Lipid droplets in the nervous system:involvement in cell metabolic homeostasis

Lipid droplets serve as primary storage organelles for neutral lipids in neurons,glial cells,and other cells in the nervous system.Lipid droplet formation begins with the synthesis of neutral lipids in the endoplasmic reticulum.Previously,lipid droplets were recognized for their role in maintaining lipid metabolism and energy homeostasis;however,recent research has shown that lipid droplets are highly adaptive organelles with diverse functions in the nervous system.In addition to their role in regulating cell metabolism,lipid droplets play a protective role in various cellular stress responses.Furthermore,lipid droplets exhibit specific functions in neurons and glial cells.Dysregulation of lipid droplet formation leads to cellular dysfunction,metabolic abnormalities,and nervous system diseases.This review aims to provide an overview of the role of lipid droplets in the nervous system,covering topics such as biogenesis,cellular specificity,and functions.Additionally,it will explore the association between lipid droplets and neurodegenerative disorders.Understanding the involvement of lipid droplets in cell metabolic homeostasis related to the nervous system is crucial to determine the underlying causes and in exploring potential therapeutic approaches for these diseases.

Self-propelled Leidenfrost droplets on femtosecond-laser-induced surface with periodic hydrophobicity gradient

The controllable transfer of droplets on the surface of objects has a wide application prospect in the fields of microfluidic devices,fog collection and so on.The Leidenfrost effect can be utilized to significantly reduce motion resistance.However,the use of 3D structures limits the widespread application of self-propulsion based on Leidenfrost droplets in microelectromechanical system.To manipulate Leidenfrost droplets,it is necessary to create 2D or quasi-2D geometries.In this study,femtosecond laser is applied to fabricate a surface with periodic hydrophobicity gradient(SPHG),enabling directional self-propulsion of Leidenfrost droplets.Flow field analysis within the Leidenfrost droplets reveals that the vapor layer between the droplets and the hot surface can be modulated by the SPHG,resulting in directional propulsion of the inner gas.The viscous force between the gas and liquid then drives the droplet to move.

Production of Artificial Fog in the PAVIN Fog and Rain Platform: In Search of Big Droplets Fog

In fog, visibility is reduced. This reduction in visibility is measured by the meteorological optical range (MOR), which is important for studying human perception and various sensors in foggy conditions. The Cerema PAVIN Fog & Rain platform is capable of producing calibrated fog in order to better analyses it and understand its consequences. The problem is that the droplets produced by the platform are not large enough to resemble real fog. This can have a major impact on measurements since the interaction between electromagnetic waves and fog depends on the wavelength and diameter of the droplets. To remedy this, Cerema is building a new platform with new equipment capable of generating fog. This study analyses different nozzles and associated usage parameters such as the type of water used and the pressure used. The aim is to select the best nozzle with the associated parameters for producing large-diameter droplets and therefore more realistic fog.

Triboelectric‘electrostatic tweezers'for manipulating droplets on lubricated slippery surfaces prepared by femtosecond laser processing

The use of‘Electrostatic tweezers'is a promising tool for droplet manipulation,but it faces many limitations in manipulating droplets on superhydrophobic surfaces.Here,we achieve noncontact and multifunctional droplet manipulation on Nepenthes-inspired lubricated slippery surfaces via triboelectric electrostatic tweezers(TETs).The TET manipulation of droplets on a slippery surface has many advantages over electrostatic droplet manipulation on a superhydrophobic surface.The electrostatic field induces the redistribution of the charges inside the neutral droplet,which causes the triboelectric charged rod to drive the droplet to move forward under the electrostatic force.Positively or negatively charged droplets can also be driven by TET based on electrostatic attraction and repulsion.TET enables us to manipulate droplets under diverse conditions,including anti-gravity climb,suspended droplets,corrosive liquids,low-surface-tension liquids(e.g.ethanol with a surface tension of 22.3 mN·m^(-1)),different droplet volumes(from 100 nl to 0.5 ml),passing through narrow slits,sliding over damaged areas,on various solid substrates,and even droplets in an enclosed system.Various droplet-related applications,such as motion guidance,motion switching,droplet-based microreactions,surface cleaning,surface defogging,liquid sorting,and cell labeling,can be easily achieved with TETs.

Effect of Free-fall Nozzle Channel Dispersion Angle on TC4 Discontinuous Droplets Pre-breakup in EIGA

The effect of the inlet gas pressure,supplementary gas pressure and nozzle channel dispersion angle on the pre-breakup behavior of Ti-6Al-4V(TC4)discontinuous droplets during EIGA was investigated by combining numerical simulation with experiments.The results show that the axial velocity at the recirculation zone before the stagnation location was first increased and decreased then increased significantly after the peak value,while the pressure of the recirculation zone increased with the increase in inlet pressure.With the supplementary pressure increasing,the velocity magnitude and range of the recirculation zone gradually decreased.As the dispersion angle of the nozzle channel increased,the pre-breakup efficiency of droplets gradually decreased,but the adhesion phenomenon of droplets on the inner wall surface of the nozzle channel(IWSNC)gradually weakened.Under the inlet pressure of 4 MPa,a supplementary pressure of 0.05 MPa,and the dispersion angle of 15°,the uniform and spherical TC4 powders with diameter of 70μm were prepared,which was consistent with the simulation results.The optimized process parameters is a balance between the size of the pre-atomized particles and the back-spraying and bonding phenomenons of droplets.

Lipid droplets imaging with three-photon microscopy

Lipid droplets(LDs)participate in many physiological processes,the abnormality of which will cause chronic diseases and pathologies such as diabetes and obesity.It is crucial to monitor the distribution of LDs at high spatial resolution and large depth.Herein,we carried three-photon imaging of LDs in fat liver.Owing to the large three-photon absorption cross-section of the luminogen named NAP-CF_(3)(1:67×10^(-79) cm^(6) s^(2)),three-photon fluorescence fat liver imaging reached the largest depth of 80μm.Fat liver diagnosis was successfully carried out with excellent performance,providing great potential for LDs-associated pathologies research.

Interaction of water droplets with pyrolyzing coal particles and tablets

The paper presents the experimental research findings for the patterns of collisions of water droplets with pressed tableted samples used as substrates and with small particles of a pyrolyzing solid fuel.Brown coal samples were used.Droplet-substrate interactions were studied when varying the droplet diameter in the range from 1 to 4 mm and velocity from 0.5 to 4 m/s.That corresponded to the Weber number range of 7-830.The coal tablet surface temperature was varied from 20 to 700℃.In the interactions of water droplets(0.7-1.5 mm in diameter,pre-collision velocity from 1 to 3 m/s)with coal particles(with a size of 0.2-1 mm,pre-collision velocity 0.7-2 m/s),the temperature of the latter was varied in the range of 330-480℃.The following regimes of the interaction of droplets with solid particles during chemical reactions and phase transformations were distinguished:spreading/agglomeration and break-up/separation.Differences in the characteristics of the interaction of water droplets with coal particles at varying temperatures were identified.Droplet-particle interaction regime maps for B(We),We(Oh)and We(Ca)were constructed.The collision regime boundaries were described using fitted curves that can be utilized to develop the existing mathematical models of droplet-particle collisions in gas.It was established that the gaseous volatile production in coal pyrolysis has a modest effect on the regimes and characteristics of the droplet destruction in the temperature range under consideration(20-700℃).

Simulation on deposition and solidification processes of 7075 Al alloy droplets in 3D printing technology

In order to study the successive deposition and solidification processes of uniform alloy droplets during the drop-on-demand three dimensional（3D） printing method,based on the volume of fluid（VOF） method,a 3D numerical model was employed.In this model,the 7075 alloy with larger temperature range for phase change was used.The simulation results show that the successive deposition and solidification processes of uniform 7075 alloy droplets can be well characterized by this model.Simulated droplets shapes agree well with SEM images under the same condition.The effects of deposition and solidification of droplets result in vertical and L-shaped ridges on the surface of droplets,and tips of dendrites appear near the overlap of droplets due to rapid solidification.

Rapid velocity reduction and drift potential assessment of off-nozzle pesticide droplets

The droplet velocity and diameter significantly affect both the spatial drift loss and the interfacial deposition behaviors, thus determining the ultimate utilization efficiency during pesticide spraying.Investigating the spatial velocity and diameter evolutions can reveal the mechanism of drift loss and guide to design regulation strategy. Here, we explored the spatial velocity distribution of droplets after leaving the nozzle by particle image velocimetry technology and particle tracking model, considering that the effect of nozzle configuration and the air velocity. It shows that all droplets decelerate rapidly with the velocity attenuation ratio ranging from 50% to 80% within the region of 200 mm below the nozzle.The spatial velocity evolution differences between droplets in crossflow are determined by the competition of vertical drag force and net gravity, and the drag force sharply increases as the droplet diameter decreases, especially for that smaller than 150 μm. Based on the spatial evolution differences of the droplet velocity and diameter, a functional adjuvant was added to the liquid for improving the diameter distribution. And the drift loss was significantly reduced due to the reduction of the proportion of easily drifting droplets.

Numerical Simulation of Water Droplets Deposition on the Last-Stage Stationary Blade of Steam Turbine

Based on the method of discrete phase, the law of droplets’ deposition in the last stage stationary blade of a supercritical 600 MW Steam Turbine is simulated in the first place of this paper by using the Wet-steam model in commercial software FLUENT, where the influence of inlet angle of water droplets of the stationary blades is also considered. Through the calculation, the relationship between the deposition and the diameter of water droplets is revealed. Then, the amount of droplets deposition in the suction and pressure surface is derived. The result is compared with experimental data and it proves that the numerical simulation result obtained in this paper is reasonable. Finally, a formula of the relationship between the diameter of water droplets and the inlet angle is fit, which could be used for approximate calculation in the engineering applications.

The influence of charge characteristics of suspension droplets on the ion flow field in different temperatures and humidity

In order to clarify the charging characteristics of suspension droplets in ion flow field under different temperatures and humidity,the effective charging factor used to characterize the charging characteristics of suspension droplets is introduced in this paper,and a calculation method of charging factor is proposed based on the upstream finite element method(FEM).Then,the charging factor under different temperatures and humidity is calculated,and the analytic expression of the charging factor considering the influence of temperature and humidity is obtained by fitting the calculation results.The influence of suspension droplets on the ion flow field is analyzed.The results show that the charging factor is small and increases little with the relative humidity when the relative humidity is less than 60%,and the charging factor is large and increases rapidly with the relative humidity when the relative humidity is more than 60%.At the same relative humidity,the charging factor increases linearly with the temperature.The influence of charged suspension droplets on the ion flow field can be ignored when the relative humidity is less than 60%and must be considered under high temperature and humidity.The calculation method and analytic expression of the charging factor proposed in this paper can be used to model of ion flow field considering the influence of temperature and humidity and provide technical support for the construction of HVDC transmission lines across high temperature and humidity.

Effect of testicular capsulotomy on lipid droplets in the seminiferous tubules of rats

Aim: In order to reveal the histochemical alteration that might occur during the processes of the spermatogenic dis-ruption induced by testicular capsulotomy, the location and alteration of lipid droplets in the seminiferous tubules wereobserved in the present study. Methods: Osmium tetroxide was used to demonstrate the lipid droplets in the semi-niferous tubules of capsulotomized and sham-operated control testes. Results: In the seminiferous tubules of thesham-operated rat testes, many small lipid droplets were located close to the basement membrane of the seminiferoustubules. But for the capsulotomized testes, the lipid droplets in the seminiferous tubules had increased in size and num-ber, with many lipid droplets migrated towards the lumen of the tubules. Conclusion: The results indicated that aprogressive fatty degeneration occurred in the seminiferous tubules after testicular capsulotomy.

Lipid droplets as metabolic determinants for stemness and chemoresistance in cancer

Previously regarded as simple fat storage particles,new evidence suggests thatlipid droplets(LDs)are dynamic and functional organelles involved in keycellular processes such as membrane biosynthesis,lipid metabolism,cellsignalling and inflammation.Indeed,an increased LD content is one of the mostapparent features resulting from lipid metabolism reprogramming necessary tosupport the basic functions of cancer cells.LDs have been associated to differentcellular processes involved in cancer progression and aggressiveness,such astumorigenicity,invasion and metastasis,as well as chemoresistance.Interestingly,all of these processes are controlled by a subpopulation of highly aggressivetumoral cells named cancer stem cells(CSCs),suggesting that LDs may befundamental elements for stemness in cancer.Considering the key role of CSCs onchemoresistance and disease relapse,main factors of therapy failure,the design ofnovel therapeutic approaches targeting these cells may be the only chance forlong-term survival in cancer patients.In this sense,their biology and functionalproperties render LDs excellent candidates for target discovery and design ofcombined therapeutic strategies.In this review,we summarise the currentknowledge identifying LDs and CSCs as main contributors to cancer aggressiveness,metastasis and chemoresistance.

Anti-lipid droplets accumulation effect of Annona montana(mountain soursop)leaves extract on differentiation of preadipocytes

The Annona genus is a member of Annonaceae,one of the largest families of plants across tropical and subtropical regions.This family has been used in several ethnomedicinal practices to treat a multitude of human diseases.However,the molecular mechanism underlying its effect on the lipid droplet formation and on the expression of adipogenic markers of this plant remain to be investigated.In this study,we examined whether the extracts from the aerial part of Annona montana affect in vitro differentiation of preadipocytes.For our investigations,both mouse embryo fibroblast 3T3-L1 and normal human primary subcutaneous preadipocytes were incubated with Annona montana extracts(-and its subfractions-)and then analyzed on preadipocyte differentiation,lipid content,lipid droplet size and number,the expression of adipogenic-specific transcriptional factors,as well as cell survival.From our examinations,we found the Annona montana ethyl acetate extract to exhibit a potent inhibitory effect on adipogenesis,without affecting cell survival,in a dose-dependent manner.Such inhibitory effects included a significant decrease in the accumulation of lipid content by both a dramatic reduction of size and number of lipid droplets.This extract strongly attenuated the expression of PPARγand HMGB2.It also inhibited the expression of CEBPα,FAS,and Akt without influencing Erk1/2 activities.Our findings suggest that specifically,the Annona montana ethyl acetate extract has a prominent inhibitory effect in cellular pathways of adipocyte differentiation by modulating specific gene expression,which is known to perform a pivotal role during adipogenesis.

Equilibrium morphology of gas–liquid Janus droplets: A numerical analysis of buoyancy effect

In this article, a theoretical model for predicting the equilibrium morphology of gas–liquid Janus droplets was built. Based on this model, the effects of bubble radius and volume ratio on morphology change was systematically studied. The increase of bubble radius causes the two parts(bubble and oil drop) in Janus droplets tend to merge while the impact of volume ratio is complicated. When volume ratio increases, these two parts firstly tend to merge, then gradually separate. The accuracy of this model was verified by experimental results.

Measurement of Concentration of Sorbent Particles and Water Droplets in Hydration Desulfurization Reactor with PIV

Vortexing limestone injection into furnace combined with calcium lime hydration in the downstream is the most promising technology for controlling SO 2 emission. Particle imaging velocimetry (PIV) is used to measure the gas liquid solid three phase flow field in a reactor. By image processing based on newly developed software, the number concentrations of sorbent particles and water droplets are presented. The measuring results are very helpful for better understanding the desulfurization mechanism and optimizing configurational and operational parameters in the hydration reactor.

Droplets diameter distribution using maximum entropy formulation combined with a new energy-based sub-model

The maximum entropy principle(MEP) is one of the first methods which have been used to predict droplet size and velocity distributions of liquid sprays. This method needs a mean droplets diameter as an input to predict the droplet size distribution. This paper presents a new sub-model based on the deterministic aspects of liquid atomization process independent of the experimental data to provide the mean droplets diameter for using in the maximum entropy formulation(MEF). For this purpose, a theoretical model based on the approach of energy conservation law entitled energy-based model(EBM) is presented. Based on this approach, atomization occurs due to the kinetic energy loss. Prediction of the combined model(MEF/EBM) is in good agreement with the available experimental data. The energy-based model can be used as a fast and reliable enough model to obtain a good estimation of the mean droplets diameter of a spray and the combined model(MEF/EBM) can be used to well predict the droplet size distribution at the primary breakup.

Molecular Dynamics Simulation of Behaviours of Non-Polar Droplets Merging and Interactions with Hydrophobic Surfaces

This paper presents a molecular dynamics simulation of the behaviours of non-polar droplets merging and also the fluid molecules interacting with a hydrophobic surface. Such behaviours and transport phenomena are popular in general microchannel flow boiling and two-phase flow. The droplets are assumed to be composed of Lennards-Jones type molecules. Periodic boundary conditions are applied in three coordinate directions of a 3-D system, where there exist two liquid droplets and their vapour. The two droplets merge when they come within the prescribed small distance. The merging of two droplets apart from each other at different initial distances is tested and the possible larger （or critical） non-dimensional distance, in which droplets merging can occur, is discussed. The evolution of the merging process is simulated numerically by employing the Molecular Dynamics （MD） method. For interactions with hydrophobic solid wall, a system with fluid confined between two walls is used to study the wetting phenomena of fluid and solid wall. The results are compared with those of hydrophilic wall to show the unique characteristics of hydrophobic interactions by microscopic methods.

Nonlinear effects of line tension in adhesion of small droplets

Three-phase line tensions may become crucial in the adhesion of miero-nano or small droplets on solid planes. In this paper we study for the first time the nonlinear effects in adhesion spanning the full range of physically possible parameters of surface tension, line tension, and droplet size. It is shown that the nonlinear adhesion solution spaces can be characterized into four regions. Within each region the adhesion behaves essentially the same. Especially, inside the characteristic regions with violent nonlinearities, the co-existence of multiple adhesion states for given materials is disclosed. Besides, two common fixed points in the solution space are revealed. These new results are consistent with numerical analysis and experimental observations reported in the literatures.

Numerical simulation of two droplets impacting upon a dynamic liquid film

The impact of droplets on the liquid film is widely involved in industrial and agricultural fields.In recent years,plenty of works are limited to dry walls or stationary liquid films,and the research of multi-droplet impact dynamic films is not sufficient.Based on this,this paper employs a coupled level set and volume of fluid(CLSVOF) method to numerically simulate two-droplet impingement on a dynamic liquid film.In our work,the dynamic film thickness,horizontal central distance between the droplets,droplets’ initial impact speed,and simultaneously the flow velocity of the moving film are analyzed.The evolution phenomenon and mechanism caused by the collision are analyzed in detail.We find that within a certain period of time,the droplet spacing does not affect the peripheral crown height;when the droplet spacing decreases or the initial impact velocity increases,the height of the peripheral crown increases at the beginning,and then,because the crown splashed under Rayleigh-Plateau instability,this results in the reduction of the crown height.At the same time,it is found that when the initial impact velocity increases,the angle between the upstream peripheral jet and the dynamic film becomes larger.The more obvious the horizontal movement characteristics,the more restrained the crown height;the spread length increases with the increase of the dynamic film speed,droplet spacing and the initial impact velocity.When the liquid film is thicker,more fluid enters the crown,due to the crown being unstable,the surface tension is not enough to overcome the weight of the rim at the end of the crown,resulting in droplets falling off.