In this article, the observations from two different experimental studies on CO2 two-phase flow regimes in a near horizontal pipe are analysed. These experiments show significant bubble entrainment ...in a stratified flow, and the bubble entrainment in liquid is found to be a dominant mechanism for the flow regime transition between the stratified and bubbly flow. The hydrodynamic slug flow is not observed in these experimental studies. The X-ray measurement of the experimental study in a near horizontal pipe of 44 mm internal diameter is processed to obtain the bubble volume fraction in the liquid layer, which is found to be a function of two-phase Froude number. This Froude number definition takes into account gas density and pipe inclination effects. A parametric study shows that the bubble entrainment into the liquid layer decreases significantly with an increase of pipe internal diameter.
This paper is concerned with the second-order nonlinear Robin problem involving the first-order derivative:
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•This study theorizes three types of artificial autonomy—sensing, thought, and action autonomy.•The authors operationalize the two dimensions of human-like perceptions—competence and warmth ...perceptions.•The authors find the comparative effects of competence and warmth perceptions of IPAs.
In the era of the Internet of Things (IoT), emerging artificial intelligence (AI) technologies provide various artificial autonomy features that allow intelligent personal assistants (IPAs) to assist users in managing the dynamically expanding applications, devices, and services in their daily lives. However, limited academic research has been done to validate empirically artificial autonomy and its downstream consequences on human behavior. This study investigates the role of artificial autonomy by dividing it into three types of autonomy in terms of task primitives, namely, sensing, thought, and action autonomy. Drawing on mind perception theory, the authors hypothesize that the two fundamental dimensions of humanlike perceptions—competence and warmth—of non-human entities could explain the mechanism between artificial autonomy and IPA usage. Our results reveal that the comparative effects of competence and warmth perception exist when artificial autonomy contributes to users' continuance usage intention. Theoretically, this study increases our understanding of AI-enabled artificial autonomy in information systems research. These findings also provide insightful suggestions for practitioners regarding AI artifacts design.
Although marketing managers are relying increasingly on customer data, insight into the best approaches for resolving the personalization–privacy paradox remains limited. Specifically, we argue for ...the success of a personalization involving the integration of two stages: the self-disclosure stage and the personalization stage. Using a conceptual framework grounded in the foot-in-the-door effect, we argue that compliance with commitment to self-disclosure as the initial small request induces greater compliance with the later target request. The results of a large-scale two-stage field experiment based on a combined propensity score matching and difference-in-difference model show positive causal effects of the act of self-disclosure and the positive effect of the intensity of self-disclosure on purchase responses to personalized promotions. The results also indicate that a combination of privacy assurance and personalization declaration drives customers’ act of self-disclosure and increases the intensity of self-disclosure. Findings empower managers to capitalize on new opportunities in personalization.
This study investigates the effects of Chinese companies’ institutional environment on the development of trust and information integration between buyers and suppliers. Three aspects of China's ...institutional environment are salient: legal protection, government support, and the importance of guanxi (interpersonal relationships). This study uses structural equation modeling to analyze data collected from 398 Chinese manufacturing companies. Government support and importance of guanxi significantly affect trust, which subsequently influences two elements of information integration, namely, information sharing and collaborative planning. Furthermore, the importance of guanxi has a direct, positive impact on information sharing, and government support has a direct, positive effect on both information sharing and collaborative planning.
In this paper we study the existence of positive solutions of a second-order integral boundary value problems for ordinary differential equations. Our results presented here unify, generalize and ...substantially improve the existing results in the literature. Moreover, it is worthwhile to point out that our method will dispense with constructing a new Green function.
The “fixed” or “flexible” design of plasmonic hotspots is a frontier area of research in the field of surface-enhanced Raman scattering (SERS). Most reported SERS hotspots have been shown to exist in ...zero-dimensional point-like, one-dimensional linear, or two-dimensional planar geometries. Here, we demonstrate a novel three-dimensional (3D) hotspot matrix that can hold hotspots between every two adjacent particles in 3D space, simply achieved by evaporating a droplet of citrate-Ag sols on a fluorosilylated silicon wafer. In situ synchrotron-radiation small-angle X-ray scattering (SR-SAXS), combined with dark-field microscopy and in situ micro-UV, was employed to explore the evolution of the 3D geometry and plasmonic properties of Ag nanoparticles in a single droplet. In such a droplet, there is a distinct 3D geometry with minimal polydispersity of particle size and maximal uniformity of interparticle distance, significantly different from the dry state. According to theoretical simulations, the liquid adhesive force promotes a closely packed assembly of particles, and the interparticle distance is not fixed but can be balanced in a small range by the interplay of the van der Waals attraction and electrostatic repulsion experienced by a particle. The “trapping well” for immobilizing particles in 3D space can result in a large number of hotspots in a 3D geometry. Both theoretical and experimental results demonstrate that the 3D hotspots are predictable and time-ordered in the absence of any sample manipulation. Use of the matrix not only produces giant Raman enhancement at least 2 orders of magnitude larger than that of dried substrates, but also provides the structural basis for trapping molecules. Even a single molecule of resonant dye can generate a large SERS signal. With a portable Raman spectrometer, the detection capability is also greatly improved for various analytes with different natures, including pesticides and drugs. This 3D hotspot matrix overcomes the long-standing limitations of SERS for the ultrasensitive characterization of various substrates and analytes and promises to transform SERS into a practical analytical technique.
Antibiotics target specific biochemical mechanisms in bacteria. In response to new drugs, pathogenic bacteria rapidly develop resistance. In contrast, antimicrobial peptides (AMPs) have retained ...broad spectrum antibacterial potency over millions of years. We present single-cell fluorescence assays that detect reactive oxygen species (ROS) in the Escherichia coli cytoplasm in real time. Within 30 s of permeabilization of the cytoplasmic membrane by the cationic AMP CM15 combining residues 1–7 of cecropin A (from moth) with residues 2–9 of melittin (bee venom), three fluorescence signals report oxidative stress in the cytoplasm, apparently involving O ₂⁻, H ₂O ₂, and •OH. Mechanistic studies indicate that active respiration is a prerequisite to the CM15-induced oxidative damage. In anaerobic conditions, signals from ROS are greatly diminished and the minimum inhibitory concentration increases 20-fold. Evidently the natural human AMP LL-37 also induces a burst of ROS. Oxidative stress may prove a significant bacteriostatic mechanism for a variety of cationic AMPs. If so, host organisms may use the local oxygen level to modulate AMP potency.
Significance Antimicrobial peptides (AMPs) help to kill invading bacteria on skin and lung surfaces. We are developing fluorescence microscopy assays that reveal the mechanisms of action of AMPs in real time. It is increasingly clear AMP damage to bacterial cells goes far beyond permeabilization of membranes. Here we demonstrate that for Escherichia coli in aerobic conditions, the peptide CM15 combining residues 1–7 of cecropin A (from moth) with residues 2–9 of melittin (bee venom), induces a burst of biochemically harmful reactive oxygen species within 30 s of membrane permeabilization. In anaerobic conditions, CM15 is 20-fold less potent. AMP efficacy in vivo may be tuned to the local level of oxygenation.
Tip-enhanced Raman spectroscopy (TERS) with sub-nanometer spatial resolution has been recently demonstrated experimentally. However, the physical mechanism underlying is still under discussion. Here ...we theoretically investigate the electric field gradient of a coupled tip-substrate system. Our calculations suggest that the ultra-high spatial resolution of TERS can be partially attributed to the electric field gradient effect owning to its tighter spatial confinement and sensitivity to the infrared (IR)-active of molecules. Particularly, in the case of TERS of flat-lying H₂TBPP molecules,we find the electric field gradient enhancement is the dominating factor for the high spatial resolution, which qualitatively coincides with previous experimental report. Our theoretical study offers a new paradigm for understanding the mechanisms of the ultra-high spatial resolution demonstrated in tip-enhanced spectroscopy which is of importance but neglected.
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