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Showing results for: heat

Three-dimensional dynamics of a particle with a finite energy of magnetic anisotropy in a rotating magnetic field.

Research RF Safe Research Library Jan 1, 2013

This paper presents a theoretical model of a single ferromagnetic particle with finite coupling between its magnetic moment and particle body in a rotating magnetic field. It describes synchronous and asynchronous motion regimes, including planar motion at low frequencies and a precession regime at high frequencies,…

Biodegradable shape memory nanocomposites with thermal and magnetic field responsiveness.

Research RF Safe Research Library Jan 1, 2013

This engineering study reports fabrication of a biodegradable PLLA shape-memory nanocomposite incorporating surface-modified Fe3O4 nanoparticles. The composite showed improved tensile/mechanical and shape-memory properties compared with PLLA, and shape recovery could be triggered by an alternating magnetic field.…

Citrate-capped gold nanoparticle electrophoretic heat production in response to a time-varying radiofrequency electric-field.

Research RF Safe Research Library Jan 1, 2012

This in vitro study examines RF-induced heat production in citrate-capped gold nanoparticle suspensions while minimizing confounding Joule heating from ionic buffers. It reports size-dependent heating detectable only for ≤10 nm particles, with heating scaling with concentration and surface area and being attenuated…

Hyperthermic effects of dissipative structures of magnetic nanoparticles in large alternating magnetic fields.

Research RF Safe Research Library Jan 1, 2011

This paper addresses heat dissipation mechanisms of magnetic nanoparticles used in targeted hyperthermia under large alternating magnetic fields. Using numerical comparisons, it reports additional features in relaxation loss for rotatable superparamagnetic nanoparticles and field-induced formation of oriented…

Reduction of implant RF heating through modification of transmit coil electric field.

Research RF Safe Research Library Jan 1, 2011

This engineering study describes modifying MRI RF transmit coil electric-field distributions to create electric field-free zones without substantially changing transmit sensitivity. Phantom experiments are reported to show reduced implant heating when a zero electric-field plane is aligned with the implant location.…

Evaluation of magnetic resonance safety of veterinary radiofrequency identification devices at 1 T.

Research RF Safe Research Library Jan 1, 2011

This study evaluated MRI safety parameters for three commercial veterinary RFID microchips at 1 T, assessing movement forces, heating, artifacts, and device function. Translation and torque were reported to be larger than expected from normal activity, but no significant heating was observed and microchip function…

Ohmic heating of peaches in the wide range of frequencies (50 Hz to 1 MHz).

Research RF Safe Research Library Jan 1, 2010

This engineering/food science study examined ohmic heating of peaches at 60 V/cm using bipolar pulses across frequencies from 50 Hz to 1 MHz. Heating time to a target temperature and multiple electrical properties were frequency-dependent, particularly for intact tissue. The authors report faster electro-thermal…

Thermodynamic behavior of the XXZ Heisenberg s = 1/2 chain around the factorizing magnetic field.

Research RF Safe Research Library Jan 1, 2010

This paper theoretically investigates zero- and finite-temperature behavior of an anisotropic antiferromagnetic Heisenberg XXZ spin-1/2 chain under a transverse magnetic field, focusing between the factorizing and critical fields. It reports an entanglement phase transition at the factorizing field where entanglement…

The influence of temperature and electric field history on the conductivity of the charge density wave system o-TaS3.

Research RF Safe Research Library Jan 1, 2010

This laboratory study examined how temperature and prior electric-field exposure affect low-field conductivity in the charge density wave material o-TaS3. Conductivity differed between cooling and heating below the CDW transition, and applying increasing electric fields drove the system toward a stable,…

Cutaneous remodeling and photorejuvenation using radiofrequency devices.

Research RF Safe Research Library Jan 1, 2009

This concise review discusses radiofrequency (RF) dermatologic devices used for nonablative skin rejuvenation and related indications. It characterizes RF effects on tissue as primarily thermal, aiming to heat targeted skin layers to trigger collagen changes and subsequent remodeling. The abstract cites preliminary…

The effect of postoperative immobilization on the healing of radiofrequency heat probe modified tissue: assessment of tissue length, stiffness, and morphology.

Research RF Safe Research Library Jan 1, 2008

This animal study examined how postoperative immobilization affects healing after radiofrequency heat probe shrinkage in rabbit patellar tendons. Tendon length increased across all groups by 8 weeks, but 4 weeks of immobilization resulted in less elongation than free activity. Immobilized groups had reduced…

Influence of mashed potato dielectric properties and circulating water electric conductivity on radio frequency heating at 27 MHz.

Research RF Safe Research Library Jan 1, 2008

This engineering study used experiments, computer simulations, and simplified analytical calculations to examine how mashed potato dielectric properties and circulating water electrical conductivity affect RF heating at 27 MHz. The authors report that higher circulating water conductivity and higher salt content in…

Improvement in magnetic field immunity of externally-coupled transcutaneous energy transmission system for a totally implantable artificial heart.

Research RF Safe Research Library Jan 1, 2008

This engineering study addresses interference between induction-heating cookers and an externally coupled transcutaneous energy transmission system for a totally implantable artificial heart. The authors report that magnetic flux from an IH cooker can couple into the TET transformer and affect system performance. A…

Coil design considerations for deep-brain transcranial magnetic stimulation (dTMS).

Research RF Safe Research Library Jan 1, 2008

This engineering-focused conference paper proposes figures of merit to evaluate deep-brain transcranial magnetic stimulation (dTMS) coil designs, focusing on depth penetration, scalp stimulation, focality, and energy. It analyzes circular crown and C-core coils and reports reduced electric-field attenuation with…

Combined effect of temperature and pulsed electric fields on apple juice peroxidase and polyphenoloxidase inactivation.

Research RF Safe Research Library Jan 1, 2008

This laboratory study evaluated pulsed electric fields (PEF) combined with preheating to inactivate peroxidase (POD) and polyphenoloxidase (PPO) in freshly prepared apple juice. The highest reported inactivation occurred with preheating to 50°C and PEF at 40 kV/cm for 100 μs, exceeding the reductions seen with…

Alkali (NaOH) pretreatment of switchgrass by radio frequency-based dielectric heating.

Research RF Safe Research Library Jan 1, 2008

This engineering study reports using radio-frequency (RF)-based dielectric heating to assist NaOH pretreatment of switchgrass to improve enzymatic digestibility. Under the stated conditions, RF-assisted pretreatment produced higher xylose and glucose yields than conventional heating and maintained higher yields at…

In-line application of electric field in capillary separation systems: Joule heating, pH and conductivity.

Research RF Safe Research Library Jan 1, 2008

This engineering study investigated factors affecting current when an electric field is applied in-line in a capillary separation system. Temperature measurements and a replicated cooling setup were used to estimate Joule heating effects, which were reported to be relatively small. In contrast, significant pH shifts…

Dependence of RF heating on SAR and implant position in a 1.5T MR system.

Research RF Safe Research Library Jan 1, 2007

This phantom study measured RF-induced heating of a stainless steel humerus implant during 1.5T MR imaging while varying SAR, implant angle to B0, and implant position in the RF coil. Temperature rise at implant tips increased linearly with SAR, with larger rises when the implant was parallel to B0. Heating decreased…

Polarization reversal in multiferroic TbMnO3 with a rotating magnetic field direction.

Research RF Safe Research Library Jan 1, 2007

This Physical Review Letters paper reports a method to reverse electric polarization in multiferroic TbMnO3 using a rotating magnetic-field direction, without applying an electric field or heat. The authors state that the direction of magnetic-field-induced polarization along the a axis is retained as a memory even…

20 kHz Magnetic Field Emission of Induction Cooking Heaters

Research RF Safe Research Library Jan 1, 2004

This exposure assessment measured 20 kHz magnetic field leakage from induction cooking heaters across four models and compared results with ICNIRP general public limits. The maximum reported magnetic flux density was 16 µT at a specified measurement point using two S-type pans. Field leakage depended on pan size and…

Physics and biology of mobile telephony

Research RF Safe Research Library Jan 1, 2000

This review argues that current mobile-telephony safety guidelines address excessive microwave heating but may not account for potential non-thermal influences of low-intensity, pulsed radiation. It highlights an asserted oscillatory similarity between pulsed microwave signals and certain electrochemical activities…

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