Use Of Glass Capillaries Research Articles

Design of an ELC resonator-based reusable RF microfluidic sensor for blood glucose estimation

Design of a reusable microfluidic sensor for blood glucose estimation at microwave frequencies is presented. The sensing unit primarily comprises a complementary electric LC (CELC) resonator, which is made reusable by filling the test sample in a glass capillary before mounting it inside a groove cut in the central arm of the resonator. The use of glass capillary in the present situation to contain the blood sample actually eliminates the possibility of any direct contact of the sensor with the test sample, and hence wards off any coincidental contamination of the sensor. Usage of the capillary provides additional benefits as only microliters of the sample are required, besides offering sterile measuring environment since these capillaries are disposable. The capillary made of borosilicate glass is highly biocompatible and exhibits exceptionally high chemical resistance in corrosive environments. Apart from reusability, the novelty of the proposed sensor also lies in its enhanced sensitivity which is quite an essential factor when it comes to the measurement of glucose concentration in the human physiological range. The applicability of the proposed scheme for glucose sensing is demonstrated by performing RF measurements of aqueous glucose solutions and goat blood samples using the fabricated sensor.

Use of glass capillaries to suppress thermal convection in NMR tubes in diffusion measurements.

Diffusion ordered spectroscopy (DOSY) is used to determine the translational diffusion coefficients of molecules in solution. However, DOSY is highly susceptible to spurious spectral peaks resulting from thermal convection occurring in the NMR tube. Thermal convection therefore must be suppressed for accurate estimation of translational diffusion coefficients. In this study, we developed a new method to effectively suppress thermal convection using glass capillaries. A total of 6 to 18 capillaries (0.8-mm outer diameter) were inserted into a regular 5-mm NMR tube. The capillaries had minimal effect on magnetic field homogeneity and enabled us to obtain clean DOSY spectra of a mixture of small organic compounds. Moreover, the capillaries did not affect chemical shifts or signal intensities in two-dimensional heteronuclear single quantum coherence spectra. Capillaries are a simple and inexpensive means of suppressing thermal convection and thus can be used in a wide variety of DOSY experiments. Copyright © 2016 John Wiley & Sons, Ltd.

Microfluidic PMMA interfaces for rectangular glass capillaries

We present the design and fabrication of a polymeric capillary fluidic interface fabricated by micro-milling. The design enables the use of glass capillaries with any kind of cross-section in complex microfluidic setups. We demonstrate two different designs of the interface; a double-inlet interface for hydrodynamic focusing and a capillary interface with integrated pneumatic valves. Both capillary interfaces are presented together with examples of practical applications. This communication shows the design optimization and presents details of the fabrication process. The capillary interface opens up for the use of complex microfluidic systems in single-use glass capillaries. They also enable simple fabrication of glass/polymer hybrid devices that can be beneficial in many research fields where a pure polymer chip negatively affects the device's performance, e.g. acoustofluidics.

Study of the effect of cerium nitrate on AA2024-T3 by means of electrochemical micro-cell technique

► We evaluate the cerium nitrate effect on the electrochemical behavior of AA2024-T3. ► We examine how AA2024-T3 microstructure affects cerium precipitation mechanism. ► The entire AA2024-T3 surface is involved in cerium precipitation. ► Anodic and cathodic inhibitions are both provided by cerium precipitation. ► Mg-rich intermetallics are preferential sites for cerium precipitation. This work evaluates the effect of cerium nitrate as corrosion inhibitor for AA2024-T3 in the view of its introduction in sol–gel coatings able to provide self-healing ability. Since it is well established that deposition of Ce species is activated by the local pH increase, the objective of this paper is to investigate the behavior of AA2024-T3 (open circuit potential and polarization curves) in the presence of Ce species in aggressive solutions by means of a local technique, the electrochemical micro-cell. This technique enables the investigation of small areas with resolution in the micrometer range by the use of glass capillaries to define the working electrode area. The micro-cell results clearly displayed that the entire AA2024-T3 area exposed to the cerium-containing electrolyte was involved in the cerium precipitation mechanism. The heterogeneous electrochemical behavior of the microstructure is minimized by the formation of a cerium-containing layer able to protect the metal substrate.

VIABILIDADE DE FOLÍCULOS PRÉ-ANTRAIS BOVINOS ISOLADOS DE OVÁRIOS APÓS VITRIFICAÇÃO

The aim of this study was to evaluate isolated bovine preantral follicles after vitrification procedure. Ovaries were obtained at a local slaughterhouse and submitted to follicular isolation. From the obtained suspension, one part was destined to control group. The remaining suspension was divided into two parts, one to the toxicity test and the other one to the vitrification procedure. For vitrification, the follicles were exposed for 1 min to vitrification solution-1, composed of 10% ethylene glycol, 10% DMSO in saline solution (NaCl 0.9%), and then 1 min to vitrification solution-2, composed of 20% ethylene glycol, 20% DMSO in the same saline solution supplemented with 0.5 M sucrose. The follicles were vitrified by use of glass capillaries and remained vitrified for 24 h. After warming, they were transferred to a 0.25 M sucrose solution for 5 min and then transferred to a 0.15 M sucrose solution for another 5 min. For the toxicity test, the follicles were only exposed to cryoprotectants and analised. The preantral follicles were classified as non-viable orviable when they were stained or not stained by trypan blue, respectively. Differences (P<0.05) in follicular viability were observed among the control, non-vitrified group (93.6%), and exposed (64.1%) or vitrified follicles (66%). The percentages of normal follicles found after exposure to cryoprotectant did not differ significantly (P>0.05) from that found after vitrification, indicating that the reduction of percentage of viable preantral follicles was due to a toxic effect of cryoprotectants and not to the vitrification procedure itself.KEYWORDS: bovine; cryoprotectants; oocytes; vitrification.

Advantageous Use of Glass Capillaries as Primary Optics for X-Ray Residual Stress Analyses and a Novel Concept for “Micro Diffraction” Stress Analysis

The use of glass capillaries as primary optics for X-ray diffraction equipment and especially for X-ray stress analyses is frequently discussed as possibility to achieve a small irradiated area for investigations of micro systems and a reasonably high X-ray intensity in order to keep the measuring time within reasonable limits. These aims, however, can generally not be reached to a satisfying extent due to physical and experimental obstacles. The major drawbacks are the limited brilliancy of the available X-ray tubes and the large divergence of the X-ray beam exiting conventional cylindrical capillaries. A novel concept of X-ray capillary is presented which allows an efficient variation of the X-ray spot size on the sample and enables to reduce the irradiated area down to few 10 μm, even when using conventional X-ray tubes. At the same time, the presented capillaries offer a more than one order of magnitude higher intensity than conventional capillaries delivering comparable spot sizes.

Use of Glass Capillaries Avoids the Time Changes in High Blood Po2 Observed With Plastic Syringes

In adults, arterial blood samples are usually drawn using plastic syringes. In contrast to glass syringes, plastic syringes let oxygen diffuse through their wall. This results in PO(2) changes during storage, especially when PO(2) is high. An alternative to glass syringes is the Microsampler (Roche Diagnostics; Schaffhausen, Switzerland), a commercially available device consisting of a heparinized glass capillary fitted with a 26-gauge needle and used to collect arterial blood in the same way as a plastic syringe fitted with a needle. We evaluated the performance of the Roche Microsampler for storing arterial blood in view of PO(2) measurement, comparatively with glass and plastic syringes. Five approximate initial PO(2) levels (650, 400, 200, 130, and 80 mm Hg) and two storage temperatures (ambient temperature and 4 degrees C) were studied. Bench study. Plastic syringes allowed reliable measurement of PO(2) values when initial PO(2) was too low to ensure complete hemoglobin oxygen saturation, but were associated with time-dependent underestimation of PO(2) at higher initial PO(2) values. No such underestimation occurred with the Roche Microsampler stored at 4 degrees C for up to 1 h for all PO(2) levels studied. The Roche Microsamplers appeared to be reliable devices in preventing oxygen diffusion.

An improved DSC glass sample container technique

A simple method has been developed for the use of glass capillaries in DSC. The metal block holder used by previous workers was found to be unnecessary. It was found that different positions of the glass capillary in the cell or long term use of the same baseline do not affect the DSC curves for the same samples. The experimental results for NH 4NO 3 and an organic dye show significant differences between a standard aluminum pan and the glass capillary due to the interference of volatilization from the aluminum pan.

Methods and techniques of gas chromatography with glass capillary columns

After a general introduction on the advantages and special requirements of gas chromatography in glass capillaries the methods of preparing and testing thin film capillaries are described to an extent not convered in the authors' previous paper. By means of a series of chromatograms of typical artificial and genuine samples it is shown that the use of glass capillaries of variable length and with various stationary liquids does not present technical or methodical difficulties. With regard to temperature stability there is no difference in performance between packed and glass capillary columns. Moreover the preparation of glass capillary columns is easy, their separation efficiency is much better and the tailing behaviour is often superior in comparison with packed columns.

Use of Glass Capillaries as Critical Orifices

Use of Glass Capillaries as Critical Orifices