Fluidization dynamic characteristics of carbon nanotube particles in a tapered fluidized bed

In this work,a tapered fluidized bed(TFB)without a distributor for fluidizing carbon nanotube(CNT)was applied for improving the dead zone,blockage,and fracture of distributor,which occurred in actual production.Experiments were performed under different superficial gas velocities,static bed heights,CNT agglomerate size,and positions of pressure probe.To obtain multi-perspective and multi-scale understanding of fluidization dynamics of gas–CNT flow in the TFB without a distributor,the standard deviation,skewness,kurtosis,wavelet decompositions and homogeneous index analysis methods were adopted.Some noticeable phenomena were observed.Particle movements including inter-particle,gas–particle and particle–wall dominate dynamic characteristics.The amplitudes of pressure fluctuations of coarse agglomerated multi-walled CNT were more sensitive to the gas velocity than that of fine agglomerated multi-walled CNT.The sensitively of energy contribution of the meso-and macrostructures was that the sensitivity of the measured position was less than the sensitivity of the energy contribution by the changes of particle size,and the sensitivity of the energy contribution by the changes of particle size was less than the energy contribution by the changes of gas velocity.The fluidization quality of coarse agglomerated multi-walled CNT was better than that of fine agglomerated multi-walled CNT,which was verified by the skewness and wavelet analysis.

The motion mechanism and characteristic of bubble in a pseudo-2D tapered fluidized bed

The different carbon nanotube(CNT)particles(^(@)A and^(@)V)were bed materials in the pseudo-2D tapered fluidized bed(TFB)with/without a distributor.A detailed investigation of the motion mechanism of bubbles was carried out.The high-speed photography and image analysis techniques were used to study bubble characteristic and mixing behavior in the tapered angle of TFB without a distributor.The fractal analysis method was used to analyze the degree of particles movement.Results showed that an S-shaped motion trajectory of bubbles was captured in the bed of^(@)V particles.The population of observational bubbles in the bed of^(@)V particles was more than that of^(@)A particles,and the bubble size was smaller in the bed of^(@)V particles than that of^(@)A particles.The motion mechanism of bubbles had been shown to be related to bed materials and initial bed height in terms of analysis and comparison of bubble diameter,bubble aspect ratio and bubble shape factor.Importantly,compared to the TFB with a distributor,the TFB without a distributor had been proved to be beneficial to the CNT fluidization according to the study of bubble characteristic and the degree of the particle movement.Additionally,it was found that the mixing behavior of^(@)V particles was better than^(@)A particles in the tapered angle of TFB without a distributor.

A novel reporter mouse line for studying alveolar macrophages

Alveolar macrophages(AMs)are self-maintained immune cells that play vital roles in lung homeostasis and immunity.Although reporter mice and culture systems have been established for studying macrophages,an accurate and specific reporter line for alveolar macrophage study is still not available.Here we reported a novel Rspo1-tdTomato gene reporter mouse line that could specifically label mouse AMs in a cell-intrinsic manner.Using this reporter system,we visualized the dynamics of alveolar macrophages intravitally under steady state and characterized the alveolar macrophage differentiation under in vitro condition.By performing ATAC-seq,we found that insertion of the tdTomato cassette in the Rspo1 locus increased the accessibility of a PPARE motif within the Rspo1 locus and revealed a potential regulation by key transcription factor PPAR-γfor alveolar macrophage differentiation in vitro and in vivo.Consistently,perturbation of PPAR-γby its agonist rosiglitazone or inhibitor GW9662 resulted in corresponding alteration of tdTomato expression in alveolar macrophages together with the transcription of PPAR-γdownstream target genes.Furthermore,global transcriptomic analyses of AMs from the wild type mice and the Rspo1-tdTomato mice showed comparable gene expression profiles,especially those AM-specific genes,confirming that the insertion of the tdTomato cassette in the Rspo1 locus does not impact the cell identity and biological function of AMs under normal condition.Taken together,our study provides an alternative tool for in vivo and in vitro labeling of alveolar macrophages with high specificity which could also be utilized as an indicator of PPAR-γactivity for future development of PPAR-γspecific targeting drugs.

Hydrodynamic analysis of carbon nanotube clusters in distributor-less conical fluidized beds with step-by-step scaling

As a high-performance material with great application potential,the application of carbon nanotubes has been limited by their production volume.A distributor-less conical fluidized bed is the main equipment used in the industrial production of carbon nanotubes.To improve the production volume and product quality of carbon nanotubes,the study of fluidized-bed-diameter scaling is important.Three different diameters of distributor-less conical fluidized beds were established,and then the particle behavior and bubble characteristics of carbon nanotube clusters at these bed diameters were investigated.Time-series and wavelet analysis methods were used to analyze the pressure-fluctuation signals inside the fluidized beds.Results showed that the distributor-less design caused the airflow to break through the middle of the bed,which did not change with the change in bed diameter.The powder-bridging phenomenon of carbon nanotube clusters in a 100-mm-diameter fluidized bed was related to the special microstructure of carbon nanotube clusters.The frequency of pressure fluctuations in the bed decreased nonlinearly with increasing bed diameter.This study can guide the design and scale-up of distributor-less conical fluidized beds,especially for the scale-up of carbon nanotube production equipment,which can contribute to the improvement of carbon nanotubes’capacity and quality in industrial production.