With the growing availability and popularity of web-based opinion platforms, online product reviews are now an emerging market phenomenon that is playing an increasingly important role in consumer ...purchase decisions. Generally speaking, there are two types of online reviews: consumer-generated reviews that are based on personal experiences, and reviews that are written by professional editors. However, little prior research efforts have been devoted to evaluate whether these two types of reviews have different influences on the behavior of online users. This study shows that consumer-generated ratings about the quality of food, environment and service of restaurants, and the volume of online consumer reviews are positively associated with the online popularity of restaurants; whereas editor reviews have a negative relationship with consumers’ intention to visit a restaurant's webpage. The findings will help hospitality researchers and practitioners better understand the impact of electronic word-of-mouth on purchase decisions.
Three‐dimensional (3D) printing has received extensive attention due to its unique multidimensional functionality and customizability and has been recognized as one of the most revolutionary ...manufacturing technologies. Functional 3D printed products represent an important orientation for next‐generation manufacturing and attract a great spotlight for the application in sensors, actuators, robots, electronics, and medical devices. However, the lack of functions of printing polymeric materials dramatically limits the development of functional 3D printing. Different from traditional processing, the physical properties, such as geometry and rheological behavior, of the polymeric materials must match the printing process, making the selection of printable materials limited. More importantly, challenges in large‐scale production of such materials further stifle the development of functional 3D printing industry. In this review, we aim to outline recent advances in polymeric materials and methodologies for the functional 3D printing technology. The reports are classified based on functionalities, including electronic conductive, thermally conductive, electromagnetic interference shielding, energy storage, and energy harvesting materials. This study attempts to provide a comprehensive overview of the challenges and opportunities for 3D printing functional polymeric materials/devices, also seeks to enlighten the orientation of future research in this field.
The idea of harnessing the customization competence of 3D printing technology has recently come under the spotlight, enabling the realization of manifold functional polymeric devices with unprecedented properties to which conventional measures are inaccessible. Recent advances in materials and methodologies to realize functional polymeric devices derived from 3D printing technology are summarized. Specifically, applications categorized according to their specific functionalities are discussed, having areas such as electronic conductive, thermal conductive, electromagnetic interference shielding, energy storage, and energy harvesting applications embodied. In the end, the challenges and opportunities are outlined, which highlights future endeavors that should be directed to this field.
Developments in miniaturized microscopes have enabled visualization of brain activities and structural dynamics in animals engaging in self-determined behaviors. However, it remains a challenge to ...resolve activity at single dendritic spines in freely behaving animals. Here, we report the design and application of a fast high-resolution, miniaturized two-photon microscope (FHIRM-TPM) that accomplishes this goal. With a headpiece weighing 2.15 g and a hollow-core photonic crystal fiber delivering 920-nm femtosecond laser pulses, the FHIRM-TPM is capable of imaging commonly used biosensors (GFP and GCaMP6) at high spatiotemporal resolution (0.64 μm laterally and 3.35 μm axially, 40 Hz at 256 × 256 pixels for raster scanning and 10,000 Hz for free-line scanning). We demonstrate the microscope's robustness with hour-long recordings of neuronal activities at the level of spines in mice experiencing vigorous body movements.
•A functionalized magnetic covalent organic framework (Fe3O4@COF-(NO2)2) was fabricated.•Fe3O4@COF-(NO2)2 showed excellent extraction efficiency for neonicotinoids.•The MSPE-HPLC exhibited a wide ...linear range, low LODs, and high enrichment factor.•A sensitive MSPE-HPLC method for monitoring trace insecticides residue in vegetable samples.
A functionalized magnetic covalent organic framework containing the nitro groups (Fe3O4@COF-(NO2)2) with core-shell structure was synthesized for magnetic solid phase extraction (MSPE) of six neonicotinoid insecticides residue in vegetable samples. The structure of Fe3O4@COF-(NO2)2 was investigated by various characterization techniques. The Fe3O4@COF-(NO2)2 exhibits the excellent thermal and chemical stability, high surface area (254.72 m2 g−1), total pore volume (0.19 cm3 g−1), high magnetic responsivity (27.7 emu g−1), which can be used as an ideal adsorbent for rapid isolation and enrichment of target analytes. A sensitive method was developed by using Fe3O4@COF-(NO2)2-based MSPE coupled with HPLC with UV detection. It offered good linearity within the range of 0.1–30 ng mL−1, low limits of detection (S/N = 3) of 0.02–0.05 ng mL−1. Furthermore, high enrichment factors of 170–250 for six neonicotinoid insecticides were obtained. The applicability of Fe3O4@COF-(NO2)2 is demonstrated for measuring trace neonicotinoid residues in vegetable samples with satisfactory recoveries, which ranged from 77.5 to 110.2%. The results indicated that the Fe3O4@COF-(NO2)2 microspheres offer great potential for efficient extraction of neonicotinoid insecticides from complex samples.
This letter proposes a novel framework to detect common salient objects in a group of images automatically and efficiently. Different from most existing co-saliency models which directly redesign ...algorithms for multiple images, the saliency model for a single image is fully exploited under the proposed framework to guide the co-saliency detection. Given single image saliency maps, a two-stage guided detection pipeline led by queries is proposed to obtain the guided saliency maps of the image set through a ranking scheme. Then the guided saliency maps generated by different queries are fused in a way that takes advantages of both averaging and multiplication. The proposed model makes existing saliency models work well in co-saliency scenarios. Experimental results on two benchmark databases demonstrate that the proposed framework outperforms the state-of-the-art models in terms of both accuracy and efficiency.
The molecularly imprinted polymer based on polypyrrole film with incorporated graphene oxide was fabricated and used for electrochemical determination of quercetin. The electrochemical behavior of ...quercetin on the modified electrode was studied in detail using differential pulse voltammetry. The oxidation peak current of quercetin in B-R buffer solution (pH = 3.5) at the modified electrode was regressed with the concentration in the range from 6.0 × 10(-7) to 1.5 × 10(-5) mol/L (r2 = 0.997) with a detection limit of 4.8 × 10(-8) mol/L (S/N = 3). This electrode showed good stability and reproducibility. In the above mentioned range, rutin or morin which has similar structures and at the same concentration as quercetin did not interfere with the determination of quercetin. The applicability of the method for complex matrix analysis was also evaluated.
Tight sandstone gas reservoirs constitute an important type of unconventional gas resources and may be of crucial significance as environment-friendly source of energy in the world. However, the ...dynamics of densification and evolution of the low-porosity and low-permeability sandstone reservoirs are intensively debated in literature. Recently, the question of sequence of reservoir densification and hydrocarbon accumulation has arisen. A typical tight sandstone reservoir (the first member of the Shanxi Formation and the eighth member of Shihezi Formation) in the Permian Sulige gas field in Central China provides an excellent case study to probe these questions. By using a variety of different methodologies such as scanning electron microscopy (SEM), X-ray diffraction (XRD), cathodoluminescence, fluid inclusion analysis and confocal Raman spectrometer analysis, we identified different authigenic minerals such as illite, kaolinite, dickite, chlorite and smectite illitization coexisting with siliceous and calcitic cements. These authigenic minerals precipitated at different diagenetic stages, related to the changing conditions during compaction and lithification, and therefore, changed the porosities of the host rocks during each of these stages. The types of pores in the Sulige gas field are dominated by illite and kaolinite intercrystalline pores, matrix solution pores, and primary intergranular pores. The results of this study suggest that compaction and cementation are the reasons for the most distinct loss in porosity. On the other hand, kaolinite and illite preserve their intercrystalline pores, which could be identified as the main reserve space of the tight gas reservoirs. Therefore, the secondary porosity of the sandstone reservoirs forms the most important contributor to the gas reservoir potential in the Sulige gas field. In addition, it could be inferred that the tight gas accumulation took place during the densification of the reservoirs. The implications of the presented results may also help to understand the formation of other tight reservoirs world-wide.
Display omitted
•First description of the sequential order of authigenic mineral formation.•The secondary porosity forms the main contributor for the reservoir potential.•Tight gas accumulation took place concomitant with densification of the reservoir.
Abstract
Datacenter applications generate diverse flows, including deadline flows and non‐deadline flows. The deadline flows require to complete within strict deadline, while non‐deadline flows seek ...a shorter flow completion time. The state‐of‐the‐art deadline‐aware methods either transmit deadline flows with best‐effort at high priority, resulting in the starvation of non‐deadline flows, or blindly restrict the sending rates of deadline flows, leading to a high deadline missing ratio. To meet the different requirements of mix‐flows, a novel traffic‐aware rate control (TRC) method is proposed. TRC dynamically adjusts the sending rates of deadline flows according to their deadlines and the predicted future traffic patterns. If the intense competition is predicted among deadline flows, TRC will adopt a more aggressive manner to transmit the current deadline flows to avoid bandwidth contention in the future, reducing the deadline missing ratio. Otherwise, TRC will conservatively transmit deadline flows and complete these flows near their respective deadlines, relinquishing the excess bandwidth to non‐deadline flows. Meanwhile, TRC schedules non‐deadline flows in accordance with their sizes, minimizing the average FCT. The performance of TRC in large‐scale scenarios is evaluated through NS2 simulations. The test results show that TRC reduces the deadline missing ratio of deadline flows and the FCT of non‐deadline flows by up to 69.5% and 78.7% compared to the state‐of‐the‐art deadline‐aware schemes, respectively.
PDF
