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A biocompatible and fully erodible PEDOT derivative is reported. An implanted rechargeable Zn–polymer battery demonstrates high rate capacity and full biodegradation in vivo.

In this paper, quaternary oxide semiconductor was applied as sensing material for the fabrication of gas sensors. One-step solvothermal method was utilized to synthesize the sensing material. Various characterization methods including XRD, XPS, SEM, HRTEM were employed to analyze the composition and structure of the sensing material. Composite composed of CuInW2O8 and CuWO4 was successfully prepared at last characterized by XRD result. The SEM result revealed the structure of the sensing material: nanoparticles assembled spindle-like nanostructure with ~200 nm long axis and ~60 nm short axis. Sensor based on the spindle-like nanostructures was systemically tested to acquire the information about the sensing properties. The sensor exhibited responses to acetone at the operating temperatures from 190 to 275 °C. The results showed that the sensor was more sensitive to acetone compared with other gases at the optimal operating temperature of 210 °C. The response of the sensor was also tested under the relative humidity from 25 RH% to 95 RH% at the operating temperature of 210 °C. The response variation was only 13.9%, demonstrating that the sensor possessed strong anti-humidity ability. It was worth noting that the sensor showed acceptable long-term stability compared with other acetone sensors. The gas sensing mechanism was also discussed here. This work might provide ideas for the development of novel sensitive materials for the application of gas sensors.

Lipid droplets (LDs) are important cellular organelles associated with many physiological processes. To visualize and study LDs, particularly the nascent LDs (diameters of 30–60 nm), super-resoluti...

A long-standing goal has been to create artificial enzymes with natural enzyme-like catalytic activity. Herein, a laccase-mimicking catalyst (GSH-Cu) is designed by simulating the copper active sites and spatial amino acid microenvironment of natural enzymes. In particular, the engineered GSH-Cu shows a catalytic function that conforms to Michaelis-Menten kinetics of natural laccase. The high catalytic activity of GSH-Cu can be easily inhibited by thiram through surface passivation to produce copper nanoparticles. We demonstrate that the developed GSH-Cu with high stability and recyclability can be used to fabricate effective colorimetric sensor for sensitive detection of thiram. The resulting absorption intensity can be employed to quantify thiram in the range of 2.5-250 ng mL

Abstract Environmentally friendly degradable sensors with both hazardous gases and pressure efficient sensing capabilities are highly desired for various promising applications, including environmental pollution monitoring/prevention, wisdom medical, wearable smart devices, and artificial intelligence. However, the transient gas and pressure sensors based on only identical sensing material that concurrently meets the above detection needs have not been reported. Here, we present transient all-MXene NO2 and pressure sensors employing three-dimensional porous crumpled MXene spheres prepared by ultrasonic spray pyrolysis technology as the sensing layer, accompanied with water-soluble polyvinyl alcohol substrates embedded with patterned MXene electrodes. The gas sensor achieves a ppb-level of highly selective NO2 sensing, with a response of up to 12.11% at 5 ppm NO2 and a detection range of 50 ppb–5 ppm, while the pressure sensor has an extremely wide linear pressure detection range of 0.14–22.22 kPa and fast response time of 34 ms. In parallel, all-MXene NO2 and pressure sensors can be rapidly degraded in medical H2O2 within 6 h. This work provides a new avenue toward environmental monitoring, human physiological signal monitoring, and recyclable transient electronics.

Hedgehog-like titanium dioxide (TiO2) architectures composed of hundreds of one-dimensional (1D) nanorods and silver (Ag) loaded TiO2 with different amounts (0.2 at%, 0.5 at% and 1 at%) were successfully prepared by facile hydrothermal process and simple isometric impregnation route. The high electron mobility of 1D nanorods on the surface of TiO2 and the high porosity of Ag loaded hedgehog-like TiO2 architectures enable the sensor with fast responsive and recovered properties. TiO2 loaded with 0.5 at% Ag exhibited the highest response to xylene with low response/recovery time at the operating temperature of 375 °C. In addition, the sensitivity and selectivity of the TiO2 sensor were enhanced markedly with Ag loading.

In this work, 5–20 at% gas-accessible WO3-NiO hollow nanoflowers were synthesized through a one-step hydrothermal route and used to fabricate metal oxide semiconductor (MOS) based gas sensor. The gas-accessible WO3-NiO hollow nanostructures showed much larger BET surface areas (168.0–203.8 m2 g−1) than that of the pure NiO (45.9 m2 g−1). In the comprehensive gas sensing test, the gas device based on 10 at% WO3-NiO hollow microspheres exhibited the best xylene sensing performance, showing ultrahigh xylene sensitivity (354.7–50 ppm) with short response-recovery times within 1 min. (51 and 57 s respectively) and ultralow detection limit (1.5–50 ppb xylene). Additionally, the 10 at% WO3-NiO based sensor also showed superior xylene selectivity against other interfering gases in a wide temperature range (250–350 °C). Especially at the optimal 300 °C, the 50-ppm xylene sensitivity was 8.1 and 10.3 times higher than that of 50-ppm representative acetone (Sxylene/Sacetone = 8.1) and ethanol (Sxylene/Sethanol = 10.3) gases, respectively. The mechanisms for the excellent xylene sensing performance were also discussed.

Urchin-like hierarchical Zn doped CdS powders were successfully synthesized via simple one-pot hydrothermal process. Their SEM and TEM images indicated that the hierarchical structure were assembled by single crystal nanorods with the hexagonal wurtzite phase. EDS element mapping verified that Zn ions were homogeneously distributed among the hierarchical microstructure. The performances of gas sensors based on pure and Zn doped CdS were measured and compared. The results indicated that Zn doping could enhance their responses to some volatile organic compounds and improve its selectivity to ethanol and toluene as well. The possible reasons for this enhancement were investigated. In addition, the sensor based on Zn doped CdS exhibited the ultrafast response and recovery to ethanol ( τ response 1 , τ recovery = 8 s ), indicating that the Zn doped CdS could be a promising gas sensing candidate for online monitoring of ethanol.

Mulberry-shaped tin oxide (SnO2) hierarchical architectures and samarium oxide (Sm2O3) loaded tin oxide with different amounts (0.5, 1, 2.5, and 4 mol% Sm2O3) were successfully synthesized by facile hydrothermal synthesis method and simple isometric impregnation method. The gas sensing performance of the sensors based on pure SnO2 and Sm2O3 loaded SnO2 materials were systematically investigated. The results indicated that Sm2O3 loading considerably affected the improvement of the sensing performance of the SnO2 sensor. The 2.5 mol% Sm2O3/SnO2 exhibited the highest response (41.14) to 100 ppm acetone, the response was 2.29 times higher than that of pure SnO2 (18). In addition, with 2.5 mol% Sm2O3 loading, the low detection threshold of the sensor dropped from 500 ppb to 100 ppb. The enhanced gas sensing performance was mainly bacause of the increased oxygen vacancies created by the substitution of samarium in the SnO2 lattice, which enhanced the adsorption of oxygen and the exceptional catalytic effect of Sm2O3.

On-site monitoring of carbamate pesticide in complex matrix remians as a challenge in terms of the real-time control of food safety and supervision of environmental quality. Herein, we fabricated robust upconversion nanoparticles (UCNPS)/polydopamine (PDA)-based hydrogel portable suit that precisely quantified carbaryl in complex tea samples with smartphone detector. UCNPS/PDA nanoprobe was developed by polymerization of dopamine monomers on the surface of NaErF4: 0.5% Tm3+@NaYF4 through electrostatic interaction, leading to efficient red luminescence quenching of UCNPS under near-infrared excitation, which circumvented autofluorescence and background interference in complicated environment. Such a luminescence quenching could be suppressed by thiocholine that was produced by acetylcholinesterase-mediated catalytic reaction, thus enabling carbaryl bioassay by inhibiting the activity of enzyme. Bestowed with the feasibility analysis of fluorescent output, portable platform was designed by integrating UCNPS-embedded sodium alginate hydrogel with 3D-printed smartphone device for quantitatively on-site monitoring of carbaryl in the range of 0.5–200 ng mL-1 in tea sample, accompanied by a detection limit of 0.5 ng mL-1. Owing to specific UCNPS signatures and hydrogel immobilization, this modular platform displayed sensitive response, portability and anti-interference capability in complex matrix analysis, thus holding great potential in point-of-care application.

In this work, ethanol gas sensor with high performance was fabricated successfully with hierarchical CoO/SnO2 heterojunction by two-steps hydrothermal method. The response value of CoO/SnO2 sensor is up to 145 at 250 °C when exposed to 100 ppm ethanol gas, which is much higher than that (13.5) of SnO2 sensor. These good sensing performances mainly attribute to the formation of the CoO/SnO2 heterojunction, which makes great variation of resistance in air and ethanol gas. Thus, the combination of n-type SnO2 and p-type CoO provides an effective strategy to design new ethanol gas sensors. The unique nanostructure also played an important role in detecting ethanol, due to its contribution in facilitating the transport rate of the ethanol gas molecules. Also, we provide a general two-step strategy for designing the heterojunction based on the SnO2 nanostructure.

The NO2 sensing performance of a stabilized zirconia (YSZ)-based mixed potential type gas sensor utilizing a Co3V2O8 sensing electrode (SE) was improved by the addition of a noble metal. Among the different types of noble metal (Au, Pt, Pd and Rh), the sensor attached with Co3V2O8-SE loaded with Rh exhibited a noticeable improvement in NO2 response and the maximum response value was obtained when the loading mass fraction of Rh was 3 wt%. Results showed that the response for the sensor utilizing 3 wt% Rh/Co3V2O8-SE was 113.5 mV to 50 ppm NO2 and the sensitivity to 10–300 ppm NO2 was 85 mV per decade at the operating temperature of 650 °C, which were enhanced by 77.5 mV and 39 mV per decade compared to those of a sensor attached with Co3V2O8-SE, respectively. It is noteworthy that the response for each of sensor displayed a good linear relationship to the logarithm of NO2 concentration in the ranges of 10–300 ppm at 650 °C. Additionally, the sensor attached with 3 wt% Rh/Co3V2O8-SE also exhibited a low detection limit of 500 ppb and good selectivity to NO2 at 650 °C. The improvement of sensing characteristics for a sensor using 3 wt% Rh/Co3V2O8-SE may be attributed to enhanced electrochemical catalytic reaction activity to NO2 and a mixed potential mechanism was further verified by polarization curve.

Precise monitoring of pesticide with portable device was challenging because it required high sensitivity, short response time, strong stability and excellent selectivity. Herein, we newly constructed a stimuli-responsive hydrogel (SRHg)-based portable kit by embedding copper nanoparticles (CuNPs) in agarose hydrogel. In this work, dimethoate as inhibitor of urease restrained the generation of ammonia, which reduced in-situ etching of CuNPs, resulting in the fluorescence color response of test kit under ultraviolet illumination. Interestingly, by means of smartphone-based nanocolorimetry, the photo image of portable kit could be translated into digital information using ImageJ software, achieving a direct quantitative tool for dimethoate identification. The simplicity of SRHg-based portable kit combined with smartphone-based color recognition not only improved the analysis sensitivity (detection limit of 1.0 μg L−1), accuracy and stability, but also simplified operation process and shortened sample-to-answer analysis time (55 min), demonstrating that the methodology met the needs of daily testing and provided a new sight for on-site monitoring of food safety and human health.

Accurate analysis of organophosphate pesticides (OPs) with portable devices remain an elusive goal that have received widespread investigative attention in the areas of environmental contamination and disease prevention. Herein, using all-in-one enzyme-inorganic hybrid nanoflowers (ACC-HNFs) to fabricate high-performance artificial enzyme cascade system, we established a sensitive and affordable lab-on-paper biosensor. This biosensor incorporated disposable screen-printed carbon electrode (SPCE) and colorimetric test strips, which enabled the dual-modal readout (electrochemical and colorimetric signal) for on-site monitoring of OPs, achieving an “on-demand” tuning of the detection performance. Using paraoxon as a model analyte, the ACC-HNFs-based lab-on-paper platform could reach a limit of detection down to the femtogram/mL level (6 fg mL−1). Meticulous design of ACC-HNFs provided a versatile approach for constructing artificial enzyme as a recognizer and amplifier to fill the gap in constructing robust artificial enzyme systems which can be used for on-site contamination monitoring and biological diagnosis.

A mixed-potential type stabilized zirconia (YSZ)-based gas sensor using columbite type composite oxide sensing electrode was developed and fabricated, aiming at sensitive detection of ethanol. Among the different oxide sensing electrodes (SEs) developed, the sensor attached with ZnNb2O6-SE was found to achieve the largest sensitivity to ethanol at 625 °C. Furthermore, the result of the effect of sintering temperature on sensing characteristic showed that the sensor utilizing ZnNb2O6-SE sintered at 1000 °C displayed the highest response of −175 mV to 100 ppm ethanol and a low detection limit of 0.5 ppm at 625 °C. ΔV of the present sensor exhibited a segmentally linear relationship to the logarithm of ethanol concentration in the ranges of 0.5–5 ppm and 5–200 ppm, for which the sensitivities were −29 and −112 mV decade−1, respectively. Moreover, the fabricated device also displayed fast response and recovery times, good repeatability, small fluctuation during 30 days continuous high temperature of 625 °C measured periods, and acceptable selectivity to some other interfering gases. Additionally, the sensing mechanism involving mixed potential was further demonstrated by polarization curves.

Pd-doped SnO2 hollow spheres were synthesized via a facile one-step hydrothermal route. Utilized as the materials in sensors, the 3.0 wt% Pd-doped SnO2 demonstrated more excellent gas-sensing properties towards CO than 1.5 wt% and 4.5 wt% Pd-doped SnO2. Compared with the SnO2 hollow spheres gas sensor, the optimum operating temperature of the Pd-doped SnO2 hollow spheres gas sensor dropped to 200 °C from 250 °C; the response value to 100 ppm CO was raised to 14.7 from 2.5 accordingly. Furthermore, the response and recovery times of the 3.0 wt% Pd-doped SnO2 sensor are 5 s and 92 s, respectively, to 100 ppm CO at 200 °C. It is believed that its enhanced gas-sensing performances are derived from the synergistic interactions between the dispersed Pd and the characteristic configuration of the SnO2 hollow sphere. In addition, theoretical calculations have also been performed with periodic slab models by using density functional theory, which explain well our experimental phenomenon.

In this study, indium oxide (In2O3) hollow nanofibers were synthesized through a two-step process. In2O3 solid nanofibers were prepared by electrospinning, and 10% HNO3 was used to corrode these nanofibers to obtain In2O3 hollow nanofibers. Moreover, the effects of corrosion on the morphology and acetone-sensing properties of In2O3 nanofibers were investigated. In2O3 nanofibers that were corroded for 2 h displayed hollow structures and exhibited a high response (resistance ratio) of 151 to 5 ppm of acetone at 300 °C. The minimum detection limit was 20 ppb. The hollow In2O3 nanofibers also exhibited high selectivity to acetone along with negligible cross-responses to interference gases at 300 °C, These gases include NO2, H2, CO, benzene, p-xylene, and toluene. The strong response to acetone was attributed to the enhanced accessibility of gas for gas-sensing reactions due to the hollow morphology.

Oxalate is commonly employed as adjuvant of pesticide agent, causing renal injury of human even in trace residues. Despite the great achievements of the existing point-of-care testing (POCT) technology, accurate on-site screening of oxalate remains a tricky issue. To this aim, we proposed a “lab in a tube” platform which integrated portable hydrogel kit with smartphone for real-time monitoring of oxalate to achieve quantitatively precise analysis. In this work, a stimuli-responsive hydrogel-based kit was constructed via embedding manganese dioxide (MnO2) nanosheets into sodium alginate hydrogel system. Based on the intrinsic oxidase-like activity, MnO2 nanosheets-based nanozyme triggered color reaction by introducing a common sensing probe 3,3′,5,5′-tetramethylbenzidine. Meanwhile, the presence of oxalate would decompose MnO2 nanosheets, inducing the decrease of nanozyme activity, which resulted in the color response of portable kit. Coupling with ImageJ software, the image information of kit captured via smartphone could be transduced into the hue intensity, which provided a directly quantitative tool to detect oxalate with a detection limit of 8.0 μmol L−1. This portable smartphone biosensor was successfully applied for screening urine sample within 10 min for high-throughput analysis (twelve samples) without the need for any advanced analytical instruments. Based on the merits of simple operation, cost-efficiency, and good selectivity, the availability of the miniaturized biosensor platform for POCT will achieve the requirements of routine screening and disease prevention.

In this work, 5-20 at% gas-accessible WO

Nitrogen dioxide (NO2), as a typical threatening atmospheric pollutant, is hazardous to the environment and human health. Thus, the development of a gas sensor with high response and low detection limit for NO2 detection is highly important. The highly ordered mesoporous indium trioxide (In2O3) prepared by simple nanocasting method using mesoporous silica as template and decorated with Au nanoparticles was investigated for NO2 detection. The prepared materials were characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Characterization results showed that the samples exhibited ordered mesostructure and were successfully decorated with Au. The gas sensing performance of the sensors based on a series of Au-loaded mesoporous In2O3 were systematically investigated. The Au loading level strongly affected the sensing performance toward NO2. The optimal sensor, which was based on 0.5 wt% Au-loaded In2O3, displayed high sensor response and low detection limit of 10 ppb at low operating temperature of 65 °C. The excellent sensing properties were mainly attributed to the ordered mesoporous structure and the catalytic performance of Au. We believe that the Au-loaded mesoporous In2O3 can provide a promising platform for NO2 gas sensors with excellent performance.

In this work, flower-like In2O3 nanostructures were prepared with a solvothermal method in the presence of K3C6H5O7·H2O. The as-synthesized samples were characterized by using X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The results indicate that the synthesized flower-like In2O3 nanostructures were constructed by porous nanosheets. The gas sensing properties of the as-obtained products were investigated. It was found that the sensor based on such flower-like In2O3 nanostructures exhibited high response and good selectivity to NO2.

In this work, ethanol gas sensor with high performance was fabricated successfully with hierarchical CoO/SnO

A novel flame retardant containing phosphorus and sulfur, bis(2-tienyl)phenylphosphine (BTPP) was synthesized and characterized with Fourier transform infrared spectroscopy, 1H, 13C, and 31P nuclear magnetic resonance. BTPP was used to impart flame retardancy to polycarbonate (PC). Combustion behaviors and thermal degradation properties of PC/BTPP system were assayed by limiting oxygen index (LOI), vertical burning test (UL-94), cone calorimeter test, and thermogravimetric analysis. PC/3 wt% BTPP passed UL-94 V-0 rating with 3.0 mm samples and the LOI value was 36.5%. PC/6 wt% BTPP passed UL-94 V-0 rating with 1.6 mm samples and the LOI value was 38.5%. Scanning electron microscopy revealed that char properties had direct effects on the flame retardancy. Mechanical properties and water resistance of PC/BTPP system were also examined. After water resistance test, PC/3 wt% BTPP with 3.0 mm samples and PC/6 wt% BTPP with 1.6 mm samples kept V-0 rating and mass loss were only 0.2%. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

In order to get an accurate understanding of the construction safety of deep foundation pit in metro station and reduce the probability and loss of risk occurrence, a risk assessment method based on G-COWA is proposed. Firstly, relying on the specific engineering examples and the construction characteristics of deep foundation pit, an evaluation index system based on the five factors of "human, management, technology, material and environment" is established. Secondly, the C-OWA operator is introduced to realize the evaluation index empowerment and weaken the negative influence of expert subjective preference. The gray cluster analysis and fuzzy comprehensive evaluation method are combined to construct the construction risk assessment model of deep foundation pit, which can effectively solve the uncertainties. Finally, the model is applied to the actual project of deep foundation pit of Qingdao Metro North Station, determine its construction risk rating is "medium", evaluate the model is feasible and reasonable. And then corresponding control measures are put forward and useful reference are provided.