Heat and Mass Transfer in Outward Convex Corrugated Tube Heat Exchangers

Heat and mass transfer in outward convex corrugated tube heat exchangers is of significant importance for the optimization, fabrication, and application of outward convex corrugated tube heat exchangers. This chapter gives a deep investigation of the heat and mass transfer in outward convex corrugated tube heat exchangers. Based on the experimental setup developed, the performances of a novel outward convex corrugated tube heat exchanger are presented. Simulation methods are then used to detail the heat and mass transfer at tube side and shell side of the outward convex corrugated tube heat exchanger, and these include the flow structure, temperature distribution, and turbulence kinetic energy. Heat and mass transfer enhancements of the outward convex corrugated tube heat exchanger are also studied, and they are from tube side, shell side, and overall system aspects. Finally, multi-objective optimization of the outward convex corrugated tube heat exchanger is conducted to obtain the optimal performances through using Response Surface Methodology (RSM) and Non-dominated Sorting Genetic Algorithm (NSGA-II). Main conclusions and future outlook are then briefly stated and summarized. We firmly believe that the contents presented in this chapter can not only enrich the knowledge of heat exchangers but also develop methods for studying heat exchangers

Data-based bipartite formation control for multi-agent systems with communication constraints

This article investigates data-driven distributed bipartite formation issues for discrete-time multi-agent systems with communication constraints. We propose a quantized data-driven distributed bipartite formation control approach based on the plant’s quantized and saturated information. Moreover, compared with existing results, we consider both the fixed and switching topologies of multi-agent systems with the cooperative-competitive interactions. We establish a time-varying linear data model for each agent by utilizing the dynamic linearization method. Then, using the incomplete input and output data of each agent and its neighbors, we construct the proposed quantized data-driven distributed bipartite formation control scheme without employing any dynamics information of multi-agent systems. We strictly prove the convergence of the proposed algorithm, where the proposed approach can ensure that the bipartite formation tracking errors converge to the origin, even though the communication topology of multi-agent systems is time-varying switching. Finally, simulation and hardware tests demonstrate the effectiveness of the proposed scheme

Numerical study on the influencing mechanism of twisted ratio in outward convex corrugated tubes with a twisted tape insert

Numerical investigations were conducted on flow and heat transfer in an outward convex corrugated tube with various structural twisted tape inserts. The study investigated the influence of twisted ratio on thermodynamic regulation and mechanism in the corrugated tube. The results indicate that Nusselt number in the corrugated tube (Nuc) exceeds those in the corrugated tube and smooth tube by 120-136% and 171-317%, respectively. Meanwhile, the friction factor increases by 148-153% and 476-514%, respectively. The best overall thermal performance (h = 1.97) is obtained with a high twist ratio (y/w = 5). However, the highest thermal performance (Nuc/Nus = 4.78) is obtained with the lowest twist ratio (y/w = 1.25)

Experimental study on the effects of light intensity on energy conversion efficiency of photo-thermo chemical synergetic catalytic water splitting

Hydrogen production from water using a catalyst and solar energy was an ideal future fuel source. In this study, an elaborate experimental test rig of hydrogen production from solar water splitting was designed and established with self- controlled temperature system. The effects of light intensity on the reaction rate of hydrogen production from solar water splitting were experimentally investigated with the consideration of optical losses, reaction temperature, and photocatalysts powder cluster. Besides, a revised expression of full-spectrum solar-to-hydrogen energy conversion efficiency with the consideration of optical losses was also put forward, which can be more accurate to evaluate the full-spectrum solar-to-hydrogen energy of photo-catalysts powders. The results indicated that optical losses of solar water splitting reactor increased with the increase of the incoming light intensity, and the hydrogen production rate increased linearly with the increase of effective light intensity even at higher light intensity region when the optical losses of solar water splitting reactor were considered

Mesenchymal stem cells shift the pro-inflammatory phenotype of neutrophils to ameliorate acute lung injury

Abstract Background Mesenchymal stem cell (MSC) treatment plays a major role in the management of acute lung injury (ALI), and neutrophils are the initial line of defense against ALI. However, the effect of MSCs on neutrophils in ALI remains mostly unknown. Methods We investigated the characteristics of neutrophils in lung tissue of ALI mice induced by lipopolysaccharide after treatment with MSCs using single-cell RNA sequencing. Neutrophils separated from lung tissue in ALI were co-cultured with MSCs, and then samples were collected for reverse transcription-polymerase chain reaction and flow cytometry. Results During inflammation, six clusters of neutrophils were identified, annotated as activated, aged, and circulatory neutrophils. Activated neutrophils had higher chemotaxis, reactive oxygen species (ROS) production, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase scores than aged neutrophils. Circulatory neutrophils occurred mainly in healthy tissue and were characterized by higher expression of Cxcr2 and Sell. Activated neutrophils tended to exhibit higher expression of Cxcl10 and Cd47, and lower expression of Cd24a, while aged neutrophils expressed a lower level of Cd47 and higher level of Cd24a. MSC treatment shifted activated neutrophils toward an aged neutrophil phenotype by upregulating the expression of CD24, thereby inhibiting inflammation by reducing chemotaxis, ROS production, and NADPH oxidase. Conclusion We identified the immunosuppressive effects of MSCs on the subtype distribution of neutrophils and provided new insight into the therapeutic mechanism of MSC treatment in ALI

Fc effector of anti-Aβ antibody induces synapse loss and cognitive deficits in Alzheimer's disease-like mouse model

Passive immunotherapy is one of the most promising interventions for Alzheimer's disease (AD).However,almost all immune-modulating strategies fail in clinical trials with unclear causes although they attenuate neuropathology and cognitive deficits in AD animal models.Here,we showed that Aβ-targeting antibodies including their IgG1 and IgG4 subtypes induced microglial engulfment of neuronal synapses by activating CR3 or FcγRllb via the complex of Aβ,antibody,and complement.Notably,anti-Aβ antibodies without Fc fragment,or with blockage of CR3 or FcγRllb,did not exert these adverse effects.Consistently,Aβ-targeting antibodies,but not their Fab fragments,significantly induced acute microglial synapse removal and rapidly exacerbated cognitive deficits and neuroinflammation in APP/PS1 mice post-treatment,whereas the memory impairments in mice were gradually rescued thereafter.Since the recovery rate of synapses in humans is much lower than that in mice,our findings may clarify the variances in the preclinical and clinical studies assessing AD immunotherapies.Therefore,Aβ-targeting antibodies lack of Fc fragment,or with reduced Fc effector function,may not induce microglial synaptic pruning,providing a safer and more efficient therapeutic alternative for passive immunotherapy for AD

Fc effector of anti-Aβ antibody induces synapse loss and cognitive deficits in Alzheimer's disease-like mouse model

Passive immunotherapy is one of the most promising interventions for Alzheimer's disease (AD).However,almost all immune-modulating strategies fail in clinical trials with unclear causes although they attenuate neuropathology and cognitive deficits in AD animal models.Here,we showed that Aβ-targeting antibodies including their IgG1 and IgG4 subtypes induced microglial engulfment of neuronal synapses by activating CR3 or FcγRllb via the complex of Aβ,antibody,and complement.Notably,anti-Aβ antibodies without Fc fragment,or with blockage of CR3 or FcγRllb,did not exert these adverse effects.Consistently,Aβ-targeting antibodies,but not their Fab fragments,significantly induced acute microglial synapse removal and rapidly exacerbated cognitive deficits and neuroinflammation in APP/PS1 mice post-treatment,whereas the memory impairments in mice were gradually rescued thereafter.Since the recovery rate of synapses in humans is much lower than that in mice,our findings may clarify the variances in the preclinical and clinical studies assessing AD immunotherapies.Therefore,Aβ-targeting antibodies lack of Fc fragment,or with reduced Fc effector function,may not induce microglial synaptic pruning,providing a safer and more efficient therapeutic alternative for passive immunotherapy for AD