Study of the effect of dipole interactions on hyperthermia heating the cluster composed of superparamagnetic nanoparticles

In the present work, we investigate the effect of dipole interactions on hyperthermia heating the cluster composed of multi superparamagnetic nanoparticles via time-quantified Monte Carlo simulation. The dynamic hysteresis loop area of non-interacting particles calculated by a modified Rosensweig’s model is shown to be proportional to the field frequency. The inverse of the total number of Monte Carlo steps per field cycle is considered as a computational frequency in our modelling. By comparing the two proportionality constants gained from the simulation and from the Rosensweig’s model, respectively, the time scale of one Monte Carlo step is estimated. The shape of the cluster is characterised by treating it as an equivalent ellipsoid. When the morphology of cluster is highly anisotropic such in a chain and cylinder, dipole interactions align the moments of the particles to the morphology anisotropy axis of the cluster. The strength of such alignment depends on the magnitude of morphology anisotropy of the cluster. The alignment helps improve heating capability of the chain and cylinder clusters at the most angles between the field direction and morphology anisotropy axis. However, when the field direction is away from the axis too much, the high energy barrier will hamper the cluster to maintain the magnetization, leading to a reduced heating efficiency. Once the cluster loses its morphology anisotropy (i.e. cube), the influence of dipole interactions on hysteresis losses is reduced to the minimum; the probability to obtain an improved heating becomes very low no matter with the type of particle arrangement

An experimental investigation on the effect of ferrofluids on the efficiency of novel parabolic trough solar collector under laminar flow conditions

The paper is related to the use of magnetic nanofluids (ferrofluids) in a direct absorption solar parabolic trough collectors enhances thermal efficiency compared to conventional solar collectors. By applying the right magnetic intensity and magnetic field direction, the thermal conductivity of the fluid increased higher than typical nanofluids. Moreover, the ferrofluids exhibit excellent optical properties. The external magnetic source is installed to alter the thermos-physical properties of the fluid, and the absorber tube does not have selective surface allowing ferrofluids to absorb the incoming solar irradiance directly. In this paper, an experimental investigation of the performance of direct absorption solar collector using ferrofluids as an absorber. Various nanoparticle concentrations 0% to 1vol% at the operational temperatures between 19°C and 40°C were used in the current study. The results show that using ferrofluids as a heat transfer fluid increases the efficiency of solar collectors. In the presence of the external magnetic field, the solar collector efficiency increases to the maximum, 25% higher than the conventional parabolic trough. At higher temperatures, the ferrofluids show much better efficiency than conventional heat transfer fluid. The study indicated that nanofluids, even of low-content, have good absorption of solar radiation, and can improve the outlet temperatures and system efficiencies

Characterizing the culturable surface microbiomes of diverse marine animals

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Keller, A. G., Apprill, A., Lebaron, P., Robbins, J., Romano, T. A., Overton, E., Rong, Y., Yuan, R., Pollara, S., & Whalen, K. E. Characterizing the culturable surface microbiomes of diverse marine animals. FEMS Microbiology Ecology, 97(4), (2021): fiab040, https://doi.org/10.1093/femsec/fiab040.Biofilm-forming bacteria have the potential to contribute to the health, physiology, behavior and ecology of the host and serve as its first line of defense against adverse conditions in the environment. While metabarcoding and metagenomic information furthers our understanding of microbiome composition, fewer studies use cultured samples to study the diverse interactions among the host and its microbiome, as cultured representatives are often lacking. This study examines the surface microbiomes cultured from three shallow-water coral species and two whale species. These unique marine animals place strong selective pressures on their microbial symbionts and contain members under similar environmental and anthropogenic stress. We developed an intense cultivation procedure, utilizing a suite of culture conditions targeting a rich assortment of biofilm-forming microorganisms. We identified 592 microbial isolates contained within 15 bacterial orders representing 50 bacterial genera, and two fungal species. Culturable bacteria from coral and whale samples paralleled taxonomic groups identified in culture-independent surveys, including 29% of all bacterial genera identified in the Megaptera novaeangliae skin microbiome through culture-independent methods. This microbial repository provides raw material and biological input for more nuanced studies which can explore how members of the microbiome both shape their micro-niche and impact host fitness.Funding was provided by the National Science Foundation (Biological Oceanography) award #1657808 and National Institutes of Health grants 1R21-AI119311–01 to K. E. Whalen, as well as funding from the Koshland Integrated Natural Science Center and Green Fund at Haverford College. This constitutes scientific manuscript #298 from the Sea Research Foundation

Performance prediction of PM 2.5 removal of real fibrous filters with a novel model considering rebound effect

Fibrous filters have been proved to be one of the most cost-effective way of particulate matters (specifically PM 2.5) purification. However, due to the complex structure of real fibrous filters, it is difficult to accurately predict the performance of PM2.5 removal. In this study, a new 3D filtration modeling approach is proposed to predict the removal efficiencies of particles by real fibrous filters, by taking the particle rebound effect into consideration. A real filter is considered and its SEM image-based 3D structure is established for modeling. Then based on the simulation result, the filtration efficiency and pressure drop are calculated. The obtained values are compared and validated by experimental data and empirical correlations, and the results are proven to be in good agreement with each other. At last, influences of various parameters including the face velocity, particle size and the particle rebound effect on the filtration performance of fibrous filters are investigated. The results provide useful guidelines for the optimization and enhancement of PM2.5 removal by fibrous filter

Functional Supramolecular Gels Based on the Hierarchical Assembly of Porphyrins and Phthalocyanines

Supramolecular gels containing porphyrins and phthalocyanines motifs are attracting increased interests in a wide range of research areas. Based on the supramolecular gels systems, porphyrin or phthalocyanines can form assemblies with plentiful nanostructures, dynamic, and stimuli-responsive properties. And these π-conjugated molecular building blocks also afford supramolecular gels with many new features, depending on their photochemical and electrochemical characteristics. As one of the most characteristic models, the supramolecular chirality of these soft matters was investigated. Notably, the application of supramolecular gels containing porphyrins and phthalocyanines has been developed in the field of catalysis, molecular sensing, biological imaging, drug delivery and photodynamic therapy. And some photoelectric devices were also fabricated depending on the gelation of porphyrins or phthalocyanines. This paper presents an overview of the progress achieved in this issue along with some perspectives for further advances

Single cell atlas for 11 non-model mammals, reptiles and birds.

The availability of viral entry factors is a prerequisite for the cross-species transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Large-scale single-cell screening of animal cells could reveal the expression patterns of viral entry genes in different hosts. However, such exploration for SARS-CoV-2 remains limited. Here, we perform single-nucleus RNA sequencing for 11 non-model species, including pets (cat, dog, hamster, and lizard), livestock (goat and rabbit), poultry (duck and pigeon), and wildlife (pangolin, tiger, and deer), and investigated the co-expression of ACE2 and TMPRSS2. Furthermore, cross-species analysis of the lung cell atlas of the studied mammals, reptiles, and birds reveals core developmental programs, critical connectomes, and conserved regulatory circuits among these evolutionarily distant species. Overall, our work provides a compendium of gene expression profiles for non-model animals, which could be employed to identify potential SARS-CoV-2 target cells and putative zoonotic reservoirs

Thermo-physical properties and thermo-magnetic convection of ferrofluid

The increasing interest in developing nanofluids in general and ferrofluids in particular offers a possibility of controlling and enhancing the flow and heat transfer in engineering processes. This paper attempts to review the benchmark thermo-physical and magnetic properties (thermal conductivity, convective heat transfer and viscosity) of ferrofluids reported in literature. The main focus of this review was to investigate the influence on the thermo-physical properties of a ferrofluid when external magnet field was applied. It was reported that the thermal conductivity of a ferrofluid could be up to 300 times that of base fluid and that the viscosity could also be increased due the formation of chain-like particle assembly in the magnetic field along the direction the thermal gradient. In addition recommendations for future work have drawn particularly in the area of understanding the magnetic nanoparticles distribution in the presence of magnetic field, developing realistic thermal conductivity models based on clustering and experimental validation of the theoretical models

Modeling and study of pressure-dependent boiling crisis in membrane-based heat sink

A theoretical model is developed to study the pressure-dependent boiling crisis of membrane-based heat sink. It has been reported that the critical heat flux of this heat sink can be increased to 1.8 kW/cm2 by using a piece of hydrophobic membrane to promote bubble departure. In the modeling, two boiling crisis mechanisms are applied. The free energy and the forces acting on the bubble are considered in the calculations of the bubble's geometric dimensions, the vapor venting rate, and the pressure drop for driving the wicking flow. Wetting and the evaporating rate beneath the bubble are computed based on the reported coupled wicking and evaporation model. The modeling explains why there exist two regions in the profile of the critical heat flux against the pressure drop. The time for rewetting the dry spot is obtained with the modeling to establish the correlation between the critical heat flux and the pressure drop at higher heat flux. When the boiling surface has a relatively high area ratio, the modeling error is 3 % with the suggested membrane permeability and critical temperature rise of the dry spot

Evaporation Characteristics and Morphological Evolutions of Fuel Droplets After Hitting Different Wettability Surfaces

To solve the wall-wetting problem in internal combustion engines, the physical and chemical etching 11 methods are used to prepare different wettability surfaces with various microstructures. The evaporation 12 characteristics and morphological evolution processes of diesel and n-butanol droplets after hitting the various 13 surfaces are investigated. The results show that the surface microstructures increase the surface roughness (Ra), 14 enhancing the oleophilic property of the oleophilic surfaces. Compared to n-butanol droplets, the same surface 15 shows stronger oleophobicity to diesel droplets. When a droplet hits an oleophilic property surface with a lower 16 temperature, the stronger the oleophilicity, the shorter the evaporation time. For oleophilic surfaces, larger Ra leads to a higher Leidenfrost temperature (TLeid ). The low TLeid 17 caused by enhanced oleophobicity, dense 18 microstructures and increased convex dome height facilitates droplet rebound and promotes the evaporation of 19 the wall-impinging droplets into the cylinder. The evaporation rate of the droplets is not only related to the 20 characteristics of the solid surfaces and the fuel droplets but also affected by the heat transfer rate of the droplets 21 at different boiling regimes. The spreading diameter of a droplet on an oleophobic surface varies significantly 22 less with time than that on an oleophilic surface under the same surface temperature

Omnidirectional Free-Degree Wireless Power Transfer System Based on Magnetic Dipole Coils for Multiple Receivers

Wireless power transfer (WPT) technology offers a potential solution for the energy-supply problem. In this paper, we propose a novel magnetic coupling mechanism for omnidirectional and multiple-pickup energy transfer based on the magnetic dipole coils. Firstly, a cubic transmitter structure capable of generating three-dimension (3D) homogeneous magnetic field is fabricated to weaken directional sensitivity of receiving coil. Furthermore, the direction of current flowing through each dipole coil is also studied in detail. Numerical and simulated analysis is implemented to verify the omnidirectionality of the transmitter. Secondly, the equivalent circuit model for WPT systems with ferrite is analyzed. In addition, optimal loads, power distribution and transfer efficiency for multiple receivers are discussed and used to achieve the proper system design. Finally, experimental prototype is set up to validate the transmission performance of the proposed WPT system. The results have showed that genuine 3D high degree of freedom (DoF) can be achieved. Meantime, above 60% efficiency at least 30 W of total output power can be obtained for WPT systems with eight pick-ups. We believe the proposed system will give a new guideline for future low power electronic applications, such as monitoring sensors, miniature robots and household devices