This paper presents an ultra-low-power event-driven analog-to-digital converter (ADC) with real-time QRS detection for wearable electrocardiogram (ECG) sensors in wireless body sensor network (WBSN) ...applications. Two QRS detection algorithms, pulse-triggered (PUT) and time-assisted PUT (t-PUT), are proposed based on the level-crossing events generated from the ADC. The PUT detector achieves 97.63% sensitivity and 97.33% positive prediction in simulation on the MIT-BIH Arrhythmia Database. The t-PUT improves the sensitivity and positive prediction to 97.76% and 98.59% respectively. Fabricated in 0.13 μm CMOS technology, the ADC with QRS detector consumes only 220 nW measured under 300 mV power supply, making it the first nanoWatt compact analog-to-information (A2I) converter with embedded QRS detector.
This paper presents a fully integrated wireless electrocardiogram (ECG) SoC implemented in asynchronous architecture, which does not require system clock as well as off-chip antenna. Several low ...power techniques are proposed to minimize power consumption. At the system level, a newly introduced event-driven system architecture facilitates the asynchronous implementation, thus removes the system clock leading to a true ECG-on-chip solution. A DC-coupled analog front-end is introduced together with a baseline stabilizer to boost the input impedance to 3.6 GQ and mitigate the electrode offset, which is less sensitive to motion artefact and contact impedance imbalance, making it well suited for dry-electrode based applications. Level-crossing analog-to-digital converter (LC-ADC) is employed to take the advantage of burst nature of ECG signal leading to at least 5 times reduction in sampling points compared to Nyquist sampling. A digitally implemented impulse-radio ultra-wideband transmitter is seamlessly integrated with LC-ADC and an on-chip antenna for wireless communications. Implemented in 0.13 μm CMOS technology, the ECG-on-chip consumes 2.89 μW under 1.2 V supply while transmitting the raw ECG data, which attains one order of magnitude lower than the current state-of-the-art designs. The fully integrated ECG SoC requires no external clocks and off-chip antenna, making it a good candidate for low cost and disposable wireless ECG patches, such as epidermal electronics.
A low quiescent current digital low-dropout (DLDO) voltage regulator with fast-transient response time is proposed for self-powered wireless sensor applications operating at near/subthreshold supply ...voltage. The D-LDO regulator incorporates both hill-climbing and binary search algorithms (HCBS) in the control logic, thus leveraging on each other's strengths to minimize the output voltage's ripple and the quiescent current during the steady-state period as well as output voltage's spike and response time during the transition period. Additional features such as hysteresis mode control and freeze mode control are incorporated into the system to improve the performance of the D-LDO regulator. A dynamic comparator is proposed for the near/subthreshold supply voltage operation, which minimizes the voltage error and improves the maximum operating frequency. Fabricated in 130-nm CMOS technology, the D-LDO regulator regulates the output voltage V OUT from 350 to 1150 mV, while the input supply voltage VIN ranges from 450 to 1200 mV. At a V OUT of 450 mV, V IN of 500 mV and an operating frequency of 10 MHz, the regulator delivers 1500-μA load current with I QUIESCENT of 8.9 μA and a transient response time of 1.6 μs. The maximum current and power efficiencies reach 99.9% and 89.9%, respectively. The measured line regulation and load regulation are 1.6 and 0.6 mV/mA, respectively.
Magnesium alloys have become more attractive because of their low density and electromagnetic shielding effectiveness in the aerospace industry. However, some unpredictable situation may lead to the ...ignition of magnesium alloys. In this review, the thermodynamic conditions and transfer processes of magnesium alloys ignition are analyzed from the point of mechanisms. The criteria of ignition are emphasized. In addition, ignitability and flammability test systems are compared. And a more suitable method to assess the potential ignition and flammability risks of magnesium alloys in extreme environments is recommended. Furthermore, the ignition characteristics of magnesium alloys are discussed in detail. It was found that the ignition of magnesium alloys is a complex process determined by internal properties such as thermo-physical properties, oxide film properties, chemical compositions and geometrical parameters, as well as the external environment such as gas species, oxygen concentration and oxygen pressure. Ignition temperature is not physical constants of materials. It is not simply assumed that ignition may occur when the temperature of Mg alloys reaches a certain ignition point. Finally, the unsolved issues in the ignition of magnesium alloys are pointed out and the future investigation are suggested for improving the safety and reliability of magnesium alloys in the aerospace applications.
A novel wearable electrocardiograph (ECG) QRS detection algorithm for wearable ECG devices in body area networks is presented in this paper, which utilizes the multistage multiscale mathematical ...morphology filtering to suppress the impulsive noise and uses the multiframe differential modulus accumulation to remove the baseline drift and enhance the signal. The proposed algorithm, verified with data from the MIT/BIH Arrhythmia Database and wearable ECG devices, achieves an average QRS detection rate of 99.61%, a sensitivity of 99.81%, and a positive prediction of 99.80%. It compares favorably to the published methods.
In this paper, CoNiP and CoNiP/Cr2O3 composite coatings were successfully electrodeposited onto Cr-Ni-Mo-V steels substrate by using direct current (DC). The effects of Cr2O3 particle contents and ...heat treatment on the microstructures, coating compositions, microhardness and wear resistance properties of the coatings were investigated by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), Vickers hardness tester and ball-on-disk tribometer. The results showed that the coatings transformed from amorphous to crystalline structures by heat treatment at 350 °C, and their microhardness significantly increased. The contents of Cr2O3 particles in the coatings reached a stable value for the coatings deposited in the plating bath with concentration of Cr2O3 higher than 15 g/L, meanwhile the coating deposited in the plating bath of 15 g/L Cr2O3 (CoNiP-15 g/L Cr2O3) possessed the highest microhardness. Wear test results at room temperature, 200, 300, 400 and 500 °C showed that the wear resistance of the coatings was improved by the addition of Cr2O3 particles, and the CoNiP-15 g/L Cr2O3 coating had the lowest coefficient of friction and wear loss among all the samples.
•The CoNiP/Cr2O3 composite coatings were prepared on the steel substrate.•The effect of heat treatment on the microstructure and microhardness of the coatings were studied.•The effects of Cr2O3 particle contents on the microstructures and wear resistance properties of the coatings were investigated.•The wear of the substrate and coatings at different wear temperatures were studied.
•CUMS-induced depression-like behavior needs participation of NLRP3 inflammasome.•NLRP3 gene knockout blocks activation of NF-κB protein complex in CUMS-induced depression mouse model.•The NLRP3 ...inflammasome regulates CUMS-induced MAPK pathway activation.
Abundant researches indicate that neuroinflammation has important roles in the pathophysiology of depression. Our previous study found that the NLRP3 inflammasome mediated stress-induced depression-like behavior in mice via regulating neuroinflammation. However, it still remains unclear that how the NLRP3 inflammasome influences related inflammatory signaling pathway to contribute to neuroinflammation in depression.
We used wild-type mice and NLRP3 gene knockout mice to explore the role of NLRP3 inflammasome and related inflammatory signaling pathways in chronic unpredictable mild stress (CUMS) induced depression mouse model.
Both wild-type and NLRP3 knockout stress group mice gained less weight than control group mice after 4 weeks CUMS exposure. The wild-type mice subjected to 4 weeks CUMS displayed depression-like behaviors, including decreased sucrose preference and increased immobility time in the tail suspension test. The NLRP3 knockout stress group mice didn’t demonstrate depression-like behaviors. The levels of interleukin-1β protein in serum and hippocampi of CUMS exposed wild-type mice were significantly higher, while the NLRP3 knockout stress group mice didn’t show an elevation of interleukin-1β levels. Similarly to early researches, we found that CUMS led to promoted NLRP3 expression in hippocampi. In addition, the hippocampi in CUMS exposed wild-type mice had higher p-JNK and p-p38 protein expression, which indicated activation of the mitogen-activated protein kinases (MAPK) pathway. The knockout of NLRP3 gene inhibited CUMS-induced activation of the MAPK pathway. The nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) protein complex was activated in the hippocampi of wild-type mice after CUMS exposure, while knockout of NLRP3 gene hindered its activation.
These data further proved that the NLRP3 inflammasome mediated CUMS-induced depression-like behavior. The NLRP3 inflammasome regulated CUMS-induced MAPK pathway and NF-κB protein complex activation in depression mouse model. Further researches targeting the NLRP3 inflammasome-signaling pathway might be under a promising future in the prevention and treatment of depression.
Abstract Background Insomnia is a widespread and debilitating condition that affects sleep quality and daily productivity. Although mindfulness meditation (MM) has been suggested as a potentially ...effective supplement to medical treatment for insomnia, no comprehensively quantitative research has been conducted in this field. Therefore, we performed a meta-analysis on the findings of related randomized controlled trials (RCTs) to evaluate the effects of MM on insomnia. Methods Related publications in PubMed, EMBASE, the Cochrane Library and PsycINFO were searched up to July 2015. To calculate the standardized mean differences (SMDs) and 95% confidence intervals (CIs), we used a fixed effect model when heterogeneity was negligible and a random effect model when heterogeneity was significant. Results A total of 330 participants in 6 RCTs that met the selection criteria were included in this meta-analysis. Analysis of overall effect revealed that MM significantly improved total wake time and sleep quality, but had no significant effects on sleep onset latency, total sleep time, wake after sleep onset, sleep efficiency, total wake time, ISI, PSQI and DBAS. Subgroup analyses showed that although there were no significant differences between MM and control groups in terms of total sleep time. Significant effects were found in total wake time, sleep onset latency, sleep quality, sleep efficiency, and PSQI global score (absolute value of SMD range: 0.44–1.09, all p < 0.05). Conclusions The results suggest that MM may mildly improve some sleep parameters in patients with insomnia. MM can serve as an auxiliary treatment to medication for sleep complaints.
Depression is one of the most common mental disorders characterized mainly by low mood and loss of interest or pleasure. About a third of patients with depression do not respond to classic ...antidepressant treatments. Recent evidence suggests that Mrp8/14 (myeloid-related protein 8/14) plays a crucial role in cognitive dysfunction and neuroinflammatory diseases, yet its role in mood regulation remains largely uninvestigated. In the present work, we explored the potential role of Mrp8/14 in the progression of depression.
After 4 weeks of chronic unpredictable mild stress (CUMS), depressive-like symptoms and Mrp8/14 were determined. To verify the effects of Mrp8/14 on depressive-like behaviors, the inhibitor TAK-242 and recombinant Mrp8/14 were used. Furthermore, the molecular mechanisms in Mrp8/14-induced behavioral and biological changes were examined in vivo and ex vivo.
Four-week CUMS contributed to the development of depressive symptoms. Mrp8 and Mrp14 were upregulated in the hippocampus and serum after exposure to CUMS. Pharmacological inhibition of Mrp14 attenuated CUMS-induced TLR4/NF-κB signaling activation and depressive-like behaviors. Furthermore, central administration of recombinant Mrp8, Mrp14, and Mrp8/14 resulted in neuroinflammation and depressive-like behaviors. Mrp8/14-provoked proinflammatory effects and depressive-like behaviors were improved by pretreatment with a TLR4 inhibitor. Moreover, pharmacological inhibition of TLR4 reduced the release of nitric oxide and reactive oxygen species in Mrp8/14-activated BV2 microglia.
These data suggest that the hippocampal Mrp8/14-TLR4-mediated neuroinflammation contributes to the development of depressive-like behaviors. Targeting the Mrp8/14 may be a novel promising antidepressant approach.
•HMGB1 can activate the rate limiting enzyme IDO and two downstream enzymes of KMO and KYNU in the KP.•HMGB1 evokes depressive-like behavior through kynurenine pathway.•Ethyl pyruvate blocks the ...increase of HMGB1 which is induced by CUMS both in hippocampi and serum.
Our previous study has reported that the proactive secretion and role of central high mobility group box 1 (HMGB1) in lipopolysaccharide-induced depressive behavior. Here, the potential mechanism of HMGB1 mediating chronic-stress-induced depression through the kynurenine pathway (KP) was further explored both in vivo and in vitro. Depression model was established with the 4-week chronic unpredictable mild stress (CUMS). Sucrose preference and Barnes maze test were performed to reflect depressive behaviors. The ratio of kynurenine (KYN)/tryptophan (Trp) represented the enzyme activity of indoleamine-2,3-dioxygenase (IDO). Gene transcription and protein expression were assayed by real-time RT-PCR and western-blot or ELISA kit respectively. Along with depressive behaviors, HMGB1 concentrations in the hippocampus and serum substantially increased post 4-week CUMS exposure. Concurrent with the upregulated HMGB1 protein, the regulator of translocation of HMGB1, sirtuin 1 (SIRT1) concentration in the hippocampus remarkably increased. In addition to HMGB1 and SIRT1, IDO, the rate limiting enzyme of KP, was upregulated at the level of mRNA expression and enzyme activity in stressed hippocampi and LPS/HMGB1-treated hippocampal slices. The gene transcription of kynurenine monooxygenase (KMO) and kynureninase (KYNU) in the downstream of KP also increased both in vivo and in vitro. Mice treated with ethyl pyruvate (EP), the inhibitor of HMGB1 releasing, were observed with lower tendency of developing depressive behaviors and reduced activation of enzymes in KP. All of these experiments demonstrate that the role of HMGB1 on the induction of depressive behavior is mediated by KP activation.
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