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Copyright of Journal of Molecular Science is the property of Journal of Molecular Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Molybdenum disulfide (MoS2) was introduced into the polyacrylamide/chitosan (PAM/CS) hydrogel system by free radical polymerization, and the PAM/CS/MoS2 composite polymer hydrogel with interpenetrating network structure was prepared. The composition and morphology of the hydrogels were analyzed by Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and laser scanning confocal microscopy. The mechanical properties and hydrophilic properties were tested by a universal testing machine and a contact angle measuring instrument. Finally, the application of the composite hydrogel film in the field of humidity sensing was explored by a quartz crystal microbalance (QCM). The PAM/CS/MoS2-0.4 (mass of MoS2 in this system is 0.4 mg) composite hydrogel has a maximum compressive stress of 584.6 kPa and a maximum compressive strain of 83.8%. The introduction of MoS2 improves the hydrophilicity of the composite hydrogel. As the relative humidity of the environment increases from 11% to 95%, the frequency response of the QCM humidity sensor modified by the composite hydrogel film reaches a maximum of 2 642 Hz, and its sensitivity of 1% change of relative humidity is 31.45 Hz, which is expected to be applied in the field of humidity sensing. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using acrylamide (AM) as monomer, chitosan (CS) and graphene oxide (GO) as functional components, N, N'- methylene bisacrylamide (MBA) as crosslinking agent, a series of PAM/CS/GO composite hydrogels with three-dimensional network structure were prepared by free radical polymerization. The chemical composition, structure, morphology, and mechanical properties of the composite hydrogels were analyzed using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometer (XRD), scanning electron microscope (SEM), and universal testing machine. The experimental results show that GO is uniformly dispersed in the PAM/CS hydrogel matrix. Compared with PAM/CS hydrogels, PAM/CS/GO hydrogels have a tighter porous structure with an average pore diameter of about 55.7 μm. In addition, the mechanical properties of PAM/CS/GO hydrogels have been significantly improved, the largest elongation at break is 2 039%, and the maximum breaking stress reaches 237 kPa. This is due to the fact that GO acts as a physical crosslinking agent in the PAM/CS hydrogel to form good interface bonds. The hydrogel with cross-linked network structure and plenty of hydrophilic groups can be used as the sensing coating of the quartz crystal microbalance (QCM), and the QCM humidity sensor based on the functional hydrogel film is prepared. The moisture absorption behavior of composite hydrogel films was studied using QCM technology under different humidity conditions. As the air relative humidity (RH) increases from 33% to 85%, the frequency response of the composite hydrogel film modified QCM sensor increases from 12.2 Hz to 22.3 Hz. This research work provides valuable reference for the application of the hydrogel coating in the field of QCM humidity sensors. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Guangdong University of Technology is the property of Journal of Guangdong University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: Quartz crystal microbalance (QCM) was used for the dynamic monitoring of cell adhesion in real time of rat myocardial cells (H9C2) onto self-assembled film containing cell recognition peptide RGD, as well as the subsequent interactions with two cardiovascular drugs (one positively inotropic and the other negatively inotropic). Methods: A self-assembling 3-mercaptopropionic acid (MPA) monolayer was formed on the gold QCM electrode surface, allowing for subsequent covalent coupling with the cell adhesion peptide KRGD, to form a dense molecular self-assembled monolayer with specific recognition motif for myocardial cells. QCM was successfully used for the dynamic monitoring of the MPA/RGD self-assembly process and the subsequent myocardial cell adhesion process in the concentration range of 5×104- 4×105 cells/m L of H9C2 cells in real time. Additionally, QCM was used to assess the cells-cardiovascular drug interactions using 20,000 H9C2 cells and positive inotropic drug, isoprenaline and negative inotropic drug, verapamil. Results: Compared to bare gold electrode, the MPA/RGD-modified gold electrode yielded enhanced frequency shift (△f) and motional resistance change (△R) with the adhesion of H9C2 cells. In the tested H9C2 concentration range (5×104- 4×105 cells/m L), △f was linearly related to the cell concentration, whereas △R was a power function of the cell concentration. Cell Viscoelastic Index (CVI= △R/△f) was used to characterize the cells' viscoelasticity. Under the effect of positive inotrope, isoprenaline, cell-QCM surface adhesion became stronger with increased △f and △R; CVI increased and the cells became stiffer. Whereas under the effect of negative inotrope, verapamil, cell-QCM surface adhesion became weaker with decreased △f and △R; CVI dropped and the cells became softer. Conclusions: QCM can be used to monitor dynamic cell adhesion of different concentrations of H9C2 rat myocardial cells; and differentiate the effects of positive and negative inotropic drugs based on changes in cell adhesion strength and cells' viscoelasticity, demonstrating its potential as a screening tool for cardiovascular drugs. [ABSTRACT FROM AUTHOR]

The ripeness stage is one of the important factors of banana quality, which will affect the sale price of bananas. To consumers, inadequate ripeness means low quality, and over-ripeness means a short shelf life, and both of them will lead to low income to sellers. In order to obtain optimal quality, keep a long shelf period, and minimize losses, it is necessary to automatically detect banana ripeness nondestructively. One promising strategy is using a quartz crystal microbalance (QCM) system to detect volatile organic compounds (VOCs) released during banana ripening. The advantages of this method are quick detection, high sensitivity, and low cost. A QCM sensor is a mass sensor, which is a device of an oscillating circuit. When the mass on its surface is changed, the frequency of an oscillating circuit will change simultaneously. When coated by cross-sensitivity materials, which can absorb VOCs. QCM sensors can be used to detect the change of ambient VOCs. Therefore, it is possible to use QCM sensors for recognizing the banana ripeness stage. This research aimed to discriminate the ripeness stage of banana based on QCM sensors. The measurement system was constructed with 9 MHz of gold electrodes quartz crystals, which were modified by sensitive materials of 1, 2-dioleoyl-sn-glycero-3-[phosphor-L-serine] (DOPS), galactosylceramide (GC), cellulose acetate (CA), and ethyl cellulose (EC). The sensitive materials were dissolved in chloroform (CHL) and tetrahydrofuran (THF). The QCM sensors were fabricated by dropping 5 mg/mL DOPS/CHL, GC/CHL, and CA/THF, EC/THF on quartz crystal electrodes, respectively. Bananas were purchased from the Philippines in green condition, and they were ripened in a room with a constant temperature of (22±1)℃. During ripening, the bananas were divided into 7 ripening stages according to a Von Loesecke H W chart, the banana VOCs were obtained by static head-space through putting bananas into a 2000 mL teflon chamber for 1 hour at every ripening stage. The measurement was conducted by injecting 50 mL VOCs into a 150 mL measurement chamber. The response of these 4 sensors to VOCs of bananas from the 1 to 7 ripening stage was recorded by LabVIEW software. The experiments were repeated 8 times, and the response value was analyzed by principal-components analysis (PCA) and linear discriminant analysis (LDA). The results showed that the response of a sensor modified by CA was more sensitive to banana VOCs than DOPS, GC, and EC. For the sensor coated by CA, the response tended to increase with the ripening stage from stage 1 to stage 4, the frequency shift reached its peak at ripening stage 4 due to an increase of aldehydes and esters in the banana VOCs. After ripening stage 4, the frequency shift declined with a decrease of acetates and an increase of butyrates and alcohols. The other three sensitive materials modified sensors' response were lower than CA, though their trends were not the same. The frequency shift of 4 sensors coated by 4 sensitive materials to banana VOCs of 7 ripening stages was classified by PCA and LDA, with accuracies of 97% and 100%, respectively. The research showed that it was feasible to classify the ripening stage of banana using four materials as sensitive film, and that the LDA is a potential classification method. Accordingly, this research is helpful for banana automatic grading. [ABSTRACT FROM AUTHOR]

Copyright of Taiwanese Journal of Agricultural Chemistry & Food Science is the property of Agricultural Chemical Society of Taiwan and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)