of compression is 8.7L and the siphon valve effectively inhibits whole blood to overflow the crest of siphon at 4 000 r/min speed. With lowering the spin speed to 1 000 r/min, the release of compressed air overcomes the centrifugal force and drives the plasma to flow past the crest of siphon. Then the plasma extraction is realized in quantitation.

Detoxification of chemical warfare agents by CuBTC

The detoxification of chemical warfare agents by the metal–organic framework CuBTC (HKUST-1) was studied using nuclear magnetic resonance spectroscopy. All agents were shown to hydrolyze within the substrate. The degradation of VX and soman (GD) was determined to be relatively slow, with half-lives over 1 day, while the half life of distilled mustard (HD) was determined to be about 13 h. HD half lives, measured by MAS NMR, were dependant on spinning speed, with observed half lives decreasing at higher spinning speeds.

The N-terminal domains of spider silk proteins assemble ultrafast and protected from charge screening

Web spiders assemble spidroin monomers into silk fibres of unrivalled tensile strength at remarkably high spinning speeds of up to 1 m s(-1). The spidroin N-terminal domain contains a charge-driven, pH-sensitive relay that controls self-association by an elusive mechanism. The underlying kinetics have not yet been reported. Here we engineer a fluorescence switch into the isolated N-terminal domain from spidroin 1 of the major ampullate gland of the nursery web spider E. australis that monitors dimerization. We observe ultrafast association that is surprisingly insensitive to salt, contrasting the classical screening effects in accelerated, charged protein interfaces. To gain deeper mechanistic insight, we mutate each of the protonatable residue side chains and probe their contributions. Two vicinal aspartic acids are critically involved in an unusual process of accelerated protein association that is protected from screening by electrolytes, potentially facilitating the rapid synthesis of silk fibres by web spiders.

Polymer structure and antimicrobial activity of polyvinylpyrrolidone-based iodine nanofibers prepared with high-speed rotary spinning technique

Poly(vinylpyrrolidone)/poly(vinylpyrrolidone-vinylacetate)/iodine nanofibers of different polymer ratios were successfully prepared by a high-speed rotary spinning technique. The obtained fiber mats were subjected to detailed morphological analysis using an optical and scanning electron microscope (SEM), while the supramolecular structure of the samples was analyzed by positron annihilation lifetime spectroscopy (PALS). The maximum dissolved iodine of the fiber samples was determined, and microbiological assay was carried out to test their effect on the bacterial growth. SEM images showed that the polymer fibers were linear, homogenous, and contained no beads. The PALS results, both the o-positronium (o-Ps) lifetime values and distributions, revealed the changes of the free volume holes of fibers as a function of their composition and the presence of iodine. The micro- and macrostructural characterisation of polymer fiber mats enabled the selection of the required composition from the point of their applicability as a wound dressing.

Characterization of liquid flow in the spinning cloth disc reactor: Residence time distribution, visual study and modeling

The spinning cloth disc reactor (SCDR) is an innovative enzymatic reaction intensification technology. The SCDR uses centrifugal forces to allow the spread of thin film across the spinning disc which has a cloth with immobilized enzyme. Research has shown this geometry promotes accelerated reactions due to high mass transfer rates and rapid mixing. In this study, the flow regimes in the SCDR were characterized by means of residence time distribution (RTD) analysis and visual study tracking dye staining.RTD analysis showed that the flow pattern on the spinning disc with/without cloth became closer to plug flow with an increase of spinning speed and flow rate. With the cloth, the equivalent number of tanks-in-series was at least 2 times lower than that without cloth at different spinning speeds and flow rates, indicating the flow is better mixed, in contrast to the typical plug flow found for conventional spinning disc reactor. Two flow regimes were observed in the visual study with the dye spreading within the spinning cloth: radial finger-like flow and concentric flow. At low spinning speeds and high flow rates, the flow was in the form of a few random and uneven radial streams, with the zone between these streams free of dye. At higher spinning speeds and lower flow rates, this uneven radial flow was replaced by an even concentric flow. Using tributyrin hydrolysis as a model reaction, a SCDR reactor mathematical model based on perfectly mixed model was developed to simulate the variation in SCDR conversion with spinning speed and flow rate, and the model fitted well with the experimental data. The overall results indicate the SCDR is neither a conventional spinning disc reactor nor a rotating packed bed, but a separate class of spinning disc-type reactor for process intensification, called ‘spinning mesh disc reactors’ (SMDRs).

Spraying Pattern Overlap and Movement Design of Automatic Electrostatic Top Spraying Machine

The high-speed spinning bell electrostatic automatic machine is the key equipment of the automotive coating line. A simplified mathematical model of the process of spraying aggradation was proposed by analyzing the working principle of electrostatic spray. Furthermore, the relationships among spraying distance, spraying speed and number of spraying pattern overlap were investigated and revealed. And the expressions for the velocities of both side spraying machine and top spraying machine are derived. This work provides an important theoretical basis for the spraying trajectory planning .

Multinuclear Solid State Nuclear Magnetic Resonance Investigation of Water Penetration in Proton Exchange Membrane Nafion-117 by Mechanical Spinning

(1)H, (17)O, and (19)F solid state NMR spectroscopies have been used to investigate water penetration in Nafion-117 under mechanical spinning. It is found that both (1)H and (17)O spectra depend on the orientation of the membrane with respect to the magnetic field. The intensities of the side chain (19)F spectra depend slightly on the orientation of membrane with respect to the magnetic field, but the backbone (19)F spectra do not exhibit orientation dependence. By analyzing the orientation dependent (1)H and (17)O spectra and time-resolved (1)H spectra, we show that the water loaded in Nafion-117, under high spinning speed, may penetrate into regions that are normally inaccessible by water. Water penetration is enhanced as the spinning speed is increased or the spinning time is increased. In the meantime, mechanical spinning accelerates water exchange. It is also found that water penetration by mechanical spinning is persistent; i.e., after spinning, water remains in those newly found regions. While water penetration changes the pores and channels in Nafion, (19)F spectra indicate that the chemical environments of the polymer backbone do not show change. These results provide new insights about the structure and dynamics of Nafion-117 and related materials. They are relevant to proton exchange membrane aging and offer enlightening points of view on antiaging and modification of this material for better proton conductivity. It is also interesting to view this phenomenon in the perspective of forced nanofiltration.

Finite Element Analysis of Contact between Laying Head Pipe and High-Speed Wire Rod

Wire spinning, which is a deformation process of great complexity in laying head pipe, was simulated using MSC. Marc, a software for finite element analysis, with the aid of production data collected in a high-speed wire spinning production line. The stress condition and the temperature distribution of the laying head inner wall, under the condition of high speed dry sliding friction, were obtained. The effects of different feed speeds on the contact stress and the transient temperature of the easily-wear part were analyzed. The simulation result coincides with the actual wear condition in the laying head pipe, indicating the soundness of the finite element model and making a contribution to optimizing the special curve of the laying head pipe and the finished rolling speed.

A nuclear magnetic resonance spectrometer concept for hermetically sealed magic angle spinning investigations on highly toxic, radiotoxic, or air sensitive materials

A concept to integrate a commercial high-resolution, magic angle spinning nuclear magnetic resonance (MAS-NMR) probe capable of very rapid rotation rates (70 kHz) in a hermetically sealed enclosure for the study of highly radiotoxic materials has been developed and successfully demonstrated. The concept centres on a conventional wide bore (89 mm) solid-state NMR magnet operating with industry standard 54 mm diameter probes designed for narrow bore magnets. Rotor insertion and probe tuning take place within a hermetically enclosed glovebox, which extends into the bore of the magnet, in the space between the probe and the magnet shim system. Oxygen-17 MAS-NMR measurements demonstrate the possibility of obtaining high quality spectra from small sample masses (~10 mg) of highly radiotoxic material and the need for high spinning speeds to improve the spectral resolution when working with actinides. The large paramagnetic susceptibility arising from actinide paramagnetism in (Th(1-x)U(x))O2 solid solutions gives rise to extensive spinning sidebands and poor resolution at 15 kHz, which is dramatically improved at 55 kHz. The first (17)O MAS-NMR measurements on NpO(2+x) samples spinning at 55 kHz are also reported. The glovebox approach developed here for radiotoxic materials can be easily adapted to work with other hazardous or even air sensitive materials.

ChemInform Abstract: Physical Methods and Techniques: NMR Spectroscopy

AbstractReview: 134 refs.

Experimental Identification of Characteristic Matrices in Vibration Equation for a Rotor (Theory and Simulation)

The predictive accuracy for the dynamic behaviour of a rotor under conditions of high-speed spinning depends on the accuracy of the numerical model of the rotor, the dynamic characteristics of the bearings and/or the seals, and the external force. In order to improve the accuracy of the numerical model, we propose a method to identify all characteristic matrices in the vibration equation of a rotor based on the information on rigid and elastic properties which can be obtained by a vibration test without spinning. The rotor is assumed to be composed of a shaft which can be modeled as beam elements and rigid discs. The proposed method can be applied for model reduction in which the reduced number of beam elements is feasible to calculate the dynamic behaviour of the rotor.

The Processing of Porous Superfine-Denier Nylon 6 FDY Yarn

In this paper, the porous superfine-denier Nylon 6 FDY(22dtex/35f) was successfully manufactured by blending Nylon 6 chips with a compound masterbatch according to a certain proportion through adjusting the process conditions on high speed spinning machine. The influence of masterbatch’s content and spinning technologies on the properties of FDY fibers with porous superfine-denier is also particularly discussed. And finally we find out the best spinning techniques for Nylon 6 FDY fiber with porous superfine-denier.

In-Plane and Transverse Eigenmodes of High-Speed Rotating Composite Disks

We apply Hamilton's principle and model the coupled in-plane and transverse vibrations of high-speed spinning disks, which are fiber-reinforced circumferentially. We search for eigenmodes in the linear regime using a collocation scheme, and compare the mode shapes of composite and isotropic disks. As the azimuthal wavenumber varies, the radial nodes of in-plane waves are remarkably displaced in isotropic disks while they resist such displacements in composite disks. The reverse of this phenomenon happens for transversal waves and the radial nodes move toward the outer disk edge as the azimuthal wavenumber is increased in composite disks. This result is in accordance with the predictions of Nowinski's theory, and therefore, it is independent of the magnitude of the spinning velocity and the mode frequency. Although there are notable differences between the form of governing equations derived from Hamilton's principle and Nowinski's theory, transverse eigenmodes differ a little in the two approaches. We argue that the application of orthotropic composites as the core material of the next generation of hard disk drives, together with an angular velocity controller, can enhance the data access rate.

Robust and efficient 19F heteronuclear dipolar decoupling using refocused continuous-wave rf irradiation

Refocused continuous wave (rCW) decoupling is presented as an efficient and robust means to obtain well-resolved magic-angle-spinning solid-state NMR spectra of low-γ spins, such as 13C dipolar coupled to fluorine. The rCW decoupling sequences, recently introduced for 1H decoupling, are very robust towards large isotropic and anisotropic shift ranges as often encountered for 19F spins. In rCW decoupling, the so-called refocusing pulses inserted into the CW irradiation eliminate critical residual second- and third-order dipolar coupling and dipolar-coupling against chemical shielding anisotropy cross-terms in the effective Hamiltonian through time-reversal (i.e. refocusing). As important additional assets, the rCW decoupling sequences are robust towards variations in rf amplitudes, operational at low to high spinning speeds, and easy to set-up for optimal performance experimentally. These aspects are demonstrated analytically/numerically and experimentally in comparison to state-of-the-art decoupling sequences such as TPPM, SPINAL-64, and frequency-swept variants of these.

Complete analytical solution of electromagnetic field problem of high-speed spinning ball

In this article, a small sphere spinning in a rotating magnetic field is analyzed in terms of the resulting magnetic flux density distribution and the current density distribution inside the ball. From these densities, the motor torque and the eddy current losses can be calculated. An analytical model is derived, and its results are compared to a 3D finite element analysis. The model gives insight into the torque and loss characteristics of a solid rotor induction machine setup, which aims at rotating the sphere beyond 25 Mrpm.

Microstructure and magnetic properties of melt spinning Ni–Mn–Ga

Textured Ni51Mn28.5Ga20.5 polycrystalline ribbons were prepared by melt spinning method with different spinning speeds. The effect of spinning speed on microstructure, phase transformation and magnetization behavior were investigated. The martensitic transformation temperatures were hardly affected by the spinning speed. The Curie temperature was significantly decreased, the saturation magnetization was reduced, and the critical field driving the detwinning was increased at higher spinning speed. Local and long-range effects were revealed for the melt spinning ribbons.

Modification of the mechanical properties of polyamide 6 multifilaments in high-speed melt spinning with nano silicates

In the last few years research activities have been focused on the modification of fiber properties with nano-scaled additives. One of the most important fields of research is the alteration of mechanical properties such as the tenacity and the specific breaking load. In this study, we determined the influence of nano-phyllosilicates on the drawability of polyamide 6 multifilament yarns. It was first demonstrated that the drawability of the fibers drastically increased in an industrially relevant high-speed melt spinning process. Structural properties of the material are identified by wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). Changes in the crystalline properties as well as in the alignment of the silicates are compared with the stress–strain curves of the fibers, and a molecular mechanism for the drawing process is derived from these experiments. In a first step, a significant phase transition in the crystalline structure unaffected by the silicates occurs for low draw ratios (DRs). Beyond this point, where unmodified fibers start to break, a gliding between the silicate layers takes place, which is responsible for an extended drawability of the fibers. This mechanism leads to new possibilities for fiber processing, which can be used to research ultra-fine filaments in future studies.

Broadband finite-pulse radio-frequency-driven recoupling (fp-RFDR) with (XY8)41 super-cycling for homo-nuclear correlations in very high magnetic fields at fast and ultra-fast MAS frequencies

We demonstrate that inter-residue 13C–13C proximities (of about 380pm) in uniformly 13C-labeled proteins can be probed by applying robust first-order recoupling during several milliseconds in single-quantum single-quantum dipolar homo-nuclear correlation (SQ–SQ D-HOMCOR) 2D experiments. We show that the intensity of medium-range homo-nuclear correlations in these experiments is enhanced using broadband first-order finite-pulse radio-frequency-driven recoupling (fp-RFDR) NMR sequence with a nested (XY8)41 super-cycling. The robustness and the efficiency of the fp-RFDR-(XY8)41 method is demonstrated at high magnetic field (21.1T) and high Magic-Angle Spinning (MAS) speeds (up to 60kHz). The introduced super-cycling, formed by combining phase inversion and a global four-quantum phase cycle, improves the robustness of fp-RFDR to (i) chemical shift anisotropy (CSA), (ii) spread in isotropic chemical shifts, (iii) rf-inhomogeneity and (iv) hetero-nuclear dipolar couplings for long recoupling times. We show that fp-RFDR-(XY8)41 is efficient sans1H decoupling, which is beneficial for temperature-sensitive biomolecules. The efficiency and the robustness of fp-RFDR-(XY8)41 is investigated by spin dynamics numerical simulations as well as solid-state NMR experiments on [U-13C]-l-histidine·HCl, a tetra-peptide (Fmoc-[U-13C,15N]-Val-[U-13C,15N]-Ala-[U-13C,15N]-Phe-Gly-t-Boc) and Al(PO3)3.

Research on the Rheological Properties of Domestic and International PPS Resin

Using the capillary rheometer to study the effect of shear rate, shear stress and temperature of Japanese and domestic PPS resin( fiber grade) on the apparent viscosity, index of non-Newtonian and viscous flow activation energy.The results show that with the increase of shear rate and temperature,compared to the domestic sample, Japanese sample has higher apparent viscosity, smaller non-Newtonian index(n),lower viscous flow activation energy,and smaller sensitivity to temperature.The Japanese specimens are suitable for processing and forming under high shear rate and spinning speed, but the domestic specimens are suitable for processing and froming under low shear rate and spinning speed.

Three-dimensional three-component particle velocimetry for microscale flows using volumetric scanning

We present a diagnostic platform for measuring three-dimensional three-component (3D3C) velocity fields in microscopic volumes. The imaging system uses high-speed Nipkow spinning disk confocal microscopy. Confocal microscopy provides optical sectioning using pinhole spatial filtering which rejects light originating from out-of-focus objects. The system accomplishes volumetric scanning by rapid translation of the high numerical aperture objective using a piezo objective positioner. The motion of fluorescent microspheres is quantified using 3D3C super resolution particle-imaging velocimetry with instantaneous spatial resolutions of the order of 5 µm or less in all three dimensions. We examine 3D3C flow in a PDMS microchannel with an expanding section at 3D acquisition rates of 30 Hz, and find strong agreement with a computational model. Equations from the PIV and PTV literature adapted for a scanning objective provide estimates of maximum measurable velocity. The technique allows for isosurface visualization of 3D particle motion and robust high spatial resolution velocity measurements without requiring a calibration step or reconstruction algorithms.