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Radio-frequency (RF)-powered backscattering communication (BC) has many advantages, such as low-power consumption, battery-free, small size, low cost, full sealing, manual maintenance-free, and easy mass deployment. However, the weak RF energy harvested and the short BC distance have become the two critical obstacles in the real-world implementation of this potential technology. In this article, we propose a high-sensitivity RF energy harvesting (RFEH) and long-distance BC method, and for the first time, we demonstrate the RF-powered self-sustainable long-distance BC device named RFEH LoRa. In order to improve RFEH sensitivity, an ultralow-power (ULP) consumption voltage monitoring and startup control circuit topology is designed to reduce the power consumption to 245 nanowatt (nW) during the accumulation of RF energy. While in order to increase the BC distance, a direct digital frequency synthesis technology is used to generate a linear frequency modulation square wave sequence conforming to the LoRa specifications based on the ULP microcontroller unit, and the square wave is used to drive an RF switch to achieve long-distance BC of hundreds of meters. Test results show that the instantaneous BC current is as low as 130 microampere ( ${\mu }\text{A}$ ), and the standby current is only 52 nanoampere (nA). RFEH LoRa is implemented with commercial off-the-shelf components. It can self-startup by harvesting RF energy as low as −22.5 dBm, and send its sensing data to the receiver of 381-m away.

Research on the damage and seepage characteristics of unloading rock with high water pressure can help to further understand the mechanism of water inrush in deep mine floor and prevent water inrush. This paper used the RFPA2D-flow finite element software to study the failure and seepage characteristics of unloading rock with high water pressure and high stress and comparatively analyzed the failure modes and seepage characteristics of unloading rock with and without water pressure. The effects of different water pressure differences on the failure of unloading rock and the law of seepage were investigated by analyzing the change of acoustic emission and permeability coefficient with stress. The results showed that the unloading rock without water pressure was brittle failure, and the initial damage of the unloading model with water pressure was earlier than that of the model without water pressure and showed greater brittleness, and its cracks first break through at the bottom of the sample with higher osmotic pressure. With the increase in unloading, the permeability of rock increased gradually until it appeared an abrupt change. The failure mode and permeability law of the rock with different water pressure differences were basically the same, but the greater the pressure difference, the smaller the effective unloading capacity when the permeability coefficient changes suddenly, and the greater the possibility of water inrush in the rock.

The application of Wireless Power Transmission (WPT) has attracted more and more attention, but the energy efficiency cannot be high due to the inevitable loss. Energy efficient WPT is increasingly demanded especially in implantable devices due to their wireless inefficiency nature. In addition, many implantable devices include digital circuits such as a Microcontroller Unit (MCU) in which the supply voltage may fluctuate severely with the driving clock of digital circuits switches between ground (Gnd) and supply voltage (Vdd), since the power transmitted wirelessly is limited, and the system may even cut off under wireless charging conditions. Therefore, the load regulation is also required in a WPT system. This paper presents a WPT system with load regulation and optimized antenna design for implantable devices, for which measurement results show that the maximum transmission efficiency can reach 79.3% and it can still necessitate a large dynamic load current range. When the load current is switched between 12 uA and 5 mA, the overshoot and undershoot of the output voltage are 150 mV and 80 mV, respectively. Finally, several state-of-the-art WPT applications in biomedical devices are introduced.

Compound-specific isotope analysis (CSIA) is a useful technique that has received an increasing attention for studying the degradation mechanisms of organic contaminants based on stable isotope fractionation concepts. This study reports the degradation mechanisms of p-chloroaniline (PCA) at different pH values (3, 5, 7 and 9) induced by persulfate (PS) based on 13C isotope fractionation during its preferential oxidation with SO4 − and OH. The results showed that the degradation of PCA followed first-order kinetics (rate constants, 0.026, 0.0362, 0.0754 and 0.0497 h−1 at pH = 3, 5, 7 and 9, respectively), with the fastest degradation under neutral conditions (pH 7). The degradation rate was found to be higher under alkaline conditions (pH 9) compared to acidic conditions (pH 3 and 5). A normal carbon isotope fractionation of PAC was observed under neutral and alkaline conditions (eg., eC = −0.8‰ ±0.10 at pH 7 and eC = −1.0‰ ±0.17 at pH 9). However, a reverse carbon isotope effect at pH 3 (eC = 0.6‰ ±0.07) and pH 5 (eC = 1.1‰ ±0.06) was observed, respectively. Based on the identified transformation products and the insights revealed by CSIA, the degradation pathways were proposed. The current findings are crucial in understanding the PCA degradation mechanisms with SO4 − and OH in aqueous systems.

As the research base damage and water inrush problem, this article obtains from the body micro units, on the basis of seepage of rock mass and rock mechanics theory, considering the heterogeneity of rock, and established the heterogeneity of rock containing random defects of mesoscopic scale on the seepage flow in heterogeneous model by means of FLAC3D simulation software built-in fish language from the model unit randomly in the unit ID number, total group as defects in the model group, while the rest of the unit as a complete set, the different group gives different mechanics parameter values, implement different defect degrees of homogenization model established The results show that the overall bearing capacity of rocks with high defect degree decreases obviously, and the failure of rocks precedes that of intact rocks.

A Frequency Hopping (FH) communication method for uplink and downlink of satellite and ground station on the basis of GPS time service and satellite ephemeris is proposed. By adopting the SGP4 model to predict the satellite orbit, the relative position and velocity between satellite and ground station can be calculated precisely. The ground station completes pre-correction and compensation of the propagation delay and Doppler shift that have been estimated. The result shows that our proposed system performs lower hardware complexity and higher frequency hopping rate than traditional FH system. The propagation delay estimation precision is better than 250 ns. The Doppler shift estimation precision is better than 1 Hz. When the system cost is 1%, frequency hopping rate can reach 20000 Hops/s. The proposed system has strong anti-interference ability and strong anti-interception ability.

Background We aimed to determine the risk conferred by metabolic syndrome ( METS ) and diabetes mellitus ( DM ) to recurrent stroke in patients with minor ischemic stroke or transient ischemic attack from the CHANCE (Clopidogrel in High‐risk patients with Acute Non‐disabling Cerebrovascular Events) trial. Methods and Results In total, 3044 patients were included. Patients were stratified into 4 groups: neither, METS only, DM only, or both. METS was defined using the Chinese Diabetes Society ( CDS ) and International Diabetes Foundation ( IDF ) definitions. The primary outcome was new stroke (including ischemic and hemorrhagic) at 90 days. A multivariable Cox regression model was used to assess the relationship of METS and DM status to the risk of recurrent stroke adjusted for potential covariates. Using the CDS criteria of METS , 53.2%, 17.2%, 19.8%, and 9.8% of patients were diagnosed as neither, METS only, DM only, and both, respectively. After 90 days of follow‐up, there were 299 new strokes (293 ischemic, 6 hemorrhagic). Patients with DM only (16.1% versus 6.8%; adjusted hazard ratio 2.50, 95% CI 1.89–3.39) and both (17.1% versus 6.8%; adjusted hazard ratio 2.76, 95% CI 1.98–3.86) had significantly increased rates of recurrent stroke. No interaction effect of antiplatelet therapy by different METS or DM status for the risk of recurrent stroke ( P =0.82 for interaction in the fully adjusted model of CDS ) was observed. Using the METS ( IDF ) criteria demonstrated similar results. Conclusions Concurrent METS and DM was associated with an increased risk of recurrent stroke in patients with minor stroke and transient ischemic attack.

International audience; Understanding the mechanism(s) of microbial resistance to antimony (Sb) is critical in the bioremediation of Sb polluted environments. Here a novel bacterium (Acinetobacter sp. JH7) isolated from mine tailings decreased the Microtox toxicity of a Sb(III)-containing medium. DNA sequencing and physiological testing were employed for the identification and characterization of strain JH7. Following a batch experiment, Fourier transform infrared spectroscopy (FTIR) and antimony speciation analyses determined the adsorption and oxidation of antimony. Analyses of Sb(III) distribution revealed that extracellular polymeric substances and cell walls inhibited Sb(III) entry into JH7 cells. FTIR studies indicated that key functional groups including –OH, C–N, and C–O likely participated in Sb(III) biosorption. Isothermal and kinetic studies revealed that Sb(III) sorption to viable JH7 cells fitted the Langmuir model (R2 = 0.99) and could be described by pseudo-second order kinetics (R2 = 0.99). Furthermore, the increase of anti-oxidative enzymatic activity of JH7 enhanced the intracellular detoxification of Sb(III), which would indirectly contribute to the Sb(III) resistance ability of strain JH7. Our results indicate that biosorption and ROS oxidation of Sb(III) were likely responsible for the decreased toxicity of Sb. The greater understanding how Acinetobacter sp. JH7 lowers the environmental Sb(III) toxicity could provide a basis for future research and subsequent development of technologies for the remediation of Sb contaminated sites.

In this paper, based on the results of SEM and EDS analysis, there are two main reasons for Silicon-aluminum alloy cavity leakage. First, silicon-aluminum alloy material is unqualified; second, it produces cracks and pores during laser welding defects. In the test, silicon-aluminum alloy material is manufactured by powder metallurgy. It is pressure-type is not dense. In the uneven distribution of silicon particles can appear stress concentration, and the substrate itself do not close with the combination of silicon, in the material porosity increased, there may be no or only a few of the aluminum substrate distribution, but also for aluminum ductility is better than silicon ductility, lead to formation and extension of cracks. It is difficult to meet the electronic packaging air tightness. In the process of laser welding, the water on the surface of aluminum silicon alloy or not removed the film decompose to produce hydrogen under the instantaneous heat input of laser. Due to the hydrogen solubility in the solid and liquid aluminum vary widely, when laser welding molten pool start cooling, hydrogen solubility in the aluminum decrescent fast and hydrogen precipitate. Along the edge of the fusion many porosity, crack, and a certain extent coarsening the weld microstructure, which lead to a fall in the microwave cavity air tightness.

In this work, effects of long-term high temperature services on surface micro-structures and components of SmCo magnets with Ni coating were studied. The magnets have been serviced at 550 °C in air (0∼5000 h). And the laws of the surface degradation were studied. And the characters of surface micro-structures and composition were observed by SEM, EDS, and XRD.

In order to finding the reason why there is no output signal when the voltage signals inputted during the voltage stabilizing circuit module works, Scanning electron microscope and energy disperse spectroscopy were used to detecting the surface morphology and the internal composition. The analysis results show that it is the cold solder in the wire bonding caused by the inappropriate mounting depression that lead to the failure of this product, besides, Solder balls can be easily found in this circuit, Which would potential threat to it's stability. we could decrease the amount of the solder ball from the quality of solder and the condition of reflow.

To investigate the causes and strategy of difficult intraarterial mechanical thrombectomy (≥3 times) in patients with acute ischemic stroke (AIS).The clinical data of 8 cases of AIS with thrombectomy ≥3 times admitted in Department of Neurology, the 306(th) Hospital of People's Liberation Army from June to October in 2015 was analyzed retrospectively. There were 7 male and 1 female patients, aged from 38 to 86 years with an average age of (70±15) years, in which 5 cases were cardiogenic cerebral embolism and 3 cases were large artery atherosclerotic infarction. The National Institute of Health stroke scale (NIHSS) score (M (QR)) was 16 (12) before procedure and modified thrombolysis in cerebral infarction (mTICI)score were 0 in all the patients. Solitaire AB was used in thrombectomy in the occlusion of the arteries.The causes of difficult intraarterial thrombectomy included multiple thrombus, tortuosity in vascular paths, guiding catheter being placed below the internal carotid artery siphon leading to weak strength of suction and support of stent, embolus dropping in the thrombectomy and inadequate anesthesia. After successful thrombectomy 3 cases had mTICI score of 2a, 4 cases of 2b, 1 case of 3. The NIHSS score was 5 (24) at 7(th) day after treatment. At the 90-day follow-up 5 patients had good prognosis (modified Rankin score 0 to 2) and 3 had disability (modified Rankin score 3 to 4).Cases of AIS with difficult intraarterial thrombectomy can be treated by improving thrombectomy materials and technique, reasonable anesthesia and perioperative medication in decision-making strategy.

Although abiogenic hydrocarbons have been found in deep-sourced geofluids, they have not been considered a significant source for global hydrocarbon reservoirs. Here, we report a multi-isotopic (C, H and He) study of gases in the Songliao basin in China, revealing the existence of a giant abiogenic hydrocarbon field in the buried volcanoes and clastics overlying volcanics in this rift basin. The progressive carbon isotopic depletion and hydrogen isotopic enrichment trends for C1-C4 n-alkanes and the strong correlation between the carbon, hydrogen and helium isotopic ratios of gases in the buried volcanoes indicate hydrocarbon production by kinetically-controlled polymerization of methane precursors related to mantlederived fluids. Given the common occurrence of buried volcanic structures in rift basins, there may exist more abiogenic hydrocarbons associated with buried volcanoes in rift basins that are unrelated to source kitchens than previously thought.

In this paper, based on the results of SEM and EDS analysis, I would like to share the discovery of MLCC failure due to insulation resistance. For external factors, The defects which caused by mechanical stress can lead to lack of insulation resistance. For the intrinsic factors, MLCC insulation resistance failure is due to the presence of defects, and the main defects include void in ceramic dielectric and delamination of porcelain body and inner electrode. These defects are difficult to analyze. With the help of SEM electron microscope detection, these defets can be see. The reason is the poor control of sintering process.In the test,these defects will cause the capacitor quickly form a conductive channel, finally lead to insulation resistance failure.

This paper proposed an enhanced solution, which adopted ways of changing methods for controlling current on inverter side, adding practical current after enabling D-Q transform and adopting triangular carrier control instead of hysteresis control, for simulating traction loads based on PWM converter. Simulation result figured that increasingly close loops on inverter side and reduction on the risk of instability may be caused by exceeded switch frequency, comparing with existing solution using hysteresis and direct current control, can be achieved in the advantages of solution proposed in this paper. Therefore, energy saving and better traction load simulating have been implemented.

Wireless sensor n?etworks (WSNs) constitute numerous microsensors that are energy limited. How to design the routing protocol to use energy with high efficiency is one of the most critical issues. In this paper, we propose a distributed singlehop-multihop switch (DSMS) routing protocol for wireless sensor networks. The main idea of DSMS is that the sensor area is divided into several rings of the same width and the nodes in the inner rings only bear forwarding task for certain percentage of network lifetime in order to guarantee energy balance. The advantage of DSMS is that the energy variance of nodes maintains at a rather low level during the network lifetime, which mean that the energy consumption is fairly balanced. The simulation results show that DSMS routing protocol could also extend network lifetime longer than either single-hop or multi-hop mode. DSMS routing protocol also has good scalability.