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Subclinical necrotic enteritis (SNE) is a severe intestinal disease in broilers which brings huge economic losses to poultry industry. Herein, the effects of Bacillus amyloliquefaciens BLCC1-0238 (B. amyloliquefaciens BLCC1-0238) alone or in combination with mannan-oligosaccharides (MOS) on the SNE challenge model in broilers were comprehensively explored. A total of 360 broilers were randomly divided into 4 groups, including an SNE infection control (IC), an antibiotic pretreatment control (AC), a B. amyloliquefaciens BLCC1-0238 pretreatment (BP), and a B. amyloliquefaciens BLCC1-0238 + MOS pretreatment (BMP). The results showed that compared with the IC, three pretreatment groups significantly improved the growth performance, lowered the overall mortality, and reduced intestinal mucosal lesions in broilers. Additionally, the expression levels of claudin-3 and peroxisome proliferator-activated receptor-gamma coactivator-1α in the BP and BMP groups and the levels of mucin-2 and mechanistic target of rapamycin in the BMP group were significantly upregulated compared with the IC. By contrast, the expression levels of interferon-γ, interleukin-10, and secretory immunoglobulin A in the BP and BMP groups were significantly downregulated. In conclusion, these findings show that B. amyloliquefaciens BLCC1-0238 in combination with MOS can exert synergetic effects by the interplay between them on improving growth performance and combating the SNE infection in broilers.

Exogenous ethylene (ethephon) is widely used to induce pineapple (Ananas comosus (L.) Merr.) flowering. However, economic losses often occur due to inappropriate flower induction, which results in a lower flowering rate or no flowering, and the molecular mechanisms of flowering induction in pineapple remain unclear. To understand the global changes in gene expression during ethylene-induced pineapple flowering, we performed single-molecule real-time (SMRT) sequencing and Illumina RNA sequencing of shoot apexes or inflorescences at six time points (0 d, 8 h, 1 d, 4 d, 7 d, and 14 d after ethephon treatment). In addition, to understand the cellular and physiological processes during flowering, we also observed histological changes and measured the changes in several endogenous plant growth regulators. In this study, we obtained 29,745 polished high-quality isoforms, of which 523 had not yet been annotated within the A. comosus genome. Furthermore, 2049 alternative splicing (AS) events, 78 fusion genes, 139 long-chain non-coding RNAs (lncRNAs), and 11,184 alternative polyadenylation (APA) events were identified by SMRT sequencing. Illumina sequencing of libraries generated from these samples yielded 106.09 Gb clean reads, and the total mapped reads were 86.53%. Comparative analysis of these transcriptome databases revealed 3,690 differentially expressed genes (DEGs) between 0 d and the other time points. Candidate genes that may be involved in pineapple flowering are predicted to encode hormone-related proteins, flowering time proteins, and transcription factors. This study contributes to transcriptome information for A. comosus and will facilitate further exploration of the molecular mechanisms of ethylene-induced pineapple flowering.

The APETALA2/ethylene-responsive factor (AP2/ERF) has important roles in regulating developmental processes and hormone signaling transduction in plants. Pineapple demonstrates a special sensitivity to ethylene, and AP2/ERFs may contribute to this distinct sensitivity of pineapples to ethylene. However, little information is available on the AP2/ERF of pineapple. In this study, 97 AP2/ERF family members were identified from the pineapple genome. The AcAP2/ERF superfamily could be further divided into five subfamilies, and different subfamily existed functional divergence in multifarious biological processes. ERF and RAV subfamily genes might play important roles in the process of ethylene response of pineapple; ERF and DREB subfamily genes had particular functions in the floral organ development. This study is the first to provide detailed information on the features of AP2/ERFs in pineapple, provide new insights into the potential functional roles of the AP2/ERF superfamily members, and will facilitate a better understanding of the molecular mechanism of flower in pineapple.

Viscoelastic fluid naturally has both viscous and elastic properties. Therefore, there are two sources of nonlinear effects, namely inertial and elastic nonlinearities. The existence of elastic nonlinearity brings about various interesting flow phenomena in viscoelastic fluid flow, especially in microfluidics where the inertial nonlinearity can be negligible while the elastic nonlinearity can dominate the flow. Specifically, purely elasticity-induced instability and turbulence can occur in microchannels when the elastic nonlinearity is strong enough. Recently, those intriguing properties of viscoelastic fluid flow have motivated lots of researches on taking viscoelastic fluid as working fluid in different types of microfluidic devices, such as micro-mixers, micro heat exchangers, logic microfluidic circuits and particle manipulation. This paper aims to provide a state-of-the-art review of the nonlinear effect of viscoelastic fluids and its applications in the aforementioned microfluidic fields, which may provide a useful guidance for the researchers who are interested in this area.

Recently, the nature of viscoelastic drag-reducing turbulence (DRT), especially the maximum drag reduction (MDR) state, has become a focus of controversy. It has long been regarded as polymer-modulated inertial turbulence (IT), but is challenged by the newly proposed concept of elasto-inertial turbulence (EIT). This study is to repicture DRT in parallel plane channels by introducing dynamics of EIT through statistical, structural and budget analysis for a series of flow regimes from the onset of drag reduction to EIT. Some underlying mechanistic links between DRT and EIT are revealed. Energy conversion between velocity fluctuations and polymers as well as pressure redistribution effects are of particular concern, based on which a new energy self-sustaining process (SSP) of DRT is repictured. The numerical results indicate that at low Reynolds number ( $Re$ ), weak IT flow is replaced by a laminar regime before the barrier of EIT dynamics is established with the increase of elasticity, whereas, at moderate $Re$ , EIT-related SSP can get involved and survive from being relaminarized. This further explains the reason why relaminarization phenomenon is observed for low $Re$ while the flow directly enters MDR and EIT at moderate $Re$ . Moreover, with the proposed energy picture, the newly discovered phenomenon that streamwise velocity fluctuations lag behind those in the wall-normal direction can be well explained. The repictured SSP certainly justifies the conjecture that IT nature is gradually replaced by that of EIT in DRT with the increase of elasticity.

The effect of viscoelasticity on the flow and heat transport in the Rayleigh–Bénard convection (RBC), a frequently encountered phenomenon in nature and industry, in a rectangular enclosure with horizontal periodic boundary is investigated via direct numerical simulation. The working fluid is described by a finitely extensible nonlinear elastic-Peterlin constitutive model almost all important features of viscoelastic fluid flow. Numerical simulations are conducted at a low concentration [Formula: see text], where [Formula: see text], μs is the solvent viscosity, and [Formula: see text] is the sum of μs and the polymer viscosity μp. A parametric analysis is performed to understand the influence of the Weissenberg number Wi, the viscosity ratio β, and the extension length L on the oscillating mode of the viscoelastic RBC. The results indicate that both Wi and β weakly inhibit the convection onset and the transition from steady to oscillatory convection. The amplitude and frequency of the oscillations in the oscillatory flow regime are both suppressed. However, the strongly elastic nonlinearity makes the flow transition irregular and even brings about the relaminarization or lead to the convection cells traveling in the horizontal direction. The increasing extension length L induces multiple pairs of roll flow patterns at a specific setting of ( Ra, Wi). Heat transport is reduced (up to 8.5%) by elasticity but still obeys the power law with Ra if the flow pattern has one pair of rolls. However, heat transfer enhancement occurs if multiple pairs of rolls are induced.

Visualization experiment is a must in realizing functional characteristics of an operational pulsating heat pipe (PHP). So far there is no general formulation which can foretell the complex and chaotic flow nature for every working fluid. Different response of working fluids and their distinct flow nature as well as their behavior can be visualized which thereby helps to understand the operational mechanism of the PHP. In this experiment, tests were conducted in a transparent PHP with 3 conventional working fluids, viz. de-ionized (DI) water, methanol, ethanol, and 300 ppm cetyltrimethyl ammonium chloride (CTAC) solution, each with fill ratio (FR) of 50%. With the help of high speed camera, flow characteristics at different operational stages for each working fluid are captured. Difference in the generation, growth, movement, and flow direction of bubbles are observed and the consequence of combined effects of various thermal properties of the fluid rather than a dominating single property. Start-up characteristics and dominating flow pattern for each fluid are reported in this paper. Moreover, peculiar flow characteristics with 300 ppm CTAC like bubble detachment, movement of cluster of micro-bubbles, and swirling are also presented.

Increasing antibiotic resistant genes (ARG) are being detected in animal manure-amended soil, causing public concerns. However, the effects of animal manure fertilization on the ARG of vegetable endophytes remain unknown. In this study, high-throughput quantitative PCR (HT-qPCR) was used to explore the effects of poultry manure fertilization on the bacterial community and resistome in the soil, root endophytes, and leaf endophytes from

Owing to the long residence times of water, water reservoirs readily contribute to the accumulation of antibiotic resistant gene (ARG). It is of great public health significance to explore bacterial communities, antibiotic resistomes, and the potential public health risks of water reservoirs. In this study, metagenomic sequencing was used to analyze and compare the bacterial communities, ARG profiles, ARG-horizontal transfer, and ARG-carrying pathogens in the water and sediments of the Dongping Lake Reservoir in the dry and the wet seasons. Compared with that of the sediments, the results showed that both the bacterial communities and ARG profiles in the water were significantly influenced by the seasons, and the total ARG abundance in the dry season was significantly higher than that in the wet season. The total ARG abundance in the sediments was higher than that in water, but the horizontal transfer potential of ARG in the water was higher than that in the sediment. A total of 377 ARG subtypes belonging to 20 ARG types were found in this study. Bacitracin and vancomycin resistance genes were the main ARG types in the water and sediments, respectively, and Proteobacteria and Actinobacteria were the major ARG-carrying bacteria in the water and sediments, respectively. In addition, 30 clinical pathogens carrying ARGs were identified, including

Reduced-order model (ROM) based on proper orthogonal decomposition (POD) is a fast computational fluid dynamics (CFD) method and has been widely applied to pure flow or heat conduction problems in the past. In this paper, the typical 2D Rayleigh–Benard convection (RBC) in a square cavity was set as a research target. Firstly, the POD-ROM of 2D RBC problem was constructed at Ra = 107, Pr = 0.71. Combining with direct numerical simulation (DNS) databases, a closure model (CM) was then proposed to correct the evolution process of POD-ROM. Based on the proposed CM, we realized the prediction of flow evolution for a new flow case under the parameters different from that used to get its POD eigenmodes. It showed that the proposed POD-ROM with CM could be able to predict the dynamics of new flow cases. Moreover, the corresponding method proposed in the present study can be also easily extended to other types of flow-heat coupling problems, such as natural heat convection, etc.

This study investigates the viscoelastic effects on droplet migration induced by a wettability gradient on a rigid substrate by a numerical simulation based on OpenFOAM with the volume-of-fluid method. The droplets are set with different rheological properties to investigate the effect of the elastic parameters. The Oldroyd-B model was employed. Quantitative differences in the migration and deformation between Newtonian and viscoelastic droplets were investigated by changing the degree of elasticity. The droplet migration shows conspicuously higher mobility for high elasticity, especially during the accelerating period. Moreover, the displacement and velocity increased with the decrease of a viscoelasticity parameter, and the velocity enhancement was regulated by the elastic instability shown at a high Weissenberg number. In addition, the velocity of the droplet changes more significantly over the range of contact angles of 130° to 60° compared to other wettability-gradient surfaces.

This paper follows Part I of the rheological and thermophysical propertires of seawater with surfactant. In Part II, the thermophysical properties of seawater with the addition of different amounts of CTAC/NaSal are measured at different temperatures, including surface tension and thermal conductivity. Uncertainty analyses are conducted for all the measurements. The effects of the temperature, the salts in the seawater and the concentration of CTAC/NaSal on the thermophysical properties are investigated, and the corresponding influence mechanisms are analyzed. The results show that the addition of salt can decrease the surface tensions of the CTAC/NaSal solutions prepared by deionized water, and the surface tension of seawater is dramatically reduced after the addition of CTAC/NaSal. There is no substantial difference in the thermal conductivity among the solutions with different CTAC/NaSal concentrations at each temperature. Tap water can be utilized instead of deionized water in the following experiments on RSCE as expected.

Efficient mixing is one of the keen interest of many bioengineering and chemical engineering processes. In this work, we designed an efficient micro-mixer with viscoelastic fluid which can induce both strong shear and strong extension by being embedded several rhombic blocks to destabilize the viscoelastic fluid flow and can be also easily integrated. Experimental visualization and direct numerical simulation (DNS) of mixing process were conducted to evaluate the mixing performance. By adding green fluorescent particles into the fluids, apparent mixing enhancement was observed for viscoelastic fluid flow when the flow rate exceeded a threshold. The efficient micro mixing progress also shows great potential for bioengineering application with the biocompatible working fluids. Through DNS, we discussed the flow patterns and the role of polymers playing in viscoelastic fluid flow to respectively figure out the underlying mechanism of efficient mixing and the occurrence of unstable flow motions. The results show that when the elasticity is strong enough, the viscoelastic fluid flow is irregularly twisting and swinging in the channel, and as a result enhances the mixing by increasing the intersecting frequency of fluids of different concentrations. Moreover, owing to the special designed geometry, the polymers act as the energy supplier of unstable flow motions, which keeps the fluctuations from decaying towards the laminar regime.

The rheological properties of seawater with the addition of surfactant additive (cetyltrimethyl ammonium chloride (CTAC)/sodium salicylate (NaSal)) are measured at different temperatures, including shear viscosity and first normal stress difference (N1). The effects of the temperature, the salts, and CTAC/NaSal concentration on the rheological properties of test solutions are investigated, and the corresponding influence mechanisms are analyzed. It shows that the addition of salt can decrease the shear viscosities of the solutions, and also decrease N1 and even eliminate the sharp augment of N1 above a certain shear rate. The growing elasticity can be characterized by the increase of the initial shear rate for shear-thickening inception. High temperature can also remove the sharp increase of N1 with salt. Nevertheless, the increase of CTAC/NaSal concentration can withstand the elimination of the sharp augment of N1.

The world is running against time to develop enough source of sustainable energy. Producing a viable and eco-friendly energy source is one part of the solving the energy crisis, and managing it efficiently is another. Since the development of Pulsating Heat Pipe (PHP) in early 1990s, it has gained a lot of attention as potential heat management system that is passive, efficient, compact yet simple, and could address the issues related to higher heat flux in micro-electronic devices. Researchers have been working on not only to develop the advanced form of the PHP, but also in understanding the working phenomenon of operational heat pipe. With the introduction of different kinds of working conditions for the operation of the device, including the geometric parameters, orientation, heat input, and other operational parameters, researches have revealed many functioning and non-functioning features which are very complex. Introduction of various kinds of fluids as the working material for the PHP have yielded different responses by the system at different fill ratio (FR). Though many scientists have worked day and night to fully understand the thermo-physical behavior through experimental investigation, numerical and computational approach and theoretical approach, full-fledge understanding of the operational mechanism is not yet achieved. This is due to the involvement of complex coupling effect of hydrodynamic and thermodynamic features, and the presence of liquid-slug and vapor-plug system. Nevertheless PHP has found many potential application fields in the area of thermal management. In recent years, researches on PHP have shifted from conventional investigation to newer dimensions that include use of non-conventional working fluids, visualization techniques, and rigorous computational works. This review paper is mainly focused on the results of experimental and numerical works done by researchers in the recent past. Authors believe that this paper will be very useful for future researchers to understand the recent trends in this arena better. This paper also exposes the latest works on PHP with potential and promising applications in novel field of thermal management.

An experimental investigation was conducted to determine the thermal performance of Pulsating Heat Pipe (PHP) with different concentrations and fill ratios (FRs) of Methanol, Ethanol and Cetyltrimethyl ammonium chloride, C19H42ClN (CTAC) and compared with that of Deionized (DI) water. In this study, effects of thermo-physical properties of these working fluids on progression of temperature at different regions of the PHP and thermal resistance at varying thermal loads ranging from 15 W to 80 W were investigated. The closed-loop pulsating heat pipe was bottom heated and kept at vertical position for the entire period of study. 35%, 50% and 65% FRs of DI water were used and it was observed that the thermal resistance was lowest when the PHP was filled with 50% FR. The lowest thermal resistance achieved with DI water was 0.34 K/W at higher heat load. Methanol and Ethanol have lower specific heat capacity and performed almost no better than DI water. Larger (dP/dT)sat values of Methanol and Ethanol produced greater fluctuations in the flow and rapid movement of the fluid was induced within the pipe because of their relatively lower surface tension and viscosity. But these properties were not dominating factors for the thermal performance at higher heat loads. Lower specific heat capacity and latent heat of vaporization of these alcohols dominated the thermal resistance. When 50 ppm, 100 ppm, 1000 ppm and 2000 ppm of CTAC surfactant solutions were used, the experimental results showed that the heat transfer capability of the PHP is highly dependent on FR. It was observed that surface tension and viscosity are dominating factor in the performance of the PHP, when CTAC surfactant solution is used, and their degree of dominance varies with FR and heat loads. Lower surface tension of CTAC solution was advantageous for lower FR and heat load. Lower viscosity offered greater advantage at higher FR and heat load. The lowest thermal resistance achieved with surfactant solution was 0.30 K/W for 35% and 50% FR with 2000 ppm CTAC solution at higher heat load which are lower than that of DI water.

In the present paper, we carried out a numerical investigation on the pulsating effect on the heat transfer performance of pseudo-plastic fluid flow in a manifold microchannel heat sink. Three types of pulsating inlet condition were introduced, including square-wave, sinusoidal-wave and semi-sinusoidal wave pulsating inlets. Special attentions were paid to the parametric effect on the thermal performance, i.e., pulsating duty ratio, amplitude and period, which together describe the pulsating pattern. The results show that introducing pulsating flow can significantly improve the overall thermal performance comparing with that of steady flow under the same mass flow rate. The thermal performance factor TP of all the cases both square-wave and sinusoidal-wave pulsating inlet studied is larger than 1 and can even reach more than 3 comparing with the steady flow. The two scenarios existing in pulsating flow are responsible for the heat transfer enhancement, which are the continuously developing characteristics of the flow and the induction of secondary flows or reversal flows in the pulsating flow. In addition, the pulsating inlet with sinusoidal wave led to the highest heat transfer coefficient among the three types of pulsating inlet conditions in consideration. Therefore, this pulsating inlet condition is more beneficial to strengthening the heat transfer during the practical application.

In order to clarify the controversies for the role of nanoparticles on heat transfer in natural convection, lattice Boltzmann method is used to investigate Rayleigh-Benard convection heat transfer in differentially-heated enclosures filled with Al2O3-water nanofluids. The results for streamline and isotherm contours, vertical velocity, and temperature profiles as well as the local and average Nusselt number are discussed for a wide range of Rayleigh numbers and nanoparticle volume fractions (0 ? ? ? 5%). The results show that with the increase of Rayleigh number and nanoparticles loading, Nuave increases. It is suggested that the addition of nanoparticles can enhance the heat transfer in Rayleigh-Benard convection.

This paper presents an experimental study on the flow structures in turbulent Rayleigh-B?nard convection with surfactant solutions. The shadowgraph visualization was used to obtain the plumes and the velocity field was measured using particle image velocimetry. The results show that the size of plumes in surfactant solution case is larger than that in Newtonian fluid case and it needs more time for surfactant solution case to start convection. The large-scale circulation fails to form in surfactant solution case and the convection velocity is smaller. A decrease of the measured Nusselt number is observed in surfactant solution case. The above phenomena are caused by the shear-shinning and elastic chara cteristics of surfactant solution.

In this paper, to study the viscoelastic effect on isotropic turbulence without wall effects, a two oscillating grid turbulence is built to investigate this phenomenon using particle image velocimetry. In the experiments, the classical drag-reducing additives are chosen: polyacrylamide (PAM) and cetyltrimethyl ammonium chloride (CTAC), which have shown remarkable drag-reducing effect in wall-bounded turbulent flows. The results show that the existence of drag-reducing additives makes velocity field more anisotropic and reduces turbulent kinetic energy. We propose an intuitive and natural definition for a reduction rate of turbulent kinetic energy to show viscoelastic effect. It suggests that there exists a critical concentration for the reduction rate of turbulent kinetic energy in the CTAC solution case. Also, the small-scale vortex structures are inhibited, which suggests the drag-reducing mechanism in grid turbulence without wall effect.

Numerical simulations were conducted on viscoelastic fluid flows in straight ducts with different cross sections, for which the origin of secondary flows and influences of material parameters and flow passage geometrical configuration were numerically investigated. The Giesekus constitutive model was chosen to describe the viscoelastic fluid with the second normal stress difference N 2 , and solved by embedding UDF (User-defined Function) into the CFD (computational fluid dynamics) code FLUENT. The origin of such kind of secondary flow was theoretically studied from the perspective of the budget of vorticity energy for the first time. Sufficient and necessary condition for the existence of secondary flow was then developed in terms of N 2 , the gradient of N 2 and cross-sectional geometry ϑ (i.e., generation term E Ω ). Moreover, helicity density was considered as an excellent indicator of secondary flow pattern. Effects of material properties (including anisotropic parameter α , solvent viscosity ratio β and relaxation time λ ) and flow passage geometrical configuration (aspect ratio of cross sections r , the number of polygon sides n ) on secondary flow strength and pattern were investigated with E Ω . Finally, a universal variable σ s was proposed to describe non-circularity of cross section, based on which the results for ducts with different cross sections can be normalized together.

Background Litchi (Litchi chinensis Sonn.) is an economically important evergreen fruit tree widely cultivated in subtropical areas. Low temperature is absolutely required for floral induction of litchi, but its molecular mechanism is not fully understood. Leaves of litchi played a key role during floral induction and could be the site of low temperature perception. Therefore, leaves were treated under different temperature (15 °C/25 °C), and high-throughput RNA sequencing (RNA-Seq) performed with leaf samples for the de novo assembly and digital gene expression (DGE) profiling analyses to investigate low temperature-induced gene expression changes. Results 83,107 RNA-Seq unigenes were de novo assembled with a mean length of 1221 bp and approximately 61% of these unigenes (50,345) were annotated against public protein databases. Differentially-expressed genes (DEGs) under low temperature treatment in comparison with the control group were the main focus of our study. Hierarchical clustering analysis arranged 2755 DEGs into eight groups with three significant expression clusters (p-value ≤ 0.05) during floral induction. With the increasing contents of sugars and starch, the expression of genes involved in metabolism of sugars increased dramatically after low temperature induction. One FT gene (Unigene0025396, LcFT1) which produces a protein called ‘florigen’ was also detected among DEGs of litchi. LcFT1 exhibited an apparent specific tissue and its expression was highly increased after low temperature induction, GUS staining results also showed GUS activity driven by LcFT1 gene promoter can be induced by low temperature, which indicated LcFT1 probably played a pivotal role in the floral induction of litchi under low temperature. Conclusions Our study provides a global survey of transcriptomes to better understand the molecular mechanisms underlying changes of leaves in response to low temperature induction in litchi. The analyses of transcriptome profiles and physiological indicators will help us study the complicated metabolism of floral induction in the subtropic evergreen plants. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3747-x) contains supplementary material, which is available to authorized users.

A total of 74,745 unigenes were generated and 1975 DEGs were identified. Candidate genes that may be involved in the adventitious root formation of mango cotyledon segment were revealed. Adventitious root formation is a crucial step in plant vegetative propagation, but the molecular mechanism of adventitious root formation remains unclear. Adventitious roots formed only at the proximal cut surface (PCS) of mango cotyledon segments, whereas no roots were formed on the opposite, distal cut surface (DCS). To identify the transcript abundance changes linked to adventitious root development, RNA was isolated from PCS and DCS at 0, 4 and 7 days after culture, respectively. Illumina sequencing of libraries generated from these samples yielded 62.36 Gb high-quality reads that were assembled into 74,745 unigenes with an average sequence length of 807 base pairs, and 33,252 of the assembled unigenes at least had homologs in one of the public databases. Comparative analysis of these transcriptome databases revealed that between the different time points at PCS there were 1966 differentially expressed genes (DEGs), while there were only 51 DEGs for the PCS vs. DCS when time-matched samples were compared. Of these DEGs, 1636 were assigned to gene ontology (GO) classes, the majority of that was involved in cellular processes, metabolic processes and single-organism processes. Candidate genes that may be involved in the adventitious root formation of mango cotyledon segment are predicted to encode polar auxin transport carriers, auxin-regulated proteins, cell wall remodeling enzymes and ethylene-related proteins. In order to validate RNA-sequencing results, we further analyzed the expression profiles of 20 genes by quantitative real-time PCR. This study expands the transcriptome information for Mangifera indica and identifies candidate genes involved in adventitious root formation in cotyledon segments of mango.

As the miniaturization and integration become the leading trend of the micro-electro-mechanical systems, it is of great significance to improve the microscaled heat transfer performance. This paper presents a three-dimensional (3D) numerical simulation on the flow characteristics and heat transfer performance of non-Newtonian fluid flow in a manifold microchannel (MMC) heat sink and traditional microchannel (TMC) heat sink. The non-Newtonian fluid was described by the power-law model. The analyses concentrated on the non-Newtonian fluid effect on the heat transfer performance, including the heat transfer efficiency and uniformity of temperature distribution, as well as the influence of inlet/outlet configurations on fluid flow and heat transfer. Comparing with Newtonian fluid flow, pseudo-plastic fluid could reduce the drag resistance in both MMC and TMC, while the dilatant fluid brought in quite larger drag resistance. For the heat transfer performance, the introduction of pseudo-plastic fluid flow greatly improved the heat transfer efficiency owing to the generation of secondary flow due to the shear-thinning property. Besides, the temperature distribution in MMC was more uniform by using pseudo-plastic fluid. Moreover, the inlet/outlet configuration was also important for the design and arrangement of microchannel heat sinks, since the present work showed that the maximum temperature was prone to locating in the corners near the inlet and outlet. This work provides guidance for optimal design of small-scale heat transfer devices in many cooling applications, such as biomedical chips, electronic systems, and advanced fuel cells.

DNA methylation changes can occur in some loci during callus culture, resulting in somaclonal variations (SVs). In the present study, we applied whole genome bisulfite sequencing to analyze context-specific DNA methylation changes in the pineapple genome between the cutting seedings and 5 SV plants. In general, SV plants exhibited methylation patterns analogous to those of cutting seedlings (CK). A total of 27.98% of the genomic cytosines of CK were methylcytosines, which was higher than that of 5 SV plants. Moreover, mCG and mCHG was hypermethylated, whereas mCHH was hypomethylated among the 5 SV plants genomic when compared with the CK. Most of the variation of DNA methylation was distributed in gene bodies, thus suggesting that phenotypic differences are probably perturbed by genes methylated from callus culture. In addition, the methylated genes were highly enriched for the Gene Ontology (GO) categories of binding and catalytic activity, cell part and organelle, cellular process, abiotic stimulus, and DNA modification. These results suggest that methylation mediates these pathways in the callus culture of pineapple. The results also suggested that the callus culture induced DNA methylation may result in the SV.

Transient flow responses of viscoelastic fluids to different external body forces are studied. As a non-Newtonian fluid, the viscoelastic fluid exhibits significant elastic response which does not raise in Newtonian fluid. Here, we investigate the transient response of a viscoelastic Poiseuille flow in a two-dimensional channel driven by external body forces in different forms. The velocity response is derived using the Oldroyd-B constitutive model in OpenFOAM. Responses in various forms like damped harmonic oscillation and periodic oscillation are induced and modulated depending on the fluid intrinsic properties like the viscosity and the elasticity. The external body forces like constant force, step force and square wave force are applied at the inlet of the channel. Through both time domain and frequency domain analysis on the fluid velocity response, it is revealed that the oscillation damping originates from the fluid viscosity while the oscillation frequency is dependent on the fluid elasticity. The velocity response of the applied square waves with different periods shows more flexible modulation signal types than constant force and step force. An innovative way is also developed to characterize the relaxation time of the viscoelastic fluid by modulating the frequency of the square wave force.

Temperature measurement is the core technique for investigating heat transfer in microfluidics. In this paper, the resistance thermometry of Titanium–Platinum (Ti–Pt) films is manufactured by microelectronic manufacturing technology and used for the micro-scaled temperature measurement. In order to obtain the accurate temperature on the bottom wall of microchannel, the Ti–Pt films are embedded on the bottom wall. With standardized calibration and error analysis, the experimental system is proven to be reliable and stable for flow and temperature measurement. The experiments of viscoelastic fluid with heat transfer at very-low- Re flow in the curved microchannel are conducted. Both viscoelastic fluid (polymeric solution) and Newtonian fluid (sucrose solution) are used as working fluids, and the corresponding heat transfer performances are obtained. Comparing with Newtonian fluid flow, higher heat transfer rate of viscoelastic fluid flow is achieved due to the irregular motion induced by the fluid viscoelasticity in the curved microchannel.

Reduced-order model (ROM) based on proper orthogonal decomposition (POD) has been widely used in different fields, such as optimization design and flow control, etc., which needs to get calculation results quickly. Most of present studies about POD-ROM focus on the Newtonian fluid flows, whereas, few studies are related with viscoelastic fluid flows. In this paper, POD-ROM is the first time developed for viscoelastic fluid flow by considering a typical two-dimensional thermal fluid problem: Rayleigh-Benard convection (RBC). Three different cases are chosen to simulate viscoelastic RBC flow at Rayleigh number of 108, Prandtl number of 7.0 and Weissenberg number of 0.1, 0.2 and 0.3, respectively. It is found that phase portraits under different POD modes share the same trend as that for DNS. By introducing ‘intrinsic stabilization scheme’ closure model, it shows that the relative errors of fluctuation velocity, temperature and conformation tensor fields decrease greatly, i.e., POD-ROM with closure model can perform better than POD-ROM without closure model for long-time prediction.

A visualization study of the bubble behavior in pool boiling of ultra-pure water and surfactant aqueous solution (Triton X-114) under different heat fluxes was performed, using a narrow transparent bare FTO heating surface with various subcooling degrees of 5°C, 25°C and 35°C, respectively. It is shown that with the decrease of liquid subcooling, bubble coalescence in ultra-pure water becomes obvious. Whilst with the increase of liquid subcooling, the bubble surface gets rough and unstable. In contrast, a newly discovered phenomenon of bubble-bubble (BB) penetration occurs in the surfactant solution under the same working condition as that in water. BB penetration behavior is a bubble interaction without coalescence. This bubble behavior is believed to be the results of micro-convection due to the shrinkage of the bubble root, and the Marangoni effect due to the surface tension gradient. Combination of Marangoni effect and bubble surface movement causes the surfactant molecules to aggregate toward the bubble root, and it effectively promotes the nucleation of the next bubble. Owe to the rapid growth of newly nucleated bubbles, the bubble-bubble penetration and piercing behaviors happen during the growth stage. The newly nucleated bubble partially accelerates the first bubble departure, also interacts with the first bubble by forming a tiny vapor channel. This phenomenon should be one of the reasons of enhanced heat transfer using surfactant solutions.

Boiling is encountered in industrial processes as an effective heat transfer method. It generates vapor to remove a large amount of heat. The evolution of vapor bubbles in a boiling liquid, especially the growth of bubbles, is one of the parameters that determine the heat transfer strength of a heating surface. The growth process of bubble is complicated due to many physical or chemical factors. Here, for the first time, we report a new phenomenon of vapor bubble–bubble interaction process (a bubble interacts with its neighboring one(s) generated at the same nucleation site) during pool boiling aided by a nonionic surfactant. The different bubble interactions are defined as bubble–bubble penetration, bubble–bubble piercing, and double penetrations. It is motivated by microbubble emission from heater in subcooled pool boiling. Bubble dynamics in aqueous surfactant solution was visualized and analyzed. Much attention was paid on the vapor bubble generation, growth, and interaction in the presence of surfactant. It is worth noting that the bubble penetration frequently occurs in the current conditions. The findings are of fundamental and practical relevance, and in the hope to contribute to better understanding of surfactant-aided boiling mechanism.

Since the development of Pulsating Heat Pipe (PHP), it has gained a lot of attention in the field of thermal management. Flow inside multi-turn PHP is dominated by the capillary action mostly driven by the surface tension and drag force. Cetyltrimethyl ammonium chloride (CTAC) surfactant solution has lower surface tension and higher viscosity values compared to water, its base fluid. Experimental results have proven that the thermal resistance of PHP has increased its thermal performance at higher fill ratios and higher heat input, however the operational mechanism is not yet understood. Vapor formation, its movement and flow pattern of phases of working fluid can be well analyzed by the computational approach. In this paper, results of numerical analysis of 3-D PHP with working fluids that has values of surface tension and viscosity equal to that of 2000 ppm of CTAC are presented to validate the experimental results, thereby explain the thermodynamic reason of decreased thermal resistance. Moreover, the reasons for degraded performance of PHP with CTAC solutions at lower fill ratio and lower heat inputs are explained based on the vapor generation and flow of liquid-vapor inside the capillary tube. The numerical investigation was carried out for the case of 35%, 50% and 65% Fill Ratios (FR) at heat supply of 20, 30, 40 and 50 Watts. Lower surface tension promoted the phase change by rapid formation of vapor from liquid phase. Higher viscosity decreased the velocity of the fluid within the pipe. Influence of surface tension and viscosity on the thermal performance of PHP varied with different fill ratios and heat input.

Fresh water deficit has been an increasingly critical global environmental issue, and seawater desalination is considered as the most effective and promising solution, which promotes the development of different desalination technologies. In order to provide a comprehensive knowledge about the development of desalination technologies, state-of-the-art of research and development on the application of desalination technologies is reviewed in this paper. At first, the overview of desalination technologies is briefly introduced, including the definition of desalination, the evaluation index of water quality and the resulting classification of water resources, the overview of desalination industry, the usages of freshwater produced by desalination, and the sources of raw water. Besides, conventional desalination methods are categorized into physical method and chemical method according to whether there is new substance generated in the desalination process. In the following section conventional desalination methods are reviewed from the perspectives of basic processes and principles, the performances and technical characteristics. However, the shortcomings of conventional desalination technologies mainly lie in high energy consumption and complex treatment process, such as the decrease of heat transfer coefficient caused by the scaling and fouling generated on the solid heat transfer walls for multi-stage flash (MSF) and multiple effect distillation (MED), and rigorous pre-treatment and low recovery factor for reverse osmosis (RO). With the aims of overcoming these disadvantages and thus decreasing the energy consumption, different improvements have been put forward and new desalination methods have been developed. Therefore, the development of desalination technology is then exhaustively analyzed and forecasted in the following four aspects: improvement for the existing technology, combination of different technologies, desalination technology in combination with new energy, and development of new desalination technologies utilizing unemployed physical phenomena. The improvements mainly focus on the shortcomings of MSF, MED and RO, which are the current major large-scale industrial desalination technologies. The combination of different technologies can integrate their respective advantages to improve the desalination performance and decrease the energy consumption and the cost. The limitations of the decrease of traditional fossil energy and its increasing cost can be broken through the combination with solar, wind, geothermal, ocean and nuclear energies, which is also regarded as a potential solution for climate change. The newly developed desalination technologies have the advantages of lower energy consumption and cost, but most of which are still in lab-scale and need further improvement. Due to the important role in the assessment of the desalination efficient, special attention is paid to the analysis of energy consumption of each desalination technology.

‘Sijihua’ longan (Dimocarpus longan Lour.) blossoms throughout the year, and hence it is a useful material for studies on the mechanism of flowering. However, few genomic resources such as DNA sequences or markers are currently available for ‘Sijihua’ longan. To increase our understanding of the genetic control of important flowering characteristics in ‘Sijihua’ longan, we constructed a mixed cDNA library of ‘Sijihua’ longan using Illumina paired-end sequencing technology and obtained a total of 90,069,246 high-quality reads. Among the unigenes, 43.16% (59,588) had at least one BLASTX hit against the Arabidopsis thaliana sequence database and 42.83% (59,130) had significant similarity with proteins in the NCBI non-redundant protein database. Of these annotated unigenes, a total of 15,956 (11.56%) were mapped onto 271 pathways using the Kyoto Encyclopedia of Genes and Genomes Pathway database. Furthermore, 11,402 unigenes were converted into 13,236 potential simple sequence repeats (SSRs). Dinucleo...

Extended Biologische Bundesantalt, Bundessortenamt and Chemische Industrie scale was applied to achieve precise and normative description of each growth stage of longan. The entire growth cycle of longan was divided into seven primary stages, namely, development of shoots, leaves and branches, formation of inflorescence, flowering, fruit development and maturity. These primary stages were further subdivided into 47 secondary stages. This study focused on the entire fruit development process of longan. The correlation between phenology, temperature and humidity was also discussed. Knowledge of these rules will provide guidance for the implementation of production management measures, including fertilisation, disease and pest control, branch control, flower induction, flower and fruit retention and application of growth regulator. The present findings will also help longan planters to adopt the most appropriate cultivation and management measures according to the climate conditions and growth status of the trees.