Formation Of Liquid Droplets Research Articles

Exploring liquid-liquid phase separation in vitro and in vivo using multimodal nonlinear optical imaging.

Liquid-liquid phase separation leads to the formation of liquid droplets (LqDs) such as P granules in Caenorhabditis elegans (C. elegans). In this study, we demonstrate the label-free visualization of LqDs using multimodal nonlinear optical imaging both in vitro and in vivo. In vitro measurements with polymerized adenine [poly(A)], we found significantly higher poly(A) concentrations in LqDs compared to surrounding solutions, with the limit of detection (LoD) of 32mg/mL. In vivo measurements, we performed label-free imaging of C. elegans. Despite efforts to detect P granules within P lineage cells in both wild-type C. elegans and green fluorescent protein (GFP)-tagged strains, no clear RNA-specific signals were observed. This indicates that the RNA concentration in P granules is lower than anticipated and falls below our in vitro LoD. These results underscore the challenges of label-free RNA detection in P granules.

Liquid metal droplet generation based on T-junction microchannels

Galinstan liquid metal remains liquid at room temperature and exhibits unique physical properties including fluidity and high electrical conductivity, and its manipulation is a subject of extensive research interest. In contrast to existing control methods, such as electric and magnetic fields, we focus on a novel and efficient approach based on generating liquid metal droplets through microchannels. The present investigation mainly deals with generating liquid metal droplets through establishing a two-dimensional computational model based on the phase-field method for the droplet microfluidics in a T-junction structure. To enhance its performance, a constraint structure is added to expand the adjustment range of droplet formation. The constraint structure and increasing flow rate enhance the viscous shear effect, which reduces the droplet formation length and increases the generation frequency. Polymethyl methacrylate and pressure-sensitive adhesive are laser-cut to fabricate the microchannels. A peristaltic pump is utilized as the driving device, and a high-speed camera is employed to record the liquid metal droplet formation process. Both reducing the constraint ratio and increasing the flow ratio result in accelerated shear rate and increased droplet formation frequency, which is consistent with the simulation results. In experiments, the constraint structure enhanced the viscous shear effect, and relocation of the fracture location was observed. In addition, the high surface tension and inertia of the liquid metal released energy during droplet breakup, leading to noticeable oscillation and deformation of the droplet. Both the simulation and experimental results provide guidelines for the application of liquid metal generation in reconfigurable metasurfaces.

Coarse-Grained Simulation Study of the Association of Selected Dipeptides.

The association of 55 dipeptides extracted from aggregation-prone regions of selected proteins was studied by means of multiplexed replica-exchange molecular dynamics simulations with the coarse-grained UNRES model of polypeptide chains. Each simulation was carried out with 320 dipeptide molecules in a periodic box at 0.24 mol/dm3 concentration, in the 260-370 K temperature range. The temperature profiles of the degree of association, distributions of dipeptide cluster size, and structures of clusters were examined. It has been found that the dipeptides composed of strongly nonpolar (aromatic or aliphatic) residues associate nearly completely at all temperatures to form tight clusters, while those composed of charged or polar residues exhibited no or residual association. The dipeptides composed of nonpolar and small polar residues and those composed of less hydrophobic residues formed single clusters, gradually dissolving with increasing temperature, while those composed of phenylalanine or tryptophan and polar or charged residues formed multiple irregular clusters with room to accommodate water inside, suggesting the formation of liquid droplets or gels. The logarithms of the average degree of association and the free energy of aggregation per monomer were found to correlate with the dipeptide hydrophobicity.

Tailoring the Polarity Sensitivity of Fluorescence Lifetime Imaging Probes to Reveal Interplays of Mitochondria Dysfunction with Lipid Droplets Formation

Tailoring the Polarity Sensitivity of Fluorescence Lifetime Imaging Probes to Reveal Interplays of Mitochondria Dysfunction with Lipid Droplets Formation

Clr4SUV39H1 ubiquitination and non-coding RNA mediate transcriptional silencing of heterochromatin via Swi6 phase separation

Transcriptional silencing by RNAi paradoxically relies on transcription, but how the transition from transcription to silencing is achieved has remained unclear. The Cryptic Loci Regulator complex (CLRC) in Schizosaccharomyces pombe is a cullin-ring E3 ligase required for silencing that is recruited by RNAi. We found that the E2 ubiquitin conjugating enzyme Ubc4 interacts with CLRC and mono-ubiquitinates the histone H3K9 methyltransferase Clr4SUV39H1, promoting the transition from co-transcriptional gene silencing (H3K9me2) to transcriptional gene silencing (H3K9me3). Ubiquitination of Clr4 occurs in an intrinsically disordered region (Clr4IDR), which undergoes liquid droplet formation in vitro, along with Swi6HP1 the effector of transcriptional gene silencing. Our data suggests that phase separation is exquisitely sensitive to non-coding RNA (ncRNA) which promotes self-association of Clr4, chromatin association, and di-, but not tri- methylation instead. Ubc4-CLRC also targets the transcriptional co-activator Bdf2BRD4, down-regulating centromeric transcription and small RNA (sRNA) production. The deubiquitinase Ubp3 counteracts both activities.

Frost growth on silver iodide (AgI) stripe patterned surface under condensation frosting condition

Frost growth on silver iodide (AgI) stripe patterned surface under condensation frosting condition

Liquid crystal droplets formation and stabilization during phase transition process

Abstract The study of phase transition processes in liquid crystals (LCs) remains challenging. Most thermotropic LCs exhibit a narrow temperature range and a rapid phase transition from the isotropic (ISO) to the nematic (N) phase, which make it difficult to capture and manipulate the phase transition process. In this study, we observed the evolution of small droplets during the ISO–N phase transition in ferroelectric nematic (NF) LC RM734. After doping with metal nanoparticles (NPs), the temperature range of the phase transition broadened, and the droplets formed during the phase transition remained stable, with their diameter increasing linearly with temperature. In addition, droplets doped with NPs can be well controlled by an external electric field. This discovery not only aids in understanding the fundamental mechanisms of LC phase transitions but also provides a simple alternative method for preparing droplets, which is potentially valuable for applications in optoelectronic devices and sensors.

ZMAT2 condensates regulate the alternative splicing of TRIM28 to reduce cellular ROS accumulation, thereby promoting the proliferation of HCC cells

Dysregulation of splicing factor expression plays a crucial role in the progression of hepatocellular carcinoma (HCC). Our research found that the expression level of splicing factor ZMAT2 was increased in HCC, promoting the proliferation of HCC cells. RNAseq data indicated that the absence of ZMAT2 induced skipping exon of mRNA, while RIPseq data further revealed the mRNA binding motifs of ZMAT2. A comprehensive analysis of RNAseq and RIPseq data indicateed that ZMAT2 played a crucial role in the maturation process of TRIM28 mRNA. Knocking down of ZMAT2 led to the deletion of 25 bases in exon 11 of TRIM28, ultimately resulting in nonsense-mediated decay (NMD). Our data revealed that ZMAT2 could regulate TRIM28 to reduce the accumulation of ROS in HCC cells, thereby promoting their proliferation. Our research also discovered that ZMAT2 was capable of undergoing phase separation, resulting in the formation of liquid droplet condensates within HCC cells. Additionally, it was found that ZMAT2 was able to form protein-nucleic acid condensates with TRIM28 mRNA. In summary, this study is the first to reveal that ZMAT2 and TRIM28 mRNA form protein-nucleic acid condensates, thereby regulating the splicing of TRIM28 mRNA. The increased expression of ZMAT2 in HCC leads to upregulated TRIM28 expression and reduced ROS accumulation, ultimately accelerating the proliferation of HCC cells.

Influence of Atomizing Gas Pressure on Microstructure and Properties of Nickel Silicide Intended for Additive Manufacturing

Nickel silicides are crucial in advanced technology applications ranging from semiconductor devices to high-temperature materials. Gas atomization is a process that involves the formation of fine liquid droplets and their rapid cooling and solidification to make powder particles. The final microstructure and the properties of the particles are highly sensitive to the gas atomization process parameters. In the present study, gas atomization of NiSi12-wt% was performed at three different pressures (35, 40, and 45 bars) to optimize the particle size distribution for additive manufacturing applications. A comprehensive range of characterization techniques, including scanning electron microscopy, X-ray diffraction, particle size distribution measurements, light optical microscopy, and density measurements, was used to evaluate the microstructural features, phase composition, and density of the produced NiSi12-wt% powders. Higher atomizing gas pressures resulted in a finer particle size distribution due to improved molten droplet breakup, increased satellite formation, and a well-suited particle size distribution for additive manufacturing applications.

Experimental study on the characteristics of frost formation and defrosting water retention between vertical double surfaces with different wettability

Experimental study on the characteristics of frost formation and defrosting water retention between vertical double surfaces with different wettability

Angle between DNA linker and nucleosome core particle regulates array compaction revealed by individual-particle cryo-electron tomography

The conformational dynamics of nucleosome arrays generate a diverse spectrum of microscopic states, posing challenges to their structural determination. Leveraging cryogenic electron tomography (cryo-ET), we determine the three-dimensional (3D) structures of individual mononucleosomes and arrays comprising di-, tri-, and tetranucleosomes. By slowing the rate of condensation through a reduction in ionic strength, we probe the intra-array structural transitions that precede inter-array interactions and liquid droplet formation. Under these conditions, the arrays exhibite irregular zig-zag conformations with loose packing. Increasing the ionic strength promoted intra-array compaction, yet we do not observe the previously reported regular 30-nanometer fibers. Interestingly, the presence of H1 do not induce array compaction; instead, one-third of the arrays display nucleosomes invaded by foreign DNA, suggesting an alternative role for H1 in chromatin network construction. We also find that the crucial parameter determining the structure adopted by chromatin arrays is the angle between the entry and exit of the DNA and the corresponding tangents to the nucleosomal disc. Our results provide insights into the initial stages of intra-array compaction, a critical precursor to condensation in the regulation of chromatin organization.

Membrane supported liquid-liquid oxygenation for use in extracorporeal life support – Proof of principle

Membrane supported liquid-liquid oxygenation for use in extracorporeal life support – Proof of principle

Enabling High Activation of Glucose-6-Phosphate Dehydrogenase Activity Through Liquid Condensate Formation and Compression.

Droplet formation via liquid-liquid phase separation is thought to be involved in the regulation of various biological processes, including enzymatic reactions. We investigated a glycolytic enzymatic reaction, the conversion of glucose-6-phosphate to 6-phospho-D-glucono-1,5-lactone with concomitant reduction of NADP+ to NADPH both in the absence and presence of dynamically controlled liquid droplet formation. Here, the nucleotide serves as substrate as well as the scaffold required for the formation of liquid droplets. To further expand the process parameter space, temperature and pressure dependent measurements were performed. Incorporation of the reactants in the liquid droplet phase led to a boost in enzymatic activity, which was most pronounced at medium-high pressures. The crowded environment of the droplet phase induced a marked increase of the affinity of the enzyme and substrate. An increase in turnover number in the droplet phase at high pressure contributed to a further strong increase in catalytic efficiency. Enzyme systems that are dynamically coupled to liquid condensate formation may be the key to deciphering many biochemical reactions. Expanding the process parameter space by adjusting temperature and pressure conditions can be a means to further increase the efficiency of industrial enzyme utilization and help uncover regulatory mechanisms adopted by extremophiles.

Experimental study of liquid aluminum droplet breakup characteristics based on a Drop-on-demand (DOD) magnetohydrodynamic actuation

Experimental study of liquid aluminum droplet breakup characteristics based on a Drop-on-demand (DOD) magnetohydrodynamic actuation

A new educational approach to surface tension and Young-Laplace law by using computer-based simulations

Here we present a pedagogical approach to surface tension phenomena based on a novel mesoscopic fluid model. We show that computer simulations based on this model can provide quantitative results that are consistent with experimental results. We simulate the formation of a two-dimensional liquid droplet without gravity and obtain its surface tension as a result by also verifying Young-Laplace’s law. By controlling some simulation parameters, students can understand step by step how some physical quantities (e.g., the intensity of the interaction between two fluid particles) can affect the behaviour of fluids. This approach will provide students with an explicative model of surface phenomena.

Multifunctional coatings fabricated from Chinese hemp–derived superhydrophobic micro–nanocellulose

Multifunctional coatings fabricated from Chinese hemp–derived superhydrophobic micro–nanocellulose

New insights into the mechanism of ultrasonic atomization for the production of metal powders in additive manufacturing

Ultrasonic atomization is one of the promising technologies for producing metal powders for additive manufacturing, where precise control of particle size and morphology is essential. In this study, we coupled an ultrasonic transducer with a carbon fiber plate and atomized liquid droplets and films under different vibration amplitudes. Water, glycerol, and pure aluminum melt were used to study the atomization mechanism and the resulting droplet/powder characteristics, respectively. High-speed optical and ultrafast synchrotron X-ray imaging were used to study in situ the ultrasonic atomization dynamics, including pulsation and clustering of cavities inside the liquid layer/films, development of capillary waves, and formation of liquid droplets. For the first time, we observed and captured the occurrence of cavitation during the atomization of resting drops, films and impact droplets. The inertial cavitation events interfered with the capillary waves across the interphase boundary, puncturing and breaking the boundary to produce atomized mist. The in situ observation revealed the intricate dynamics of ultrasonic atomization and underscored the pivotal role of cavitation events throughout the entire atomization process. We also conducted experiments on ultrasonic atomization of liquid aluminum, producing particles of perfectly spherical shape. The particle size tended to decrease with reduced vibration amplitude Our work has demonstrated the important processing strategies on how to tailor the particle size while ensuring consistent particle shape and morphology, which is the key processing capability for producing high quality powders for additive manufacturing applications.

The molecular basis for the increased stability of the FUS-LC fibril at the anionic membrane- and air-water interfaces.

Self-organization of biomolecules can lead to the formation of liquid droplets, hydrogels, and irreversible aggregates that bear immense significance in biology and diseases. Despite the considerable number of studies conducted on biomolecular condensation in bulk solution, there is still a lack of understanding of how different surfaces regulate the condensation process. In this context, recent studies showed that, in contrast to zwitterionic lipid membranes, anionic membranes promoted the production of liquid droplets of FUsed in Sarcoma Low Complexity domain (FUS-LC) despite exhibiting no specific protein-lipid interactions. Moreover, the air-water interface led to a solid fibril-like aggregate of FUS-LC. The molecular mechanism of condensation/aggregation of proteins in response to surfaces of various charged states or levels of hydrophobicity remains to be better elucidated. Here, we provide initial insights into this question by investigating the stability of a small β fibril state of FUS-LC in bulk solution vs. membrane- and air-water interfaces. We perform multiple independent molecular dynamics simulations with distinct starting conformations for each system to demonstrate the statistical significance of our findings. Our study demonstrates the stability of the FUS-LC fibril in the presence of anionic membranes on the μs timescale while the fibril falls apart in bulk solution. We observe that a zwitterionic membrane does not enhance the stability of the fibril and 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS) has a higher propensity to stabilize the fibril than dioleoylphosphatidylglycerol (DOPG), in qualitative agreement with experiments. We further show that the fibril becomes more stable at the air-water interface. We pinpoint interfacial solvation at the membrane- and air-water interfaces as a key factor that contributes to the stabilization of the peptide assembly.

A study of the application of wet steam modeling for thermocompressor simulation in TVC desalination

A study of the application of wet steam modeling for thermocompressor simulation in TVC desalination

Rheology of a sodium‐molybdenum borosilicate melt undergoing phase separation

AbstractDuring glass production, phase separation can result in the formation of suspended liquid droplets, which can cause changes in the system rheology. In nuclear waste vitrification context, some new glassy matrices may present this phase separation matter, but the mechanisms controlling the viscosity changes have not yet been determined. Here, we measure the viscosity of a sodium‐borosilicate melt containing dissolved MoO3 at different temperatures and subject to different applied shear strain rates. We observe that (i) the viscosity increases sharply as the temperature decreases and (ii) at any constant temperature below 1000°C, the system presents non‐Newtonian response. Using transmission electron microscope observations coupled with viscosity calculations, we interpret the cause of the observed changes as the result of phase separation. We show that the viscosity increase on cooling is in excess of the predicted temperature dependence for a homogeneous melt of the starting composition. The increase is due to the formation of a second phase and is controlled by chemical and structural modifications of the matrix during the loss of the elements that form the droplets. This work provides insights into the rheology of a system composed of two composition sets due to a miscibility gap.