Structural, Optical, and Magnetic Properties of Gd Doped CdTe Quantum Dots for Magnetic Imaging Applications

The effect of pressure on the electronic and optical properties of SrAl2O4 up to 25 GPa was studied by means of the pseudo-potential plane waves method within the generalized gradient approximation for exchange and correlation. The calculated lattice parameters are consistent with available experimental and theoretical data. By analyzing the electronic and optical properties, the pressure dependences of the electronic structures and optical constants were investigated. The band structures show an indirect band gap for this compound and the calculated band gaps expend with increasing pressure. Meanwhile, the optical properties including the dielectric spectra, absorption coefficient spectra, reflectivity, and the real part of the refractive index spectra in the low energy range have a blue shift. Given this, the optical properties of SrAl2O4 could be tuned by changing pressure to some degree, which is beneficial to the optical applications.

Cardiac involvement in sarcoidosis: Evolving concepts in diagnosis and treatment

Clinically evident cardiac involvement has been noted in at least 2 to 7% of patients with sarcoidosis, but occult involvement is much higher (> 20%). Cardiac Sarcoidosis (CS) is often not recognized as an antemortem, as sudden death may be the presenting feature. Cardiac involvement may occur at any point during the course of sarcoidosis and may occur in the absence of pulmonary or systemic involvement. Sarcoidosis can involve any part of the heart. The prognosis of CS is related to the extent and site(s) of involvement. Most deaths due to CS are due to arrhythmias or conduction defects, but granulomatous infiltration of the myocardium may cause progressive and ultimately lethal cardiomyopathy. The definitive diagnosis of isolated CS is difficult and the yield of Endomyocardial Biopsies (EMB) is low. Treatment of CS is often warranted even in the absence of histologic proof. Radionuclide scans are integral to the diagnosis. Gadolinium-enhanced cardiac magnetic imaging scans and 18Fluorodeoxyglucose (18FDG)-Positron Emission Tomography (PET) are the key imaging modalities to diagnose CS. The prognosis of CS is variable, but mortality rates of untreated CS are high. Randomized therapeutic trials have not been done, but corticosteroids (alone or combined with additional immunosuppressive agents) are the mainstay of therapy. Additionally, anti-arrhythmic agents and therapy for heart failure are often required. Because of the potential for sudden cardiac death, an Implantable Cardioverter-Defibrillator (ICD) should be placed in any patient with CS and serious ventricular arrhythmias or heart block and should be considered for cardiomyopathy. Cardiac transplantation is a viable option for patients with end-stage CS refractory to medical therapy.

Radio Frequency MRI coils and safety: how infrared thermography can support quality assurance

Background The safety controls in Resonance Magnetic Imaging (MRI) diagnostic site are numerous and complex. Some of these are contained in international directives and regularly conducted by medical physics expert after acceptance tests, consisting of a series of checks, measurements, evaluations called quality controls (QCs) and made to guarantee the image quality of the equipment. In this context, ensuring that the coils are in proper operating conditions is important to prevent and reduce errors in use and to preserve patient safety. Results A study by thermography was conducted to evaluate temperature changes of MRI coils during Quality Control (QC), in order to prevent any problems for the patient due to Radio Frequency waves. This experiment involves use of a thermal camera to detect temperature variations during MRI scans using head and body coils of two different tomography 1.5 T and 3.0 T static magnetic field. Thermal camera was positioned inside the MRI room to acquire images every 15 s for all the scansions duration. The observations have shown a temperature increase only for body coil of 1.5 MRI tomography, whereas no significative temperature variation has occurred for the other coils under observation. This temperature increase was later related to a fault of such coil. Conclusions The authors believe this simple method useful as first approach, during routinely QCs, to verify coils functioning and so to avoid patient hazards and are preparing a methodological study about functioning of the coils with respect to their temperature variation.

Quantum magnetic imaging of iron organelles within the pigeon cochlea

The ability of pigeons to sense geomagnetic fields has been conclusively established despite a notable lack of determination of the underlying biophysical mechanisms. Quasi-spherical iron organelles previously termed “cuticulosomes” in the cochlea of pigeons have potential relevance to magnetoreception due to their location and iron composition; however, data regarding the magnetic susceptibility of these structures are currently limited. Here quantum magnetic imaging techniques are applied to characterize the magnetic properties of individual iron cuticulosomes in situ. The stray magnetic fields emanating from cuticulosomes are mapped and compared to a detailed analytical model to provide an estimate of the magnetic susceptibility of the individual particles. The images reveal the presence of superparamagnetic and ferrimagnetic domains within individual cuticulosomes and magnetic susceptibilities within the range 0.029 to 0.22. These results provide insights into the elusive physiological roles of cuticulosomes. The susceptibilities measured are not consistent with a torque-based model of magnetoreception, placing iron storage and stereocilia stabilization as the two leading putative cuticulosome functions. This work establishes quantum magnetic imaging as an important tool to complement the existing array of techniques used to screen for potential magnetic particle–based magnetoreceptor candidates.

Integrating micromagnets and hybrid nanowires for topological quantum computing

Majorana zero modes are expected to arise in semiconductor-superconductor hybrid systems, with potential topological quantum computing applications. One limitation of this approach is the need for a relatively high external magnetic field that should also change direction at the nanoscale. This proposal considers devices that incorporate micromagnets to address this challenge. We perform numerical simulations of stray magnetic fields from different micromagnet configurations, which are then used to solve for Majorana wavefunctions. Several devices are proposed, starting with the basic four-magnet design to align magnetic field with the nanowire and scaling up to nanowire T-junctions. The feasibility of the approach is assessed by performing magnetic imaging of prototype patterns.

Recent Advances in Processing, Characterizations and Biomedical Applications of Spinel Ferrite Nanoparticles

Many researchers are interested in investigating ceramic materials because of the potential for their use in nanotechnology. Spinel ferrites are a diverse group of materials with many applications. Electronic devices such as inductors, power, information storage, microwave, and induction tuners are only a few examples. As ferrite materials exhibit super-paramagnetic activity, their potential for biological applications such as drug delivery, hyperthermia, and resonance magnetic imaging. As a result, super-paramagnetism is a highly desirable property in spinel ferrites. Due to the size dependence, the methodologies used to synthesis of these materials have emerged as a critical step in achieving the desired properties. Many synthesis strategies have been developed in this regard such as sol-gel, co-precipitation, solid-state, solution combustion method and so on. As a result, this study provides a historical overview of spinel ferrites, as well as key principles for comprehending their various characterization techniques and properties. Recent developments in the synthesis and applications of spinel ferrites are also discussed.

Unraveling Dissipation-Related Features in Magnetic Imaging by Bimodal Magnetic Force Microscopy

Magnetic Force Microscopy (MFM) is the principal characterization technique for the study of low-dimensional magnetic materials. Nonetheless, during years, the samples under study was limited to samples in the field of data storage, such as longitudinal hard disk, thin films, or patterned nanostructures. Nowadays, thanks to the advances and developments in the MFM modes and instrumentation, other fields are emerging like skyrmionic structures, 2D materials or biological samples. However, in these experiments artifacts in the magnetic images can have strong impact and need to be carefully verified for a correct interpretation of the results. For that reason, in this paper we will explore new ideas combining the multifrequency modes with the information obtained from the experimental dissipation of energy associated to tip-sample interactions.

Magnetic Guiding with Permanent Magnets: Concept, Realization and Applications to Nanoparticles and Cells

The idea of remote magnetic guiding is developed from the underlying physics of a concept that allows for bijective force generation over the inner volume of magnet systems. This concept can equally be implemented by electro- or permanent magnets. Here, permanent magnets are in the focus because they offer many advantages. The equations of magnetic fields and forces as well as velocities are derived in detail and physical limits are discussed. The special hydrodynamics of nanoparticle dispersions under these circumstances is reviewed and related to technical constraints. The possibility of 3D guiding and magnetic imaging techniques are discussed. Finally, the first results in guiding macroscopic objects, superparamagnetic nanoparticles, and cells with incorporated nanoparticles are presented. The constructed magnet systems allow for orientation, movement, and acceleration of magnetic objects and, in principle, can be scaled up to human size.

Case Report: Cerebral venous thrombosis revealing celiac disease

Celiac disease (CD) is an autoimmune enteropathy resulting from intolerance of an individual genetically predisposed to gluten. It has a large clinical polymorphism ranging from a classic digestive clinical presentation due to the malabsorption syndrome to extra-intestinal symptoms. Among the hematologic abnormalities, venous thromboembolic disease (VTE) has been reported, and they are most often located in the abdomen or lower limbs, but the cerebral localization was exceptionally described. We report a case of CD revealed by cerebral thrombophlebitis. A 44-year-old patient with no medical history and no drug intake, presented with hemiplegia followed by a status epilepticus in a context of apyrexia, initially hospitalized in intensive care. Magnetic imaging resonance displayed a cerebral venous thrombosis of the sigmoid sinus requiring anticoagulant treatment, then transferred to our department for the etiological investigation. On questioning, the patient reported chronic diarrhea and weight loss with no other associated symptoms. The examination revealed an underweight patient with pale conjunctiva, improvement of her deficit symptoms, and no other abnormalities. Laboratory tests noted biological signs of malabsorption. The thrombophilia assessment revealed a protein C deficiency with a slight increase in anticardiolipin antibodies and anti-Beta 2 glycoprotein 1 antibodies. Immunological tests noted positives anti-transglutaminase and IgA anti-endomysium antibodies. Duodenal biopsy demonstrated villous atrophy. After ruling out the other causes of VTE, the diagnosis of cerebral venous thrombosis secondary to CD was retained. Early diagnosis and treatment of CD improves the quality-of-life for patients and may spare them various long-term or even fatal complications.

Dynamic Patterns of Global Brain Communication Differentiate Conscious From Unconscious Patients After Severe Brain Injury

The neurophysiology of the subjective sensation of being conscious is elusive; therefore, it remains controversial how consciousness can be recognized in patients who are not responsive but seemingly awake. During general anesthesia, a model for the transition between consciousness and unconsciousness, specific covariance matrices between the activity of brain regions that we call patterns of global brain communication reliably disappear when people lose consciousness. This functional magnetic imaging study investigates how patterns of global brain communication relate to consciousness and unconsciousness in a heterogeneous sample during general anesthesia and after brain injury. First, we describe specific patterns of global brain communication during wakefulness that disappear during propofol (n = 11) and sevoflurane (n = 14) general anesthesia. Second, we search for these patterns in a cohort of unresponsive wakeful patients (n = 18) and unmatched healthy controls (n = 20) in order to evaluate their potential use in clinical practice. We found that patterns of global brain communication characterized by high covariance in sensory and motor areas or low overall covariance and their dynamic change were strictly associated with intact consciousness in this cohort. In addition, we show that the occurrence of these two patterns is significantly related to activity within the frontoparietal network of the brain, a network known to play a crucial role in conscious perception. We propose that this approach potentially recognizes consciousness in the clinical routine setting.