Spin Forces Research Articles

Forcespinning: An Alternative Method to Produce Metal Sulfides/Carbon Composite Nanofibers As Anode Materials for Lithium-Ion and Sodium-Ion Batteries

We present results on the Forcespinning (FS) of SnS2/SnO2/PAN and MoS2/PAN precursors for the mass production of SnS2/SnO2 /carbon and MoS2/C as anode materials for Lithium-ion and Sodium-ion batteries. The binary composite nanofiber electrodes of SnS2/SnO2/C and MoS2/C are produced using a scalable technique (FS) and subsequent thermal treatment (calcination). The composite nanofiber anodes were porous and flexible. The nanofiber preparation process involved the FS of SnS2/SnO2/PAN and MoS2/PAN precursors into nanofibers and subsequent stabilization in air at 280oC and calcination at 800oC under an inert atmosphere. The flexible composite nanofibers were directly used as working electrode in lithium-ion and sodium-ion batteries without a current collector, conducting additives, or binder. The SnS2/C and SnS2/SnO2/C electrodes delivered a specific capacity of 556 mAhg-1 and 965 mAhg-1 respectively during the first sodiation cycle. This initial high capacity is attributed to the irreversible formation of a stable SEI layer and to the porous structure of the Forcespun composite nanofibers. In the subsequent cycles, the SnS2/C electrode exhibited a much stable cycling performance compared to SnS2/SnO2/C i.e. 145 mAhg-1 was maintained after 50 cycles. The MoS2/C composite nanofiber electrodes delivered a good electrochemical performance and Coulombic efficiency when used for Lithium-ion batteries. This study provides a novel and feasible pathway for designing and developing promising anodes and cathodes for high-performance lithium ion and sodium-ion batteries.

Modeling and computation of nonlinear rotating polymeric jets during forcespinning process

In the usual forcespinning (FS) process, a meso-scale fluid jet is forced through an orifice of a rotating spinneret, where the ambient fluid is air. This leads to the formation of a jet with a curved centerline. In this study we make use of a phenomenological viscosity model for polymeric fluid to investigate the properties of nonlinear polymeric fiber jets during FS process. We apply multi-scale and perturbation techniques to determine the governing modeling systems for such nonlinear rotating jets and their stabilities. First, we calculate numerically the expressions for the leading order nonlinear steady solutions for the jet quantities such as radius, speed, stretching rate, strain rate and trajectory versus arc length, and we determine, in particular, these quantities for different values of the parameters that represent effects due to rotation, viscosity and relaxation time. Next, we calculate the stability of the nonlinear jet versus different types of perturbations. We find that the nonlinear fiber jet flow can be stable in most cases and uncover conditions for which fiber radius reduces and the jet speed or stretching rate increases.

A comparative study on the performance of binary SnO2/NiO/C and Sn/C composite nanofibers as alternative anode materials for lithium ion batteries

The development of alternative anode materials out of flexible composite nanofibers has seen a growing interest. In this paper, binary carbon nanofiber electrodes of SnO2/NiO and Sn nanoparticles are produced using a scalable technique, Forcespinning (FS), and subsequent thermal treatment (carbonization). The Sn/C composite nanofibers were porous and flexible, while the SnO2/NiO composite nanofibers had “hairy-like” particles and pores on the fiber strands. The nanofiber preparation process involved the FS of Sn/PAN and SnO2/NiO/PAN solution precursors into nanofibers and subsequent stabilization in air at 280°C and calcination at 800°C under an inert atmosphere. The flexible composite nanofibers were directly used as working electrodes in lithium-ion batteries without a current collector, conducting additives, or binder. The electrochemical performance of the SnO2/NiO/C and Sn/C composite fiber anodes showed a comparable cycle performance of about 675 mAhg−1 after 100 cycles. However, the SnO2/NiO/C electrode exhibited a better rate performance than the Sn/C composite anode and was able to recover its capacity after charging with a higher current density. A postmortem analysis of the composite nanofiber electrode after the aging process revealed a heavily passivated electrode from the electrolyte decomposition by-products. The synthesis and processing methods used to produce these composite nanofibers clearly were a factor for the high rate capability and excellent cycle performance of these binary composite electrodes, largely on the account of the unique structure and properties of the composite nanofibers.

Study of spin-polarized plasma driven by spin force in a two-dimensional quantum electron gas

We examine the collective spin-polarized density motion in an unmagnetized plasma under a high frequency electromagnetic (EM) wave modulation. Spin effect in a quantum plasma is considered for the first time at a finite temperature near the Fermi temperature with considering collisional damping. A nonlinear two-fluid spin quantum magnetohydrodynamic model is used and solved self-consistently. The nonlinear effect and the reducing g-factor enhance the spin-polarization, while the collisional damping decreases the spin polarization. Strong spin-polarization is derived and the contribution of the spin-polarized current to the EM wave is much larger than that of the classical current.

Forcespinning of Microfibers and their Applications in Lithium-Ion and Sodium-Ion Batteries

In this paper, a scalable technique, Forcespinning (FS) is employed to produce SnO2/carbon composite microfibers as anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SBIs). The fiber preparation process involved the FS of Tin (II) 2-ethylhexanoate/PAN and PAN solution precursors into fibers and subsequently stabilizing in air at 280oC and calcined at 800oC under an inert atmosphere. A hollow and pore microstructure of the SnO2/CFs were produced that were flexible and were directly used as free-standing anodes in LIBs and SBIs An improved electrochemical performance was observed in the SnO2/C composite electrode in particular for the sodium ion battery (SIB), with a recorded specific capacity of 198 mAhg-1 after 50 cycles at a current density of 100 mAg-1. The FS method clearly produced both carbon and SnO2/C composite fiber electrodes that showed improved electrochemical performance for the SIB due largely to the unique structure and properties of the microfibers.

Creation of Titanium and Zirconium Carbide Fibers with the Forcespinning Technique

The forcespinning (FS) technique is used here to produce titanium dioxide and carbon composite fibers, as well as zirconium dioxide and carbon composite fibers. Subsequent carbothermal reduction of these fibers facilitated the creation of titanium carbide and zirconium carbide fibers respectably. The role of FS parameters such as the revolutions per minute (RPM) and the collector distance employed is examined. Sol‐gel chemistry is used to produce the solutions for the initial FS, and the control of sol‐gel chemistry and its effect on the end fiber products is also investigated. The effect of these variables is examined using X‐ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The results confirm that titanium and zirconium carbide fibers can be produced using the sol‐gel and FS techniques.

SnO2/NiO/Carbon Composite Nanofibers Produced By Forcespinning of Poly Acrylonitrile /SnO2 Precursor As Anodes for Lithium Ion Batteries

The development of alternative anode materials out of flexible nanofibers has seen a growing interest. In this paper, binary carbon nanofiber electrodes of SnO2/NiO and Tin nanoparticles are produced using a scalable technique, Forcespinning (FS) and subsequent thermal treatment (calcination). The Sn/C nanofibers were porous and flexible, while the SnO2-NiO nanofibers had “hairy-like” particles and pores on the fiber strands. The nanofiber preparation process involved FS the Sn/PAN and SnO2/NiO/PAN precursors into nanofibers and subsequently stabilizing in air at 280oC and calcination at 800oC under an inert atmosphere. The flexible composite nanofibers were directly used as working electrode in lithium-ion batteries without a current collector, conducting additives, or binder. The electrochemical performance of the SnO2/NiO/C and Sn/C electrodes showed a comparable cycle performance of about 675 mAhg-1 after 100 cycles. However, the SnO2/NiO/C electrode exhibited a better rate performance than Sn/C anode and was able to recover its capacity after charging with a higher current density. The synthesis and processing methods used to produce these nanofibers clearly was a factor for the high rate capability and excellent cyclic performance of these binary composite electrodes, largely on the account of the unique structure and properties of the composite nanofibers.

Forcespinning: A new method for the mass production of Sn/C composite nanofiber anodes for lithium ion batteries

The development of nanostructured anode materials for rechargeable Lithium-ion Batteries has seen a growing interest. We herein report the use of a new scalable technique, Forcespinning (FS) to produce binder-free porous Sn/C composite nanofibers with different Sn particle size loading. The preparation process involves the FS of Sn/PAN precursor nanofibers and subsequently stabilizing in air at 280°C followed by carbonization at 800°C under an inert atmosphere. The Sn/C composite nanofibers are highly flexible and were directly used as binder-free anodes for lithium-ion batteries. The produced Sn/C composite nanofibers showed an improved discharge capacity of about 724mAhg−1 at a current density of 100mAg−1 for over 50cycles compared to most nanofiber electrodes prepared by electrospinning and centrifugal spinning. The FS method clearly produces Sn/C nanofiber composite electrodes that have a high specific capacity and excellent cyclic performance, owing to the unique structure and properties of the nanofibers. The FS technology is thus a viable method for the large scale production of nano/micro fibers for battery electrodes, separators, and other applications. To the best of our knowledge, this is the first time to report results on the use of Forcespinning technology to produce composite nanofiber anodes for lithium-ion batteries.

Tailoring PLGA nanoparticle release profiles via centrifugal fractioning

Event Abstract Back to Event Tailoring PLGA nanoparticle release profiles via centrifugal fractioning Dipankar Dutta1*, Mariama Salifu1*, Rachael W. Sirianni1, 2* and Sarah E. Stabenfeldt1* 1 Arizona State University, School of Biological and Health Systems Engineering, United States 2 Barrow Neurological Institute, Barrow Brain Tumor Research Center, United States Introduction: Poly(D,L-lactic-co­-glycolic) acid (PLGA)-based nanoparticles (NP) are uniquely posed to overcome limitations of conventional drug delivery systems. However, tailoring cargo/payload release profiles from PLGA NPs typically requires the optimization of the multi-parameter NP formulation, where small changes may cause drastic shifts in the resulting release profiles[1],[2]. In this study, we aimed to establish whether refining the average diameter of NP populations through centrifugal fractioning after particle formulation represents a feasible tool to tailor PLGA NP release characteristics. We hypothesized that the average NP size would directly affect protein loading and subsequent release characteristics. Materials and Methods: PLGA NPs were produced via double-emulsion followed by solvent evaporation to encapsulate the model protein, bovine serum albumin (BSA). NPs were then subjected to centrifugal fractioning protocols varying in both spin time and force. After separation of supernatant and pellet, NP size distributions of initial and fractioned groups were determined using scanning electron microscopy. Release profiles were quantified by determining protein encapsulation efficiencies and in vitro release assays. Statistical analyses were performed using analysis of variance with Tukey’s post-hoc test. Results and Discussion: Centrifugal fractioning significantly modulated NP size distribution as a function of spin time and force without negatively affecting yield and NP morphology. Average diameters for all groups in the study ranged between 211.2–707.5nm relative to 340.9nm for the initial batch of NPs. Additionally, we found the average NP diameter was related to marked alterations in encapsulation efficiencies (range: 36.4-49.4%; Fig 1A), burst release (range: 15.8-49.1%; Fig 1B), protein release rate (Fig 1C), and time for total cargo release (range: 38-78 days; Fig 1D). Our data corroborated previous reports relating NP size with such release characteristics[3],[4]. However, this is the first study, to our knowledge, to directly compare NP population size and protein release profile while holding all formulation parameters constant. Conclusion: Previous studies have evaluated the influence of the fabrication parameters on the cargo loading and release from PLGA particles to provide general formulation trends on obtaining broad release profile characteristics. However, seemingly simple changes in the NP formulation may ultimately lead to a loss of desirable attribute(s). We report that protein encapsulation efficiency and several parameters of the release curve are correlated to t. Thus centrifugal fractioning represents a potential tool for tuning NP properties without modifying formulation parameters. Figure 1: Encapsulation efficiency and duration of release was directly proportional to the average particle diameter (A and D). Conversely, the magnitude of the burst release and the rate of protein release were inversely proportional to average particle diameter (B and C). Linear regression was used to empirically model trends (solid line) with 95% confidence interval (dotted lines). NIH (1DP2HD084067; SES); NSF (1454282; SES); ASU Start-up Funds (SES); Ben and Catherine Ivy Foundation (RWS); DoD (W81XWH-14-1-0311; RWS)

Quantum dust magnetosonic waves with spin and exchange correlation effects

Dust magnetosonic waves are studied in degenerate dusty plasmas with spin and exchange correlation effects. Using the fluid equations of magnetoplasma with quantum corrections due to the Bohm potential, temperature degeneracy, spin magnetization energy, and exchange correlation, a generalized dispersion relation is derived. Spin effects are incorporated via spin force and macroscopic spin magnetization current. The exchange-correlation potentials are used, based on the adiabatic local-density approximation, and can be described as a function of the electron density. For three different values of angle, the dispersion relation is reduced to three different modes under the low frequency magnetohydrodynamic assumptions. It is found that the effects of quantum corrections in the presence of dust concentration significantly modify the dispersive properties of these modes. The results are useful for understanding numerous collective phenomena in quantum plasmas, such as those in compact astrophysical objects (e.g., the cores of white dwarf stars and giant planets) and in plasma-assisted nanotechnology (e.g., quantum diodes, quantum free-electron lasers, etc.).

Tailoring sub-micron PLGA particle release profiles via centrifugal fractioning.

Poly(D,L-lactic-co -glycolic) acid (PLGA)-based sub-micron particles are uniquely posed to overcome limitations of conventional drug delivery systems. However, tailoring cargo/payload release profiles from PLGA micro/nanoparticles typically requires optimization of the multi-parameter formulation, where small changes may cause drastic shifts in the resulting release profiles. In this study, we aimed to establish whether refining the average diameter of sub-micron particle populations after formulation alters protein release profiles. PLGA particles were first produced via double emulsion-solvent evaporation method to encapsulate bovine serum albumin. Particles were then subjected to centrifugal fractioning protocols varying in both spin time and force to determine encapsulation efficiency and release profile of differently sized populations that originated from a single batch. We found the average particle diameter was related to marked alterations in encapsulation efficiencies (range: 36.4-49.4%), burst release (range: 15.8-49.1%), and time for total cargo release (range: 38-78 days). Our data corroborate previous reports relating PLGA particle size with such release characteristics, however, this is the first study, to our knowledge, to directly compare particle population size while holding all formulation parameters constant. In summary, centrifugal fractioning to selectively control the population distribution of sub-micron PLGA particles represents a feasible tool to tailor release characteristics. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A 104A: 688-696, 2016.

Detection of HIT antibody dependent platelet aggregation using novel surface imprinting approach

We present a fast, robust and straightforward spin force assisted surface imprinting approach for activated platelets and demonstrate that Heparin induced thrombocytopenia (HIT) platelet aggregation can be measured by this approach. A critical and challenging step in functional assays for HIT is platelet separation from the healthy donor's platelet-rich plasma (PRP). Our approach using surface imprinted polymer (MIP) for measurements on a quartz crystal microbalance with dissipation (QCM-D) enables monitoring of platelet aggregation directly in PRP thus eliminating the challenge of platelet separation. This is the first report of platelet imprinting. We also provide proof of principle that QCM-D technology can be applied for functional measurements of HIT antibodies.

Fabrication of cellulose fine fiber based membranes embedded with silver nanoparticles via Forcespinning

Abstract This study presents the successful development of cellulose fiber based membranes embedded with silver nanoparticles. These fine fiber membranes were developed utilizing the Forcespinning (FS) technique followed by alkaline hydrolysis treatment. The fiber morphology, homogeneity and yield were optimized by varying spinning parameters such as polymer concentration and angular velocity of the spinnerets. The structure, thermal and mechanical properties, and water absorption capability of the developed membranes were investigated. The cellulose acetate (CA) present in the membrane was converted to cellulose in the presence of embedded silver nanoparticles by alkaline hydrolysis. The silver nanoparticles embedded cellulose membrane exhibits outstanding water absorption capacity with fast uptake rate. Its high porosity, three-dimensional network structure with well-interconnected pores, as well as the intrinsically highly hydrophilic nature of cellulose material greatly favor its potential application as wound dressings. The antimicrobial activity was evaluated by the disk diffusion method. The composite membranes exhibit excellent antimicrobial activity against Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, and Gram-positive Staphylococcus aureus, owing to the slow and sustained release of embedded silver nanoparticles.

Comparison of the electron-spin force and radiation reaction force

It is shown that the forces that originate from the electron-spin interacting with the electromagnetic field can play, along with the Lorentz force, a fundamentally important role in determining the electron motion in a high energy density plasma embedded in strong high-frequency radiation, a situation that pertains to both laser-produced and astrophysical systems. These forces, for instance, dominate the standard radiation reaction force as long as there is a ‘sufficiently’ strong ambient magnetic field for affecting spin alignment. The inclusion of spin forces in any advanced modelling of electron dynamics pertaining to high energy density systems (for instance in particle-in-cell codes), therefore, is a must.

Spin force and intrinsic spin Hall effect in spintronics systems

We investigate the spin Hall effect (SHE) in a wide class of spin-orbit coupling systems by using the spin force picture. We derive the general relation equation between spin force and spin current and show that the longitudinal force component can induce a spin Hall current, from which we reproduce the spin Hall conductivity obtained previously using Kubo's formula. This simple spin force picture gives a clear and intuitive explanation for SHE.

Spin force and the generation of sustained spin current in time-dependent Rashba and Dresselhaus systems

The generation of spin current and spin polarization in a two-dimensional electron gas structure is studied in the presence of Dresselhaus and Rashba spin-orbit couplings (SOC), the strength of the latter being modulated in time by an ac gate voltage. By means of the non-Abelian gauge field approach, we established the relation between the Lorentz spin force and the spin current in the SOC system, and showed that the longitudinal component of the spin force induces a transverse spin current. For a constant (time-invariant) Rashba system, we recover the universal spin Hall conductivity of e8π, derived previously via the Berry phase and semi-classical methods. In the case of a time-dependent SOC system, the spin current is sustained even under strong impurity scattering. We evaluated the ac spin current generated by a time-modulated Rashba SOC in the absence of any dc electric field. The magnitude of the spin current reaches a maximum when the modulation frequency matches the Larmor frequency of the electrons.

Spin Force on Pseudo Spin Current in Graphene

The present study investigated spin force by using pseudo spin-orbit coupling in an artificial atomic structure for graphene. This spin force, which is applied on pseudo spin current, can be controlled by graphene gap and electric field due to charged nanodot. It seems that, by this force can be constructed a logical system from graphene and semiconductors. In addition, this force can be used for understanding the Zitterbewegung of electron wave packet with pseudo spin-orbit coupling in graphene and create of the charge Hall effect in semiconductors and graphene.

Observation of Ferromagnetic Resonance in Magnetic Exchange Force Microscopy (MExFM)

The atomic spin interaction is very important for understanding the superficially magnetic feature of nanostructure at atomic level. Magnetic exchange force microscopy (MExFM) is an innovative means of measuring surface spin force. But it is difficult to separate the surface topography and spin information. We develop the magnetic exchange force microscopy using ferromagnetic resonance (FMR-MExFM). The theoretical and experimental results demonstrate that this method can separate the two kinds of information effectively. Here, in order to obtain the high sensitivity in detecting the ferromagnetic resonance, we fabricate the microwave irradiation device to optimize the position between the device and the cantilever. We have succeeded in observing the ferromagnetic resonance effect and determining its resonant frequency using the homemade microwave irradiation device and the network analyzer. This research is very important for developing FMR-MExFM and novel magnetic sensor, detecting the magnetic information, etc.

Persistent spin and charge currents in an Aharonov–Casher conducting ring

We investigate the persistent spin and charge currents within an open mesoscopic ring embedded in a textured electric field. The persistent spin and charge currents are obtained analytically, and can be controlled by the electric field. Since the spin-up (down) electron can feel the different transverse spin forces generated by the spin–orbit coupling, the spin-up (down) electron will travel clockwise (anticlockwise) along the ring. As a result, the persistent charge current will change its direction within the ring according to different spin state electron injections, whilst the persistent spin current remains in the same direction. A pure persistent spin current, without any accompanying charge current, can be produced by tuning the strength and/or the angle of the textured electric field.

Quantum hydrodynamics approach to the research of quantum effects and vorticity evolution in spin quantum plasmas

In this paper we explicate a method of magneto quantum hydrodynamics (MQHD) for the study of the quantum evolution of a system of spinning fermions in an external electromagnetic field. The fundamental equations of microscopic quantum hydrodynamics (the momentum balance equation and the magnetic moment density equation) were derived from the many-particle microscopic Schroodinger equation with $Spin-Spin and Coulomb modified Hamiltonian. Using the developed approach the extended vorticity evolution equation for the quantum spinning plasma were derived. The effects of new spin forces and spin-spin interaction contributions on the motion of fermions, evolution of the magnetic moment density and vorticity generation were predicted. The influence of the intrinsic spin of electrons in the nonlinear whistler mode turbulence was investigated. This results can be used for the theoretical studies of spinning many-particle systems, especially dense quantum plasmas in compact astrophysical objects, plasmas in semiconductors and micro-mechanical systems, in quantum x-ray free-electron lasers.