Spontaneous Transfer of Droplets across a Microfluidic Liquid-Liquid Interface.

The droplet transfer across an interface in a microchannel is extensively utilized in diverse fields; however, it is challenging to drive droplets to penetrate the interface at such a small scale. In this study, a novel flow pattern of droplet transfer is observed and the mechanism is investigated; accordingly, an accurate prediction equation for determining the critical condition of droplet transfer is proposed. Meanwhile, the liquid film entrainment is also observed, which leads to the formation of an oil-in-water-in-water system. This study serves as a valuable reference for further studies on the mechanism of droplet transfer and provides practical guidance for its industrial application.

The complete chloroplast genome sequence of Pinus bhutanica (Pinaceae) and its phylogenetic implications.

Pinus bhutanica is a critically endangered conifer and occurs only in central Bhutan, northwestern Yunnan and southeastern Xizang in China. In this study, the complete chloroplast genome of Pinus bhutanica was first assembled based on next-generation sequencing. The genome sequence was 116,919 bp in length with an overall GC content of 38.75%. A total of 106 functional genes were detected in the genome, including 72 protein-coding genes (PCGs), 30 transfer RNA (tRNA) genes, and four ribosomal RNA (rRNA) genes. The phylogenetic tree reconstructed by 12 chloroplast genomes revealed that P. bhutanica is most closely related to Pinus wangii in subsection Strobus of Pinus.

Formation of Droplets of Shear-Thinning Non-Newtonian Fluids in Asymmetrical Parallelized Microchannels.

Fluids containing polymers are frequently utilized in the chemical industry and exhibit shear-thinning characteristics. The flow distribution of non-Newtonian fluids in parallelized microchannels is a key issue to be solved during numbering-up. Numbering-up means increasing the number of parallelized microchannels. In this study, a high-speed camera is used to explore the distribution of fluid flow as well as the uniformity and stability of droplets in conceptual asymmetrical parallelized microchannels. Cyclohexane and carboxymethylcellulose sodium (CMC) aqueous solutions are used as the continuous phase and dispersed phase, respectively. The effects of fluctuation of pressure difference around the T-junction, the hydrodynamic resistance in microchannels, and the shear-thinning property of fluids on flow distribution and droplet formation are revealed. The uniformity and stability of droplets in microdevices with various cavity settings are compared, and an optimal configuration is proposed. Finally, prediction models for the flow distribution of shear-thinning fluids in asymmetrical parallelized microchannels are established.

Transcriptome analysis provides insights into light condition effect on paclitaxel biosynthesis in yew saplings.

BACKGROUND: Taxus is a rare gymnosperm plant that is the sole producer of the anticancer drug paclitaxel. The growth and development of Taxus is affected by environmental factors such as light. However, little is known about how light conditions affect growth and metabolic processes, especially paclitaxel biosynthesis. RESULTS: In this study, we applied three different light conditions to Taxus chinensis young saplings and investigated the physiological response and gene expression. Our observations showed that exposure to high light led to oxidative stress, caused photoinhibition, and damaged the photosynthetic systems in T. chinensis. The paclitaxel content in T. chinensis leaves was significantly decreased after the light intensity increased. Transcriptomic analysis revealed that numerous genes involved in paclitaxel biosynthesis and phenylpropanoid metabolic pathways were downregulated under high light. We also analyzed the expression of JA signaling genes, bHLH, MYB, AP2/ERF transcription factors, and the CYP450 families that are potentially related to paclitaxel biosynthesis. We found that several CYP450s, MYB and AP2/ERF genes were induced by high light. These genes may play an important role in tolerance to excessive light or heat stress in T. chinensis. CONCLUSIONS: Our study elucidates the molecular mechanism of the effects of light conditions on the growth and development of T. chinensis and paclitaxel biosynthesis, thus facilitating the artificial regeneration of Taxus and enhancing paclitaxel production.

Fluticasone propionate nanosuspensions for sustained nebulization delivery: An in vitro and in vivo evaluation.

This study intended to investigate the in vivo pulmonary fate of intratracheally dosed nanosuspensions of fluticasone propionate (FP). Three FP suspensions, including a microsuspension and two nanosuspensions with different dissolution profiles, were prepared and they exhibited comparable aerodynamic performances after nebulization via a jet nebulizer. Following intratracheal administration to rats, the microsuspension underwent extensive mucociliary clearance, leading to a limited absorption time whereas the nanosuspensions decreased the mucociliary clearance and allowed dissolution rate-limiting and extended pulmonary absorption, resulting in prolonged pulmonary retention and long-acting anti-inflammatory efficacy in a lipopolysaccharide induced lung injury model. Delaying the FP dissolution of a nanosuspension by phospholipid coating increased AUC value in lung tissues to 1.72-fold of a conventional nanosuspension, but led to a decreased pharmacological efficacy. This study demonstrated that inhalable nanosuspensions were a feasible means for the sustained pulmonary delivery of FP and the local anti-inflammatory efficacy was highly dependent on the dissolution profiles.

Initial coalescence of a drop at a planar liquid surface.

The initial coalescence of a pendant drop at bulk liquid was jointly investigated by an ultrahigh-speed DC electrical device, a high-speed camera, and a fast micro-Particle Image Velocimetry (micro-PIV). Extended to highly viscous non-Newtonian liquids, the variation of the coalescing width vs time confirms the distinct regimes reported for drop-drop configuration: linear in the inertially limited viscous regime; square root in the inertial regime; possibly a transient viscous regime in between with a logarithmic correction. The measured flow fields during coalescence reveal the transformation of surface energy to kinetic energy, so that the highly located inertia could play a dominant role in relation to the viscous force.

Multispectral optoacoustic tomography (MSOT) for imaging the particle size-dependent intratumoral distribution of polymeric micelles.

PURPOSE: This study proposes the utilization of multispectral optoacoustic tomography (MSOT) to investigate the intratumoral distribution of polymeric micelles and effect of size on the biodistribution and antitumor efficacy (ATE). MATERIALS AND METHODS: Docetaxel and/or optoacoustic agent-loaded polymeric micelles (with diameters of 22, 48, and 124 nm) were prepared using amphiphilic block copolymers poly (ethylene glycol) methyl ether-block-poly (D,L lactide) (PEG2000-PDLLAx). Subcutaneous 4T1 tumor-bearing mice were monitored with MSOT imaging and IVIS® Spectrum in vivo live imaging after tail vein injection of micelles. The in vivo results and ex vivo confocal imaging results were then compared. Next, ATE of the three micelles was found and compared. RESULTS: We found that MSOT imaging offers spatiotemporal and quantitative information on intratumoral distribution of micelles in living animals. All the polymeric micelles rapidly extravasated into tumor site after intravenous injection, but only the 22-nm micelle preferred to distribute into the inner tumor tissues, leading to a superior ATE than that of 48- and 124-nm micelles. CONCLUSION: This study demonstrated that MSOT is theranostically a powerful imaging modality, offering quantitative information on size-dependent spatiotemporal distribution patterns after the extravasation of nanomedicine from tumor blood vessels.

Ciclesonide and budesonide suspensions for nebulization delivery: An in vivo inhalation biopharmaceutics investigation.

The pulmonary fate of inhaled poorly water-soluble drugs is not entirely clear. In this study, the main objective was to investigate the in vivo inhalation biopharmaceutics in the aspects of dissolution, mucociliary clearance, absorption and tissue binding using intratracheally administered budesonide and ciclesonide suspensions as model drugs. In doing so, this study first developed a method to differentiate between dissolved and undissolved ciclesonide in the lungs for evaluating in vivo dissolution. Following deposited in rat airways, the drug particles underwent rapid dissolution and mucociliary clearance, leading to the complete removal of drugs from the airways within 2 h and a limited absorption time less than 2 h. Upon dissolution, budesonide and ciclesonide were taken up and retained in the lung tissues for up to 12 h and 24 h, respectively. The in vivo dissolution profiles in the airways exhibited the sameness as the in vitro counterparts in a 0.5% sodium dodecyl sulfate solution as indicated by the similarity factor f2. The efficacy results in a lipopolysaccharide induced lung injury model showed that the duration of local anti-inflammatory was dependent on the drug levels in the lung tissues, but not on the in vitro/in vivo dissolution and plasma pharmacokinetics. The present results demonstrated that ciclesonide suspension has the potential to achieve once-daily dosing for nebulization therapy and the in vitro dissolution profile has limited usefulness in predicting in vitro-in vivo correlation.

Inertio-capillary cross-streamline drift of droplets in Poiseuille flow using dissipative particle dynamics simulations.

We find using dissipative particle dynamics (DPD) simulations that a deformable droplet sheared in a narrow microchannel migrates to steady-state position that depends upon the dimensionless particle capillary number , which controls the droplet deformability (with Vmax the centerline velocity, µf the fluid viscosity, Γ the surface tension, R the droplet radius, and H the gap), the droplet (particle) Reynolds number , which controls inertia, where ρ is the fluid density, as well as on the viscosity ratio of the droplet to the suspending fluid κ = µd/µf. We find that when the Ohnesorge number is around 0.06, so that inertia is stronger than capillarity, at small capillary number Cap < 0.1, the droplet migrates to a position close to that observed for hard spheres by Segre and Silberberg, around 60% of the distance from the centerline to the wall, while for increasing Cap the droplet steady-state position moves smoothly towards the centerline, reaching around 20% of the distance from centerline to the wall when Cap reaches 0.5 or so. For higher Oh, the droplet position is much less sensitive to Cap, and remains at around 30% of the distance from centerline to the wall over the whole accessible range of Cap. The results are insensitive to viscosity ratios from unity to the highest value studied here, around 13, and the drift towards the centerline for increasing Cap is observed for ratios of droplet diameter to gap size ranging from 0.1 to 0.3. We also find consistency between our predictions and existing perturbation theory for small droplet or particle size, as well as with experimental data. Additionally, we assess the accuracy of the DPD method and conclude that with current computer resources and methods DPD is not readily able to predict cross-stream-line drift for small particle Reynolds number (much less than unity), or for droplets that are less than one tenth the gap size, owing to excessive noise and inadequate numbers of DPD particles per droplet.

Dynamics of bubble breakup at a T junction.

The gas-liquid interfacial dynamics of bubble breakup in a T junction was investigated. Four regimes were observed for a bubble passing through the T junction. It was identified by the stop flow that a critical width of the bubble neck existed: if the minimum width of the bubble neck was less than the critical value, the breakup was irreversible and fast; while if the minimum width of the bubble neck was larger than the critical value, the breakup was reversible and slow. The fast breakup was driven by the surface tension and liquid inertia and is independent of the operating conditions. The minimum width of the bubble neck could be scaled with the remaining time as a power law with an exponent of 0.22 in the beginning and of 0.5 approaching the final fast pinch-off. The slow breakup was driven by the continuous phase and the gas-liquid interface was in the equilibrium stage. Before the appearance of the tunnel, the width of the depression region could be scaled with the time as a power law with an exponent of 0.75; while after that, the width of the depression was a logarithmic function with the time.