472 research outputs found
Online Impulse Buying Behavior Amongst Undergraduate Students in Tianjin, The People’s Republic of China
The aim of this study is to understand online business, regarding impulse buying behavioramongst undergraduate students in Tianjin, China. This study concentrated on the Taobao.complatform, and considered variables of website quality (security, navigability, and visual appeal),hedonic shopping value (product novelty, fun and escapism), and product knowledge (wordof mouth and social norms), to learn how online shop owners increase their profits byencouraging impulse buying behavior. The results suggest that Taobao.com online shop ownersmanage their websites to be physically attractive; consider changing their products; and evenimprove shopping through word of mouth regarding the products they offer
Extended Duality in Fuzzy Optimization Problems
Duality theorem is an attractive approach for solving fuzzy optimization problems. However, the duality gap is generally nonzero for nonconvex problems. So far, most of the studies focus on continuous variables in fuzzy optimization problems. And, in real problems and models, fuzzy optimization problems also involve discrete and mixed variables. To address the above problems, we improve the extended duality theory by adding fuzzy objective functions. In this paper, we first define continuous fuzzy nonlinear programming problems, discrete fuzzy nonlinear programming problems, and mixed fuzzy nonlinear programming problems and then provide the extended dual problems, respectively. Finally we prove the weak and strong extended duality theorems, and the results show no duality gap between the original problem and extended dual problem
Decreasing the uncertainty of atomic clocks via real-time noise distinguish
The environmental perturbation on atoms is the key factor restricting the
performance of atomic frequency standards, especially in long term scale. In
this letter, we demonstrate a real-time noise distinguish operation of atomic
clocks. The operation improves the statistical uncertainty by about an order of
magnitude of our fountain clock which is deteriorated previously by extra
noises. The frequency offset bring by the extra noise is also corrected. The
experiment proves the real-time noise distinguish operation can reduce the
contribution of ambient noises and improve the uncertainty limit of atomic
clocks.Comment: 5 pages, 4 figures, 1 tabl
Syntheses and luminescent properties of a series of new lanthanide azelates
A series of new lanthanide azelates [Ln(aze)(Haze)(H2O)]·H2O {Ln = La (1a), Ce (1b), Pr (1c); H2aze = azelaic acid}, [Ln2(aze)3(phen)2]·H2O [Ln = Nd (2a), Er (2b); phen = 1,10-phenanthroline], [Sm(aze)(Haze)(phen)]·2H2O (3), [Gd(aze)(phen)2]·ClO4 (4) and (Hphen)[Tb2(aze)2(phen)4]·3ClO4 (5) were hydrothermally prepared and structurally characterized.1a-c are isostructural and show 3-D framework based on 1-D infinite [Ln-O-Ln]n chain. 2a-b exhibit sql layer, while 3 displays 1-D chain, where phen ligands locate at both sides of the chain. The Ln3+ ions of 4 and 5 are connected by aze2− into two different types of rare cationic 1-D chains. The luminescent investigations show that both 2a and 2b exhibit interesting NIR luminescence and 5 displays a good potentiality as a luminescent sensor targeted for Fe3+ ion. Of particular interest, lanthanide azelates have not been to date documented, while this work presents the only examples of lanthanide azelates exhibiting luminescent properties. The magnetic properties of some lanthanide azelates were also investigated.publishe
Synthesis and Immobilization of Pt Nanoparticles on Amino-Functionalized Halloysite Nanotubes toward Highly Active Catalysts
A simple and effective method for the preparation of platinum nanoparticles (Pt NPs) grown on amino-functionalized halloysite nanotubes (HNTs) was developed. The nanostructures were synthesized through the functionalization of the HNTs, followed by an in situ approach to generate Pt NPs with diameter of approximately 1.5 nm within the entire HNTs. The synthesis process, composition and morphology of the nanostructures were characterized. The results suggest PtNPs/NH2-HNTs nanostructures with ultrafine PtNPs were successfully synthesized by green chemically-reducing H2PtCl6 without the use of surfactant. The nanostructures exhibit promising catalytic properties for reducing potassium hexacyanoferrate(III) to potassium hexacyanoferrate(II). The presented experiment for novel PtNPs/NH2-HNTs nanostructures is quite simple and environmentally benign, permitting it as a potential application in the future field of catalysts
Bulk dense fine-grain (1-x)BiScO\u3csub\u3e3\u3c/sub\u3e–xPbTiO\u3csub\u3e3\u3c/sub\u3e ceramics with high piezoelectric coefficient
High density fine grain (1−x)BiScO3–xPbTiO3 ceramics were successfully prepared by two-step sintering and their ferroelectric properties were investigated. Experimental evidence indicates the existence of a morphotropic phase boundary at the composition zx=0.635, which exhibits a piezoelectric coefficient d33 of 700 pC/N at room temperature, significantly higher than the reported values to date. Furthermore, a higher electromechanical coupling factor Kp=0.632 and a larger remnant polarization Pr=47.3 µC/cm2 were obtained. The paraelectric-to-ferroelectric phase transition occurs at 446 °C, slightly lower than in the coarse grain ceramics with a similar composition, suggesting a grain size effect. The local effective piezoelectric coefficient d33* was estimated to be 795 pC/N at 2.29 V, measured by scanning probe microscopy. Further atomic force microscope observation revealed the existence of 90° domains of about 60–70 nm in width, confirming the previous results that small domain structure enhances the piezoelectric properties
Dwell Time Modelling and Optimized Simulations for Crowded Rail Transit Lines Based on Train Capacity
Understanding the nature of rail transit dwell time has potential benefits for both the users and the operators. Crowded passenger trains cause longer dwell times and may prevent some passengers from boarding the first available train that arrives. Actual dwell time and the process of passenger alighting and boarding are interdependent through the sequence of train stops and propagated delays. A comprehensive and feasible dwell time simulation model was developed and optimized to address the problems associated with scheduled timetables. The paper introduces the factors that affect dwell time in urban rail transit systems, including train headway, the process and number of passengers alighting and boarding the train, and the inability of train doors to properly close the first time because of overcrowded vehicles. Finally, based on a time-driven micro-simulation system, Shanghai rail transit Line 8 is used as an example to quantify the feasibility of scheduled dwell times for different stations, directions of travel and time periods, and a proposed dwell time during peak hours in several crowded stations is presented according to the simulation results
Structural insights into VirB-DNA complexes reveal mechanism of transcriptional activation of virulence genes
VirB activates transcription of virulence genes in Shigella flexneri by alleviating heat-stable nucleoid-structuring protein-mediated promoter repression. VirB is unrelated to the conventional transcriptional regulators, but homologous to the plasmid partitioning proteins. We determined the crystal structures of VirB HTH domain bound by the cis-acting site containing the inverted repeat, revealing that the VirB-DNA complex is related to ParB-ParS-like complexes, presenting an example that a ParB-like protein acts exclusively in transcriptional regulation. The HTH domain of VirB docks DNA major groove and provides multiple contacts to backbone and bases, in which the only specific base readout is mediated by R167. VirB only recognizes one half site of the inverted repeats containing the most matches to the consensus for VirB binding. The binding of VirB induces DNA conformational changes and introduces a bend at an invariant A-tract segment in the cis-acting site, suggesting a role of DNA remodeling. VirB exhibits positive cooperativity in DNA binding that is contributed by the C-terminal domain facilitating VirB oligomerization. The isolated HTH domain only confers partial DNA specificity. Additional determinants for sequence specificity may reside in N- or C-terminal domains. Collectively, our findings support and extend a previously proposed model for relieving heat-stable nucleoid-structuring protein-mediated repression by Vir
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