A method to calculate the surface tension of a cylindrical droplet

The history of Laplace's equations for spherical and cylindrical droplets and the concept of dividing surface in Gibbs' thermodynamic theory of capillary phenomena are briefly reviewed. The existing theories of surface tensions of cylindrical droplets are briefly reviewed too. For cylindrical droplets, a new method to calculate the radius and the surface tension of the surface of tension is given. This method is suitable to be used by molecular dynamics simulations.

Experimental study of Electro-elasto-capillarity:Electric field driven unwrapping of water drop with elastic film

<正>Elasto-capillarity has drawn much of scientists' attention in the past several years.By inducing electric field into the droplet,the encapsulation and release procedure can be realized and we call it electro-elasto-capillarity(EEC).EEC offers a novel method for micro-scale actuation and self-assemble of moveable devices.It also provides a good candidate for the drug delivery at micro- or nanoscale.

Droplet Image Feedback Control System in Evaporation Experiment

In order to realize the steady-state droplet evaporation, image feedback control system is designed based on DSP. The system has three main functions: to capture and store droplet images during the experiment; to calculate droplet geometrical and physical parameters such as volume, surface area, surface tension and evaporation velocity at a high-precision level; to keep the droplet volume constant. The DSP can drive an injection controller with the PID control to inject liquid so as to keep the droplet volume constant. The evaporation velocity of droplet can be calculated by measuring the injected volume during the evaporation. The structure of hardware and software of the control system, key processing methods such as contour fitting and experimental results are described.

Individual dispersion of synthetic imogolite nanotubes via droplet evaporation

Morphology of synthetic imogolite nanotubes formed in droplet evaporation was investigated by transmission electron microscopy and electron diffraction. The nanotubes form a dense entangled network at higher concentrations, while at lower concentrations the nanotubes are liable to form oriented bundles. Under enthanol atmosphere, individual dispersion of nanotubes was observed for the first time, which reveals the length polydispersity of synthetic imogolite nanotubes.

The influencing factors on the macroporous formation in polymer films by water droplet templating

Regular micrometer-size porous polystyrene film is prepared by water droplet templating, i.e. breath figures are stabilized by the polymer in solution and thermocapillary flow arranges them into ordered packing. The influences of polystyrene molecular weight, solvent properties, and the relative humidity of atmosphere on the pattern formation and hole sizes are investigated. Two different kinds of hole packing fashion are also observed and their formation mechanisms are discussed.

Ordered droplet formation by thin polymer film dewetting on a stripe-patterned substrate

The dewetting process of thin polystyrene (PS) film on flat and stripe-patterned substrates is presented. Different dewetting processes were observed when the thin PS films annealed at above the glass transition temperature on these different kinds of substrates. The final dewetting on the flat substrate led to formation of polygonal liquid droplets, while on the stripe-patterned substrate, the droplets were observed to align at the centers of the stripes. A possible explanation for the dewetting process on the stripe-patterned substrate is proposed.

Remote electricity actuation and monitoring mote

This work presents the design and evaluation of the REAM (Remote Electricity Actuation and Monitoring) node based around the modular Tyndall Mote platform. The REAM node enables the user to remotely actuate power to a mains power extension board while sampling the current, voltage, power and power factor of the attached load. The node contains a current transformer interfaced to an Energy Metering IC which continuously samples current and voltage. These values are periodically read from the part by a PIC24 microcontroller, which calculates the RMS current and voltage, power factor and overall power. The resultant values can then be queried wirelessly employing the Tyndall 802.15.4 compliant wireless module.

Effect of biodiesel oil composition on droplet size distribution

Droplet size distribution of biodiesel oil with various compositions was investigated in this work. The droplets generated by a two-fluid atomizer were measured by a commercial PDA. It was found that viscosity of the fuel has a strong effect on the drop size distribution. Additionally, effect of air injection pressures applied to atomize the spray was taken into account. Shear force induced by flow field exerts an effect on distribution of biodiesel droplets in atomized spray.

Error recovery in cyberphysical digital microfluidic biochips

Droplet-based digital microfluidics technology has now come of age, and software-controlled biochips for healthcare applications are starting to emerge. However, today's digital microfluidic biochips suffer from the drawback that there is no feedback to the control software from the underlying hardware platform. Due to the lack of precision inherent in biochemical experiments, errors are likely during droplet manipulation; error recovery based on the repetition of experiments leads to wastage of expensive reagents and hard-to-prepare samples. By exploiting recent advances in the integration of optical detectors (sensors) into a digital microfluidics biochip, we present a physical-aware system reconfiguration technique that uses sensor data at intermediate checkpoints to dynamically reconfigure the biochip. A cyberphysical resynthesis technique is used to recompute electrode-actuation sequences, thereby deriving new schedules, module placement, and droplet routing pathways, with minimum impact on the time-to-response. © 2012 IEEE.

Chlamydia trachomatis Infection Leads to Defined Alterations to the Lipid Droplet Proteome in Epithelial Cells.

The obligate intracellular bacterium Chlamydia trachomatis is a major human pathogen and a main cause of genital and ocular diseases. During its intracellular cycle, C. trachomatis replicates inside a membrane-bound vacuole termed an "inclusion". Acquisition of lipids (and other nutrients) from the host cell is a critical step in chlamydial replication. Lipid droplets (LD) are ubiquitous, ER-derived neutral lipid-rich storage organelles surrounded by a phospholipids monolayer and associated proteins. Previous studies have shown that LDs accumulate at the periphery of, and eventually translocate into, the chlamydial inclusion. These observations point out to Chlamydia-mediated manipulation of LDs in infected cells, which may impact the function and thereby the protein composition of these organelles. By means of a label-free quantitative mass spectrometry approach we found that the LD proteome is modified in the context of C. trachomatis infection. We determined that LDs isolated from C. trachomatis-infected cells were enriched in proteins related to lipid metabolism, biosynthesis and LD-specific functions. Interestingly, consistent with the observation that LDs intimately associate with the inclusion, a subset of inclusion membrane proteins co-purified with LD protein extracts. Finally, genetic ablation of LDs negatively affected generation of C. trachomatis infectious progeny, consistent with a role for LD biogenesis in optimal chlamydial growth.

Mechanism of motion of an optical fiber aligned by a solder droplet

Solder is often used as an adhesive to attach optical fibers to a circuit board. In this proceeding we will discuss efforts to model the motion of an optical fiber during the wetting and solidification of the adhesive solder droplet. The extent of motion is determined by several competing forces, during three “stages” of solder joint formation. First, capillary forces of the liquid phase control the fiber position. Second, during solidification, the presence of the liquid-solid-vapor triple line as well as a reduced liquid solder volume leads to a change in the net capillary force on the optical fiber. Finally, the solidification front itself impinges on the fiber. Publicly-available finite element models are used to calculate the time-dependent position of the solidification front and shape of the free surface.

Modelling electromagnetically levitated liquid droplet oscillations

This work comprises accurate computational analysis of levitated liquid droplet oscillations in AC and DC magnetic fields. The AC magnetic field interacting with the induced electric current within the liquid metal droplet generates intense fluid flow and the coupled free surface oscillations. The pseudo-spectral technique is used to solve the turbulent fluid flow equations for the continuously dynamically transformed axisymmetric fluid volume. The volume electromagnetic force distribution is updated with the shape and position change. We start with the ideal fluid test case for undamped Rayleigh frequency oscillations in the absence of gravity, and then add the viscous and the DC magnetic field damping. The oscillation frequency spectra are further analysed for droplets levitated against gravity in AC and DC magnetic fields at various combinations. In the extreme case electrically poorly conducting, diamagnetic droplet (water) levitation dynamics are simulated. Applications are aimed at pure electromagnetic material processing techniques and the material properties measurements in uncontaminated conditions.