1,722,181 research outputs found
Replication Data for: The Impact of Corporate Scale on Carbon Emission Efficiency: Empirical Analysis and Nonlinear Dynamics
No full text29 industries in the Chinese manufacturing sector from 2012 to 2021
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Understanding Structure-property Relationships between Tribological Properties and Chemistry of Phosphonium Ionic Liquids
Full text linkIonic liquids (ILs) have many advantages compared to conventional organic compounds in terms of biological, chemical, physical, and thermal properties. Therefore, ILs are considered as promising green engineering liquids for replacement of commonly used volatile organic compounds that offer a convenient solution to challenges associated with both solvent emission and catalytic recycling for a diverse range of applications. Here, we primarily focus on ILs as lubricants and lubricant additives. For the application in tribology as lubricants/lubricant additives, phosphonium ILs have been the rising star of the ILs family as they have been reported to exhibit lower wear and friction, as well as superior resistance to corrosion and tribo-corrosion. They are more stable in strongly basic media and more thermally stable than other ILs. Also, importantly, some phosphonium ILs can be less toxic and biodegradable than conventional organic compounds. The physico-chemical properties of phosphonium ILs are tunable depending upon the combination of cation and anion employed. Changes in properties in turn affect the performance of phosphonium ILs as lubricants and lubricant additives. Although there have been many investigations into the relationship between IL properties and ion chemistry/structure, the selection of cations and anions for phosphonium ILs is still very much trial-and-error. To optimize phosphonium ILs for lubrication, a full understanding of the relationship between chemistry/structure and material properties of is phosphonium ILs required. Toward this goal, classical and reactive molecular dynamics simulations are employed to study the molecular scale mechanisms underlying the mechanical response of phosphonium ILs with different cation and anion combinations.First, a non-reactive force field was used to predict bulk properties, including density, viscosity, and ionic conductivity. The accuracy of the modeling approach was evaluated by comparing to experiment/literature data. In particular, the effect of anions on these bulk properties was analyzed. The high accuracy in predicting bulk properties provided confidence for using this force field to investigate the wetting behavior and frictional behavior. Then the wetting behavior of phosphonium ILs on iron was studied for different cation-anion pairs to investigate the interaction of phosphonium ILs with solid surfaces. Results showed that contact angle was affected by the anion and increased as benzoate < salicylate < saccharinate longer alkyl chains in the cations led to lower contact angle. The trends were explained in terms of adhesive and cohesive energies in the simulations, and then correlated to the atomic scale differences between the anions and cations.
Since the effectiveness of lubricants depends on their frictional behavior, viscous friction that is entirely determined by the fluid properties was investigated for different phosphonium cations. It was found that viscous friction is highly related to cation alkyl chains and chain asymmetry under the same operating condition. A predictive model of viscous friction for tetraalkylphosphonium ILs was then established to capture the effect of cation moiety and operating conditions.
Lastly, in many applications, ILs are in direct contact with a metal surface and form a solid-liquid interface and possible corrosion could occur. The origins of corrosion behavior for trihexyltetradecylphosphonium benzoate and trihexyltetradecylphosphonium salicylate on ferrous surfaces was analyzed using reactive molecular dynamics simulations based on the types of bonding and orientation of the anions relative to the surface. It was found that salicylate had more possible bonding scenarios and was more likely to be tilted on the surface than benzoate, affecting the localization of surface-anion bonds and anion coverage density which could affect corrosion mechanisms.Overall, the results of these studies revealed direct correlations between tribological properties of phosphonium ILs and cation and anion chemistry. The structure-property relationship obtained from this study can ultimately be used to guide the design of high performance phosphonium ILs lubricants
Chinese Unknown Word Identification Based on Local Bigram Model
No full textThis paper presents a Chinese unknown word identification system based on a local bigram model. Generally, our word segmentation system employs a statistical-based unigram model. But to identify those unknown words, we take advantage of their contextual information and apply a bigram model locally. By adjusting the value of interpolation which is derived from a smoothing method, we combine these two models with different dimensions. As a simplification of bigram, this method is simple as well as feasible, since the complexity of its algorithm is quite low and not so many training corpora are needed. The results of our experiments show the solution is effective
Review of Epoicocladius Šulc et Zavřel from China (Diptera, Chironomidae)
No full textYan, Chuncai, Liu, Ting, Cao, Wei, Zhang, Xinghua, Liu, Wenbin (2019): Review of Epoicocladius Šulc et Zavřel from China (Diptera, Chironomidae). Zootaxa 4590 (2): 289-295, DOI: 10.11646/zootaxa.4590.2.
Aster sanqingensis (Asteraceae, Astereae), a synonym of Aster sanqingshanicus
No full textXiao, Jia-Wei, Liu, Ting, Li, Wei-Ping, Yang, Xian-Jun (2023): Aster sanqingensis (Asteraceae, Astereae), a synonym of Aster sanqingshanicus. Phytotaxa 591 (1): 87-90, DOI: 10.11646/phytotaxa.591.1.11, URL: http://dx.doi.org/10.1094/PDIS-04-22-0755-PD
FIGURES 2–7 in Review of Epoicocladius Šulc et Zavřel from China (Diptera, Chironomidae)
No full textFIGURES 2–7. Epoicocladius ephemerae (Kieffer, 1924). Larvae. 2—mandible; 3—mentum; 4—antenna; 5—labro-epipha- ryngeal region. Pupae. 6—Thoracic horn and precorneals in Chinese specimen; 7—precorneals in European specimens.Published as part of Yan, Chuncai, Liu, Ting, Cao, Wei, Zhang, Xinghua & Liu, Wenbin, 2019, Review of Epoicocladius Šulc et Zavřel from China (Diptera, Chironomidae), pp. 289-295 in Zootaxa 4590 (2) on page 292, DOI: 10.11646/zootaxa.4590.2.6, http://zenodo.org/record/265202
A new species of Olecryptotendipes Zorina from China (Diptera, Chironomidae)
No full textYan, Chuncai, Liu, Ting, Zhao, Guangjun, Shi, Yafeng, Wang, Xinhua (2017): A new species of Olecryptotendipes Zorina from China (Diptera, Chironomidae). Zootaxa 4299 (2): 291-296, DOI: https://doi.org/10.11646/zootaxa.4299.2.1
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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