Electronic Nose Drift Suppression Based on Smooth Conditional Domain Adversarial Networks.

Anti-drift is a new and serious challenge in the field related to gas sensors. Gas sensor drift causes the probability distribution of the measured data to be inconsistent with the probability distribution of the calibrated data, which leads to the failure of the original classification algorithm. In order to make the probability distributions of the drifted data and the regular data consistent, we introduce the Conditional Adversarial Domain Adaptation Network (CDAN)+ Sharpness Aware Minimization (SAM) optimizer-a state-of-the-art deep transfer learning method.The core approach involves the construction of feature extractors and domain discriminators designed to extract shared features from both drift and clean data. These extracted features are subsequently input into a classifier, thereby amplifying the overall model's generalization capabilities. The method boasts three key advantages: (1) Implementation of semi-supervised learning, thereby negating the necessity for labels on drift data. (2) Unlike conventional deep transfer learning methods such as the Domain-adversarial Neural Network (DANN) and Wasserstein Domain-adversarial Neural Network (WDANN), it accommodates inter-class correlations. (3) It exhibits enhanced ease of training and convergence compared to traditional deep transfer learning networks. Through rigorous experimentation on two publicly available datasets, we substantiate the efficiency and effectiveness of our proposed anti-drift methodology when juxtaposed with state-of-the-art techniques.

A Non-Disposable Electrochemical Sensor Based on Laser-Synthesized Pd/LIG Nanocomposite-Modified Screen-Printed Electrodes for the Detection of H2O2.

There have been many studies on the significant correlation between the hydrogen peroxide content of different tissues or cells in the human body and the risk of disease, so the preparation of biosensors for detecting hydrogen peroxide concentration has been a hot topic for researchers. In this paper, palladium nanoparticles (PdNPs) and laser-induced graphene (LIG) were prepared by liquid-phase pulsed laser ablation and laser-induced technology, respectively. The complexes were prepared by stirring and used for the modification of screen-printed electrodes to develop a non-enzymatic hydrogen peroxide biosensor that is low cost and mass preparable. The PdNPs prepared with anhydrous ethanol as a solvent have a uniform particle size distribution. The LIG prepared by laser direct writing has good electrical conductivity, and its loose porous structure provides more adsorption sites. The electrochemical properties of the modified electrode were characterized by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. Compared with bare screen-printed electrodes, the modified electrodes are more sensitive for the detection of hydrogen peroxide. The sensor has a linear response range of 5 µM-0.9 mM and 0.9 mM-5 mM. The limit of detection is 0.37 µM. The above conclusions indicate that the hydrogen peroxide electrochemical biosensor prepared in this paper has great advantages and potential in electrochemical catalysis.

Experimental and Density Functional Theory Simulation Research on PdO-SnO2 Nanosheet Ethanol Gas Sensors.

Pure SnO2 and 1 at.% PdO-SnO2 materials were prepared using a simple hydrothermal method. The micromorphology and element valence state of the material were characterized using XRD, SEM, TEM, and XPS methods. The SEM results showed that the prepared material had a two-dimensional nanosheet morphology, and the formation of PdO and SnO2 heterostructures was validated through TEM. Due to the influence of the heterojunction, in the XPS test, the energy spectrum peaks of Sn and O in PdO-SnO2 were shifted by 0.2 eV compared with SnO2. The PdO-SnO2 sensor showed improved ethanol sensing performance compared to the pure SnO2 sensor, since it benefited from the large specific surface area of the nanosheet structure, the modulation effect of the PdO-SnO2 heterojunction on resistance, and the catalyst effect of PdO on the adsorption of oxygen. A DFT calculation study of the ethanol adsorption characteristics of the PdO-SnO2 surface was conducted to provide a detailed explanation of the gas-sensing mechanism. PdO was found to improve the reducibility of ethanol, enhance the adsorption of ethanol's methyl group, and increase the number of adsorption sites. A synergistic effect based on the continuous adsorption sites was also deduced.

In Situ Growth of Leakage-Free Direct-Bridging GaN Nanowires: Application to Gas Sensors for Long-Term Stability, Low Power Consumption, and Sub-ppb Detection Limit.

Direct-bridge growth of aligned GaN nanowires (NWs) over the trench of GaN-coated sapphire substrate was realized in which the issues of parasitic deposition and resultant bypass current were resolved by combining the novel shadowing effect of the deep trench with the surface-passivation effect of the SiO2 coating. Due to the robust connection and the absence of a contact barrier in bridging NWs, the intrinsic sensing properties of the NW itself can be obtained. For the first time, the gas-sensing properties (e.g., NO2) of the bridging GaN NWs were studied. With the assistance of UV light, the detection limit was improved from 4.5 to 0.5 ppb at room temperature, and the corresponding response time was reduced from 518 to 18 s. This kind of sensor is promising for high sensitivity (detection of less than parts per billion), low power consumption (capable of room-temperature operation), high stability (variation in resistance of <0.8% during 240 days), and in situ monolithic integration.

Rapid Prototyping Flexible Capacitive Pressure Sensors Based on Porous Electrodes.

Flexible pressure sensors are widely applied in tactile perception, fingerprint recognition, medical monitoring, human-machine interfaces, and the Internet of Things. Among them, flexible capacitive pressure sensors have the advantages of low energy consumption, slight signal drift, and high response repeatability. However, current research on flexible capacitive pressure sensors focuses on optimizing the dielectric layer for improved sensitivity and pressure response range. Moreover, complicated and time-consuming fabrication methods are commonly applied to generate microstructure dielectric layers. Here, we propose a rapid and straightforward fabrication approach to prototyping flexible capacitive pressure sensors based on porous electrodes. Laser-induced graphene (LIG) is produced on both sides of the polyimide paper, resulting in paired compressible electrodes with 3D porous structures. When the elastic LIG electrodes are compressed, the effective electrode area, the relative distance between electrodes, and the dielectric property vary accordingly, thereby generating a sensitive pressure sensor in a relatively large working range (0-9.6 kPa). The sensitivity of the sensor is up to 7.71%/kPa-1, and it can detect pressure as small as 10 Pa. The simple and robust structure allows the sensor to produce quick and repeatable responses. Our pressure sensor exhibits broad potential in practical applications in health monitoring, given its outstanding comprehensive performance combined with its simple and quick fabrication method.

Electrochemical Sensor Made with 3D Micro-/Mesoporous Structures of CoNi-N/GaN for Noninvasive Detection of Glucose.

Noninvasive detection of glucose (NGD) is important because ∼10% of the global population is suffering from diabetes. Herein, a three-dimensional (3D) micro-/mesoporous structure, i.e., a CoNi-N nanosheet-coated GaN 3D scaffold (CoNi-N@GaN-3S), was proposed for detecting saliva glucose, where the GaN scaffold can provide a large open surface for nanosheet decoration, while the catalytic nanosheets can increase the surface area and prevent the GaN-3S from anodic corrosion. Moreover, it was found that high-temperature ammoniation of CoNi can lead to dense atomic holes and an N-terminated surface (CoNi-N), which promoted the ionization of CoNi with a higher catalytic activity. It is the first time that dense atomic holes have been observed in CoNi to our knowledge. The designed CoNi-N@GaN-3S sensor was applied to the electrochemical detection of glucose with a low limit of detection (LOD) of 60 nM and a high sensitivity, selectivity, and stability. In addition, detection of human-saliva glucose was realized with an LOD of 5 µM, which was more than 4-fold lower than reported reliable LODs. An integrated sensor with a low consumption of saliva sample was demonstrated for NGD.

Biobased Plasticizers from Tartaric Acid: Synthesis and Effect of Alkyl Chain Length on the Properties of Poly(vinyl chloride).

A series of tartaric acid (TA) esters with different side chain lengths [dibutyl TA esters (DBTAE)-Cn], as plasticizers for poly(vinyl chloride) (PVC), is herein reported. Their structures have been fully characterized using proton nuclear magnetic resonance and Fourier-transform infrared spectroscopy. Their compatibility and plasticizing effect for soft PVC were evaluated using thermogravimetric analysis, dynamic mechanical analysis, tensile testing, and migration testing. The results showed that all these TA esters exhibit good plasticizing performance. At a concentration of 30 phr in PVC, the best results for the plasticizing effect, in terms of glass transition temperature reduction and elongation at break, were achieved when the ester DBTAE-C4 was used. However, the longer side chains of these esters improved the thermal stability of soft PVC blends yet exacerbated the migration behavior of these esters from PVC films in n-hexane. The properties of the plasticized PVC blends depended on the structural features of DBTAE-Cn. The plasticizing performances of the esters DBTAE-C1 and DBTAE-C4 rivaled that of dioctyl phthalate (DOP), suggesting that they have the potential to replace DOP in soft PVC materials.

Electrical and photoresponse properties of an intramolecular p-n homojunction in single phosphorus-doped ZnO nanowires.

The single-crystal n-type and p-type ZnO nanowires (NWs) were synthesized via a chemical vapor deposition method, where phosphorus pentoxide was used as the dopant source. The electrical and photoluminescence studies reveal that phosphorus-doped ZnO NWs (ZnO:P NWs) can be changed from n-type to p-type with increasing P concentration. Furthermore, we report for the first time the formation of an intramolecular p-n homojunction in a single ZnO:P NW. The p-n junction diode has a high on/off current ratio of 2.5 x 10(3) and a low forward turn-on voltage of approximately 1.37 V. Finally, the photoresponse properties of the diode were investigated under UV (325 nm) excitation in air at room temperature. The high photocurrent/dark current ratio (3.2 x 10(4)) reveals that the diode has a potential as extreme sensitive UV photodetectors.

Role of sp-d exchange interactions in room-temperature photoluminescence and ferromagnetism of CuCo Co-doped ZnO nanorods.

CuCo co-doped ZnO nanorods have been synthesized via a soft chemistry route without using any surfactant, seed and catalyst. Structural analyses reveal that the samples of nominal compositions Cu0.01Co0.02Zn0.97O and Cu0.02Co0.01Zn0.97O have single hexagonal wurtzite structure without forming any extra secondary phase. Photoluminescence (PL) measurements show that the Cu co-doping in Co doped ZnO nanorods strongly influences the optical band structure and gives significant red shifts in the PL spectra. Furthermore, magnetic measurements of CuCo co-doped ZnO nanorods exhibit obvious room temperature ferromagnetism at low concentrations of Cu (< 1%) co-doping, while at higher concentrations of Cu co-doping, magnetization drops off sharply. An experimental relationship has been found to explain the redshift of E(g) edge in PL and the origin of observed ferromagnetism as function of Cu co-dopant concentration due to the spin exchange interactions between the sp band and localized spins of d electrons of dopants, which is useful for future semiconductor based spintronic devices.

DFT calculation and analysis of the gas sensing mechanism of methoxy propanol on Ag decorated SnO2 (110) surface.

Methoxy propanol has been widely used in modern industry and consumer products. Inhalation or skin exposure to methoxy propanol for a long period would bring about safety challenges on human habitat and health. Ag decorated SnO2 mesoporous material has been synthesized and shown to exhibit high sensitivity and good selectivity to methoxy propanol among other interferential VOC gases. Density Functional Theory study were conducted to yield insight into the surface-adsorbate interactions and therefore the gas sensing improvement mechanism by presenting accurate energetic and electronic properties for the Ag/SnO2 system. Firstly, an electron transfer model on Ag and SnO2 grain interface was put forward to illustrate the methoxy propanol gas sensing mechanism. Then, a three-layer adsorption model (TLAM) was proposed to investigate methoxy propanol gas sensing properties on a SnO2 (110) surface. In the TLAM method, taking SnO2 (110) surface for the basis, layer 1 illustrates the decoration of metal Ag on SnO2 (110) surface. Layer 2 represents the adsorption of molecular oxygen on metal Ag decorated SnO2 (110) surface. Layer 3 indicates the adsorption of methoxy propanol, and for comparison, three other VOC gases (namely, ethanol, isopropanol and p-xylene) on Ag decorated SnO2 (110) surface with oxygen species pre-adsorbed consecutively. All the adsorption processes were calculated by means of Density Functional Theory method; the adsorption energy, net charge transfer, DOS, PDOS and also experimental data were utilized to investigate the methoxy propanol gas sensing mechanism on Ag decorated SnO2 (110) surface with oxygen species pre-adsorbed.

A Capillary-Evaporation Micropump for Real-Time Sweat Rate Monitoring with an Electrochemical Sensor.

Sweat collection and real time monitoring of sweat rate play essential roles in physiology monitoring and assessment of an athlete's performance during exercise. In this paper, we report a micropump for sweat simulant collection based on the capillary-evaporation effect. An electrochemical sensor is integrated into the micropump, which monitors the flow rate in real-time by detecting the current using three electrodes. The evaporation rate from micropore array, equivalent to the sweat rate, was theoretically and numerically investigated. The designed micropump yields the maximum collection rate as high as 0.235 µ L/min. In addition, the collection capability of the micropump was validated experimentally; the flow rate through the microchannel was further detected in real-time with the electrochemical sensor. The experimental maximum collection rate showed good consistency with the theoretical data. Our proposed device shows the potential for sweat collection and real-time monitoring of sweat rate, which is a promising candidate for being a wearable platform for real-time physiology and performance monitoring during exercise.

Raman and photoluminescence properties of highly Cu doped ZnO nanowires fabricated by vapor-liquid-solid process.

Highly Cu doped ZnO nanowires have been fabricated by vapor-liquid-solid (VLS) process. The average concentration of Cu in the ZnO nanowires is estimated to be 6 at. %. The ultrafine synthesized nanowires have diameters nearly 80 nm, while their average length lies in the range of 40 to 90 mum. Raman spectroscopy shows that the Cu doped ZnO nanowires have a typical wurtzite structure. High resolution transmission electron microscopy (HRTEM) investigations of individual nanowires demonstrate that the nanowires have single crystalline structure in which the growth direction is oriented along the c axis. Room temperature photoluminescence spectrum of as prepared nanowires shows two emissions in UV and visible regions that can be ascribed to the near band edge (NBE) transition and defects respectively, while the spectrum of the annealed nanowires exhibits a red shift in UV and a suppression in visible bands. Furthermore, the low temperature (10 K) PL spectrum illustrates a novel dominant blue emission relating to the different valence states of Cu atoms in ZnO, which is explained on the basis of Dingle model.

Inflammatory infiltration and tissue remodeling in nasal polyps and adjacent mucosa of unaffected sinus.

BACKGROUND: This study was designed to explore the characteristics of inflammatory infiltration and tissue remodeling in the adjacent unaffected sinus mucosa of the polyp tissue (ANP). METHODS: Nasal polyps (NP) and ANP were obtained from 24 CRSwNP patients who received endoscopic sinus surgery. The frequency and distribution of Eosinophils, T lymphocytes (CD4+ T cells and CD8+ T cells), B lymphocytes, native macrophages, regulatory T cells and the total of inflammatory cells were detected by immunohistochemistry and hematoxylin-eosin stain. The thickness of the basal membrane was evaluated. RESULTS: Multivariate analysis of Variance (MANOVA) and F-tests were conducted for each independent variable between two groups. With test criterion alpha = 0.05, significant differences were observed between NP and ANP groups in terms of CD3 (F-Value = 10.47, P-value = 0.0120), CD4 (F-Value = 9.03, P-value = 0.0169), CD8 (F-Value = 17.03, P-value = 0.0033) and regulatory T cells (F-Value = 60.42, P-value <0.0001). Wilks' Lambda test (F-Value = 25.74, P-value = 0.1513) was conducted and no significant difference was observed between the NP group and the ANP group. The percentage of regulatory T cells in ANP was significantly higher than that in NP (3.7110±0.2395 vs 14.6300±1.8360). CONCLUSION: ANP and NP may be one disease entity. Treg cells have impacts on the morphology of the tissues and might be a key factor in the further development of ANP.

Invasive molecular prenatal diagnosis of alpha and beta thalassemia among Hakka pregnant women.

This study is a retrospective analysis of the prenatal genetic diagnosis results of fetuses with high risk of major thalassemia to provide information for clinical genetic counseling and to better control the birth of major thalassemia child in Hakka population. Totally, 467 fetuses in at-risk pregnancies were collected from Meizhou people's hospital from January 2014 to December 2017. Genomic DNAs were extracted from peripheral blood of the couples and villus, amniotic fluid or cord blood of the fetuses. DNA-based diagnosis was performed using polymerase chain reaction (PCR) and flow-through hybridization technique. Follow-up visits were done half a year after the fetuses were born. Around 467 fetus at-risk pregnancies were performed prenatal diagnosis. We detected 88 CVS samples, 375 amniocentesis fluid samples and, 4 cord blood samples. The 356 fetuses in α-thalassemia families consisted of 69 (19.38%) with Bart's hydrops syndrome, 20 (5.62%) fetuses with Hb H disease, and 184 (51.68%) fetuses with heterozygote. And the 111 fetuses in ß-thalassemia families consisted of 31 (27.93%) thalassemia major, 51 (45.95%) fetuses with heterozygote. There are 13 fetuses with α+ß-thalassemia, including 2 cases with severe ß-thalassemia. DNA-based testing prenatal diagnosis of thalassemia was found to be highly reliable. Our findings provide key information for clinical genetic counseling of prenatal diagnosis for major thalassemia in Hakka pregnant women. Our work plays an important role in the prevention and control of thalassemia in Hakka population. We will also combine other techniques to further improve our molecular prenatal diagnostic capabilities, including the next-generation sequencing (NGS), Sanger sequencing and MLPA.

Capacitive Behavior of Single Gallium Oxide Nanobelt.

In this research, monocrystalline gallium oxide (Ga2O3) nanobelts were synthesized through oxidation of metal gallium at high temperature. An electronic device, based on an individual Ga2O3 nanobelt on Pt interdigital electrodes (IDEs), was fabricated to investigate the electrical characteristics of the Ga2O3 nanobelt in a dry atmosphere at room temperature. The current-voltage (I-V) and I/V-t characteristics show the capacitive behavior of the Ga2O3 nanobelt, indicating the existence of capacitive elements in the Pt/Ga2O3/Pt structure.