High Response Ability Research Articles

Phytic acid assist for self-healing nanocomposite hydrogels and their application in flexible strain sensors

Nanocomposite hydrogels have been applied in the field of flexible sensors to monitor human body signals. In this manuscript, phytic acid (PA) was successfully adsorbed on the surface of graphene oxide@polydopamine (GO@PDA). The obtained graphene oxide@polydopamine-phytic acid (GO@PDA-PA) was further implanted to the poly acrylic acid (PAA) hydrogels as flexible strain sensors. Dopamine (DA) was self-polymerized on both two sides of GO by mussel-inspired chemistry to synthetize GO@PDA. PA was decorated on the surface of GO@PDA to obtain GO@PDA-PA nanocomposites with Pickering emulsion in oil-in-water (O/W) emulsion. The GO@PDA-PA hydrogels’ self-healing efficiency (98.6%) and mechanical strength (1.77 MPa) were both improved due to the presence of reversible interaction such as hydrogen bond and metal-ligand coordination. The wearable flexible sensors based on the prepared GO@PDA-PA hydrogels have high sensitivity (gauge factor (GF) = 3.3), stability, durability and high response ability. It can detect the sharp movement signals of human body and tiny movement signals such as breathing. The excellent performance of nanocomposite hydrogels is expected to promote the evolution of flexible sensors.

Spatio-Temporal Evolution and Development Path of Industry–University–Research Cooperation and Economic Vulnerability: Evidence from China’s Yangtze River Economic Belt

This study explores the impact of industry–university–research (IUR) cooperation on the economic system. The study constructs a vulnerability evaluation index comprising 42 indicators in five dimensions. The Yangtze River Economic Belt (YREB) panel data from 2006–2018 are used to assess economic vulnerability in China. The research results show that, firstly, from 2006–2018, the index values indicated a good development trend, with fluctuations in the values of the sensitivity and economic vulnerability indices. The response ability index values gradually increased, especially later in this period. This showed a promising trend of low sensitivity, high response ability, and low vulnerability. Secondly, the spatial distribution pattern demonstrated certain laws and continuity, but the development process was unstable, while the eastern < the central < the western showed a “ladder” evolution pattern, “extremely poor” characteristics, and an “agglomeration” evolutionary path. Thirdly, the impact of IUR cooperation on regional economic development can be divided into three phases: knowledge interaction, creation, and application. The interaction and synergy between universities, research institutions, and enterprises play a role in regional economic development. The study recommends strengthening the coupling coordination of the production, research and development (R&D), cooperation, and innovation, with the dual functions of government guidance and market decision making.

Long-term and stable detection of H2S in a pig house at low operating temperature based on Ce2O3/In2O3 hollow microspheres with a remote monitoring system

A remote system for real time monitoring of H2S in a pig house combining with a new type of gas sensor fabricated via Ce2O3/In2O3 hollow microspheres (HMS) was successfully built. The microstructure and morphology of the microspheres and their gas sensing performance were investigated in detail. At optimal operating temperature (100 ℃), the Ce2O3/In2O3 HMS composite exhibited excellent sensing properties towards H2S, which afforded a linear response range from 0.10 to 100 ppm with a detection limit of 0.06 ppm and a short response time of 59 s. Compared with In2O3 based sensor, the Ce2O3/In2O3 HMS sensor presented not only low power consumption for efficient energy-saving, but also even high response ability. After 10 months of continuous monitoring of H2S gas in pig farm via Alibaba Cloud transmission network, only 5.4% of the sensor's response attenuated was found, indicating that the HMS based sensor had a long-term stable service lifetime suitable for remote monitoring in practical scene. Moreover, the sensor presented good thermo- and humidity-stability with good reproducibility and selectivity, making it an excellent monitor for H2S in atmospheric environment on livestock-raising field.

Feasibility of detection of infested rice using an electronic nose

Electronic nose (E-nose) technology has a potential to be used for detecting insects in stored rice. It may provide a new method to detect the insect activity by providing smell prints for the headspace volatiles in rice mass. The objective of this research was to study the feasibility of using E-nose to detect infested rice during the storage process. An E-nose instrument (Cyranose 320) consisting of 32 sensors for detecting the volatile components produced in infested rice was used for this study. Storage rice with moisture content of 11.8 ± 0.3% was used for conducting the tests. The rice samples were infested with different numbers of adult insects, including rice weevil (Sitophilus oryzae), lesser grain borer (Rhyzopertha dominica) and red flour beetle (Tribolium castaneum), in containers containing 1 kg of rice. The samples were stored at temperatures of 15 °C and 30 °C for four weeks. Air samples in the containers were taken for measurements every five days. The data were analyzed using the principal component analysis (PCA) method. The results revealed that the E-nose was not able to distinguish the clean rice and infested rice with lesser grain borer. While the E-nose had high response ability to the volatile components produced by rice weevil and red flour beetle after four weeks of storage. Consequently, the E-nose could discriminate the clean and infested rice with above insects after four weeks of storage at temperature of 30 °C. Additionally, under the aforementioned conditions, the E-nose could not distinguish the clean and infested rice during the first, second and third weeks of storage. The classification accuracy of E-nose for clean and infested rice was low at storage temperature of 15 °C for the tested insets. It can be concluded that the E-nose has the capability to detect infested rice after four weeks of storage.

Development of post-fire vegetation response-ability model in grassland mountainous ecosystem using GIS and remote sensing

The mountainous grassland ecosystem in Golden Gate National Park (South Africa) has post-fire ecological resilience. However, vegetation species composition and structure can alter when the ecosystem continually has uncontrolled fires. This study developed a vegetation response-ability model by integrating environmental factors (elevation, aspect, rainfall, land surface temperature, soil, and fire severity), adaptive strategies (flowering months, water requirements, resprouter/seeders) and ecological status (increaser or decreaser) for the park. Vegetation recovery index derived from pre- and post-fire normalised difference vegetation index (NDVI) was used with correlation and regression analysis to validate the model. The results showed that amongst the environmental variables, elevation and fire were the most important factors influencing vegetation response-ability followed by soil, aspect, rainfall, and land surface temperature. Almost half (48%) of the park had a high vegetation response-ability, 43% medium, and 9% low. On the other hand, the vegetation recovery index showed 34% of the park fully recovered to pre-fire conditions, while 61% and 5% largely and slightly recovered, respectively. There was a strong correlation between vegetation response-ability and vegetation recovery index. The regression analysis showed a good relationship between vegetation response-ability and vegetation recovery index (R = 0.91) with 83.34% coefficient of determination.

Flexible nitrogen dioxide gas sensor based on reduced graphene oxide sensing material using silver nanowire electrode

In recent years, flexible gas sensors have aroused wide interest of researchers due to their enormous potential applications in wearable electronic devices. In this paper, a flexible gas sensor is prepared. We use silver nanowires as flexible interdigital electrodes for gas sensors and reduced graphene oxide as gas-sensing materials. We also study its gas sensitivity and flexibility properties such as responsiveness, recovery, and repeatability to nitrogen dioxide. The experimental results show that the silver nanowire flexible electrode and the reduced graphene oxide gas sensor prepared can detect the NO<sub>2</sub> gas with a concentration of 5—50 ppm at room temperature. The response (<i>R</i><sub>a</sub>/<i>R</i><sub>g</sub>) of the sensor to 50 ppm NO<sub>2</sub> is 1.19. It demonstrates high response ability and repeatability. The recovery rate can be kept above 76%. The sensitivity of the sensor is 0.00281 ppm<sup>-1</sup>. The response time and recovery time of the prepared AgNWs IDE-rGO sensor for 5 ppm NO<sub>2</sub> gas are 990 s and 1566 s, respectively. At the same time, the sensor still exhibits excellent gas sensing performance at a bending angle in range from 0° to 45°. The device has relatively stable conductivity and good bending tolerance. The sensing mechanism of the sensor can be attributed to the direct charge transfer between the reduced graphene oxide material and NO<sub>2</sub> gas molecules. In addition, the high catalytic activity and excellent conductivity of Ag that is a common catalyst material, may also play an important role in improving the gas sensitivity of reduced graphene oxide materials. Silver nanowires, as a material for interdigital electrodes, provide excellent conductivity for device as well as support for the flexibility of device. It provides the fabricated sensor for good mechanical flexibility. And the gas-sensing performance of the AgNWs IDE-rGO sensor is mainly achieved by the use of reduced oxidized graphene material reduced by hydrazine hydrate. In summary, the silver nanowire flexible electrode and the graphene gas sensor prepared in this work are helpful in realizing the flexibility of the gas sensor. It lays a foundation for the further application of flexible gas sensors and has great application prospects in wearable electronic equipments.

Enhanced Opsonization-Independent Phagocytosis and High Response Ability to Opsonized Antigen–Antibody Complexes: A New Role of Kupffer Cells in the Accelerated Blood Clearance Phenomenon upon Repeated Injection of PEGylated Emulsions

The accelerated blood clearance (ABC) phenomenon is an immune response against the first injection of PEGylated colloidal drug delivery systems (CDDSs), which causes the accelerated clearance of the second dose. The enhanced complement-mediated phagocytic activity of Kupffer cells is responsible for accelerated second-dose clearance. Nevertheless, few studies have focused on the role of Kupffer cells in the induction phase of the ABC phenomenon. In this study, the intrinsic phagocytic activity of Kupffer cells was significantly enhanced at 6 days after the initial injected PEGylated emulsions (PEs) using the carbon clearance test and single-pass liver perfusion experiment. Furthermore, PE could stimulate Kupffer cells activation, leading to enhanced cell viability of Kupffer cells and opsonization-independent cellular uptake. It was also found that the response ability of Kupffer cells to the antigen-antibody complexes was augmented by the first injection of PE. Conclusively, we proposed that, besides anti-PEG IgM and complement activation-mediated hepatic uptake, enhanced opsonization-independent phagocytosis of Kupffer cells and the high response ability to opsonized antigen-antibody complexes contribute to the accelerated clearance of the second administration. The results indicated that Kupffer cells play an indispensable role in the ABC phenomenon and provided novel insights into the current view on the mechanism of the ABC effect.

A comparative study on the glucose sensors modified by two different β-cyclodextrin functionalized reduced graphene oxide based Au nanocomposites synthesized through developed post immobilization and in situ growth technologies

Graphene based metal nanocomposites are widely used in electrochemical glucose sensors for their prominent synergistic effects. Many reviews have been reported to summarize and compare the two types of synthetic technologies that post immobilization and in situ growth for preparing these nanocomposites. However, these comparisons and evaluations are almost based on the nanomaterials comprised of different components. Based on rationally selecting β-cyclodextrins as the common functional reagents, we have innovatively synthesized two novel graphene based metal nanocomposites composed of the identical ingredients through the developed post immobilization method and new one-step electrodeposition in situ growth approach respectively. After optimized the key parameters to ensure the optimal synthesis conditions were provided, we have further performanced the systematically comparative study on properties of the two nanocomposites from many aspects, so as to scientifically evaluate the two synthesis technologies. Glucose sensors based on the two resultant nanocomposites have been fabricated successfully, both of them showed high response ability. Sensitivity of the sensor modified by the nanocomposite synthesized through in situ growth was improved 3–8 times, demonstrated this strategy is more effective. Our work would provide guidelines to synthesize graphene based metal nanocomposites which has potential applications in electroanalysis.

A plain method of prediction of visibility of peptides in mass spectrometry with electrospray ionization

A new method for screening of essential peptides for protein detection and quantification analysis in the direct positive electrospray mass spectrometry has been proposed. Our method is based on the prediction of the normalized abundance of the mass spectrometric peaks using a linear regression model. This method has the following limitations: (i) selected peptides should be taken so that at pH 2.5 the tested peptides must be presented mainly as the 2+ and 3+ ions; (ii) only peptides having C-terminal lysine or arginine residues are considered. The amino acid composition of the peptide, the peptide concentration, the ratio of the polar surface of peptide to common surface and ratio of the polar volume to common volume are used as independent variables in equation. Several combinations of variables were considered and the best linear regression model had a determination coefficient in leave-one-out validation procedure equal 0.54. This model confidently discriminates peptides with high response ability and peptides with low response ability, and therefore it allows to select only the most promising peptides. This screening method, a plain and fast, can be successfully applied to reduce the list of observed peptides.