Flexible Capillary Tube Research Articles

Cylindrical Confinement of Nanocolloidal Cholesteric Liquid Crystal.

The organization of nanocolloidal liquid crystals in constrained geometries has fundamental and practical importance, since under confinement, liquid crystals contain stable topological defects that can serve as templates for nanoparticle organization. Three-dimensional confinement of cholesteric (Ch) liquid crystals formed by cellulose nanocrystals (CNCs) have been extensively studied; however, their two-dimensional confinement remains under-investigated. Here, we report the results of systematic experimental studies of two-dimensional confinement of Ch-CNC liquid crystal in cylindrical capillaries with varying inner diameters. Confinement resulted in phase separation of the Ch-CNC liquid crystal into a Ch shell formed by concentric CNC pseudolayers with the helicoidal axis perpendicular to the inner surface of the capillary walls, and a micrometer-diameter isotropic core thread running parallel to the long axis of the capillary. The morphology of the confined Ch-CNC liquid crystal varied when progressively increasing the degree confinement. Finally, we show that phase separation of the Ch-CNC liquid crystal into a Ch shell and an isotropic core is preserved in flexible capillary tubing, suggesting the applicability of this system for the fabrication of flexible optical waveguides.

Cryogenic Oscillating Heat Pipe for Conduction-Cooled Superconducting Magnets

The cryogenic oscillating heat pipe (OHP) is considered as a convenient thermal link between the crycooler head and the superconducting magnet due to the employment of flexible capillary tube. In this paper, a cryogenic OHP using nitrogen as the working fluid is fabricated. The copper blocks connecting with the evaporator of the cryogenic OHP are used as a mock-up superconducting magnet, and a heating sheet is attached on the copper blocks to simulate the heat generation of the superconducting magnet system during the operation process. The cooling down processes and the operation characteristics of the cryogenic OHP at the different condenser temperature are investigated. The results show that the cryogenic OHP has not only large cooling capacity during the cooling down process, but also excellent heat transfer performance during the operation process.

A modular approach for the generation, storage, mixing, and detection of droplet libraries for high throughput screening

The desire to make microfluidic technology more accessible to the biological research community has led to the notion of "modular microfluidics", where users can build a fluidic system using a toolkit of building blocks. This paper applies a modular approach for performing droplet-based screening, including the four integral steps of library generation, storage, mixing, and optical interrogation. Commercially available cross-junctions are used for drop generation, flexible capillary tubing for storage, and tee-junctions for serial mixing. Optical interrogation of the drops is achieved using fiber-optic detection modules which can be incorporated inline at one or more points in the system. Modularity enables the user to hand-assemble systems for functional assays or applications. Three examples are shown: (1) a "mix and read" assay commonly used in high throughput screening (HTS); (2) generation of chemically distinct droplets using microfractionation in droplets (microFD); and (3) in situ encapsulation and culture of eukaryotes. Using components with IDs ranging from 150 microm to 1.5 mm, this approach can accommodate drop assays with volumes ranging from 2 nL to 2 microL, and storage densities ranging from 300 to 3000 drops per metre tubing. Generation rates are up to 200 drops per second and merging rates are up to 10 drops per second. The impact of length scale, carrier fluid viscosity, and flow rates on system performance is considered theoretically and illustratively using 2D CFD simulations. Due to its flexibility, the widespread availability of components, and some favorable material properties compared to PDMS, this approach can be a useful part of a researcher's toolkit for prototyping droplet-based assays.

Noise levels during nCPAP are flow-dependent but not device-dependent

Objective:Nasal continuous positive airway pressure (nCPAP) has been shown to improve the outcome of infants with respiratory distress syndrome. However, noise generation could be of concern. Therefore, our study was...

Molar mass of dry air in mass metrology

Since 1980, the different national metrology institutes use the same procedure and formula for air density determination. The formula employed assumes some hypotheses on the composition of dry air and is expressed in terms of its molar mass and the four environmental parameters: air pressure, air temperature and concentrations of carbon dioxide and water vapour. In this formula (known as CIPM-1981/91) recommended by the Comité International des Poids et Mesures, the mole fraction of argon is fixed at 9.17 × 10 −3. This value is now questioned and new measurements involving different techniques are of great interest. This paper describes the experimental set-up used to evaluate the concentration of argon relative to that of nitrogen contained in air sampled from mass laboratory. The method uses a flexible capillary tube, maintained at constant temperature, for gas admission. With this system, air from different samples of atmospheric air is introduced into the vacuum chamber to be analysed. Preliminary measurements show that the value of P p ( Ar ) / P p ( N 2 ) is closer to 1.196 × 10 −2, given in some publications, than the value of 1.174 × 10 −2, used in the current method for air density determination. In the future, comparison between argon and oxygen concentration will allow a more precise measurement with regard to the existing values.

Lactulose breath testing, bacterial overgrowth, and IBS: just a lot of hot air?

Lactulose breath testing, bacterial overgrowth, and IBS: just a lot of hot air?

Capillary Impactor with Optical Detection in Collection of Carbonaceous Particles

A new single-orifice capillary system for optical analysis of carbonaceous matter is reported. The special feature of this system is the use of long, flexible capillary tubing for sampling.

Thermometer for measuring body temperature in hypothermia.

To meet the need for a rugged, easily read thermometer having a flexible probe, a relatively simple instrument has been devised and tested. It consists of a thermistor that rapidly changes in electrical resistance with small changes in temperature, a source of current, and a device to measure the flow of current that is calibrated in such a way as to read temperature directly. It is designed to operate linearly in the range in which experimental and clinical work in hypothermia is involved, 20 C (68 F) to 41 C (105 F). For a discussion of other types of instruments for measuring temperature, the review by Burton1may be consulted. The apparatus described by Weiss and Ripstein,2which is useful for continuous recording, has the disadvantage of depending on a flexible capillary tube that may break or change its characteristics on continued bending. The temperature-sensitive thermistor element is