Impact of social influence on users' continuance intention toward sports and fitness applications.

The purpose of this paper is to explore how social influence (SI), which is disaggregated into subjective norms (SN), social image (SIM), and social identity (SID), predicts perceived usefulness (PU), perceived pleasure (PP), and continuance intention (CI) toward sports and fitness applications. The underlying context is the socialization and gamification of exercise during the Covid-19 pandemic. Based on the theory of SI and the technology acceptance model, a theoretical framework was built where PU and PP mediate the influence of SI on CI, and proposed hypotheses were tested. The responses of 296 Keep users (a popular sports and fitness application in China) to a questionnaire survey were analyzed. SN and SIM were found to have significant positive effects on SID; SID has significant positive effects on PU and PP; both PU and PP have significant positive effects on the CI of users; SID and PU positively and significantly mediate the relationship between SN/SIM and CI; PU positively and significantly mediates the SID-CI relationship. However, the role of PP in mediating the influence of SI on CI is non-significant. This paper deepens the current understanding of the mechanisms that influence the relationship between SI and CI under the context of socialization and gamification services.

Recombinant Rice Quiescin Sulfhydryl Oxidase Strengthens the Gluten Structure through Thiol/Disulfide Exchange and Hydrogen Peroxide Oxidation.

Recombinant rice quiescin sulfhydryl oxidase (rQSOX) has the potential to improve the flour processing quality, but the mechanisms remain unclear. The effects of rQSOX on bread quality, dough rheology, and gluten structure and composition, with glucose oxidase as a positive control, were investigated. rQSOX addition could improve the dough processing quality, as proved by enhanced viscoelastic properties of dough as well as a softer crumb, higher specific volume, and lower moisture loss of bread. These beneficial effects were attributed to gluten protein polymerization and gluten network strengthening, evidenced by the improved concentration of SDS-insoluble gluten and formation of large gluten aggregates and the increased α-helix and ß-turn conformation. Furthermore, decreased free sulfhydryl and increased dityrosine in gluten as well as improved H2O2 content in dough suggested that the rQSOX dough strengthening mechanism was mainly based on the formation of disulfide bonds and dityrosine cross-links in gluten by both thiol/disulfide direct exchange and hydrogen peroxide indirect oxidation pathways.

Molecular Identification and Antibacterial Activity Analysis of Blue Fox (Vulpes lagopus) ß-Defensins 108 and 122.

The blue fox (Vulpes lagopus), a fur-bearing animal, is an important component of the breeding industry in China. Semen quality is a key factor for the reproductive process and the breeding effectiveness of the farmed blue fox. However, bacterial contamination in semen samples utilized in artificial fertilization is very common. The ß-defensins, a class of important antimicrobial peptides in mammals, could protect the reproductive system of male animals from bacterial invasion, maintain the stability of the genital tract microenvironment and improve semen quality. In this study, molecular cloning and bioinformatics analysis were conducted to analyze the protein structure and function of blue fox ß-defensin 108 (Vulpes lagopus beta-defensin 108, vBD108) and 122 (Vulpes lagopus beta-defensin 122, vBD122). To evaluate the bacteriostatic effect of recombinant vBDs (Vulpes lagopus beta-defensins) protein, varying concentrations (0, 25, 50, 100, 200 µg/mL) were taken to evaluate the effects on Escherichia coli and Staphylococcus aureus at different times (0, 2, 4, 6, 8, 12 h). The results showed that vBD108 and vBD122 existed in different forms in protein structure and had antibacterial activity. Both proteins, at 50 µg/mL, had efficacious bacteriostatic activity. This study shows that recombinant vBD108 and vBD122 proteins have good antibacterial activity in vitro. This implies a potential role in improving semen quality and hygienic measures in the process of artificial insemination as an extender of semen dilution with antibacterial activity.

[Expression and characterization of recombinant wheat quiescin sulfhydryl oxidase and its effect on bread quality].

Wheat quiescin sulfhydryl oxidase was expressed in Escherichia coli for developing a new biological flour improver. The synthesized wqsox gene was constructed into the vector pMAL-c5x and expressed in E. coli, then the expression conditions of recombinant protein was optimized. The MBP fusion label in recombinant protein was removed by protease digestion after affinity purification. Moreover, enzymatic properties of the purified wQSOX and its effect on bread quality were investigated. The synthesized wqsox gene contained 1 359 bp and encoded 453 amino acids with a deduced molecular weight of 51 kDa. The constructed recombinant vector pMAL-c5x-wqsox could successfully express soluble recombinant protein MBP-wQSOX in E. coli Rosetta gamiB(DE3), and the optimal induced expression conditions for recombinant protein were 25 °C, 0.3 mmol/L IPTG and 6 h. MBP fusion tag was cut out by factor Xa protease and wQSOX was prepared after affinity purification. wQSOX could catalyze the oxidation of DTT, GSH and Cys, accompanying the production of H2O2, and exhibited the highest substrate specificity for DTT. Furthermore, enzymatic properties results demonstrated that the optimal temperature and pH for wQSOX catalyzing oxidation of DTT was 50 °C and 10.0, respectively, and wQSOX presented a good stability under high temperature and alkaline environment. The addition of wQSOX with 1.1 U/g flour significantly (P<0.05) increased 26.4% specific volume of the bread, and reduced 20.5% hardness and 24.8% chewiness of bread crumb compared to the control, indicating a remarkable ability to improve the quality of bread.

[Recombinant expression of black sesame polyphenol oxidase and its enzymatic properties].

To investigate the enzyme properties of the black sesame polyphenol oxidase (BsPPO), a synthesized Bsppo gene was cloned into the vector pMAL-c5x and expressed in E. coli. Subsequently, the MBP fusion label in the recombinant protein was removed by protease digestion after affinity purification. The synthesized Bsppo gene contained 1 752 bp which encodes 585 amino acids with a deduced molecular weight of 65.3 kDa. Transformation of the recombinant vector into E. coli BL21(DE3) resulted in soluble expression of the fusion protein MBP-BsPPO. The enzymatic properties of the recombinant BsPPO was investigated after MBP fusion tag excision followed by affinity purification. The results demonstrated that the optimal temperature and pH for BsPPO was 25°C and 4.0, respectively. BsPPO exhibited a good stability under low temperature and acidic environment. Low-intensity short-term light exposure increased the activity of BsPPO. Cu²âº could improve the activity of BsPPO while Zn²âº and Ca²âº showed the opposite effect. BsPPO could catalyze the oxidation of monophenols, diphenols, and triphenols, and exhibited good catalytic activity on l-tyrosine and vanillic acid. Moreover, BsPPO exhibited high catalytic activity on black sesame metabolites, including 2-methoxy cinnamic acid, indole-3-carboxylic acid and phloretin. These results may serve as a basis for further characterization of BsPPO.

Characterization of recombinant rice quiescin sulfhydryl oxidase and its improvement effect on wheat flour-processing quality.

In this study, recombinant rice quiescin sulfhydryl oxidase (rQSOX) was expressed and characterized, and its performance in flour-processing quality was further evaluated. The purified rQSOX exhibited the highest sulfhydryl oxidation activity (1.96 IU/mg) using dithiothreitol as a substrate, accompanying the production of H2O2. The optimal temperature and pH were 60 °C and pH 8.0 for rQSOX catalyzing oxidation of dithiothreitol. And rQSOX retained 50% of its maximum activity after incubation at 80 °C for 1 h. Moreover, rQSOX supplementation improved the farinograph properties of dough, indicated by the increased dough stability time and decreased degree of softening, and enhanced viscoelastic properties of the dough. Addition of rQSOX (10 IU/g flour) provided remarkable improvement in specific volume (37%) and springiness (17%) of the steamed bread, and significantly reduced the hardness by half, which was attributed to the strengthened gluten network. The results provide an understanding for rQSOX using in flour-processing industry.

Capture, isolation and electrochemical detection of industrially-relevant engineered aerosol nanoparticles using poly (amic) acid, phase-inverted, nano-membranes.

Workplace exposure to engineered nanoparticles (ENPs) is a potential health and environmental hazard. This paper reports a novel approach for tracking hazardous airborne ENPs by applying online poly (amic) acid membranes (PAA) with offline electrochemical detection. Test aerosol (Fe2O3, TiO2 and ZnO) nanoparticles were produced using the Harvard (Versatile Engineered Generation System) VENGES system. The particle morphology, size and elemental composition were determined using SEM, XRD and EDS. The PAA membrane electrodes used to capture the airborne ENPs were either stand-alone or with electron-beam gold-coated paper substrates. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to conceptually illustrate that exposure levels of industry-relevant classes of airborne nanoparticles could be captured and electrochemically detected at PAA membranes filter electrodes. CV parameters showed that PAA catalyzed the reduction of Fe2O3 to Fe(2+) with a size-dependent shift in reduction potential (E(0)). Using the proportionality of peak current to concentration, the amount of Fe2O3 was found to be 4.15×10(-17)mol/cm(3) PAA electrodes. Using EIS, the maximum phase angle (Φmax) and the interfacial charge transfer resistance (Rct) increased significantly using 100µg and 1000µg of TiO2 and ZnO respectively. The observed increase in Φmax and Rct at increasing concentration is consistent with the addition of an insulating layer of material on the electrode surface. The integrated VENGES/PAA filter sensor system has the potential to be used as a portable monitoring system.

Environmental applications of poly(amic acid)-based nanomaterials.

Nanoscale materials offer new possibilities for the development of novel remediation and environmental monitoring technologies. Different nanoscale materials have been exploited for preventing environmental degradation and pollutant transformation. However, the rapid self-aggregation of nanoparticles or their association with suspended solids or sediments where they could bioaccumulate supports the need for polymeric coatings to improve mobility, allows faster site cleanups and reduces remediation cost. The ideal material must be able to coordinate different nanomaterials functionalities and exhibit the potential for reusability. We hereby describe two novel environmental applications of nanostructured poly (amic acid)-based (nPAA) materials. In the first application, nPAA was used as both reductant and stabilizer during the in situ chemical reduction of chromium(vi) to chromium(iii). Results showed that Cr(vi) species were rapidly reduced within the concentration range of 10(-1) to 10(2) mM with efficiency of 99.9% at 40 °C in water samples and 90% at 40 °C in soil samples respectively. Furthermore, the presence of PdNPs on the PAA-Au electrode was found to significantly enhance the rate of reduction. In the second application, nPAA membranes were tested as filters to capture, isolate and detect nanosilver. Preliminary results demonstrate the capability of the nPAA membranes to quantitatively capture nanoparticles from suspension and quantify their abundance on the membranes. Silver nanoparticles detection at concentrations near the toxic threshold of silver was also demonstrated.

Flexible poly(amic acid) conducting polymers: effect of chemical composition on structural, electrochemical, and mechanical properties.

A new approach for creating flexible, mechanically strong poly(amic acid) (PAA) hybrid copolymers is described. The reduction of gold salts to gold nanoparticles by PAA coupled with its copolymerization in the presence of various silanes (e.g., N-[3-(trimethoxysilyl)-propyl] aniline (TMOSPA), 3-aminopropyl-trimethoxysilane (APTMOS), dichlorodimethylsilane (DCMS), and tetramethoxysilane (TMOS)) has enabled the design of a series of polymeric films. The resulting poly(amic acid), silane, and gold (PSG) solutions were employed for the fabrication of flexible, ternary polymers with a minimum bend ratio of 3 mm using thermal desolvation and/or wet-phase inversion techniques. By controlling the composition and synthesis conditions, porous PSG films were produced that are flexible or rigid, transparent or opaque, and/or mechanically strong. (1)H NMR, (13)C NMR, and Fourier transform infrared spectroscopy (FTIR) characterization results showed that the carboxylic acid moieties were retained in the PSG copolymer. Thermal stabilities with degradation characteristics of the polymers were determined using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Although structurally and morphologically different from the parent PAA, copolymerization with silanes had significantly improved the mechanical and interfacial property of the PSG class of films.

[Structure-activity relationships of phenylethanoid glycosides in plants of Cistanche salsa on antioxidative activity].

OBJECTIVE: To study the structure-activity relationships of phenylethanoid glycosides in plants of Cistanche salsa on antioxidative activity. METHODS: By the assay systems of DPPH*, the antioxidant activity of six phenylethanoid glycosides from plants of Cistanche salsa was determined to investigate the relationship between the antioxidant activities and phenylethanoid glycosides's structural characteristics. RESULTS: The antioxidative activity of phenylethanoid glycosides was variant with dose-dependent effect. The sequence of the strength of the antioxidative activity of the six components was shown to be 2'-Acetylacteoside > Acteoside > or = Tubuloside B > or = Isoacteoside > Echinacoside > Cistanoside A. CONCLUSION: The antioxidative activity of phenylethanoid glycosides is related to the number of phenolic hydroxyl, steric hindrance, 2-acetyl on the middle glucopyranose, and the location of phenolic hydroxyl. Additionally, it may be related to the alpha, beta-unsaturated ketone of phenl-2-propenoyl.

[Studies on chemical constituents of cultivated Cistanche salsa].

OBJECTIVE: To study the chemical constituents of cultivated Cistanche salsa. METHODS: Compounds were isolated and purified on several chromatography, and then were identified by physico-chemical properties and structurally elucidated by spectral analysis. RESULTS: Seven compounds were isolated and identified as beta-sitosterol (I), daucosterol (II), beta-sitosteryl glucoside 3'-O-heptadecoicate (III), 8-hydroxygeraniol 1-beta-D-glucopyranoside (IV), 2-methanol-5-hydroxy-pyridine (V), betaine (VI), galactitol (VII). CONCLUSION: The chemical constituents of artificial cultivated Cistanche salsa are studied for the first time. Among them, compound III and IV are isolated from the plant for the first time, compound V is isolated from this genus for the first time.

[Studies on chemical constituents from root of Hedysarum polybotrys].

OBJECTIVE: To study the chemical constituents of Hedysarum polybotrys. METHOD: Chromatographic methods were used to isolate compounds from H. polybotrys and chemical and spectral methods were used to elucidate the structures of the isolated compounds. RESULT: Five compounds, N,N,N-trimethyl-tropaphone inner salt (hypaphorine) (1), octadecyl-3-methoxy-4-hydroxy-benzeneacrylate (2), 5,7,4'-trihydroxy-dihydroflavanone 5,7-di-O-beta-D-glucopyranoside (3), 3,4,5-trimethoxy cinnamic acid methy ester (4) and vanillic acid (5), were isolated from the roots of H. polybotrys. CONCLUSION: Compounds 1, 2 and 3 were obtained from this plant for the first time, while compounds 1 and 2 were isolated from Hedysarum for the first time.

[Studies on chemical constituents of Hedysarum polybotrys].

AIM: To study the chemical constituents of Hedysarum polybotrys Hand.-Mazz.. METHODS: The compounds were separated with Sephadex LH-20 and silica gel column chromatography, and their structures were identified on the basis of spectral analysis. RESULTS: Five compounds were identified as hedysalignan A (1), isoliquiritigenin (2), formononetin (3), calycosin (4) and ononin (5). CONCLUSION: Hedysalignan (1) is a new compound and the others were obtained from the plant for the first time.

[Studies on the chemical constituents in root of Rheum rhizastachyum].

OBJECTIVE: To investigate the chemical constituents from the root and rhizome of Rheum rhizastachyum. METHOD: The compounds were isolated by column chromatography on silica gel, Sephadex LH-20, MCI-gel CHP-20P separately and their structures were elucidated by chemical and spectral technology. RESULT: Six compounds were isolated and identified as chrysophanol, emodin, gallic acid, sucrose, 1-O-beta-D-glucopyranosyl-chrysophanols, 1-O-beta-D-glucopyranosyl-emodin. CONCLUSION: All the compounds were obtained from this plant for the first time.

[Survey of pharmacology of oleanolic acid].

OBJECTIVE: To summarize the pharmacological function of oleanolic acid. METHOD: Based on the documents and related achievements, the pharmacological function and its mechanism including its clinical use were summed up. RESULT AND CONCLUSION: Oleanolic Acid is a natural chemical which has wide-ranging function and abundant source. But we should place the emphasis on improving its biotic utilization and effect on clinical treatment.

[Studies on chemical constituents in the root of Hedysarum polybotrys].

OBJECTIVE: To study the chemical constituents in the root of Hedysarum polybotrys Hand.-Mazz.. METHOD: The constituents were isolated by Sephadex LH-20 and silica gel column chromatography, and their structures were identified on the basis of spectral analysis. RESULT: Five compounds, medicarpin (I), 3-hydroxy-9-methoxycoumestan (II), 3, 9-dihydroxycoumestan (III), beta-sitosterol (IV), beta-sitosterol-3-O-beta-D-glucoside (V) were obtained. CONCLUSION: Compounds II, III, V were obtained from the plant for the first time.