Comprehensiveness and uniqueness of commercial databases and open access systems

Scientometrics - In this study, scholarly communication systems provided by commercial services and open access systems are examined on the basis of the comprehensiveness and uniqueness of their...     

Facilitation of consumer loyalty toward branded applications: The dual-route perspective

Although many brands develop mobile applications (apps) to build relationships with consumers, most branded apps fail to retain consumers’ loyalty. This study examines the facilitation of consumer loyalty toward branded apps (continuance intention, in-app purchase intention, and word-of-mouth intention) from the dual-route perspective. One route is the affective (relationship) route, where brand benefits (functional benefits, experiential benefits, symbolic benefits, and monetary benefits) drive parasocial interactions between consumers and the brand, which, in turn, influences branded app loyalty. The other route is the utility route, where system characteristics (system quality and information quality) affect perceived usefulness, which, in turn, facilitates branded app loyalty. An online survey was conducted, and the research model was empirically tested using partial least squares structural equation modeling. The findings support the dual-route perspective according to which both affective and utilitarian paths facilitate branded app loyalty. The key theoretical contribution of this study is that it moves beyond the utilitarian path and finds the affective (relationship) path to give a more complete picture of the facilitation of consumer loyalty in the branded app context. A strategy is provided to suggest to practitioners how to design branded apps to facilitate consumer loyalty.     

Rare earth element cerium substituted Ca–Si–Mg system bioceramics: From mechanism to mechanical and degradation properties

Cerium (Ce)-substituted diopsides (CaMgSi₂O₆) with enhanced mechanical strength and bioactivity were fabricated by precipitation method, followed by annealing at 1000 °C for 4 h. The mineralogical, morphological, in vitro biomineralization, degradation, and mechanical properties were investigated in order to assess the factors and mechanisms affecting the resultant properties. The X-ray diffractometer results showed that the onset of substitutional solid solubility in 0.25 mol Ce would result in new phase formation (cerium dioxide [CeO₂], and magnesium silicate [MgSiO₃]) further causing lattice instability. With increasing Ce dopant levels to 1.00 mol, the initial CaMgSi₂O₆ phase was completely replaced by new phases. The field-emission scanning electron microscopy results indicated that the 0.25 mol Ce had the best biomineralization performance in vitro, while less hydroxyapatite precipitates were found with further increasing Ce dopant levels, suggesting the new phases led to the hindrance of precipitates. The weight loss values indicated that the high dissolution rate of ions in the matrix was observed in the pure sample, while the high readsorption rate of ions in the simulated body fluid (SBF) occurred with increasing Ce dopant levels. The pH value and the inductively coupled plasma-mass spectrometer results suggested that the release of Ca and Mg ions controlled the pH value. The mechanical strength of matrices before SBF immersion was related to the phase transformation, the elastic modulus of CeO₂ and CaMgSi₂O₆, and the release of Mg ions, while the mechanical strength of matrices after SBF immersion was dominated by the structure of matrices.     

A triple (e−/O2−/H+) conducting perovskite BaCo0.4Fe0.4Zr0.1Y0.1O3-δ for low temperature solid oxide fuel cell

Low-temperature solid oxide fuel cells (LT-SOFCs) have recently gained enormous attention worldwide with a new research trend focusing on single layer fuel cells (SLFC), which have better cell performance than traditional SOFCs at low operating temperatures. In this study, a triple (e^?/O^2?/H⁺) conducting perovskite BaCo_0.4Fe_0.4Zr_0.1Y_0.1O_3-δ (BCFZY) is used as the intermediate layer material for SLFC. A high current density of 994 mA/cm² at 0.6 V and a peak power density of 610 mW/cm² with an OCV of 1.01 V has been achieved with a cell operating temperature of 550 °C, confirming the application feasibility of BCFZY in SLFCs. Furthermore, a typical proton conductor BaZr_0.8Y_0.2O_3-δ (BZY) is introduced into BCFZY to enhance the cell performance. By adjusting the mass ratio of the BCFZY-BZY layer, an optimal power density is obtained, achieving 703 mW/cm² with an OCV of 1.03 V at 550 °C with an 8BCFZY:2BZY (wt%) ratio. These findings prove that the proposed BCFZY-BZY holds great promise for developing SLFCs to realize low-temperature operation.     

Model Misspecification of Generalized Gamma Distribution for Accelerated Lifetime-Censored Data

Abstract

The performance of reliability inference strongly depends on the modeling of the product’s lifetime distribution. Many products have complex lifetime distributions whose optimal settings are not easily found. Practitioners prefer to use simpler lifetime distribution to facilitate the data modeling process while knowing the true distribution. Therefore, the effects of model mis-specification on the product’s lifetime prediction is an interesting research area. This article presents some results on the behavior of the relative bias (RB) and relative variability (RV) of pth quantile of the accelerated lifetime (ALT) experiment when the generalized Gamma (GG₃) distribution is incorrectly specified as Lognormal or Weibull distribution. Both complete and censored ALT models are analyzed. At first, the analytical expressions for the expected log-likelihood function of the misspecified model with respect to the true model is derived. Consequently, the best parameter for the incorrect model is obtained directly via a numerical optimization to achieve a higher accuracy model than the wrong one for the end-goal task. The results demonstrate that the tail quantiles are significantly overestimated (underestimated) when data are wrongly fitted by Lognormal (Weibull) distribution. Moreover, the variability of the tail quantiles is significantly enlarged when the model is incorrectly specified as Lognormal or Weibull distribution. Precisely, the effect on the tail quantiles is more significant when the sample size and censoring ratio are not large enough. Supplementary materials for this article are available online.     

Fabrication and Thermal Dissipation Properties of Carbon Nanofibers Derived from Electrospun Poly(Amic Acid) Carboxylate Salt Nanofibers

Polyimides (PIs) possess excellent mechanical properties, thermal stability, and chemical resistance and can be converted to carbon materials by thermal carbonization. The preparation of carbon nanomaterials by carbonizing PI‐based nanomaterials, however, has been less studied. In this work, the fabrication of PI nanofibers is investigated using electrospinning and their transformation to carbon nanofibers. Poly(amic acid) carboxylate salts (PAASs) solutions are first electrospun to form PAAS nanofibers. After the imidization and carbonization processes, PI and carbon nanofibers can then be obtained, respectively. The Raman spectra reveal that the carbon nanofibers are partially graphitized by the carbonization process. The diameters of the PI nanofibers are observed to be smaller than those of the PAAS nanofibers because of the formation of the more densely packed structures after the imidization processes; the diameters of the carbon nanofibers remain similar to those of the PI nanofibers after the carbonization process. The thermal dissipation behaviors of the PI and carbon nanofibers are also examined. The infrared images indicate that the transfer rates of thermal energy for the carbon nanofibers are higher than those for the PI nanofibers, due to the better thermal conductivity of carbon caused by the covalent sp² bonding between carbon atoms.     

Enhanced dielectric properties of three phase dielectric MWCNTs/BaTiO3/PVDF nanocomposites for energy storage using fused deposition modeling 3D printing

This research studied the effect of fused deposition modeling (FDM) 3D printing on three phase dielectric nanocomposites using poly(vinylidene) fluoride (PVDF), BaTiO₃ (BT), and multiwall carbon nanotubes (CNTs). PVDF polymer and BT ceramics are piezo-, pyro- and di-electric materials extensively used for sensor and energy storage/harvesting applications due to their unique characteristic of dipole polarization. To increase dielectric property, CNTs have been recently utilized for uniform dispersion of BT nanoparticles, ultrahigh polarization density, and local micro-capacitor among matrix. It was proved that 3D printing process provides homogeneous dispersion of nanoparticles, alleviating agglomeration of nanoparticles and reducing micro-crack/voids in matrix which can potentially enhance their dielectric property than traditional methods. In this research, these three-phase nanocomposites are fabricated through FDM 3D printing process and characterized for dielectric property. Increasing both BT and CNT nanoparticles improves dielectric properties, while CNTs have a percolation threshold near 1.7?wt%. The most desirable combination of dielectric constant and loss properties (118 and 0.11 at 1?kHz) is achieved with nanocomposites containing 1.7?wt%-CNT/45?wt%-BT/PVDF. These results provide not only a technique to 3D print dielectric nanocomposites with improved dielectric property but also large-scale electronic device manufacturing possibility with freedom of design, low cost, and faster process.     

Making reusable reaction-bonded silicon nitride crucibles for silicon casting from kerf-loss silicon waste

Silicon kerf loss during wafer slicing and the broken quartz crucibles after silicon casting are two major solid wastes from photovoltaic (PV) industry. Especially, the recycle of kerf-loss silicon has become an urgent issue because near 100 000 t of solid wastes are generated every year. One of the most meaningful recycle routes of the kerf-loss silicon is to make silicon nitride crucibles to replace the quartz crucibles. In this study, we demonstrated how this is feasible through acid leaching refining, slip casting, and nitridation. The reaction-bonded silicon nitride (RBSN) crucibles after oxidation were found pure enough for silicon ingot growth. More importantly, they could be reused after ingot growth. With the present examples, the potential of using the kerf-loss silicon for fine ceramics is prominent.     

Rattle‐Structured Ag/TiO2 Nanocomposite Capsules with Bactericide and Photocatalysis Activities

A structural design featuring rattle‐type silver/titania (Ag/TiO₂) core/shell, that is, Ag@TiO₂, composite microcapsules is produced. The TiO₂ shell protects the encapsulated, movable Ag nanoparticles from breaking away under moderate loading, minimizing hence adverse environmental and biological exposure due to the metal loss, whereas the mesoporous shell serves as conduits for Ag ions released from the caged Ag nanoparticles to kill Escherichia coli in aqueous solutions under dark condition. The anatase TiO₂ shell imparts an additional, synergistic photocatalysis activity under ultraviolet irradiation. A pronouncedly enhanced photocatalysis activity results when the Ag@TiO₂ composite capsules were thermally annealed under vacuum. This “rattle‐in‐ball” hybrid architecture enables bifunctional bactericide and photocatalysis capability under both light and dark conditions, as well as mitigated environmental and biological impact in practical use.