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In this paper, the static and switching characterizations of a SiC MOSFET's body diode are presented. The static characterization of SiC MOSFET's body diode is carried out using a curve tracer and a double pulse test bench is built to characterize the inductive switching behavior of SiC MOSFET's body diode. The reverse recovery of SiC MOSFET's body diode is shown at different forward conduction currents, junction temperatures and current commutation slopes. In order to evaluate the performance of SiC MOSFET's body diode in different applications, an accurate physics-based diode model is introduced to perform simulations of SiC MOSFET's body diode. The parameter extraction procedure for this body diode model is given. The validation of the body diode model shows good agreement between simulation and experimental results, which proves the accuracy of the model.

Nano metal oxides are becoming widely used in industrial, commercial and personal products (semiconductors, optics, solar cells, catalysts, paints, cosmetics, sun-cream lotions, etc.). However, the relationship of surface features (exposed planes, defects and chemical functionalities) with physiochemical properties is not well studied primarily due to lack of a simple technique for their characterization. In this study, solid state (31)P MAS NMR is used to map surfaces on various ZnO samples with the assistance of trimethylphosphine (TMP) as a chemical probe. As similar to XRD giving structural information on a crystal, it is demonstrated that this new surface-fingerprint technique not only provides qualitative (chemical shift) but also quantitative (peak intensity) information on the concentration and distribution of cations and anions, oxygen vacancies and hydroxyl groups on various facets from a single deconvoluted (31)P NMR spectrum. On the basis of this technique, a new mechanism for photocatalytic •OH radical generation from direct surface-OH oxidation is revealed, which has important implications regarding the safety of using nano oxides in personal care products.

Perovskite LaFeO3/montmorillonite nanocomposites (LaFeO3/MMT) have been successfully prepared via assembling LaFeO3 nanoparticles on the surface of montmorillonite with citric acid assisted sol-gel method. The results indicated that the uniform LaFeO3 nanoparticles were densely deposited onto the surface of montmorillonite, mainly ranging in diameter from 10 nm to 15 nm. The photocatalytic activity of LaFeO3/MMT was evaluated by the degradation of Rhodamine B (RhB) under visible light irradiation, indicating that LaFeO3/MMT exhibited remarkable adsorption efficiency and excellent photocatalytic activity with the overall removal rate of RhB up to 99.34% after visible light irradiation lasting for 90 min. The interface characteristic and possible degradation mechanism were explored. The interface characterization of LaFeO3/MMT suggested that LaFeO3 nanoparticles could be immobilized on the surface of montmorillonite with the Si-O-Fe bonds. The abundant hydroxyl groups of montmorillonite, semiconductor photocatalysis of LaFeO3 and Fenton-like reaction could enhance the photocatalytic degradation through a synergistic effect. Therefore, the LaFeO3/MMT is a very promising photocatalyst in future industrial application to treat effectively wastewater of dyes.

The dynamic failure characteristics of coal rock exposed to high temperatures were studied by using a split Hopkinson pressure bar (SHPB) system. The relationship between energy and time history under different temperature conditions was obtained. The energy evolution and the failure modes of specimens were analyzed. Results are as follows: during the test, more than 60% of the incident energy was not involved in the breaking of the sample, while it was reflected back. With the increase of temperature, the reflected energy increased continuously; transmitted and absorbed energy showed an opposite variation. At the temperature of 25 to 100°C, the absorbed energy was less than that transmitted, while this phenomenon was opposite after 100°C. The values of specific energy absorption (SEA) were distributed at 0.04 to 0.1 J·cm−3, and its evolution with temperature could be divided into four different stages. Under different temperature conditions, the failure modes and the broken blocks of the samples were obviously different, combining with the variation of microstructure characteristics of coal at high temperatures; the physical mechanism of damage and failure patterns of coal rock are explained from the viewpoint of energy.

MoSe2/montmorillonite composite nanosheets were successfully synthesized by a facile hydrothermal method, and the photocatalytic activities of the samples were evaluated by the decoloration of Rhodamine B. The structural characterizations indicate that the MoSe2 nanosheets grow uniformly on the surface of montmorillonite with interface interaction, and the active sites on the nanosheet edges are exposed. Montmorillonite can inhibit the agglomeration of MoSe2 nanosheets, improve the hydrophilicity and dispersibility of composites, and provides a larger surface area and more reactive sites for photocatalytic reaction. MoSe2/montmorillonite possesses the highest adsorption properties and photocatalytic abilities, and the overall decoloration rate is up to 98.2% after visible light irradiation for 45 min. The assembly of montmorillonite could enhance the photocatalytic ability of MoSe2, and the possible photocatalytic reaction mechanism of MoSe2/montmorillonite for Rhodamine B was explored. MoSe2/montmorillonite has potential applications in the photodegradation of organic dyes in the wastewater.

Utilizing the abnormal physiological conditions of disease tissues can result in a site-specific functionality with high control and efficiency of stimuli-responsive hydrogels. Here, a physiologically relevant pH-responsive and self-healing hydrogel is reported based on coordination between Ni2+ and four-arm poly(ethylene glycol)-b-polyhistidine (4PEG-PHis) that is synthesized by a novel and facile PHis preparation method using amino-terminalized four-arm PEG as the macroinitiator. Reversible PHisNi coordination bonds endow the hydrogel with multistimuli-triggered sol-gel transition (physiologically relevant pH, EDTA) and self-healing properties. It is also demonstrated that 4PEG-PHis could be used as an injectable hydrogel in phosphate buffer (pH 7.4), and excellent stability in neutral buffer via multivalent coordination is shown, thus indicating its potential applications in controlled drug release systems.

Deriving respiratory signal from a surface electrocardiogram (ECG) measurement has advantage of simultaneously monitoring of cardiac and respiratory activities. ECG-based cardiopulmonary coupling (CPC) analysis estimated by heart period variability and ECG-derived respiration (EDR) shows promising applications in medical field. The aim of this paper is to provide a quantitative analysis of the ECG-based CPC, and further improve its performance. Two conventional strategies were tested to obtain EDR signal: R-S wave amplitude and area of the QRS complex. An adaptive filter was utilized to extract the common component of inter-beat interval (RRI) and EDR, generating enhanced versions of EDR signal. CPC is assessed through probing the nonlinear phase interactions between RRI series and respiratory signal. Respiratory oscillations presented in both RRI series and respiratory signals were extracted by ensemble empirical mode decomposition for coupling analysis via phase synchronization index. The results demonstrated that CPC estimated from conventional EDR series exhibits constant and proportional biases, while that estimated from enhanced EDR series is more reliable. Adaptive filtering can improve the accuracy of the ECG-based CPC estimation significantly and achieve robust CPC analysis. The improved ECG-based CPC estimation may provide additional prognostic information for both sleep medicine and autonomic function analysis.

Polydopamine (PDA) preserves universal coating and metal-binding ability, and is suitable for application in synthesizing multifunctional agents. Herein, utilizing mesoporous silica assisted deposition to enhance both heterogeneous nucleation and loading amounts of PDA, the magnetic resonance (MR) T1 component (PDA-Fe3+) and MR T2/computed tomography (CT)/multiphoton luminescence (MPL) component (FePt) have been successfully integrated in aqueous solution. This four-in-one (T1, T2, CT, MPL) imaging nanocomposite, FePt@mSiO2 @PDA-polyethylene glycol (PEG), demonstrated its multi-imaging power both in vitro/in vivo. According to our in vitro/in vivo results, FePt@mSiO2@PDA-PEG reveals water-content-dependent property in T1 MR imaging, which suggests the necessity of having dual-modal MR ability in a single particle for the precision diagnosis. Most importantly, this dual (T1,T2)-MRI/CT contrast agent is demonstrated complementary to each other in the in vivo testing. PDA coated mesoporous silica also offers an advantage of delayed degradation that prevents adverse effects caused by silica fragments before excretion. The potential of this nanocomposites in both drug carrier and photothermal agent was further evaluated by using doxorubicin and monitoring solution temperature after irradiating 808 nm continuous-wave, respectively The merits of controlled polymerization, enhanced PDA loading, and biofavorable degradation make this methodology promising to other nanoparticle@mSiO2 for a wide range of bioapplications.

Among the present oxidation-assisted polishing (OAP) technique, anodic oxidation is a promising method to process reaction-sintered silicon carbide (RS-SiC) with the assistance of abrasive polishing. Projections and cracks are inevitably formed in the anodic oxidation of RS-SiC for the volume expansion force. Evolvements of the oxide morphologies along with different oxidation voltage and different oxidation time are investigated by scanning electron microscope (SEM). It can be found that when the oxidation time stays the same, size of the projections and cracks on the oxidized RS-SiC sample is gradually enlarged. Meanwhile, when the oxidation voltage stays the same, size of the projections and cracks on the oxidized RS-SiC sample is also enlarged. Details of projections and cracks on the oxidized RS-SiC sample are obtained by the SEM with high magnification. Based on the theoretical derivation, it can be concluded that the formations of projections and cracks depend on the inner volume expansion force and the resultant force generated from other grains. Research on formation of projections and cracks in anodic oxidation of RS-SiC can promote the process level of RS-SiC products.

Investigating two types of seismic signals often misclassified in practice, seismic events and quarry blasts, two novel approaches using singular value decomposition (SVD) to extract features of the main wavelet coefficients (WCs) and product function components (PFs) and the support vector machine (SVM) to classify them are proposed. This research collected and preprocessed 200 seismic events and 200 quarry blasts from the Yongshaba mine, China. Discrete wavelet transform (DWT) and local mean decomposition (LMD) were used to decompose the signals into several WCs and PFs, respectively, and the correlation coefficient and variance contribution ratio were used to select the main WCs and PFs. Finally, the singular value features of the selected six WCs and PFs, which can discriminate between seismic events and quarry blasts, were extracted, and the features were input to backpropagation (BP) neural network, Bayes, SVM, and logistic regression (LR) classifiers. The results show that SVD can effectively extract signal features, and that the SVM classifier offers better classification results than the BP neural network, Bayes, and LR classifiers. In addition, the LMD-SVD-SVM-based method is better than the DWT-SVD-SVM-based method in accuracy, specificity, and sensitivity, with values of 96.0 %, 97.0 %, and 95.0 %, and 95.5 %, 97.0 %, and 94.0 %, respectively. Therefore, DWT and LMD based on SVD and SVM techniques provide useful approaches to seismic event and quarry-blast classification.

Reaction-sintered silicon carbide (RS-SiC) is a research focus in the field of optical manufacturing. Atmospheric-pressure plasma-based chemical dry figuring and finishing, which consist of plasma chemical vaporization machining (PCVM) and plasma-assisted polishing (PAP), were applied to improve material removal rate (MRR) in rapid figuring and ameliorate surface quality in fine finishing. Through observing the processed RS-SiC sample in PCVM by scanning white-light interferometer (SWLI), the calculated peak-MRR and volume-MRR were 0.533 μm/min and 2.78×10−3 mm3/min, respectively. The comparisons of surface roughness and morphology of the RS-SiC samples before and after PCVM were obtained by the scanning electron microscope and atomic force microscope. It could be found that the processed RS-SiC surface was deteriorated with surface roughness rms 382.116 nm. The evaluations of surface quality of the processed RS-SiC sample in PAP corresponding to different collocations of autorotation speed and revolution speed were obtained by SWLI measurement. The optimal surface roughness rms of the processed RS-SiC sample in PAP was 2.186 nm. There were no subsurface damages, scratches, or residual stresses on the processed sample in PAP. The results indicate that parameters in PAP should be strictly selected, and the optimal parameters can simultaneously obtain high MRR and smooth surface.

We surely agree with Wessel et al. that heart period fluctuations are linked to many physiological oscillations. As already explained in the 1996 heart rate variability (HRV) standards,1 these oscillations include those of respiration,2 blood pressure,3 etc. The shifts in the respiration-related HRV components into the nominal low-frequency band are also known4 as is the fact that the low-frequency HRV modulations cannot be taken as a single reliable expression of sympathetic activity.1 It is difficult to consider respiration as an overwhelming determinant of short-term HRV. Adding additional provocations to constant controlled breathing still leads …

The cardiac interbeat (RR) increment time series can be decomposed into two sub-sequences: a magnitude series and a sign series. We show that the sign sequence, a simple binary representation of the original RR series, retains fundamental scaling properties of the original series, is robust with respect to outliers, and may provide useful information about neuroautonomic control mechanisms., Comment: 4 pages, latex

Quantification of nonlinear interactions between two nonstationary signals presents a computational challenge in different research fields, especially for assessments of physiological systems. Traditional approaches that are based on theories of stationary signals cannot resolve nonstationarity-related issues and, thus, cannot reliably assess nonlinear interactions in physiological systems. In this review we discuss a new technique "Multi-Modal Pressure Flow method (MMPF)" that utilizes Hilbert-Huang transformation to quantify dynamic cerebral autoregulation (CA) by studying interaction between nonstationary cerebral blood flow velocity (BFV) and blood pressure (BP). CA is an important mechanism responsible for controlling cerebral blood flow in responses to fluctuations in systemic BP within a few heart-beats. The influence of CA is traditionally assessed from the relationship between the well-pronounced systemic BP and BFV oscillations induced by clinical tests. Reliable noninvasive assessment of dynamic CA, however, remains a challenge in clinical and diagnostic medicine.In this brief review we: 1) present an overview of transfer function analysis (TFA) that is traditionally used to quantify CA; 2) describe the a MMPF method and its modifications; 3) introduce a newly developed automatic algorithm and engineering aspects of the improved MMPF method; and 4) review clinical applications of MMPF and its sensitivity for detection of CA abnormalities in clinical studies. The MMPF analysis decomposes complex nonstationary BP and BFV signals into multiple empirical modes adaptively so that the fluctuations caused by a specific physiologic process can be represented in a corresponding empirical mode. Using this technique, we recently showed that dynamic CA can be characterized by specific phase delays between the decomposed BP and BFV oscillations, and that the phase shifts are significantly reduced in hypertensive, diabetics and stroke subjects with impaired CA. In addition, the new technique enables reliable assessment of CA using both data collected during clinical test and spontaneous BP/BFV fluctuations during baseline resting conditions.