Selectivity has been considered as one of the most significant performances to evaluate the practical application of the metal oxide semiconductor (MOS) gas sensor. Temperature modulation is now a ...commonly recognized method in enhancing the sensor selectivity as it can reflect more feature reaction information. In this paper, a novel method in the gas identification by using WO3 gas sensor based on the temperature-programmed modulation is reported. This method allows us to be capable of dynamically obtaining the temperature-dependent electrical conductivity (TEC) spectra in different atmospheres. In terms of the TEC of the WO3, a rigorous method for extracting the feature parameters is presented here, which are associated with the gas adsorption/desorption and defect reaction mechanisms, from the differential curve d{lnσT3/2}/dT−T. According to the feature parameters, we can clearly figure out the gas species that cannot be accomplished by the conventional methods. The temperature-programmed modulation thus provides a fundamental method for accurately identifying the gas species and is expected aid in opening up a new way to investigate the selectivity of the MOS gas sensors.
Abstract Background Cancer and sarcopenia are both closely related to lipid metabolism, but the relationship between lipid metabolism and patients with cancer and sarcopenia has not been thoroughly ...studied. The non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) is a reliable measure of lipid metabolism. The purpose of this study was to determine the possible relationship between the NHHR and sarcopenia in individuals with cancer. Methods Data from the National Health and Nutrition Examination Survey (NHANES) database for individuals with cancer, with and without sarcopenia was analyzed using weighted multiple regression equations, weighted regression cubic spline (RCS) analysis, and weighted subgroup analysis. Results In total, 1,602 individuals with cancer were included, of whom 17.1% had sarcopenia. In Adjusted Model 2, the occurrence of sarcopenia was found to be significantly associated with a higher NHHR in cancer (95% confidence interval CI:1.01–1.39, P = 0.036). Individuals with high a NHHR had a 2.09-fold higher risk of developing sarcopenia in comparison to those with a low NHHR (95% CI:1.12–3.92, P = 0.022). RCS analysis further identified a U-shaped non-linear relationship between females with cancer and the muscle index. Subgroup analysis indicated that sex was a significant stratifying factor, whereas age, race, marital status, smoking and drinking habits, and history of cardiovascular disease, arthritis, hypertension, and diabetes had no significant impact. Conclusion From the perspective of lipid metabolism, the NHHR may serve as an indicator for monitoring and preventing the occurrence of sarcopenia in individuals with cancer, particularly for females with cancer who appear to have greater sensitivity.
•Temperature & light modulation is a effective method to enhance the selectivity of metal oxide gas sensors.•The feature extraction method we use can obtain characteristic parameters containing the ...information about surface reactions.•Combined with pattern recognition methods, tested gases can be easily discriminated.
Metal oxide (MOX) has been used as resistive gas sensors for a long time. The gas sensitive response under constant temperature measurement is a broad-spectrum response, resulting in poor selectivity. To solve this problem and enhance the selectivity of a single sensing film, gas sensor based on Pt-modified zinc oxide was prepared by homogeneous precipitation and screen printing method. Afterwards, the temperature & light modulation method is first proposed herein. This method allows us to obtain different Resistance-Temperature (R-T) curves and characteristic parameters, photoresponse and photorelaxation. Combined with pattern recognition method, five tested gases, including ethanol, methanol, acetone, formic acid and ethyl ether, can be successfully classified. Compared with temperature modulation, which is usually used as a method to enhance selectivity, temperature & light modulation method can increase the classification rate from 95.55% to 100% for sensing these five tested gases. The results indicate that the temperature & light modulation method is an effective method for improving the selectivity of the gas sensor.
3-D NAND flash memory has become increasingly popular nonvolatile storage devices due to large capacity and high performance. With the increase of program/erase (P/E) cycles and retention periods, ...the threshold voltage distribution of 3-D NAND flash memory is prone to shift such that it is difficult to accurately obtain the read reference voltage (RRV). When reading data, read retry operations perform multiple flash sensing to read bit information correctly, inducing extended read latency. To mitigate the read latency, a method of precisely acquiring the RRV is urgently needed. Using an field-programmable gate array (FPGA) hardware testing platform, this article first studies error characteristics of 3-D triple-level cell (TLC) NAND flash memory with the floating gate (FG) structure, which includes the variations of raw bit error rates (RBERs) in different layers and pages, the variations of block reads under different read modes, and the threshold voltage shifting characteristic. Then, based on these characterizations, this article develops an error characteristic aware RRV acquisition scheme, called ECRRV, to gain optimal RRV by exploiting the least square method. Experimental results show that the proposed scheme can significantly diminish the RBER and block read count.
Zn-doped SnO2 nanorods clusters with controllable size (the length and the diameter of nanorods) are prepared by adjusting the Zn2+ concentration in the precursor solution using a facile hydrothermal ...process. The as-synthesized samples are characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and energy-dispersive X-ray spectroscopy (EDS). With an increase of the molar ratio of Zn2+/Sn4+ in the solution, the length of the Zn-doped SnO2 nanorods gradually increases, and the average length of the nanorods reaches the maximum of 239nm at 0.133. However, when the molar ratio of Zn2+/Sn4+ is increased to 0.2, the length of the nanorods decreases accompanied with the generation of Zn2SnO4 phase. The Zn-doped SnO2 nanorods grow along the 112 direction and the possible growth mechanism is proposed. The gas-sensing properties of the obtained Zn-doped SnO2 samples are tested towards methanol gas. And, it is found the composition-morphology-performance relationship that the more the doping content of Zn, the longer the length of nanorods and the higher the response to methanol, which is significant for the preparation and the design of gas-sensing materials with the high performance.
In this work, we report on the gas-sensing behavior of Al-doped SnO2 nanotubes (NTs) in order to evaluate the effect of Al on improved sensing performance and propose an oxygen-vacancy-dominating ...sensing mechanism of SnO2. The hierarchical mesoporous Al-doped SnO2 NTs are fabricated by simple electrospinning method and annealing treatment. Al-doping shows profound influence on the oxygen vacancy of SnO2 which changes as a function of Al/(Al+Sn) ratio and the oxygen vacancy exhibits a maximum value when the ratio is 8%. As a result, the gas-sensing response to formaldehyde varies following the oxygen vacancies. Oxygen vacancies at the surface of SnO2 facilitate oxygen adsorption and the formation of surface catalytic active O−O−, thus the gas response is remarkably enhanced. Furthermore, a new fundamental understanding toward the gas-sensing performance of oxygen-vacancy-dominating SnO2 is proposed.
CeO
2-doped ZnO thin-film gas sensors with different Ce/Zn ratios have been fabricated by dip-coating method, starting from zinc acetate dihydrate, cerium nitrate hexahydrate (Ce(NO
3)
3·6H
2O) and ...anhydrous ethanol. Each layer was fired at 180
°C in a conventional oven for 30
min and the final coatings were sintered at 500
°C in a muffle furnace for 60
min. The microstructure and morphology of the films were characterized by XRD and FESEM, respectively. The resistance and sensitivities to volatile organic compounds were investigated on the static testing chamber. The X-ray diffraction (XRD) analysis of the films reveals the appearance of CeO
2, tetravalent cerium dioxide whose valency is different from cerium nitrate hexahydrate. The results also show that as-prepared thin films with thickness of about 5
μm are polycrystalline with the structure of hexagonal wurtzite type. They consist of almost spherical particles with size ranging from 40 to 65
nm. Pure ZnO and Ce-doped ZnO thin-film sensors were prepared and tested for specific sensitivity to alcohol, acetone and benzene. It is observed that 1
at.% Ce–ZnO and 5
at.% Ce–ZnO are more sensitive to volatile organic compounds (VOCs), compared with other films with the different dopant concentration. The sensitivity of 5
at.% Ce–ZnO thin-film sensors to 100
ppm alcohol reaches 80 or so at 320
°C. 5
at.% Ce–ZnO thin-film sensors show good selectivity to alcohol, and thus can serve as alcohol-sensing sensors. A new physical model of the CeO
2 dopant influence on the gas-sensing properties of ZnO thin films is proposed. The addition of Ce to ZnO modified the particles size distribution, electrical conductivity, the catalytic activity and thus affected gas-sensing property to some extent.
Defect graphene was reported by adding sugar through solvothermal method. The characterization results of XRD, IR, Raman, and XPS showed that the samples have tunable mount of oxygenated group, which ...plays a role as adsorption site to detecting humidity gas molecule. The sample from sucrose has the highest mount of functional oxygenated groups and shows the best humidity property.
► Graphene with tunable defect was reported through solvothermal method. ► The defect was considered as oxygenated groups based on characterization results. ► The sample from sucrose has the most mount of functional oxygenated groups. ► The defect plays a role as adsorption site to detecting humidity gas molecule. ► The sample from sucrose shows the best humidity property.
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