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This letter presents a 65-dB SNDR ECG SAR analog-to-digital converter (ADC) that utilizes a VCM-based LSB-first switching scheme for extraordinary low-power operation under low supply voltage. Unlike conventional VCO-based or OSC-based comparators which being either power inefficiency or low speed, the adaptive-latching OSC-based comparator is presented. It achieves low power while simultaneously maintaining an adequate speed under a low supply voltage through the adaptive latching scheme and asynchronous operations. The switching scheme incorporating the proposed comparator also facilitates the DAC mismatch calibration, where no additional analog hardware is necessary for the DAC mismatch detection. After calibration, the worst INL decreases from 2.6 LSBs to 0.85 LSB. The prototype, fabricated in 65-nm LP CMOS, attains 65.48-dB SNDR at 4 KS/s with an OSR = 4 while consuming only 8.1 nW at 0.55-V supply and leading to a 173.4-dB Schreier FoM.

Shield tunneling in highly fractured karst water-rich conditions easily results in water inrush disaster or even causes the roof of the karst caves to collapse. Severe water inrush disasters have occurred during the EPB (earth pressure balance) shield machine of the Jinan Metro Line R1 advanced through a karst and fissure groundwater-rich limestone ground in the spring area. To cope with the extreme water inrush risk, a multi-step combined control technology was put forward. First, a detailed geological exploration was carried out by ahead geophysical prospecting using high-density resistivity method, geological radar, etc., and geological borehole drilling was conducted from the ground surface before excavation. As a result, the distribution orientation, size, fissure development degree, and water inflow channel within the surrounding rock of the karst caves were detected. Second, multi-step grouting was performed to reinforce the surrounding rock, including pre-grouting treatment and filling rock blocks to the big karst caves from the ground surface, multiple grouting with a small amount of inert slurry each time inside the tunnel, and secondary circumferential hoop grouting at the shield tail. Third, the tunneling process was optimized, including optimizing the tunneling parameters, making full use of the air-pressurized tunneling technology of the EPB to press bentonite into the fractures around the excavation cabin to seal the fissure water, and using the drainage system of EPB and muck improvement technology to reduce the water inrush disaster. Meanwhile, shield protection slurry technology is applied to cutter inspection and replacement in the pressurized chamber under dynamic water flow environment of the spring terrain. The practice shows that the water inrush on the tunnel face is obviously alleviated after the shield machine advanced into the grouting area. According to statistics, the water inflow on the tunnel face decreases from about 4 m3/h before treatment to less than 0.3 m3/h after the abovementioned control, and the water seepage between the segmental linings reduces to almost zero. The average advance rate increased from 3 m/day without stopping or even zero when the shield machine needs to shut down 2–3 days for drainage to about 6 m/day. In addition, the treatments prevented the shield machine from jamming and the head descending disaster. This study provided a reliable control method for shield tunneling through the karst and fissure water-rich area and played an essential role in protecting the spring water.

Hospital-based and community-based ‘high-risk cohort’ studies investigating humans at risk of zoonotic infection due to occupational or residential exposure to animals were conducted in Vietnam, with diverse viruses identified from faecal samples collected from humans, domestic and wild animals. In this study, we focus on the positive-sense RNA virus family Picornaviridae, investigating the prevalence, diversity, and potential for cross-species transmission. Through metagenomic sequencing, we found picornavirus contigs in 23% of samples, belonging to 15 picornavirus genera. Prevalence was highest in bats (67%) while diversity was highest in rats (nine genera). In addition, 22% of the contigs were derived from novel viruses: Twelve phylogenetically distinct clusters were observed in rats of which seven belong to novel species or types in the genera Hunnivirus, Parechovirus, Cardiovirus, Mosavirus and Mupivirus, four distinct clusters were found in bats, belonging to one novel parechovirus species and one related to an unclassified picornavirus. There was no evidence for zoonotic transmission in our data. Our study provides an improved knowledge of the diversity and prevalence of picornaviruses, including a variety of novel picornaviruses in rats and bats. We highlight the importance of monitoring the human–animal interface for possible spill-over events.

The unique electronic properties (electron mobility and carrier lifetime) are key factors for metal oxide semiconductor devices that directly determine the device's performance and application. Electron mobility of metal oxide semiconductor has a certain impact on response and operating temperature of gas sensor. Heterojunction composites of carbon quantum dots (CQDs) and perovskite materials have attracted much attention due to their great potential for gas sensors. In this paper, a gas sensor for monitoring methanol gas was developed based on nitrogen-doped carbon quantum dot/Ag-LaFeO3 (NCQDs/Ag-LaFeO3) p-n heterojunction materials (NALPN). NCQDS and Ag-LaFeO3 form a heterojunction, which improves the carrier transport ability and separation of electron-hole pairs. The surface of NCQDs contains COOH, optimize the selectivity of Ag-LaFeO3 to methanol gas. Gas sensitivity test results show that the NALPN to 5 ppm methanol gas possessed high response (73), low operating temperature (92 °C) and good selectivity. These excellent properties prove that NALPN materials are the main competitors for future gas sensitive materials.

P-type metal oxide semiconductors with special morphology have received high expectation for their potential application in gas sensors. We have synthesized hollow dodecahedral Cu2O nanocages with exposed (1 1 1) planes by a simple solution growth approach at room temperature. Characterization results indicate that the diameters of Cu2O nanocages are about 200 nm. Gas sensing performance of the Cu2O nanocages is investigated towards ethanol gas. Remarkably, the response of Cu2O reaches 4.6 at a low working temperature of 250 °C when the concentration is 100 ppm. The unique structure of Cu2O benefits the sensing performance owing to its active (1 1 1) planes.

Highly sensitive and selective detection against toluene gas remains a tremendous challenge in gas sensor applications. In this work, a series of molecular imprinted Ag-LaFeO3 nanoparticles (IAL NPs) were synthesized in a microwave-assisted colloidal route. Especially, the one prepared with optimal amount of imprint molecules (IAL-2 NPs) have a response of 24.0 to 5 ppm toluene at the optimum working temperature of 215 °C with negligible responses to the other test gases, exhibiting enhanced gas sensing properties for toluene gas at a relatively low working temperature. The improved performance can be attributed to the favorable effect of microwave radiation, the molecular imprinting structure and the sensitization of Ag, which illuminates that IAL-2 NPs is a potential candidate for toluene detection.

High performance acetone gas sensors were fabricated with molecular imprinted polymers of Ag-LaFeO

Xylene is a hazardous volatile organic compound, however, the selective detection of ppm-level xylene using oxide semiconductor gas sensor remains a challenging issue. In this study, Ag-LaFeO 3 was modified with molecular imprinting technique, in which methacrylic acid and hydroxyethyl methylacrylate are used as functional monomers, respectively. Based on XRD, EDS, XPS, SEM, TEM, BET nitrogen adsorption observations, the structure and morphology of the samples are characterized. The as-prepared molecularly imprinted nanoparticles with methacrylic acid as functional monomer exhibit high selectivity and response to xylene gas, and the response is dependent on the type and content of the functional monomer. To 5 ppm xylene, the optimal response is 36.2 at the operating temperature of 99 °C. In addition, low cross-responses to the other test gases were observed. The remarkable enhancement in the gas-sensing properties of the samples is attributed to their high specific surface area and molecular imprinting structure.

Zinc oxide nanoparticles with the different Cd doping contents were prepared by with a surfactant-mediated method in this paper. The effects of Cd doping on the gas sensing properties of the ZnO nanoparticles were studied. The morphology and microstructure of as-prepared samples were characterized by X-ray diffraction (XRD); scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM), respectively. The results reveal that all the products are the high crystalline hexagonal wurtzite ZnO crystal structure. The gas-sensing characteristics of the Cd doped ZnO nanoparticles for volatile organic compounds (VOCs) were investigated. At its optimal operation temperature of 300 °C, the sensing properties of the Cd doped ZnO nanoparticles for n-butanol gas exhibit a high-performance gas sensing performances including high gas response, good selectivity, response/recovery time, and repeatability as well as stability. Especially, its response reaches 130 for 100 ppm n-butanol of ZnO nanoparticles with 2.5% Cd doping. Those values demonstrate the potential of using as-prepared Cd doped ZnO nanoparticles for n-butanol gas detection, making them to be promising candidates for practical detectors to n-butanol gas. Apart from these, the mechanism related to the advanced properties was also investigated and presented.

For developing highly sensitive, selective and stable gas sensing materials for the detection of volatile organic compounds, we report porous micro/nano-level structure Ag-LaFeO3 nanoparticles which have been successfully synthesized using a lotus leaf as a bio-template via a sol–gel process. Combined with the molecular imprinting technique, the selectivity of the gas sensor can be altered and enhanced gas-sensing properties are obtained due to the unique molecular recognition and large specific surface area. The Ag-LaFeO3 nanoparticles are found to exhibit an ultrahigh xylene response (Rg/Ra = 16.76 to 10 ppm), fast gas response and recovery (68 and 36 s) and superior selectivity against the other tested interfering gases at a relatively low operating temperature of 125 °C. They also exhibit excellent humidity stability and long-term stability with small deviations, and this result may deliver a new approach that enables the stable detection of xylene gas.

There is high risk of water inrush and ground collapse when tunneling in sandy cobble stratum in confined aquifer. Among various methods, artificial freezing method is an effective method to pre-reinforce the soft ground to prevent water inrush and ground collapse during tunneling. This paper mainly focuses on application of artificial freezing method using liquid nitrogen in sandy cobble stratum in confined aquifer. The R1 metro tunnel in China’s Jinan city, a well-known City of Springs, is used as a case study. In order to prevent water inrush and ground collapse accidents in the shield machine reception process, liquid nitrogen is applied as a freezing method in the sandy cobble stratum near the reception shaft. First, the heat transition of water in soil associated with liquid nitrogen vaporization is analyzed. Then, a three-dimensional (3D) model is built and the freezing process is simulated. Considering the temperature change of gas nitrogen along the freezing pipe when flowing, the distribution of temperature field and the growth of frozen wall associated with freezing time is obtained. The numerical simulation results show that the freezing method using liquid nitrogen in the sandy cobble stratum can meet the requirement of shield machine reception in sandy cobble stratum rich in groundwater.

High performance acetone gas sensors were fabricated with molecular imprinted polymers of Ag-LaFeO3 (ALFOMMIPs) and multi walled carbon nanotubes (CNTs) composite using the microwave assisted sol-gel method. The crystalline structure, functional groups, grain size and surface appearance of the synthesized materials were analyzed via different characterization techniques and the gas responses of the samples were examined. The detailed acetone gas sensing tests and analysis revealed that the CNTs and ALFOMIPs nanocomposite (CNT/ALFOMIP) sample possessed a higher response than that of the ALFOMIPs sample. Where 0.75 wt% CNTs were added into the ALFOMIPs (0.75% CNT/ALFOMIP nanocomposite) sensor, an excellent gas sensing performance was exhibited. The response of this sensor was up to 59 for 5 ppm acetone vapors and the response and recovery times were 58 and 33 s at low working temperature of 86 °C, respectively. In addition, it had the best selectivity only to acetone vapors due to the use of the molecular imprinting technique.

An ultrasensitive methanol gas sensing device based on the quasi-molecular imprinting technology (quasi-MIT) is studied in this work. We applied the sol-gel method (ALS denotes Ag-LaFeO3 prepared by the sol-gel method) and combustion synthesis (ALC denotes Ag-LaFeO3 prepared by combustion synthesis) to prepare Ag-LaFeO3 based sensors. The morphologies and structures of the Ag-LaFeO3 materials were examined via various detection techniques. The ALSM and ALCM sensor (ALSM and ALCM denotes the devices prepared by coating the ALS and ALC materials with methanol, respectively) fabricated using the sol-gel method and combustion synthesis combined with quasi-MIT exhibit good gas sensing properties to methanol, in contrast with the two devices (ALSW and ALCW denote the devices prepared for coating the ALS and ALC materials with water, respectively) without the use of quasi-MIT. The results show that quasi-MIT introduced the target gas in the fabrication process of the device, playing an important role in the design of the ultrasensitive methanol gas sensor. The sensing response and the optimum working temperature of ALSM and ALCM gas sensor are 52.29 and 155 °C and 34.89 and 155 °C, respectively, for 5 ppm methanol, and the highest response to other gases is 8. The ALSM and ALCM gas sensors reveal good selectivity and response for methanol.

An ultrasensitive methanol gas sensing device based on the quasi-molecular imprinting technology (quasi-MIT) is studied in this work. We applied the sol-gel method (ALS denotes Ag-LaFeO