In recent decades, remanufacturing is perceived to be an environmentally friendly option due to the reduced consumption of materials, energy etc. It should be noted that whether the remanufacturing operations are undertaken by the original equipment manufacturers (OEMs) or outsourced to the remanufacturers, given the size and the growth of remanufactured products, many OEMs intend to fend off the potential cannibalization of new products sales through differentiating their quality levels from those of remanufactured ones by launching upgraded versions. To understand whether and how the product upgrading strategy impacts on optimal outcomes in the context of the remanufacturing operations undertaken by OEMs or third-party remanufacturers (TPRs), in this paper, we develop two models that highlight the OEM’s product upgrading strategy under the scenarios where (1) the OEM owns its remanufacturing operations in-house (Model O) or (2) remanufacturing operations are undertaken by a TPR (Model T). Among other results, we find that, from an economic performance perspective, it is more beneficial for the OEM to perform remanufacturing operations in-house; however, from an environmental sustainability perspective, such behavior is not always good for our environment. In particular, when the level of product upgrading is pronounced, the remanufacturing operations undertaken by the OEM are always detrimental to our environment, due to indulging in remanufacturing, as seen in Model O.

SnO2 and TiO2 have attracted the most attention due to their unique chemical and electrical properties in basic research of functional materials and applied research of materials. The performance of composite oxide or solid solution material is better than that of monomer oxide. Therefore, SnO2?TiO2 composite oxide system has become one of the active composite materials studied at home and Abroad. A large number of reports have shown that a certain proportion of SnO2?TiO2 composite material can obtain the best gas-sensitive performance, but this proportion has a great relationship with the crystal structure and process conditions of the material preparation. Therefore, in this paper, Ti0.5Sn0.5O2 solid solution materials with Sn/Ti molar ratio of 1/1 were prepared at different sintering temperatures, and their structure and gas-sensitive properties were studied. After sintering at 650 °C, the samples were mainly closely combined with rutile SnO2 and anatase type TiO2 particles, and some Sn and Ti ions were replaced. After sintering at 1050 °C, the composite mode of SnO2/TiO2 was dominated by solid solution and rutile Ti?Sn?O2 solid solution. The samples prepared at different sintering temperatures have different gas-sensitive properties for methanol, ethanol and other organic gases and the gas-sensitive properties of the prepared SnO2?TiO2 composite decreased with the increase of sintering temperature.

During the construction of highway, the exhaust emissions of equipment and vehicles will affect the ecological environment in a certain range around the road, especially in environmental sensitive areas such as national nature reserves, which need to be quantitatively studied. In this work, a novel two-dimensional net-like hierarchical WO3 nanostructure was synthesized by a one-step hydrothermal route. It was amazing that this novel two-dimensional WO3 show ultra-sensitivity towards NO2, primarily attributed to abundant gas diffusion channels and large gas-sensitive reaction surface area furnished by one-dimensional net-like WO3 nanowires. Benefiting from their novel characteristic, the two dimensional net-like WO3 based sensor has been applied in NO2 monitoring of the natural protected area.

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