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Stroke is among the first pathologies that kill the most in the world, ranking second in deaths from illness. Each year, around 16 million people worldwide are victims of this disease, with approximately 38 % of cases brought to death. Computed Tomography (CT) is a super effective method to aid the medical diagnosis of stroke. But the analysis is subject to variations in the perception of specialists about its characteristics. Faced with the challenge of diagnosing stroke on CT images, this study proposes a fully automatic system based on Health of Things capable of classifying CT images of the skull through deep learning networks, classifying them into (Uninjured or Hemorrhagic stroke). After the image classification, Mask R-CNN segments the stroke through a learning transfer process, combined with machine learning methods. Our innovative method selected excellent results, both for classification with 100 % accuracy, and for segmentation in our best model (Mask + kNN) that reached 99.93% specificity and 99.73 accuracy, with segmentation time of 4.00 seconds, surpassing literature methods based on automatic models.

Owing to the lack of large-diameter and affordable AlN bulk crystals, high-quality AlN films grown on sapphire substrates have been intensively analyzed for the potential applications in optoelectr...

Tb3+/Dy3+ co-doped Y6Si3O9N4:Ce3+ oxynitride phosphors were prepared in this work. The properties of the prepared phosphors, e.g. X-ray diffraction (XRD), photoluminescence (PL) spectra, lifetime and thermal-dependent luminescence quenching were investigated systematically. Under near-UV excitation, co-doped Tb3+ and Dy3+ into Y6Si3O9N4:Ce3+ phosphor generated a narrow green line peaked at 550 nm and a yellow line peaked at 575 nm, respectively. Energy is efficiently transferred from Ce3+ to Dy3+ and Tb3+ ions according to the study results. Fluorescence decay patterns are studied as a function of Tb3+ and Dy3+ concentrations. For the new synthesized phosphors, their temperature-dependent photoluminescence properties were investigated, which demonstrates that the emission intensity at 150 ○C reduced from 100% to 32.0% measured at 30○C. Commission on illumination value of color tumble emission is also discussed in detail. This work verifies the suitable application of the new oxynitride phosphor in the LEDs.

Introduction The origin of contactin-associated protein-like 2 (Caspr2) antibodies in patients with Morvan syndrome is currently unknown. This case report investigated a possible association between the production of Caspr2 antibodies and aberrant proliferation of B lymphocytes. Case report We admitted a critically ill 65-year-old female patient with a suspected infection of the central nervous system (CNS). In addition to acquired neuromyotonia and CNS involvement, Caspr2 antibodies detected in her serum led to the presumptive diagnosis of Morvan syndrome. However, steroid and immunoglobulin treatment did not result in a satisfactory therapeutic outcome. On the basis of findings from immunohistochemistry, flow cytometric analysis, and immunoglobulin/T-cell receptor gene rearrangement detection of cerebrospinal fluid cells, we also made a concurrent diagnosis of diffuse large B-cell lymphoma in the CNS of this patient. The patient then received 4 cycles of rituximab and methylprednisolone therapy with an interval of 2 weeks, which temporarily led to a near-complete remission of her symptoms. Upon follow-up, her symptoms relapsed at 3 months after the last treatment with rituximab and methylprednisolone. Conclusions This is a first reported case of a patient who was concurrently diagnosed with Morvan syndrome and diffuse large B-cell lymphoma in the CNS. Additional studies are needed to determine whether aberrantly proliferating B lymphocytes are responsible for the production of Caspr2 antibodies.

We propose a novel fiber chemical sensing system based on reflective Mach-Zehnder interference with temperature calibration for the measurement of Cd

The influence of u-AlGaN/InGaN superlattices (SLs) last quantum barrier (LQB) and p-AlGaN/InGaN SLs electron blocking layer (EBL) on the performance of InGaN light-emitting diodes (LEDs) are analyzed experimentally and theoretically. Research results indicated that LED C with u-AlGaN/InGaN SLs LQB and p-AlGaN/InGaN SLs EBL exhibit the highest output power among the three groups of LED samples. At 200 mA, the output power of LED C is enhanced by 27.5% as compared with that of reference LED A with u-GaN LQB and p-AlGaN/GaN SLs EBL. The efficiency droop of LED C has also been suppressed effectively. At 200 mA, the efficiency droop of LED C was 28.5%, which was smaller than that of LED A 34%. By analyzing the distribution of electron/hole concentration in multiple quantum wells, it is indicated that the leakage of electrons from the active layer can be effectively reduced and the injection efficiency of holes into the active layer can be dramatically enhanced by using strain compensated AlGaN/InGaN SLs LQB and EBL. The reason is that the potential energy barriers for electrons and holes could be effectively regulated by using the strain compensated LQB and EBL, which is consistent with simulation results of energy band diagram.

The segmentation of medical images is a significant challenge for computer vision and medical techniques. In the lungs, the difficulty is mainly due to the presence of lung diseases, different dimensions of the lung, and different types and configurations of medical imaging devices. Computed tomography (CT) is a tool to aid clinical diagnosis; several systems based on computer-aided diagnostics (CAD) are developed or enhanced from CT images combined with computational methods. This study proposes an innovative approach based on the generalization of models for pulmonary segmentation in CT images, using the Convolutional Neural Network Based on Mask Regions (Mask R-CNN) combined with image processing techniques, K-means clustering, region growing and Parzen window through fine-tuning. Our models achieved satisfactory results with 97% Accuracy and 98% Dice, 99% Sensitivity, and 97% Positive Predictive Value (PPV) in our best MPK model. The method was able to generalize its learning to solve different pulmonary segmentation problems in different lung CT databases. A second set of data was used, obtaining even better results. The results obtained for this second data set were: 98% Accuracy, 99% Dice, 100% Sensitivity, and 98% PPV, demonstrating the effectiveness of our method.

This paper, for the first time, presents a comprehensive study of the structure, thermal stability and photoluminescence properties of CaLaMgTaO6:Pr3+ phosphors for LED applications. Pr3+ ions exhibits two clusters of dominant emissions peaked at 495 nm (3P0→3H4) and 657 nm (3P0→3F2) from double perovskite-structure CaLaMgTaO6 compounds. Meanwhile, the samples cover the emission wavelength of commercial blue light-emitting diode (LED) chips with high internal quantum efficiency (IQE) of 30.25% upon 450 nm excitation. The mechanism of thermal quenching for this phosphor was investigated and the corresponding activation energy ΔE was determined to be 0.23 eV. The fabricated Pr3+ single doped CaLaMgTaO6 together with a 450 nm blue LED chip is well-matched with the absorption band of photosynthesis, phototropism, and photomorphogenesis. Furthermore, this phosphor along with commercially available phosphors was applied to fabrication of 450 nm UV chip and YAG:Ce3+ emitted a well-distributed warm white light with high color rendering index (CRI) of 84.1 and a correlated color temperature (CCT) of 3914 K. All of the results indicate that this novel phosphor can compensate for the red light and has potential applications in plant cultivation and warm white LEDs field.

A new, far-red emitting phosphor Ba2LuTaO6:Mn4+ had been developed for plant growth lighting. The optical and structural property of the phosphor was investigated. Upon 365 nm near-UV excitation, the luminescence of Mn4+ exhibited a broad far-red emission band peaking at about 700 nm. The concentration quenching of Mn4+ luminescence in Ba2LuTaO6 was studied and the optimal Mn4+ doping concentration was experimentally approximately 0.6 %. The mechanism of the thermal stability based on the temperature-dependent PL spectra of Ba2LuTaO6:Mn4+ were demonstrated and this phosphor shows superior thermal behavior. Finally, the Ba2LuTaO6:Mn4+ phosphor and a 400-nm LED chip were employed to produce the LED devices. The results indicate that the Ba2LuTaO6:Mn4+ phosphors showed good potential in plant cultivation LEDs.

Towards connectivity and development of reliable systems, smarting sensors are vastly applied in hi-tech industries. The wind energy is a growing market that could benefit from edge processing technology by enhancing monitoring systems, decreasing downtime and guiding predictive maintenance. We proposed an embedded multi-sensor architecture to detect incipient short-circuit in wind turbine electrical generators, that is robust to both false positives and negatives. Five different sensor settings are tested in three feature extraction methods and four classifiers. An analysis of variance (ANOVA) and a Tukey’s honestly significant difference (HSD) statistical tests are used to determine which architectures should be embedded in a Raspberry Pi 3, NVIDIA Jetson TX2 and NVIDIA Xavier boards. A three current sensor setting with Fourier-MLP is the most suitable approach, achieving 81.20% of accuracy, 0% of false positive rate (FPR) and 0.08% of false negative rate (FNR), also detecting generator’s normal conditions 100% of the time. For a single sensor configuration, current sensor is the most suitable method for detecting fault or non-fault conditions, being 16 times more robust to false negatives than using an axial flux sensor. Comparing the processing time, the system embedded in a NVIDIA Xavier predicts a fault condition 37% faster than in a Raspberry Pi 3, with Fourier-MLP and using a single current sensor, thus being the most suitable configuration in fault detection.

The carrier confinement effect and piezoelectric field-induced quantum-confined stark effect of different GaN-based near-UV LED samples from 395 nm to 410 nm emission peak wavelength were investigated theoretically and experimentally. It is found that near-UV LEDs with InGaN/AlGaN multiple quantum wells (MQWs) active region have higher output power than those with InGaN/GaN MQWs for better carrier confinement effect. However, as emission peak wavelength is longer than 406 nm, the output power of the near-UV LEDs with AlGaN barrier is lower than that of the LEDs with GaN barrier due to more serious spatial separation of electrons and holes induced by the increase of piezoelectric field. The N-doped InGaN/AlGaN superlattices (SLs) were adopted as a strain relief layer (SRL) between n-GaN and MQWs in order to suppress the polarization field. It is demonstrated the output power of near-UV LEDs is increased obviously by using SLs SRL and AlGaN barrier for the discussed emission wavelength range. Besides, the forward voltage of near-UV LEDs with InGaN/AlGaN SLs SRL is lower than that of near-UV LEDs without SRL.

The physical mechanism in efficiency droop of GaN-based LEDs fabricated by metal organic chemical vapor deposition (MOCVD) was investigated by experiment and calculation. On this basis, the efficiency droop impact on the performance of orthogonal frequency division multiplexing (OFDM) visible-light communication (VLC) system was analyzed. The numerical results show that the VLC system performance decreases obviously under the impact of the LED efficiency droop. And, the performance deterioration of OFDM VLC system aggravates as FFT sampling rate increase due to signal dynamic range enlargement. Furthermore, the efficiency droop impact on the VLC performance can be alleviated by adjusting the LED operating condition. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Recently, there have been increasing demands for high-quality AlN/sapphire templates due to their applications in deep ultraviolet light-emitting diodes (DUV LEDs). To acquire a low threading dislocation density (TDD), AlN films are usually thickened to promote dislocation interaction. However, micro cracks are easily generated when their thicknesses exceed 2-3 μm, severely deteriorating device performances. In this study, we successfully fabricated a 5.6-μm-thick crack-free AlN film by employing a medium-temperature (MT) interlayer. It is revealed that high-density (1.7 × 1010 cm-2) nano-voids were self-organized above the MT interlayer, which effectively destroyed the coherence between the MT interlayer and the subsequent epilayer by reducing contact area. As a result, tensile stress in the AlN film during growth was significantly decreased to 0.18 GPa, demonstrating a 64% reduction compared with its counterpart without nano-voids. In addition, the thick AlN film with embeded nano-voids allowed dislocations to climb long distances for mutual annihilation, so the TDD of the AlN film was significantly decreased to an extremely low value of 4.7 × 107 cm-2. This technique paves the way for achieving high-performance DUV LEDs and other optoelectronic/electronic devices.

In this paper, we have synthesized a series of ultraviolet-emitting Ca9In(PO4)7:Ce3+,Tb3+ and Ca9In(PO4)7:Ce3+,Dy3+ phosphors. The Ca9In(PO4)7:Ce3+ phosphor exhibits bright blue emission under UV excitation. The Tb3+/Dy3+ single doped Ca9In(PO4)7 can exhibit weak green and yellow emission, respectively. Based on the efficient energy transfer from Ce3+ to Tb3+/Dy3+, the luminous efficiency of Tb3+/Dy3+ in Ca9In(PO4)7:Ce3+,Tb3+ and Ca9In(PO4)7:Ce3+,Dy3+ can be remarkably promoted. The effects of Ce3+/Tb3+/Dy3+ concentration, decay curves, PL emission and excitation spectra on the energy transfer from Ce3+ to Tb3+/Dy3+ in Ca9In(PO4)7 were investigated. The experimental results demonstrated that the energy transfer efficiency could reach 21.77 and 30.3% in Ca9In(PO4)7:Ce3+,Tb3+ and Ca9In(PO4)7:Ce3+,Dy3+, respectively. This study suggests that the synthesized Ca9In(PO4)7:Ce3+,Tb3+ and Ca9In(PO4)7:Ce3+,Dy3+ compounds have potentials to be used as white light-emitting phosphors in UV light-emitting diodes.

A novel carbon nanotube-patterned sapphire substrate (CPSS) has been utilized for the growth of GaN material and fabrication of a InGaN/GaN light emitting diode (LED) by metal-organic vapor phase epitaxy. Different lateral strain distributions and stress reductions were observed in a GaN thin film on CPSS compared with those on a conventional sapphire substrate. Nanoheteroepitaxy induced by small size nucleation islands of about 50 nm is ascribed to this significant strain modulation. The crystalline quality of the GaN thin film was also improved, as illustrated by X-ray diffraction. Performances of 1 mm × 1 mm LEDs on CPSS were also enhanced, with an operational power increase of 37.5% and higher saturation current.

The surface temperature of cone-shaped patterned sapphire substrate (PSS) in GaN epitaxial growth by MOCVD and its relation to forced convection conditions and substrate surface topography were systematically investigated. Calculations using finite element method (FEM) exhibited that increase of substrate thickness would reduce surface temperature variation on PSS in typical growth condition. A hydrodynamics model under different chamber conditions is established, suggesting that carrier gas's velocity V ∞ plays a significant role on surface temperature of PSS in comparison with planar substrate. Also, carrier gas's pressure P carrier is found to be another important factor on surface thermal distribution. Results of temperatures of surface with different pattern topographies suggested that an ideal PSS structure can confine the in-cell temperature discrepancy on surface into less than 0.4 K. Pattern scales of PSS and their influence on surface temperature variation were also discussed.

The polarized optical property of c-plane and m-plane GaN with varying strain was discussed by analyzing the changes of relative oscillator strength (ROS) of the three transitions related to the top three valence bands. The ROS was calculated by applying the effective-mass Hamiltonian based on k · p perturbation theory. For c-plane GaN, it was found that ROS of X> -like state and Y>-like state were superposed with each other. Especially, they increased with compressive strain, while that of |Z> decreased in the second band. For m-plane GaN under compressive strain, the first three bands were dominated by |X>, |Z> and |Y>-like states, respectively, which led to nearly linearly-polarized light emissions. With compressive strain, the ROS of |X>-like state increased more rapidly than |Z>-like state in the topmost valence band. As a result, TE mode emissions from both c-plane and m-plane GaN increased more rapidly than TM mode emission with compressive strain, leading to larger polarization degree. Experimental results of luminescences from InGaN/GaN quantum wells showed good coincidence with our theoretical calculations.

The polarization of spontaneous edge-emitting electroluminescence from near-UV LDs with different cavity lengths (from 400 μm to 1000 μm) was studied. It was found that TE mode dominates in InGaN/AlGaN MQWs LDs, which is consistent with the theoretical calculation results of similar MQWs. An obvious polarization decrease from P= 0.57 to 0.42 as the LD cavity length changed from 400 μm to 1000 pm was also observed, corresponding to a ratio r changing from 3.67 to 2.43, which indicated that, the TE mode attenuated more grievously than the TM mode with increasing cavity length. This is due to the inherent property of polarization selective emission from the alloys. The optical loss coefficient of TE mode was determined to be 35 cm ', while, 10 cm ' for TM mode, which is in good agreement with the results obtained from other methods.

The adsorption of K on the n-GaAs(I 0 0) surface was investigated by X-ray photoelectron spectroscopy (XPS) and synchrotron radiation photoemission spectroscopy (SR-PES). The Ga3d and As3d core level was measured for clean and K adsorbed GaAs(I 0 0) surface. The adsorption of K induced chemical reaction between K and As, and the K-As reactant formed when the K coverage theta > I ML. The chemical reaction between K and Ga did not occur, but Ga atoms were exchanged by K atoms. From the data of band bending, the Schottky barrier is 0.70 eV. The Fermi-level pinning was not caused by defect levels. The probable reason is that the dangling bonds of surface Ga atoms were filled by the outer-shell electrons of K atoms, forming a half-filled surface state. The Fermi-level pinning was caused by this half-filled surface state. (c) 2004 Elsevier B.V. All rights reserved.

GaN-based light emitting diodes (LEDs) have been fabricated on sapphire substrates with different thicknesses of GaN buffer layer grown by a combination of hydride vapor phase epitaxy and metalorganic chemical vapor deposition. We analyzed the LED efficiency and modulation characteristics with buffer thicknesses of 12 µm and 30 µm. With the buffer thickness increase, cathodoluminescence hyperspectral imaging shows that the dislocation density in the buffer layer decreases from ∼1.3X10 8 cm-2 to∼1.0 X 10 8 cm-2, and Raman spectra suggest that the compressive stress in the quantum wells is partly relaxed, which leads to a large blue shift in the peak emission wavelength of the photoluminescence and electroluminescent spectra. The combined effects of the low dislocation density and stress relaxation lead to improvements in the efficiency of LEDs with the 30 µm GaN buffer, but the electrical-to-optical modulation bandwidth is higher for the LEDs with the 12 µm GaN buffer. A rate equation analysis suggests that defect-related nonradiative recombination can help increase the modulation bandwidth but reduce the LED efficiency at low currents, suggesting that a compromise should be made in the choice of defect density.

In this study, the optical polarization properties under varying strains in a-plane GaN were investigated. The valence band (VB) structure for a-plane GaN is derived from the effective-mass Hamiltonian based on k·p perturbation theory. The relative oscillator strength (ROS) calculations of the transitions related to the top three VBs near Γ point are applied to analyzing the optical polarized properties. For a-plane GaN, the main components of the first, the second and the third VBs are |Y 〉-like (y-axis // [100]), |Z 〉-like (z-axis // [0001]) and |X 〉-like (x-axis // [110]) states, respectively. Under small compressive strain along c-axis, the polarization degree increases with compressive strain increasing. According to X-ray diffraction (XRD) scans and Raman backscattering spectra, both the in-plane and out-plane strains were evaluated. Polarized photoluminescence (PL) is employed to obtain the polarization degree. The experimental results of a-plane GaN samples under different strains showed good accordance with our theoretical calculations (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The GaN-based blue light-emitting diodes (LEDs) with superlatticelike strain relief layer (SRL) and without SRL were fabricated by metal organic vapor phase epitaxy (MOVPE). The luminescence characteristics of the different LEDs were measured experimentally and calculated theoretically. It is demonstrated that the efficiency droop of GaN-based LEDs is suppressed using the SRL due to the reduction of polarization electric field in quantum wells. This is beneficial to the mitigation of LED light output power-injection current (L-I) nonlinearity. Furthermore, using the different LEDs as light source, the performance of visible-light communication (VLC) system was also investigated. The results reveal that the VLC system performance is improved when the LEDs with SRL are applied. The reason is that the transmitted signal error decreases as the LED L-I nonlinearity mitigates. As a result, the GaN-based LEDs with SRL can be applied in the VLC to improve the system performance.

The performance of nitride-based LEDs was improved by inserting dual stage and step stage InGaN/GaN strain relief layer (SRL) between the active layer and n-GaN template. The influences of step stage InGaN/GaN SRL on the structure, electrical and optical characteristics of GaN-based LEDs were investigated. The analysis of strain effect on recombination rate based k·p method indicated 12.5% reduction of strain in InGaN/GaN MQWs by inserting SRL with step stage InGaN/GaN structures. The surface morphology was improved and a smaller blue shift in the electroluminescence (EL) spectral with increasing injection current was observed for LEDs with step stage SRL compared with conventional LEDs. The output power of LEDs operating at 20 mA was about 15.3 mW, increased by more than 108% by using step stage InGaN/GaN SRL, which shows great potential of such InGaN/GaN SRL in modulating InGaN/GaN MQWs optical properties based on its strain relief function.

The optical polarization properties of Al-rich AlGaN/AlN quantum wells (QWs) were investigated using the theoretical model based on the k·p method. Numerical results show that there is valence subband coupling which can influence the peak emission wavelength and emission intensity for TE and TM polarization components from Al-rich AlGaN/AlN QWs. Especially the valence subband coupling could be strong enough when CH1 is close to HH1 and LH1 subbands to modulate the critical Al content switching dominant emissions from TE to TM polarization. It is believed that the valence subband coupling may give important influence on polarization properties of spontaneous emissions and should be considered in designing high efficiency AlGaN-based ultraviolet (UV) LEDs.

To improve the electrostatic discharge properties of InGaN/GaN LEDs, an n+-InGaN electron injection layer and a p-InGaN/GaN hole injection layer were inserted beneath and above the InGaN/GaN MQWs. The influences of activated donor concentration in n+-InGaN and acceptor concentration in p-InGaN/GaN and on the depletion width and the internal capacitance of GaN-based n+-P LED have been investigated. Our research results indicated that the capacitance of GaN-based n+-P LED is mainly determined by the depletion width which is dependent on the activated acceptor concentration NA in the p-InGaN/GaN hole injection layer. The relationship between the internal capacitance of InGaN–LEDs and the electrostatic discharge (ESD) properties was also investigated. It was found that the LEDs with large internal capacitance were more resistant to external ESD impulses. With optimized LED structures with n+-InGaN layer and a p-InGaN/GaN SLs, the HBM-ESD pass yield at −1500 V reached 95%, much higher than the value of 15% in reference samples without inserting layers above.

Aligned carbon nanotube films were utilized to pattern a c-plane sapphire substrate. High quality GaN was obtained by epitaxy growth on carbon nanotube patterned sapphire substrates (CPSS) by a metal–organic vapor phase epitaxy system. Results of X-ray diffraction and transmission electron microscopy (TEM) confirmed the improvement of crystalline quality of GaN by introduction of the carbon nanotube film. A large number of voids with sizes of tens to hundreds of nanometers were observed on carbon nanotubes by scanning electron microscopy (SEM) and TEM. The dislocation annihilation around voids was believed to be helpful for the reduction of dislocation density. Performance of light-emitting diodes manufactured on CPSS was also clearly improved, as 15% enhancement of luminous intensity at 20 mA, and 50% delay of saturation current from 80 mA to 120 mA.

Polarization-resolved edge-emitting electroluminescence of InGaN∕GaN multiple quantum well (MQW) light emitting diodes (LEDs) from 395to455nm was measured. Polarization ratio decreased from 3.2 of near-ultraviolet LEDs (395nm) to 1.9 of blue LEDs (455nm). Based on TE mode dominant emissions in InGaN∕GaN MQWs, compressive strain in well region favors TE mode, indium induced quantum-dot-like behavior leads to an increased TM component. As wavelength increased, indium enhanced quantum-dot-like behavior became obvious and E‖C electroluminescence signal increased thus lower polarization ratio. Electroluminescence spectrum shifts confirmed that quantum dotlike behaviors rather than strain might be dominant in modifying luminescence mode of InGaN∕GaN MQWs from near ultraviolet to blue.