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Glass Capillaries (glass + capillary)

Distribution by Scientific Domains

Chemistry	45%
Polymers and Materials Science	36%
Life Sciences	18%

Selected Abstracts

Formation of Arrayed Droplets by Soft Lithography and Two-Phase Fluid Flow, and Application in Protein Crystallization,

ADVANCED MATERIALS, Issue 15 2004
B. Zheng
Abstract This paper presents an overview of our recent work on the use of soft lithography and two-phase fluid flow to form arrays of droplets. The crucial issues in the formation of stable arrays of droplets and alternating droplets of two sets of aqueous solutions include the geometry of the microchannels, the capillary number, and the water fraction of the system. Glass capillaries could be coupled to the PDMS microchannels and droplets could be transferred into glass capillaries for long-term storage. The arrays of droplets have been applied to screen the conditions for protein crystallization with microbatch and vapor diffusion techniques. [source]

Fabrication of Microbeads with a Controllable Hollow Interior and Porous Wall Using a Capillary Fluidic Device

ADVANCED FUNCTIONAL MATERIALS, Issue 18 2009
Sung-Wook Choi
Abstract Poly(D,L -lactide-co-glycolide) (PLGA) microbeads with a hollow interior and porous wall are prepared using a simple fluidic device fabricated with PVC tubes, glass capillaries, and a needle. Using the fluidic device with three flow channels, uniform water-in-oil-in-water (W-O-W) emulsions with a single inner water droplet can be achieved with controllable dimensions by varying the flow rate of each phase. The resultant W-O-W emulsions evolve into PLGA microbeads with a hollow interior and porous wall after the organic solvent in the middle oil phase evaporates. Two approaches are employed for developing a porous structure in the wall: emulsion templating and fast solvent evaporation. For emulsion templating, a homogenized, water-in-oil (W/O) emulsion is introduced as the middle phase instead of the pure oil phase. Low-molecular-weight fluorescein isothiocyanate (FITC) and high-molecular-weight fluorescein isothiocyanate,dextran conjugate (FITC,DEX) is added to the inner water phase to elucidate both the pore size and their interconnectivity in the wall of the microbeads. From optical fluorescence microscopy and scanning electron microscopy images, it is confirmed that the emulsion-templated microbeads (W-W/O-W) have larger and better interconnected pores than the W-O-W microbeads. These microstructured microbeads can potentially be employed for cell encapsulation and tissue engineering, as well as protection of active agents. [source]

Formation of Arrayed Droplets by Soft Lithography and Two-Phase Fluid Flow, and Application in Protein Crystallization,

Micro-injection of lygus salivary gland proteins to simulate feeding damage in alfalfa and cotton flowers ,

ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2005
Kenneth A. Shackel
Abstract Alfalfa and cotton flowers were pierced with small glass capillaries of an overall size and shape similar to that of Lygus stylets, and injected with small quantities (6 to 100 nL) of solutions that contained Lygus salivary enzymes. Crude and partially purified protein solutions from Lygus heads and isolated salivary glands showed substantial polygalacturonase (PG) activity, as has been previously reported. Following injection with both crude and partially purified protein solutions, as well as with pure fungal and bacterial PGs, flowers of both alfalfa and cotton exhibited damage similar to that caused by Lygus feeding. Injection with the same volume of a buffer control as well as a buffer control containing BSA at a comparable protein concentration (approximately 6 ,g/mL) showed no symptoms. These results are consistent with a previously suggested hypothesis that the extensive tissue damage caused by Lygus feeding is primarily due to the action of the PG enzyme on the host tissue, rather than to mechanical damage caused by the insect stylet. Substantial genotypic variation for a PG inhibiting protein (PGIP) exists in alfalfa and cotton. We, therefore, suggest that breeding and selection for increased native PGIP levels, or transformation with genes encoding PGIP from other plant species, may be of value in obtaining alfalfa and cotton varieties that are more resistant to Lygus feeding damage. Arch. Insect Biochem. Physiol. 58:69,83, 2005. © 2005 Wiley-Liss, Inc. [source]

Platinum Nanoelectrodes Embedded in an Insulating Alumina Matrix: An Innovative Approach,

CHEMICAL VAPOR DEPOSITION, Issue 4 2005
A. Battiston
A novel strategy, based on MOCVD, has been employed for preparation of ensembles of platinum nanoelectrodes. Pt/Al2O3 films with different Pt loading were deposited in just one step on glass capillaries. Nanocomposite films with varying Pt/Al atomic ratios were investigated by both cyclic voltammetry and TEM. Ensembles of nanoelectrodes with either overlap or no overlap of the diffusion layers of each nanoelectrode are obtained, depending on the Pt loading. From TEM measurements average Pt particle size of 3 , 7 nm was determined (Figure). [source]

Fabrication of Nanoelectrodes and Metal Clusters by Electrodeposition

CHEMPHYSCHEM, Issue 13 2010
Jeyavel Velmurugan
Abstract Most nanometer-sized electrodes reported to date are made from either Pt or Au. For technical reasons, it is difficult to make nanoelectrodes from many other metals (e.g. Hg) by heat-sealing microwires into glass capillaries or by other established techniques. Such nanoelectrodes can be useful for a wide range of analytical and physicochemical applications from high sensitivity stripping analysis (Hg) to pH nano-sensors to studies of electrocatalysis. In this paper, nanometer-sized metal electrodes are prepared by electrodeposition of Hg or Pt on disk-type, polished or recessed nanoelectrodes. The deposition of Hg is monitored chronoamperometrically to produce near-hemispherical electrodes, which are characterized by voltammetry and scanning electrochemical microscopy (SECM). The well-shaped deposits of a solid metal (Pt) at Au nanoelectrodes are prepared and imaged by scanning electron microscopy (SEM). Catalytic metal clusters can also be prepared using this methodology. Electrodes with the metal surface flush with glass insulator, most suitable for quantitative voltammetric and SECM experiments are fabricated by electrodeposition of a metal inside an etched nanocavity. [source]

Tissue-specific mechanical microdissection of higher plants

PHYSIOLOGIA PLANTARUM, Issue 3 2006
Marco Thome
Higher plants are multicellular organisms, which exhibit a high degree of differentiation with respect to their anatomy, metabolism and gene expression. Analysing entire plants or organs results in an average of information of all tissues and cells included in the sample. In this way neither physiological processes nor gene expression can be attributed to particular tissues. For revealing the contributions of specific tissues to the overall metabolism and the gene expression, highly spatially resoluted cell sampling is a prerequisite. Here, mechanical microdissection (MMD), a low cost and easy to handle alternative to existing sampling techniques (e.g. laser-assisted microdissection or glass capillary,based sampling) was tested on several plant species (Arabidopsis thaliana L., Cucurbita maxima Duch., Hordeum vulgare L. and Pelargonium hybrid cultivar ,Graveolens'). The applicability and potential of MMD for separating tissues from different organs of these plants was demonstrated. Furthermore, A. thaliana samples were, as examples, tested for their RNA quality by reverse transcription,PCR and for tissue specificity by amplifying messenger RNA of tissue marker genes. [source]

Accurate mass measurement in nano-electrospray ionization mass spectrometry by alternate switching of high voltage between sample and reference sprayers

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 4 2005
Yoshinori Satomi
An electrospray dual sprayer, which generates separate sample and reference sprays by alternately switching the high voltage between the two sprayers, is described. The technique permits accurate mass measurements in nano-electrospray ionization mass spectrometry (ESI-MS) to be obtained using a quadrupole/orthogonal acceleration time-of-flight mass spectrometer (Q-TOF). Similar to the method employed with a dual ESI source (Wolff JC et al., Anal. Chem. 2001; 73: 2605), the two sprays are orthogonal with respect to each other, but can be independently sampled without any baffle between these sprays. The reference sprayer is used in the original configuration of the ESI source and was optimized for a 1,2,,L/min flow, whereas the sample sprayer can be either a conventional glass capillary or a borosilicate tip of the type used for nano-ESI. Both sprayers can be positioned close to the cone so as to give maximum ion currents. The sample and reference sprays are independently generated by raising the potentials on the sample and reference sprayers to 1.4 and 3.0,kV, respectively; the high voltages can be rapidly turned on and off in ca. 1,ms. A nano-ESI-MS or nano-flow LC/ESI-MS experiment using a Q-TOF coupled with the above system gave mass accuracies within 3,ppm for measurements of ions up to m/z 1000 using subpicomole samples. Copyright © 2005 John Wiley & Sons, Ltd. [source]

A combined ion source for fast switching between electrospray and matrix-assisted laser desorption/ionization in Fourier transform ion cyclotron resonance mass spectrometry

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 17 2002
Gökhan Baykut
A new ion source has been developed for Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) that enables quick changes between matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) modes. When operating as an ESI source, the sample solution is sprayed through an angled nebulizer. The generated ions pass through a glass capillary followed by a skimmer and three sequential hexapole ion guides. Ions can be accumulated in the third hexapole (storage hexapole) before they are injected into the ICR trap. The second hexapole is mounted on a movable platform which also carries the MALDI sample plate. During the switch from ESI to MALDI, this platform moves the second hexapole out of the hexapole series and locates a MALDI sample plate with 384 sample positions into the area directly in front of the storage hexapole. The storage hexapole is in a medium pressure chamber (MPC) which has windows both for the incoming laser beam and for the observation optics, as well as a gas tube for pulsing collision gas into the chamber. During the MALDI operation the focused laser beam enters the MPC, passes between the hexapole rods and irradiates a MALDI sample on the target plate. The sample molecules are desorbed/ionized into the storage hexapole and simultaneously cooled by collisions with the pulsed gas. Ions desorbed from multiple laser shots can be accumulated in this hexapole before they are transferred to the ICR trap. With the combined ion source a computer-controlled switch between MALDI and ESI modes is possible in less than a minute, depending on the position of the MALDI target on the 384-spot plate. Immediate acquisition of mass spectra is possible after mode switching without the need for tuning or re-calibration. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Methodological aspects of in vitro sensing of L -glutamate in acute brain slices

THE CHEMICAL RECORD, Issue 6 2007
Masao Sugawara
Abstract L -Glutamate is a major amino acid neurotransmitter in the central neuronal system of the mammalian brain and plays a vital role in brain development, synaptic plasticity, neurotoxicity, and neuropathological disorders. Despite technical limitations, progress is being made in sensing L -glutamate in vivo and in vitro. Sophisticated microsensors with the necessary spatial and temporal resolution have recently been emerging, which enable us to discern regional distribution, concentration levels, and temporal changes of L -glutamate in acute brain slices. The L -glutamate sensors for in vitro sensing have different structures and sizes, such as glass capillary-based enzyme sensors, polymer-coated enzyme sensors, and patch sensors based on natural sensing probes. The concentration of L -glutamate released in brain slices by chemical stimulation is markedly dependent on neuronal regions, types of stimulation, and sensing methods. Real- and long-time monitoring of L -glutamate in acute hippocampal slices is beginning to shed light on L -glutamate release related to the molecular mechanisms of long-term potentiation. Progress is also being made toward the visualization of L -glutamate release in acute hippocampal slices. The methodological aspects of in vitro sensing of L -glutamate are discussed. © 2007 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 7: 317,325; 2007: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20126 [source]

Role of erythrocyte deformability during capillary wetting

BIOTECHNOLOGY & BIOENGINEERING, Issue 2 2006
Ronghui Zhou
Abstract Deformability of erythrocyte was found to fundamentally alter the wetting dynamics of red blood cell (RBC) suspensions during their invasion into capillaries. Normal RBC suspensions failed to penetrate more than 1 cm into a glass capillary when the capillary radius was smaller than a critical value that is dependent on the erythrocyte concentration (about 50 µm for whole blood). In contrast, suspensions of rigidified RBCs, after cross-linking with different concentrations of glutaraldehyde or incubating with 100 ng/mL of an endotoxin, could penetrate any capillary larger than the erythrocyte dimension. The effect of RBC deformability on penetration was attributed to the enhanced shear-induced migration of normal deformable RBCs toward the capillary centreline, which imparted a higher average velocity to the RBCs than the average plasma velocity. As a result, the erythrocytes advanced into the capillary faster than the wetting meniscus, packing behind it to form a concentrated slug. This tightly packed slug had a high hydrodynamic resistance that could arrest the penetrating flow of concentrated suspensions into the small capillaries. © 2005 Wiley Periodicals, Inc. [source]