This work reported a facile and green method to prepare highly stable and uniformly distributed Ag nanoparticles (AgNPs), in which a biopolymer xylan was used as the stabilizing and reducing agent via the Tollens reaction under microwave irradiation. Different variables were evaluated to optimize the reaction conditions. Complete characterization was performed using UV-Vis, XRD, TEM, size distribution analysis and XPS. The results revealed that AgNPs were well dispersed with diameters of 20-35 nm due to the packing of xylan. The optimal conditions were as follows: microwave irradiation temperature was 60-70 °C, microwave power was 800 W, microwave time was 30 min, the ratio of xylan to AgNO3 was 50 mg: 0.13 mmol, and ammonia concentration was 2%. In addition, the AgNPs were collected via high-speed centrifugal separation, and the supernatant was tested by HPAEC, GPC, FT-IR, and NMR. By comparing the structure of xylan before and after the reaction, the reaction mechanism was discussed. It was noted that the xylan-AgNPs composites showed high selectivity and sensitivity for Hg(2+) detection. The other 15 metal ions used had no obvious effect on the detection of Hg(2+), and the limit of detection (LOD) was 4.6 nM, which is lower than the allowed maximum level of 30 nM for drinking water by WHO. In addition, the xylan-AgNPs composites can be applied for Hg(2+) detection in real water samples. This study provides a novel way for the high-value utilization of a rich biomass resource, and a green method for the synthesis of AgNPs for the selective and sensitive detection of harmful heavy metals.

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Purpose In the literature concerning international new ventures (INVs), there has been a tension between the learning advantages of newness and absorptive capacity perspectives for explaining the performance influence of initial entry speed. To address this tension, this paper, through integrating both the motivation and ability to acquire foreign knowledge, proposes a theoretical model about the nonlinear relationship between INVs’ initial entry speed and international performance. Drawing upon upper echelons theory and the institution-based view, this study aims to extend the literature by developing two boundary conditions for this relationship: the moderating role of executives’ individual learning orientation and sub-national institutions. Design/methodology/approach The authors used the latent moderated structural equations approach specific to Mplus to test the hypotheses with data on 322 Chinese INVs. Findings The findings indicate that INVs’ international performance will increase initially and then decrease, as they accelerate initial entry speed (an inverted U-shaped relationship), and that INVs managed by executives with a higher learning orientation and located in better sub-national institutional environments achieve greater international growth gains from moderate initial entry speed. Originality/value This study mainly makes contributions to the INV literature by integrating the motivation and ability to acquire foreign knowledge to offer full understanding of the effect of initial entry speed on international performance, and by elaborating on the moderating effects of executives’ individual learning orientation and sub-national institutions on this relationship.

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Drawing on organizational learning theory and taking an institutional perspective, this study investigates (1) the dynamic relationship between internationalization and innovation in emerging market enterprises (EMEs), and (2) how state ownership moderates the focal relationships. Using a panel dataset of listed Chinese firms from 2007 to 2018, we find that internationalization encourages innovation input in EMEs, which in turn transforms into more innovation output. Higher innovation output leads to further international commitment, creating a dynamic upward spiral of internationalization and innovation. Interestingly, state ownership positively moderates the innovation input-innovation output link but negatively moderates the relationship between innovation output and internationalization. Our paper enriches and refines our understanding of the dynamic relationship between internationalization and innovation in EMEs by integrating the knowledge exploration, transformation, and exploitation perspectives, with the institutional perspective of state ownership.