Magnetic Rods Research Articles

Can You Stall a Baclofen Pump During a Magnetic Rod Lengthening?

Baclofen pumps are susceptible to magnetic forces because of the internal drug delivery mechanism. Magnetically controlled growing rods, sometimes implanted in the patients who have pumps, are lengthened using a device that generates a magnetic field. No previous study has determined if the external remote controller (ERC) can stall a baclofen pump during a rod lengthening. Two baclofen pumps were placed in proximity to the ERC while it generated a magnetic field. This process was repeated with variations in the distance between pump and ERC, speed (dose) of the pump, lengthening time, and position of the ERC relative to the pump. The presence or absence of a stall was recorded. To stall a baclofen pump, the ERC needed to be running consistently for at least 30 mm of lengthening. The pump would not stall if it was >1 cm away from the ERC. The pump was more likely to stall if it was positioned in front of or behind the magnetic field, as opposed to the center of the field. As long as the baclofen pump is >1 cm away from the ERC, the pump will not stall, regardless of the length of time the ERC generates a magnetic field.

The LightSail 2 solar sailing technology demonstration

The LightSail 2 mission is the culmination of a decade-long program sponsored by The Planetary Society to advance solar sailing technology. The objective of LightSail 2 is to demonstrate controlled solar sailing in Earth orbit using a CubeSat platform. The LightSail 2 attitude is controlled using a single-axis momentum wheel and magnetic torque rods. During solar sailing operations, two 90 degree slews are performed each orbit to harness momentum from solar photons. Flight data show that LightSail 2 is successfully controlling its orientation relative to the Sun, and the controlled thrust from solar radiation pressure is measurably reducing the rate of orbital decay. The Planetary Society declared LightSail 2 mission success on July 31, 2019. This paper provides an overview of the LightSail 2 mission implementation, including the design of the flight system and flight software, and the pre-launch testing program. A summary of LightSail 2 mission operations is provided, including a description of the ground system. Solar sailing performance is presented, and anomalies encountered during the mission are discussed. The flight team continues to refine solar sailing performance and conduct on-orbit imaging for engineering purposes and to engage public interest. The LightSail program is entirely donor-funded, with over 50,000 contributors around the globe.

New growth rod concept provides three dimensional correction, spinal growth, and preserved pulmonary function in early-onset scoliosis.

This study aims to describe a novel minimal invasive early-onset scoliosis (EOS) growth rod concept, the Cody Bünger (CB) Concept, which combines concave interval distraction and contralateral-guided growth with apical control and to investigate the 3D deformity correction, the spinal growth, and the pulmonary development. A series of 38 children with progressive EOS and growth potential, receiving a highly specialized surgical treatment, including primary and conversion cases. Mean age was 10.2years (4.4-15.8) with a mean follow-up of 5.6years, and they underwent 168/184 open/magnetic lengthening procedures. Outcomes were as follows: scoliosis, kyphosis, and lordosis angles; apical rotation; spinal length; apical translation; coronal and sagittal vertical alignment; complications; and pulmonary function in a subgroup. Scoliosis improved from mean 76° (46-129) to 35° (8-74) post-op and was 42° (13-83) at end of treatment. Apical rotation was reduced by 30% but was partially lost during treatment. Thoracic kyphosis initially decreased by mean 15° and was partially lost during treatment. Lordosis was largely unaltered during treatment. Mean T1-S1 height increased from 30.7cm (22.7-39.2) to 34.6cm (27.8-45.1) postop and further increased to 38.5cm (30.1-48.1) during treatment. This corresponded to a T1-S1 growth rate of 12mm/year, and positive growth rates were found in all height parameters evaluated. Frontal balance and apical translation improved, whereas sagittal balance was unaltered. Complications occurred in 22/38 patients, and 11/38 had an unintended reoperation. Pulmonary function (FVC and FEV) increased but the relative lung function was unchanged. The new growth rod concept provided 3D correction and spinal growth at complication rates comparable with other growth-friendly techniques for EOS, while pulmonary function was preserved. Single magnetic rod distraction was incorporated successfully, replacing surgical elongations.

Ultra-trace Cr preconcentration in honey samples by magnetic ionic liquid dispersive liquid-liquid microextraction and electrothermal atomic absorption spectrometry

An analytical method based on the dispersive liquid-liquid microextraction (DLLME) technique, using a magnetic ionic liquid (MIL) as an extraction phase, was developed for ultra trace Cr determination in honey samples. The elemental detection was performed by electrothermal atomic absorption spectrometry (ETAAS). In the developed method both centrifugation and complexation of the analyte were not required. The Cr(III) species was extracted by the MIL trihexyl(tetradecyl)phosphonium ([P6,6,6,14]FeCl4) after the formation of [CrCl2(H2O)4]Cl. The MIL phase was separated by a magnetic rod, diluted in CHCl3 and Cr was determined by ETAAS. Under optimized experimental conditions, an extraction efficiency of 98% and a sensitivity enchancement factor of 105 were achieved. A detection limit (LOD) of 5 ng L−1 Cr and relative standard deviation of 3.5% (at 50 ng L−1 Cr and n = 10) were obtained. Also, the linear range of the calibration curve was from 15 ng L−1 to 180 ng L−1. The method was applied for Cr determination in honey samples of different shades.

Magnetically controlled growing rods in early onset scoliosis surgery: a review of Englishlanguage literature

The objective of the review is to provide multifaceted information on the treatment of young children with severe onset scoliosis using magnetically-controlled growing rods (MCGR). This promising though controversial method is not yet well known in our country. The review presents the history of the development of the method, surgical technique, the frequency of etiological forms of spinal deformities, and describes in detail the results of scoliosis correction including the most severe cases. Quantitative and qualitative data describe complications that arise during the treatment including those characteristic only for this method (for example, slippage phenomena). The problem of repeated operations is separately discussed, and the capabilities of MCGR and other techniques based on the principle of distraction are compared. The review presents features of the use of MCGR in adult patients, the dynamics of the primary curve in the postoperative period (does the Sankar’s law work?), the possibilities of ultrasound when monitoring the effectiveness of magnetic rods, the use of MRI simultaneously with MCGR, and the comparative cost of the method. Particular attention is paid to the problem of a uniform protocol of staged extension of rods. It seems that the initial enthusiasm has somewhat decreased. It is commonly agreed that new research is needed.

Time-Optimal Magnetic Attitude Detumbling

The problem of minimum-time spacecraft attitude detumbling using magnetic rods is revisited in this paper within the context of optimal control theory. Two formulations are presented; the first one assumes the availability of the angular velocity measurements for feedback. The second formulation assumes the availability of only the ambient magnetic field measurements in the feedback. In both formulations, the constraint in this optimal control problem is a limit on the maximum magnetic dipole moment of the magnetic rods. It is shown that the time optimality will be achieved if the triple orthogonality condition between the torque, the dipole moment, and the magnetic field vector is fulfilled. This triple orthogonality is considered as a condition of optimality, which is often neglected in the existing B-dot law and its variants in the literature. The Pontryagin minimum principle is used to derive analytically the control logic, for each formulation, in this nonautonomous system, under the assumption of high angular velocity. The second formulation is shown to yield a new variant of the B-dot law. The Monte Carlo simulation results presented in this paper confirm that the two controls found in both formulations outperform most existing algorithms. In addition, the results show lower power consumption by the magnetic rods when using the proposed variant of the B-dot law as compared to existing B-dot laws.

Dispersion of magnetic susceptibility in a suspension of flexible ferromagnetic rods

The properties of suspensions of magnetosomes extracted from magnetotactic bacteria are investigated. By using dynamic light scattering and measuring the dispersion of magnetic susceptibility it is shown that sonicated samples with broken magnetosome chains have qualitatively different behavior in comparison with native samples. This is explained by the presence of flexible chains of magnetosomes in non-sonicated samples which have the qualitative features of magnetic susceptibility predicted by the model of flexible magnetic rods. • The model of flexible magnetic rods of magnetic susceptibility is proposed. • Broken magnetosome chains have qualitatively different behavior as native samples. • Frequency dependence of magnetosomes' complex susceptibility is analyzed.

Substitution Effect of Magnetic Materials in Halbach Cylinder for Magnetic Refrigerators

In this paper, we present the magnetic refrigeration by magnetocaloric effect, for which the magnetic flux distribution has been modified in the Halbach cylinder. The insertion of a soft magnetic rod in the bore led to the alternating magnetic field with two regions of high flux density for magnetization and two regions of low flux density for demagnetization of magnetocaloric materials in the annular gap. The two-dimensional numerical simulations by the finite element method using COMSOL Multiphysics and Poisson SUPERFISH demonstrated the substitution effect of neodymium–iron–boron permanent magnets by soft magnetic low-carbon steels. The optimized soft magnetic cross-sectional area of 0.04 m2 in the Halbach cylinder gave the maximum flux density of 2 T in the air gap, comparable to the peak field of existing prototypes. The flux density is further increased and became the largest when the ratio of external to internal radius of the cylinder is at the maximum. The cooling performance is also affected by the size of the cylinder, and the substantial value is obtained in a practical design with reserved air gap for magnetocaloric materials.

Bipolar Correction Magnet With Permanent Magnets

A bipolar correction magnet with permanent magnets for future accelerators such as ILC is proposed, which is realized by rotating permanent magnet rods. The shape of the magnet rods is adjusted, reducing sextupole and decapole components so that the flatness of the magnetic field distribution becomes better than 5e-5 [T] within ±10 mm range. The structure and the field adjustment scheme of a conceptual design is discussed.

Design and Implementation of a Test Fixture for ELF Schumann Resonance Magnetic Antenna Receiver and Magnetic Permeability Measurements

This paper presents a prototype test fixture for the absolute calibration and estimation of the equivalent magnetic flux noise of the extremely low frequency (ELF) Schumann resonant (SR) magnetic antenna receiver and rods’ magnetic permeability measurement. The test fixture, for ELF the SR detector’s calibration, consists of a constructed coil, the signal generator, and the oscilloscope. The ELF SR detector used has been operating since 2016 near the Doliana village in the Ioannina prefecture, Northwestern Greece. At precisely this spot, far away from electromagnetic noise, the whole setup and experiment took place. The experiments performed with the proposed test fixture showed a sensitivity of 70 nV/pT/Hz and an apparent magnetic permeability at around 250 for the magnetic antenna. The total sensitivity of the ELF receiver was 210 mV/pT near 20 Hz, while the total input noise was around 0.04 pT.

Torque in open-access permanent magnet variable flux sources

A flux source with four rotatable permanent magnet rods having access from two perpendicular directions through gaps exceeding the rod diameter can produce a continuously-variable flux density of up to ±300 mT at the centre when high-grade Nd-Fe-B magnets are used. The trade-off between field, access and torque in this mangle design is discussed. The maximum field, achievable when the magnets touch, is equal to the remanence of the Nd-Fe-B. The torque needed to rotate the rods scales as the square of the remanence, and it increases faster than the inverse square of the separation when the separation is comparable to the rod diameter. End effects reduce the torque significantly, but appropriate gearing is needed to ensure smooth operation. Modifications of the basic design can reduce or compensate the torque by using special end pieces, and improve access to fields > 1000 mT at small rod separation.

Steady states of non-axial dipolar rods driven by rotating fields.

We investigate a two-dimensional system of magnetic colloids with anisotropic geometry (rods) subjected to an oscillating external magnetic field. The structural and dynamical properties of the steady states are analyzed, by means of Langevin dynamics simulations, as a function of the misalignment of the intrinsic magnetic dipole moment of the rods with respect to their axial direction, and also in terms of the strength and rotation frequency of an external magnetic field. The misalignment of the dipole relative to their axial direction is inspired by recent studies, and this is extremely relevant in the microscopic aggregation states of the system. The dynamical response of the magnetic rods to the external magnetic field is strongly affected by such a misalignment. Concerning the synchronization between the magnetic rods and the direction of the external magnetic field, we define three distinct regimes of synchronization. A set of steady states diagrams are presented, showing the magnitude and rotation frequency intervals in which the distinct self-organized structures are observed.

Ferromagnetic resonance isolator based on a photonic crystal structure with terahertz vortices

A new terahertz isolator based on the ferromagnetic resonance effect is suggested and analyzed. A two-dimensional photonic crystal consisting of a square lattice of gallium arsenide rods has been employed in the design of the device. Incident electromagnetic waves interact with one magnetized ferrite rod and two stubs inserted in the photonic crystal structure, generating a vortex-like field profile in the ferrite rod. Electromagnetic signals propagating in the forward direction are transmitted with low insertion losses, while their propagation in the backward direction is not allowed due to the high losses of the ferrite rod operating at the ferromagnetic resonance regime. Computational simulations show that the operating bandwidth is equal to 0.87 GHz around the central frequency 106.6 GHz. In this frequency band, the insertion losses are lower than − 1.68 dB, the reflection levels are better than − 16 dB, and the isolation levels are greater than − 15 dB.

Synthesis of magnetic hollow mesoporous N-doped silica rods as a basic catalyst for the preparation of some spirooxindole-1,4-dihydropyridine derivatives

In this study, magnetic hollow mesoporous N-doped silica rods were successfully prepared via the in-situ calcination of different amounts of diethanolamine in the presence of silica precursor. Doping of the nitrogen atoms in to silica rod structures was performed through a new method and the structure of obtained composite confirmed by X-ray photo electron spectroscopy (XPS), X-ray diffraction (XRD) analysis, elemental analysis, TEM, FESEM and elemental mapping methods. Comparison of the synthesized N-doped catalyst with the same sample without nitrogen atoms (mesoporous silica) showed the high basic characteristic. Furthermore, the efficiency of the prepared basic catalyst was investigated for the synthesis of some spirooxindole-1,4-dihydropyridine derivatives under green conditions. High efficient heterogeneous catalyst, short reaction times (compare with other reported methods) and green conditions are some advantageous of presented method.

Cementation of Co ion in leach solution using Zn powder followed by magnetic separation of cementation-precipitate for recovery of unreacted Zn powder

A cementation process with Zn powder followed by magnetic separation was conducted to separate Co as precipitate from leach solution containing Mn ions and to recover unreacted Zn and concentrated Co from cementation precipitate. The separation of Co component from Mn could be achieved successfully by a cementation process performed under the following conditions; 200 mg/L Cu, 140 mg/L Sb, pH 3.3–3.7, temperature 85 °C, and 1% Zn powder, where Cu and Sb were used as cementation activators to avoid the redissolution of Co. Magnetic separation of the cementation-precipitate was performed using 2000 G magnetic rod, and the results showed that Zn distributed more in non-magnetic fraction while Co, Cu, Sb were contained more in magnetic fraction. The Co was concentrated to 8.3% in magnetic fraction of the precipitate obtained from 60 min-cementation test. The non-magnetic fraction contained the unreacted Zn powder, which could be reused for cementation test for precipitating Co.

P.227Secondary clinical outcomes of spinal surgery and satisfaction in patients with spinal muscular atrophy (SMA) II and non-ambulant III

Scoliosis is a highly prevalent feature of SMA and surgery is frequently required. Studies in small cohorts have reported a positive impact of spinal surgery on respiratory function, while limited data are available on motor function, weight gain, post-surgical skeletal pain and satisfaction. We retrospectively reviewed the notes of 33 patients (26 SMA II, 7 non-ambulant SMA III) who successfully underwent spinal fusion (25), magnetic (4) or traditional (4) growth rods followed by final growth spinal fusion (3) at Great Ormond Street Hospital-London. Median age at surgery was 10.9 years (4.28–16.72), median pre-operative Cobb angle 70 degrees (35–89), median follow up before and after surgery 3.9 (0.9–12.3) and 3.7 (0.4–10.5) years respectively. Mean annual rate of Forced Vital Capacity % decline improved after surgery in SMA II: -2.8 versus -7.4 (p<0.001). Similar trajectories were observed in SMA III. At first post-surgery assessment a median decline of 4.5 points (0-14) was observed on the Hammersmith Functional Motor Scale while the Revised Upper Limb Module's scores showed a less progressive deterioration. A temporary negative deviation from previous weight curve was observed in 17 patients requiring food supplements (5); one/4 type II with significant weight loss (>5% of total weight) needed gastrostomy. Hip pain was the most common skeletal pain documented (13/33) requiring painkillers (8), intra-articular steroids (1) or surgery (1). Ten patients/parents participated in a phone interview developed by the neuromuscular team on satisfaction. Nine/10 reported major improvements in posture, physical appearance, self-image and all rated the surgical procedure as very successful. However, 7/10 did not report significant improvements in quality of life due to reduced mobility and increased unmet care needs. This ongoing study expands the knowledge on outcomes after spinal surgery in SMA and highlights the importance of a careful post-operative multidisciplinary approach.

Crystallization of α-glycine by anti-solvent assisted by ultrasound.

Crystallization of α-glycine by addition of an anti-solvent (ethanol) assisted by ultrasound is studied. The experiments of crystallization are conducted at 303.15 K in a solution of 150 ml with continuous agitation by a magnetic rod. Ultrasound is then applied at powers ranging from 8 to 41 W thanks to an ultrasonic horn at 20 kHz. The supersaturation ratio (S) is followed throughout all the experiment. At the end of the experiment, the suspension is filtered, the solid is washed with ethanol and dried at 333.15 K. The resulting crystals are characterized by their final size distributions measured by laser granulometry, their morphologies observed by scanning electronic microscope (SEM) and their crystalline structures by differential scanning calorimetry (DSC). The influence of ultrasonic power (continuous 13, 28 and 40 W or pulsed modes), measured by calorimetry method, is studied for different addition rates (0.05 to 0.36 g of ethanol/min). Ultrasound permits to reduce the metastable zone width and to decrease the size of crystals due to an increase of the nucleation rate. The rate of de-supersaturation is higher in presence of ultrasound, inducing a higher nucleation rate, a higher growth rate or both. At 40 W, the decrease of supersaturation is faster, and the crystallization is finished in 40 min instead of 80 min (at 13 and 28 W) or 120 min without ultrasound. The use of pulsed ultrasound (50 on/50 off) is interesting from an economic point of view because similar results are obtained: comparable size distributions and resembling concentration profiles.

Magnetic enrichment behavior of monodispersed MFe2O4 nanoferrites (M= Mg, Ca, Ni, Co, and Cu)

Abstract The magnetic enrichment behavior of monodispersed MFe2O4 (M = Mg, Ca, Ni, Co, and Cu) ferrite nanoparticles with different size (10–130 nm) on the surface of a 15 mm o.d. NdFeB-N40 magnetic rod has been investigated. The materials were synthesized by a modified sol-gel method. They were characterized by XRD, TEM, and VSM. The magnetic field of the rod was modelled numerically using a finite element analysis software to obtain the input data for the magnitude of magnetic force. Three adsorption models can be used to describe the enrichment mechanism of ferrite nanoparticle depending on the magnetic permeability: (i) Freundlich adsorption model at low magnetic permeability ( 100 μemu/Oe) leading to the enrichment percentage above 90%.

Improved Spacecraft Magnetic Attitude Maneuvering

A magnetometer is essential in spacecraft magnetic attitude control due to the need for magnetic field information to compute the control command. The measurements of the magnetometer, however, are usually affected by other electric currents in the spacecraft, especially those of the magnetic coils when they are turned on during actuation. As a result, magnetic rods and magnetometers are usually turned on at alternate times, resulting in a reduced duty cycle of the magnetic rods, and hence longer maneuver times. This paper presents a magnetic attitude control system with extended duty cycle and low magnetometer measurements frequency. Instead of measurements, a computed magnetic field strength vector is used for updating the control command during the duty cycle. Using the measured spacecraft rotational motion, and knowing the control torque command, it is possible to compute the magnetic field strength vector. These computations are corrected using magnetometer measurements at a lower rate. The Tikhonov regularization approach is implemented to solve the singular magnetic torque system. This algorithm is demonstrated via Monte Carlo numerical simulations to have faster attitude maneuvers and lower power consumption by the magnetic rods. Real data obtained from the Cascade Smallsat and Ionospheric Polar Explorer spacecraft are used for validation of the proposed approach.

Use of Magnetic Spinal Growth Rods (MCGR) With and Without Preoperative Halo-gravity Traction (HGT) for the Treatment of Severe Early-onset Scoliosis (EOS).

Correction of severe scoliosis through distraction-based techniques poses a challenge. Magnetically controlled growing rod (MCGR) hardware complications are common with a 27.8% to 46.7% revision rate in under 2 years. Loss of correction and diminishing returns are the norm. Treatment of severe scoliosis with halo-gravity traction (HGT) before MCGR has not been previously reported. The purpose of this study was to assess initial correction, maintenance of correction, and complication rate in patients with severe scoliosis treated with and without HGT before MCGR. IRB-approved retrospective single site cohort study of a prospectively collected database. Forty-two patients underwent MCGR between 2014 and 2017 at a single site, 12 with prior growing constructs were excluded, 30 patients were included, 12 patients underwent preoperative HGT. Charts were reviewed for demographic, clinical, and radiographic information. The HGT group had larger major curves averaging 90 (69 to 114) degrees versus 77 (56 to 113) degrees in the non-HGT group P=0.018. Percent correction on preoperative flexibility films were 17% versus 40% for those in the HGT versus non-HGT group, P=0.000. An additional 22% correction of the curve magnitude occurred between the flexibility and in-traction films representing 43% of the total correction achieved, P=0.000, was achieved. EBL, and postoperative major curve and major curve correction were not significant. Thirteen percent of patients experienced complications. Average follow-up was 712 versus 561 days in the HGT versus non-HGT groups. Large, rigid curves can achieve equivalent correction to flexible curves with HGT. Forty-three percent of the total correction achieved occurred during traction. Thirty percent of the total correction occurred at implantation of the MCGR in the HGT group versus 28% in the non-HGT group. At most recent follow-up HGT patients had statistically maintained their major curve correction better than non-HGT patients. Level III-therapeutic study.