Microfossils detected in a block of ancient dense clay coated with a ferromanganese crust, Clarion-Clipperton Province, East Equatorial Pacific

The area in study is characterized by a regional stratigraphic hiatus from Early Miocene to Quaternary. Deposits from Late Eocene to Early Miocene occur on the bottom surface or under a thin sedimentary cover. Ferromanganese nodules, mostly of Oligocene age, formed on surface layers of Tertiary or Quaternary sediments. A detailed micropaleontological study of a block of dense ancient clay coated with a ferromanganese crust was carried out. Composition of found radiolarian and diatomaceous complexes proved that the crust formed in Quaternary on an eroded surface of Late Oligocene clay. In Quaternary Neogene sediments were eroded and washed away by bottom currents. It is likely that the erosion began 0.9-0.7 Ma at the beginning of the "Glacial Pleistocene". The erosion could be initiated by loosening and resuspension of surface sediments resulting from seismic activity generated by strong earthquakes in the Central America subduction zone. The same vibration maintained residual nodules at the seafloor surface. Thus, for the area in study a common reason and a common Quaternary interval for formation of the following features is supposed: a regional stratigraphic hiatus, formation of residual nodule fields, and position of ancient nodules on the surface of Quaternary sediments.

Analytical solution to the one-dimensional non-uniform absorption of solar radiation in uncoated and coated single glass panes

The analytical solution to the one-dimensional absorption–conduction heat transfer problem inside a single glass pane is presented, which correctly takes into account all the relevant physical phenomena: the appearance of multiple reflections, the spectral distribution of solar radiation, the spectral dependence of optical properties, the presence of possible coatings, the non-uniform nature of radiation absorption, and the diffusion of heat by conduction across the glass pane. Additionally to the well established and known direct absorptance αe, the derived solution introduces a new spectral quantity called direct absorptance moment βe, that indicates where in the glass pane is the absorption of radiation actually taking place. The theoretical and numerical comparison of the derived solution with existing approximate thermal models for the absorption–conduction problem reveals that the latter ones work best for low-absorbing uncoated single glass panes, something not necessarily fulfilled by modern glazings.

Highly efficient potentiometric glucose biosensor based on functionalized InN quantum dots

We present a fast, highly sensitive, and efficient potentiometric glucose biosensor based on functionalized InN quantum-dots (QDs). The InN QDs are grown by molecular beam epitaxy. The InN QDs are bio-chemically functionalized through physical adsorption of glucose oxidase (GOD). GOD enzyme-coated InN QDs based biosensor exhibits excellent linear glucose concentration dependent electrochemical response against an Ag/AgCl reference electrode over a wide logarithmic glucose concentration range (1 × 10−5 M to 1 × 10−2 M) with a high sensitivity of 80 mV/decade. It exhibits a fast response time of less than 2 s with good stability and reusability and shows negligible response to common interferents such as ascorbic acid and uric acid. The fabricated biosensor has full potential to be an attractive candidate for blood sugar concentration detection in clinical diagnoses.

An Asymptotic Solution for Surface Fields on a Dielectric-Coated Circular Cylinder with an Effective Impedance Boundary Condition.

Reverberation chambers are well known for providing a random-like electric field distribution. Detection of directivity or gain thereof requires an adequate procedure and smart post-processing. In this paper, a new method is proposed for estimating the directivity of radiating devices in a reverberation chamber (RC). The method is based on the Rician K-factor whose estimation in an RC benefits from recent improvements. Directivity estimation relies on the accurate determination of the K-factor with respect to a reference antenna. Good agreement is reported with measurements carried out in near-field anechoic chamber (AC) and using a near-field to far-field transformation.

Surface Impedance Characterization for UTD Based Solution with IBC for Surface Fields on a Dielectric-Coated PEC Circular Cylinder

A novel formulation for the surface impedance characterization is introduced for the canonical problem of surface fields on a perfect electric conductor (PEC) circular cylinder with a dielectric coating due to a electric current source using the Uniform Theory of Diffraction (UTD) with an Impedance Boundary Condition (IBC). The approach is based on a TE/TM assumption of the surface fields from the original problem. Where this surface impedance fails, an optimization is performed to minimize the error in the SD Green?s function between the original problem and the equivalent one with the IBC. This new approach requires small changes in the available UTD based solution with IBC to include the geodesic ray angle and length dependence in the surface impedance formulas. This asymptotic method, accurate for large separations between source and observer points, in combination with spectral domain (SD) Green?s functions for multidielectric coatings leads to a new hybrid SD-UTD with IBC to calculate mutual coupling among microstrip patches on a multilayer dielectric-coated PEC circular cylinder. Results are compared with the eigenfunction solution in SD, where a very good agreement is met.

Surface Impedance Characterization for Mutual Coupling Calculation of Patches on a Dielectric-Coated PEC Circular Cylinder

A novel formulation for the surface impedance characterization is introduced for the canonical problem of surface fields on a perfect electric conductor (PEC) circular cylinder with a dielectric coating due to a electric current source using the Uniform Theory of Diffraction (UTD) with an Impedance Boundary Condition (IBC). The approach is based on a TE/TM assumption of the surface fields from the original problem. Where this surface impedance fails, an optimization is performed to minimize the error in the SD Green?s function between the original problem and the equivalent one with the IBC. This asymptotic method, accurate for large separations between source and observer points, in combination with spectral domain (SD) Green?s functions for multidielectric coatings leads to a new hybrid SD-UTD with IBC to calculate mutual coupling among microstrip patches on a multilayer dielectric-coated PEC circular cylinder. Results are compared with the eigenfunction solution in SD, where a very good agreement is met.

Current collection by an active spherical electrode in an unmagnetized plasma

A theoretical model for the steady-state response of anodic contactors that emit a plasma current Ii and collect electrons from a collisionless, unmagnetized plasma is presented. The use of a (kinetic) monoenergetic population for the attracted species, well known in passive probe theory, gives both accuracy and tractability to the theory. The monoenergetic population is proved to behave like an isentropic fluid with radial plus centripetal motion, allowing direct comparisons with ad hoc fluid models. Also, a modification of the original monoenergetic equations permits analysis of contactors operating in orbit-limited conditions. Besides that, the theory predicts that, only for plasma emissions above certain threshold current a presheath/double layer/core structure for the potential is formed (the core mode), while for emissions below that threshold, a plasma contactor behaves exactly as a positive-ion emitter with a presheath/sheath structure (the no-core mode). Ion emitters are studied as a particular case. Emphasis is placed on obtaining dimensionless charts and approximate asymptotic laws of the current-voltage characteristic.

Surface impedance for scattered field on a dielectric-coated circular cylinder

In the scattering analysis of a circular cylindrical structure, the impedance boundary condition (IBC) can approximate and simplify the perfect electric conductor (PEC) boundary condition. The circular cylinder problem can be solved with modal methods but they require a large number of terms when the cylinder radius is large in terms of the wave length. The uniform theory of diffraction (UTD) [1] is commonly used to overcome this issue. The two-dimensional problem of scattering on a circular cylinder covered by a dielectric layer has been analyzed by [2]–[5], but their solutions either do not consider oblique incidence, fail on the transition region or use a constant surface impedance.

Surface impedance for electromagnetic fields over a dielectric-coated circular cylinder

For small or medium size conformal array antennas in terms of the wave length, modal solutions in spectral domain for mutual coupling analysis are convenient for canonical shapes such as circular cylinder [1] or sphere [2], but as the antenna dimensions increase a large number of terms are necessary. For large structures the uniform theory of diffraction (UTD) is commonly used to solve this problem for canonical and arbitrarily convex shaped perfect electric conductor (PEC) surfaces [3]. A UTD solution for mutual coupling on an impedance cylinder has been introduced in [4], [5] but using a constant surface impedance.

Effect of strain and magnetic field on the critical current and electric resistance of the joints between HTS coated conductors

Engineering of devices and systems such as magnets, fault current limiters or cables, based on High Temperature Superconducting wires requires a deep characterization of the possible degradation of their properties by handling at room temperature as well as during the service life thus establishing the limits for building up functional devices and systems. In the present work we report our study regarding the mechanical behavior of spliced joints between commercial HTS coated conductors based on YBCO at room temperature and service temperature, 77 K. Tensile tests under axial stress and the evolution of the critical current and the electric resistance of the joints have been measured. The complete strain contour for the tape and the joint has been obtained by using Digital Image Correlation. Also, tensile tests under external magnetic field have been performed and the effect of the applied field on the critical current and the electric resistance of the joints has been studied. Finally, a preliminary numerical study by means of Finite Element Method (FEM) of the mechanical behavior of the joints between commercial HTS is presented.

Effect of strain and magnetic field on the critical current and electric resistance of the joints between HTS coated conductors

Engineering of devices and systems such as magnets, fault current limiters or cables, based on High Temperature Superconducting wires requires a deep characterization of the possible degradation of their properties by handling at room temperature as well as during the service life thus establishing the limits for building up functional devices and systems. In the present work we report our study regarding the mechanical behavior of spliced joints between commercial HTS coated conductors based on YBCO at room temperature and service temperature, 77 K. Tensile tests under axial stress and the evolution of the critical current and the electric resistance of the joints have been measured. The complete strain contour for the tape and the joints has been obtained by using Digital Image Correlation. Also, tensile tests under external magnetic field have been performed and the effect of the applied field on the critical current and the electric resistance of the joints has been studied. Additionally, fatigue tests under constant cyclic stress and loading-unloading ramps have been carried out in order to evaluate the electromechanical behavior of the joints and the effect of maximum applied stress on the critical current. Finally, a preliminary numerical study by means of the Finite Element Method (FEM) of the electromechanical behavior of the joints between commercial HTS is presented.