Screening magnetic fields by a superconducting disk: a simple model

We introduce a simple approach to evaluate the magnetic field distribution around superconducting samples, based on the London equations; the elementary variable is the vector potential. This procedure has no adjustable parameters, only the sample geometry and the London length, $\lambda$, determine the solution. The calculated field reproduces quantitatively the measured induction field above MgB$_2$ disks of different diameters, at 20K and for applied fields lower than 0.4T. The model can be applied if the flux line penetration inside the sample can be neglected when calculating the induction field distribution outside the superconductor. Finally we show on a cup-shape geometry how one can design a magnetic shield satisfying a specific constraint

Screening magnetic fields by superconductors: A simple model

We introduce a simple approach to evaluate the magnetic field distribution around superconducting samples, based on the London equations; the elementary variable is the vector potential. This procedure has no adjustable parameters, only the sample geometry and the London length determine the solution. This approach was validated by comparing the induction field calculated to the one measured above MgB2 disks of different diameters, at 20K and for applied fields lower than 0.4T. The model can be applied if the flux line penetration inside the sample can be neglected when calculating the induction field distribution outside the superconductor. We conclude by showing on a cup-shape geometry how one can design a magnetic shield satisfying a specific constraint

Cobalt-Based Metallic Glass Microfibers for Flexible Electromagnetic Shielding and Soft Magnetic Properties

Thin and flexible materials that can provide efficient electromagnetic interference (EMI) shielding are urgently needed, particularly those that can be rapidly processed and withstand harsh environments. Cobalt-based metallic glasses stand out as prime candidates due to their excellent soft magnetic properties, satisfactory shielding features, and mechanical properties. Herein, a recently developed technique is used to fabricate metallic glass microfibers from Co66Fe4Mo2Si16B12 alloy. The produced microfibers are characterized for their size and uniformity by scanning electron microscopy and their amorphous structure is confirmed by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The cobalt-based metallic glass microfibers show an EMI shielding factor that reaches five in the static regime and obtains an up to 25-fold increase of the attenuation constant in the Ku frequency band. This performance originates from the combination of soft magnetic properties and excellent electrical conductivity. In addition, the flexible microfibers exhibit excellent hardness and elasticity making them suitable for EMI shielding of complex geometries. Their hardness and elastic modulus are measured by nanoindentation to be 11.31 +/- 0.60 GPa, and 110.54 +/- 11.24 GPa, respectively.A novel method is used to fabricate flexible Co66Fe4Mo2Si16B12 metallic-glass microfibers for electronics, boasting a hardness of 11.31 +/- 0.60 GPa and an elastic modulus of 110.54 +/- 11.24 GPa. Their EMI shielding exhibits clear anisotropy with a factor of 5 and up to 25-fold increased attenuation in the Ku band. These properties position them well for EMI shielding in intricate geometries.imag

Soft Magnetic Properties and Electromagnetic Shielding Performance of Fe40Ni40B20 Microfibers

Fi(40)Ni(40)B(20) metallic glass is a key material among the many amorphous systems investigated thus far, owing to its high strength and appealing soft magnetic properties that make it suitable for use as transformer cores. In this study, Fi(40)Ni(40)B(20) microfibers are fabricated down to 5 mu m diameter. Three different melt-spinning wheel velocities: approximate to 51 m s(-1), approximate to 59 m s(-1), and approximate to 63 m s(-1) (MG1, MG2, MG3) are used. Their fully amorphous structure is confirmed using X-ray diffraction, and differential scanning calorimetry (DSC) traces reveal a larger relaxation profile for the higher-quenched microfiber. Vibrating sample magnetometer measurements showed a higher saturation magnetization of 136 emug(-1) for annealed metallic glass microfibers with a wheel velocity of 59.66 ms(-1). Cylindrical magnetic field shields are obtained by aligning and wrapping the fibers around a cast. The observed anisotropic static field shielding behavior is in accordance with the microfibers' anisotropic nature. Composite samples are also produced by embedding the microfibers in an epoxy matrix to investigate their electromagnetic properties at GHz frequencies. Inclusion of the microfibers increase the composite's attenuation constant by 20 to 25 times, making it an ideal candidate for applications in the communications frequency range

Evidences of vortex curvature and anisotropic pinning in superconducting films by quantitative magneto-optics

We present the experimental observation of magnetic field line curvature at the surface of a superconducting film by local quantitative magneto-optics. In addition to the knowledge of the full induction field at the superconductor surface yielding the quantitative observation of the flux line curvature, our analysis method allows also local value measurements of the electrical current density inside the sample. Thus, we study the interplay between the electrodynamic constraints dictated by the film geometry and the pinning properties of the superconductor. In particular, we investigate the anisotropic vortex-pinning, due to columnar defects introduced by heavy ion irradiation, as revealed in the local current density dependence on the vortex curvature during magnetic flux diffusion inside the superconducting film.Comment: 12 pages, 11 figures, to be submitted to Phys. Rev.

Electrophysiological assessment methodology of sensory processing dysfunction in schizophrenia and dementia of the Alzheimer type

Schizophrenia and Alzheimer’s disease impacts on various sensory processings are extensively reviewed in the present publication. This article describes aspects of a research project whose aim is to delineate the neurobiology that may underlie Social Withdrawal in Alzheimer’s disease, Schizophrenia and Major Depression. This is a European-funded IMI 2 project, identified as PRISM (Psychiatric Ratings using Intermediate Stratified Markers). This paper focuses specifically on the selected electrophysiological paradigms chosen based on a comprehensive review of all relevant literature and practical constraints. The choice of the electrophysiological biomarkers were fundamentality based their metrics and capacity to discriminate between populations. The selected electrophysiological paradigms are resting state EEG, auditory mismatch negativity, auditory and visual based oddball paradigms, facial emotion processing ERP’s and auditory steady-state response. The primary objective is to study the effect of social withdrawal on various biomarkers and endophenotypes found altered in the target populations. This has never been studied in relationship to social withdrawal, an important component of CNS diseases

Human papillomavirus in cervical adenocarcinoma. An in situ hybridization study.

Twenty cervical adenocarcinomas (CACs) in women aged 22 to 71 were investigated by in situ hybridization (ISH) with 6, 11, 16, 18, 31, 35 and 51 HPV biotinylated probes. Two cases, one adenocarcinoma and one adenosquamous carcinoma (in women aged 28 and 40 respectively) showed focal nuclear positivity to 16 HPV Probe in some neoplastic glands. We used ISH, rather than other hybridization techniques, in order to exclude a positivity to viral DNA, due to adjacent squamous epithelium, either normal or metaplastic, and in squamous foci within adenosquamous tumors. Reviewing the literature, we found 33 out of 98 CACs positive to viral DNA by ISH (33.6%). In spite of the differences found from author to author, a relationship between adenocarcinomas of the uterine cervix and HPV infection seems to be possible, as was demonstrated for CIN and invasive cervical carcinomas. These data could explain why the incidence of this neoplasia has tended to increase over the last few years, mainly in younger patients

The incidental finding of abnormal cervical histology in postmenopausal patients.

A report is supplied on 216 samples of cervical tissue incidentally found in 684 endometrial specimens collected during hysteroscopic examination of postmenopausal women with uterine bleeding and a recent negative Pap smear. We found 43 (19.9%) specimens including cervical tissue with some histologic sign of pathology. Twenty-five (11.6%) had histologic features suggestive for human papillomavirus (HPV) infection, while 18 (8.3%) had cervical intraepithelial neoplasia (GIN). Of the 18 CIN cases, 9 were CIN I, 6 CIN II and 3 CIN III. Altogether, the prevalence of dysplasia in postmenopausal women with recently referred normal cervical cytology was impressive. A significant number of dysplastic lesions (14 out of 18, 77.7%) did not present any histologic sign of HPV. Also, none of the histologic diagnoses of sub-clinical HPV infection was confirmed by the in situ hybridization. Considering the significant prevalence of high grade lesions (9 CIN II and III, 4.2% of the analysed samples) found in this randomly selected patient population, our data strongly suggest the need for a regular follow-up of the transformation zone in all postmenopausal women. Although in women of postmenopausal age some low grade lesions seem to have only a reactive-reparative significance, a more accurate screening procedure, taking into account the peculiar modifications of the menopausal uterine cervix, is advisable

Cytological analysis of the distension fluid used during diagnostic office hysteroscopies in patients with suspected endometrial pathology.

Objective: Evaluation of the feasibility and usefulness of cytological analysis of the distension fluid used during diagnostic office hysteroscopy in patients with suspected endometrial pathology. Methods: In 243 consecutive patients undergoing diagnostic hysteroscopy for suspected endometrial pathology a few milliliters of the distension medium used for uterine visualization were collected and sent for cytological analysis. Findings of these "endometrial washings" were compared to visual hysteroscopic impression, endometrial biopsy and uterine histology - when available. Results: Endometrial washings were considered adequate in 227 patients (93.4%). In 12 cases (5.3%) atypical cells were detected: all of these presented either atypical complex hyperplasia or endometrial cancer at the final histological evaluation of the uterus. Four of the 16 (25%) patients diagnosed with endometrial cancer or atypical complex hyperplasia at the final histopathological analysis of the uterus had inadequate washings. No patient with cancer or atypical hyperplasia had negative cytology. Conclusions: Collection and analysis of the distension fluid is feasible and, when positive, has a remarkable value in the diagnosis of endometrial cancer and its precursors