Purpose
The purpose of this paper is to examine the effects of “social information” in Facebook News Feed ads on American users’ advertising responses, including ad credibility, ...attitude-toward-the-ad, brand interest, intention to click and purchase intention. Using social impact theory as a conceptual framework, three factors were tested – relationship strength, physical distance and number of affiliated friends. The moderating role of product involvement was also investigated.
Design/methodology/approach
A 2 (strength of relationship: weak vs strong) × 2 (immediacy of relationship: close distance vs long distance) × 2 (number of friends: one vs several) between-group factorial design was used, and 397 research participants were recruited through Amazon’s Mechanical Turk (MTurk).
Findings
Significant main effects were found for relationship strength and physical distance. Product involvement was identified as a moderating variable. No significant effects were found under the high involvement condition. Under the low involvement condition, however, relationship strength and physical distance significantly affected Facebook users’ advertising responses.
Research limitations/implications
Research samples were recruited through Amazon’s Mechanical Turk (MTurk). It is possible that the characteristics of this specific social group might have influenced the findings of the study. Only one specific product category, fast casual restaurant, was tested. Participants were asked to imagine themselves in certain scenarios. Even though the scenarios were carefully tested in the pretest and clear instructions were given, field experiments might be helpful in future research to better reflect the actual consumer experience.
Practical implications
Marketers should take advantage of the “social information” feature in Facebook News Feed ads, especially for low involvement products. Names of friends with stronger social relationships and within close physical distance should be included in the ads.
Originality/value
The study is one of the first to examine the effects of “social information” in Facebook advertising. It also confirms the Social Impact Theory in a social media setting.
We report acute antibody responses to SARS-CoV-2 in 285 patients with COVID-19. Within 19 days after symptom onset, 100% of patients tested positive for antiviral immunoglobulin-G (IgG). ...Seroconversion for IgG and IgM occurred simultaneously or sequentially. Both IgG and IgM titers plateaued within 6 days after seroconversion. Serological testing may be helpful for the diagnosis of suspected patients with negative RT-PCR results and for the identification of asymptomatic infections.
With the development and application of Web Semantic, users are no longer satisfied with basic metadata descriptions such as titles and link texts and string-matching search results. They hope that ...the resource description can provide the theme ideas, topics, and topics involved in the resource. Potential semantic information contains documents such as teaching methods and knowledge-concept relationships. This research starts from the demand for semantic annotation of resources in the process of resource library construction and sharing, and uses the LDA model to semantically model the document resources in the resource library to mine potential topics in the document. From “document-topic-keyword” scheme, the semantic description of teaching resources at different levels enriches the metadata attributes and content of resources, and adds more related topics and corresponding keyword descriptions related to disciplines, teaching content, teaching methods, etc., providing resource retrieval and sharing. The experimental results show that the LDA model can catalogues teaching resources from a macro perspective, and model LDA on teaching subject resources of the same teaching content. It can mine the inherent semantic topic features and detailed differences of resources. The final performance analysis verifies LDA’s advantages of the model in parallel computing in the big data environment.
The pandemic of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been posing great threats to the world in many aspects. Effective therapeutic and preventive approaches ...including drugs and vaccines are still unavailable although they are in development. Comprehensive understandings on the life logic of SARS-CoV-2 and the interaction of the virus with hosts are fundamentally important in the fight against SARS-CoV-2. In this review, we briefly summarized the current advances in SARS-CoV-2 research, including the epidemic situation and epidemiological characteristics of the caused disease COVID-19. We further discussed the biology of SARS-CoV-2, including the origin, evolution, and receptor recognition mechanism of SARS-CoV-2. And particularly, we introduced the protein structures of SARS-CoV-2 and structure-based therapeutics development including antibodies, antiviral compounds, and vaccines, and indicated the limitations and perspectives of SARS-CoV-2 research. We wish the information provided by this review may be helpful to the global battle against SARS-CoV-2 infection.
Deep eutectic solvents (DESs) as novel and green solvents can extract high-purity lignin from lignocellulose in a high yield; however, further utilization of the extracted lignin in the DES is a ...severe challenge in biorefinery processes. Nevertheless, the potential of lignin valorization can be precisely reflected by unveiling the chemical transformations of lignin during DES pretreatment. In this study, we aimed to understand the possible transformation pathway
via
thorough characterization of the regenerated lignin and lignin oil and transformation of lignin into value-added products. During this process, alkali lignin (AL) isolated from poplar was pretreated with choline chloride-lactic acid (ChCl-LA) and choline chloride-oxalic acid (ChCl-OA) at 80-120 °C for 6 hours to produce the regenerated lignin and lignin oil. The yield of the regenerated lignin ranged from 44 to 75% after DES pretreatment. During ChCl-LA pretreatment, γ-acetylated groups in the regenerated lignin were observed at low temperatures and then deacylation occurred at high temperatures, which was beneficial for oxidizing lignin and producing phenolic diketones. Additionally, the depolymerization of lignin fractions was the dominant reaction during DES pretreatment, accompanied by partial condensation reactions. More importantly, this is the first report of obtaining S- and G-derived diketones from lignin oil after DES pretreatment. The degradation mechanism of lignin in the DES system has been proposed. This work opens a way to produce value-added chemicals from lignin in DESs, which needs to be researched in the future.
The chemical transformations of lignin in an acidic DES system.
Photovoltaic Poverty Alleviation (PVPA) projects, which utilize the subsidies and income from PV power to alleviate poverty in rural areas, are part of a comprehensive energy policy innovation in ...China. It is expected that the projects will deploy at least 10 GW PV and benefit more than two million poor households in total by 2020. To achieve this goal, specific supporting policies and novel business models are necessary. In the present paper, the current status and existing supporting policies are introduced to give an overview of PVPA projects. Then representative business models in PV projects are summarized and compared to provide a reference for PVPA projects. Obstacles, such as subsidy delays, insufficient infrastructure, low quality of PV equipment, and inflexible profit allocation mechanism may reduce the revenue from PV operation and increase the costs of PV deployment. Therefore, this paper also proposes corresponding recommendations for policy makers considering the existing challenges.
•The financial yield of Photovoltaic Poverty Alleviation (PVPA) is analyzed.•The major policies for PVPA and photovoltaic (PV) industry are summarized.•Novel business models for PV projects are analyzed and compared.•Challenges in PVPA are summarized and corresponding strategies are proposed.
•Chitosan/biochar hydrogel beads have great potential of easy separation and regeneration.•The uptake capacity of chitosan/biochar hydrogel beads showed about 36.72 mg/g.•The regeneration of CBHB was ...still more than 25.73 mg/g after 6th regeneration.
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Biochar is effective in water treatment but it is hard to retrieve or separate biochar powder from aqueous solutions. In this study, the removal of ciprofloxacin from aqueous solutions was investigated using chitosan/biochar hydrogel beads (CBHB). The results showed that the adsorption rate was almost independent of the temperature and occurred at the homogeneous sites of adsorbent thus obeying the Langmuir model. The equilibrium time was varying for different initial concentrations and found to be 48 h for maximum one. The maximum sorption was found to be >76 mg/g of adsorbent out of 160 mg/L as initial concentration. Adsorption obeyed the second-order mechanism with leading role of intra-particle diffusion and outer diffusion. Adsorption capacity decreased from 34.90 mg/g to 15.77 mg/g in the presence of 0.01 N Na3PO4 whereas other electrolytes such as NaCl, Na2SO4, NaNO3 with same concentration did not affect the sorption capacity. However, increased concentration of NaCl reduced the sorption capacity to some extent. CBHB showed a mixed mechanism by removing CIP through π-π electron donor-acceptor (EDA) interaction, hydrogen bonding and hydrophobic interaction. The reformation of CBHB with methanol and ethanol instead of water decreased its sorption capacity to 32.69 mg/g and 29.29 mg/g. Adsorption decreased by little after every regeneration of CBHB and was still >64 ± 0.68% (25.73 mg/g) after 6th regeneration. The efficacy of CBHB for CIP removal proved that CBHB is an economical and sustainable adsorbent.
Note: RA-recycled aggregate, BF-basalt fiber, CP-chloride penetration.
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•Basalt fiber (BF) raises the early compressive strength of recycled aggregate (RA) concrete.•BF in a dosage ...dependent way lifts the splitting tensile strength of RA concrete.•BF is with a declined marginal utility in the reinforcement effect.•Concrete with low dosage of BF and high content RA has a higher specific strength.•BF decreases the porosity and the chloride penetration.
Herein, the study conducts an experimental research on the mechanical strength and durability of chopped basalt fiber (BF) reinforced recycled aggregate (RA) concrete. BF at six volumetric dosages of 0, 0.25, 0.5, 0.75, 1 and 1.5% and RA at five volumetric substitution levels of 0, 25, 50, 75 and 100% are used in determining the compressive strength, the splitting tensile strength, the specific strength ratio of splitting tensile strength and apparent density and the chloride penetration. Results show that BF reinforces both RA and nature aggregate (NA) concrete in a dosage dependent way. Relative to the late strength, BF has a better reinforcement effect on the early strength of RA concrete. BF content though is positively related to the splitting tensile strength is with a declined marginal utility. The opitmal dosage thereby exists and is identifed as 1%. Given the reinforcement of BF and the lower density of RA, the combined use of BF at low dosage and RA in high content results in a specific strength that is higher than that of RA concrete. Besides the strength enhancement effect, BF also descends the porosity and ascends the resistance to chloride penetration of RA concrete. The respond surface methodology interestingly is found to have a prominent role in establishing a mathematical model between the compressive and the splitting tensile strength because both strengths have respond surfaces that are shaped by BF and RA. Aforementioned results verify inferior properties of RA concrete can be offset by BF addition, signifying a complementary effect between BF and RA.
This paper presents a novel 400 to 12 V isolated bidirectional dc-dc converter based on a phase-shift-controlled-modified dual-active-bridge power stage. The proposed converter consists of a ...half-bridge and center tap with active clamp circuit, which has promising performance for low-voltage high-current applications. 650 V gallium-nitride high electron mobility transistors are used on the high voltage side to avoid issues encountered using Si superjunction MOSFETs in phase-shift-controlled-bidirectional power conversions. The operation principle and power transfer characteristic are obtained based on a time-domain analysis of the inductor current. Design methodology and criteria and converter's efficiency analysis are discussed. Both the analysis and experiments verify that the proposed converter is capable of achieving low power loss and high power density in soft-switching and hard-switching modes. Experimental results are presented for a 1-kW, 400 V-to-12 V dc-dc prototype converter operating at 100 kHz switching frequency. A power density of 30 W/in 3 and a peak efficiency of 98.3% in a wide input/output voltage range are achieved.
The North China Craton (NCC) underwent significant lithospheric destruction during the Mesozoic, although the mechanisms and timings associated with this process remain debated. The extensive ...magmatism associated with craton destruction includes dyke suites of diverse composition derived from lithospheric and asthenospheric sources. Here we investigate lamprophyre, dolerites and felsic dyke suites from the Laiyuan complex in North Taihang Mountain of the NCC. Zircon UPb dating shows weighted mean ages in the range of 110–115 Ma, 117–126 Ma and 127–130 Ma for the lamprophyres, dolerites and felsic dykes and their εHf (t) values show a range of −17.2 to −3.7, −23.3 to −14.2 and − 22.3 to −17.2, respectively, with an evident increase through time suggesting increasing input of asthenospheric components in the mafic suite. We present major, trace and REE data on these rocks which suggest that the mafic dykes experienced limited crustal contamination and were dominated by olivine and clinopyroxene fractional crystallization. The Laiyuan mafic dykes were derived through partial melting mantle previously enriched by subduction-related fluids, within amphibole- and garnet-stability field with increasing input of asthenospheric material through time. The felsic dykes show adakitic feature with magma generation through the reworking of ancient basement rocks induced by heat input from underplated mafic magma which was derived from the partial melting of enriched lithospheric mantle. Subsequently, the enriched mantle-derived magmas migrated through lithospheric faults and were emplaced as dolerite dykes at ~117 Ma. The asthenosphere upwelling contributed to the thermo-mechanical erosion along weak zones, and the limited lithosphere-asthenosphere interaction generated the lamprophyres during ~115 Ma to 110 Ma. Our data suggest that both delamination and thermo-mechanical erosion contributed to the craton destruction of the NCC during Early Cretaceous.
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•Early Cretaceous mafic and felsic dykes provide insights into lithospheric destruction•Magma sourced through asthenosphere-lithosphere interaction•Zircon εHf (t) values indicate increasing input of asthenospheric materials•Delamination and thermo-mechanical erosion associated with decratonization
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