In vivo measurement of the brain and skull resistivities using an EIT-based method and realistic models for the head

In vivo measurements of equivalent resistivities of skull (rho(skull)) and brain (rho(brain)) are performed for six subjects using an electric impedance tomography (EIT)-based method and realistic models for the head. The classical boundary element method (BEM) formulation for EIT is very time consuming. However, the application of the Sherman-Morrison formula reduces the computation time by a factor of 5. Using an optimal point distribution in the BEM model to optimize its accuracy, decreasing systematic errors of numerical origin, is important because cost functions are shallow. Results demonstrate that rho(skull)/rho(brain) is more likely to be within 20 and 50 rather than equal to the commonly accepted value of 80. The variation in rho(brain)(average = 301 omega x cm, SD = 13%) and rho(skull)(average = 12230 omega x cm, SD = 18%) is decreased by half, when compared with the results using the sphere model, showing that the correction for geometry errors is essential to obtain realistic estimations. However, a factor of 2.4 may still exist between values of rho(skull)/rho(brain) corresponding to different subjects. Earlier results show the necessity of calibrating rho(brain) and rho(skull) by measuring them in vivo for each subject, in order to decrease errors associated with the electroencephalogram inverse problem. We show that the proposed method is suited to this goal.     

Investigation of Ionospheric Electron Density Change During Two Partial Solar Eclipses and Its Comparison with Predictions of NeQuick 2 and IRI-2016 Models

Wireless Personal Communications - In the present study, the results obtained by incoherent scatter radar (ISR) and empirical models (NeQuick2 and IRI-2016) of the variations in mid-latitude...     

Charge-Driven Self-Assembled Microspheres Hydrogel Scaffolds for Combined Drug Delivery and Photothermal Therapy of Diabetic Wounds

The treatment of diabetic wound remains a big clinical challenge. Hydrogel that can provide physical barrier and humidity displays amazing potentials for managing the diabetic wounds healing. Herein, a new charge-driven self-assembled microsphere hydrogel scaffold (SMHS) is reported based on an electric charge interaction, by combining use of black phosphorus (BP)-contained chitosan methacryloyl (CS) microspheres with positive charge and basic fibroblast growth factor-contained hyaluronic acid methacryloyl (HA) microspheres with negative charge. The weak charge attraction among microspheres gives the SMHS the injectable characteristic. Due to the existence of BP, near-infrared (NIR) irradiation has obvious effects on the degradation and drug release behaviors of SMHS. Significantly, SMHS that combines the short-term physical (photothermal) intervention and long-term chemical (drug release) intervention may be promising in spatio-temporal regulation of regenerative microenvironment. SMHS with NIR irradiation (SMHS+NIR) can promote cell proliferation, cell migration, angiogenesis and macrophage polarization. Moreover, in diabetic rat skin wounds, SMHS+NIR significantly accelerates the wound healing process by simultaneously inhibiting the inflammatory response, promoting angiogenesis and tissues remodeling. The outcome of this research not only provides a biomaterial for diabetic wounds healing, but also demonstrates a new strategy for designing novel hydrogel-based biomaterials which have the free editing and combination functions.     

Synthesis of compositionally different multicomponent metal-oxide films (SnO2) x (ZnO)1 − x (x = 1–0.5)

The study is concerned with high-purity SnO₂ and ZnO powders produced from salt solutions of corresponding metals by low-temperature hydrothermal synthesis. Fragments of SnO₂ and ZnO ceramic targets formed as 1 × 8 cm bars are fabricated by dry pressing. The bars are used to form composite targets for ion-beam sputtering and the fabrication of compositionally different (SnO₂) _x (ZnO)_{1 ? x} (x = 1–0.5) films appropriate for the production of gas sensors or transparent electronic devices. The optical and electrical parameters of the films with different compositions are studied.     

Adaptive gain and delay mismatch cancellation for LINC transmitter

Linear amplification with Nonlinear Component (LINC) transmitter architecture is an efficient solution for high efficiency amplification of signals. Nonetheless, this solution suffers both from gain impairment and delay mismatch between the two signal paths. Indeed, a mismatch in propagation time between the paths degrades the quality of the transmit signal but also disrupts the convergence of the gain correction algorithm resulting in a degradation of its performance. In this paper, we present an adaptive algorithm based on a gradient descent formulation for the identification and correction of these delays. We also demonstrate its effectiveness when applied prior to the gain adjustment procedure. The identification approach is preferred here, to ensure monitoring facilities.     

Autonomic Self‐Repairing Glassy Materials

A new process that enables glassy materials to self‐repair from mechanical damage is presented in this paper. Contrary to intrinsic self‐healing, which involves overheating to enable crack healing by glass softening, this process is based on an extrinsic effect produced by vanadium boride (VB) particles dispersed within the glass matrix. Self‐repair is obtained through the oxidation of VB particles, and thus without the need to increase the operating temperature. The VB healing agent is selected for its capacity to oxidize at a lower temperature than the softening point of the glass. Thermogravimetric analyses indeed show that VB oxidation is rapid and occurs below the glass transition temperature. Solid‐state nuclear magnetic resonance spectroscopy indicates that VB is oxidized into V₂O₅ and B₂O₃, which enable the local formation of glass. The autonomic self‐healing effect is demonstrated by an in situ experiment visualized using an environmental scanning electron microscope. It is shown that a crack could be healed by the VB oxidation products.     

Fabrication of AD/DA microfluidic converter using deep reactive ion etching of silicon and low temperature wafer bonding

The purpose of this work is to describe an original process that has been designed for the fabrication of a microfluidic converter. The fabrication is based on deep reactive ion etching of silicon and low temperature full wafer adhesive bonding. The technology development includes an improvement of the bonding process in order to produce an adaptive strength of SU-8 bond which not only ensures absence of debonding failures during the silicon deep etching procedure and the subsequent dicing procedure, but also avoids the potential SU-8 overflow leakage into channels due to the bonding step. Besides, the originality of the work is not only in the process but also in the design of the device. Common actuation method for microfluidic system is either based on closed-channel continuous-flow microfluidic (CMF) or droplet-based microfluidic (DMF). Both of them have advantages and disadvantages, and their integration on a single system is in dire need. In this paper, we briefly discuss the concept of microfluidic converter, integrating CMF with DMF, which can: (i) continuously preload reagents, (ii) independently manipulate several droplets, (iii) recombine and export samples into closed-channel continuous flow, making it ideal for interfacing to liquid-handling instruments and micro-analytical instruments.