Christopher Jeffree | University of Edinburgh (original) (raw)

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Papers by Christopher Jeffree

New Phytologist, 1993

Soluble polysaccharides, of natural and synthetic origins, are immobilized by nylon, nitrocellulo... more Soluble polysaccharides, of natural and synthetic origins, are immobilized by nylon, nitrocellulose, and polyvinylidene difluoride blotting membranes. Retention of an acid and a neutral polysaccharide, measured using radioactive pectin and xyloglucan-rich hemicellulose, exceeded 90% on some blotting membranes eluted in aqueous media. The two polysaccharides displayed different binding characteristics.Several polyanionic uronic acid polysaccharides, bound strongly to nylon 66 (Hybond N, Amersham) and to positively charge-modified or cationic nylon blotting membranes (Hybond N +, Amersham), but much less strongly to paper, nitrocellulose or polyvinylidene difluoride. Fragments of pectin, including Rhamnogalacturonan I and Rhamnogalacturonan II, and galacturonic acid oligosaccharides as small as the dimer also bind to nylon membranes, and can be detected using cationic dyes or by means of their radioactivity. Xyloglucan-rich hemicellulose in general binds more strongly than pectin to the same substrates. Of the substrates tested charge-modified nylon gave best retention of pectin, and paper gave best retention of xyloglucan during washes in water and solutions of salts, acids and bases.The influence of pH and solutions of mono, di- and trivalent salts on the retention of some pectic polysaccharides by nylon was investigated. A large proportion, in excess of 70% of pectin applied to charge-modified nylon, remained tightly bound at all salt concentrations up to 2 M.Soluble acid polysaccharides immobilized on blotting membranes could be detected by staining with cationic dyes, such as ruthenium red, alcian blue 8GX, and coriphosphine O, providing facile detection and a simple means of characterizing the cytochemical specificity of their staining reactions. Immobilized neutral polysaccharides, which do not react with cationic dyes, could usually be detected by the periodate-Schiff reaction, or, if labelled with radionuclides, by autoradiography or scintillation counting.Soluble polysaccharides, like proteins and nucleic acids, may therefore be immobilized on blotting membranes for investigation with cytochemical, immunocytochemical, and other molecular probing and detection procedures. Quantitative binding data showed marked differences in the affinity of different polysaccharides for blotting substrates. Detailed characterization of the binding behaviour is therefore a prerequisite for optimization and rational application of polysaccharide blotting.

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000

A new method for the preparation of cross sections for transmission electron microscopy using a f... more A new method for the preparation of cross sections for transmission electron microscopy using a focused ion beam workstation is presented. The new technique consists of micromachining a freestanding cantilever into which a membrane for transmission electron microscopy is milled. An advantage of this approach over the trench and lift out focused ion beam procedures for the preparation of cross sections for transmission electron microscopy is that the resulting cross sections can be both tilted through large angles ͑ϩ45°͒ without the electron path becoming obstructed and they can be returned to the focused ion beam system for further thinning.

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000

A new method for the preparation of cross sections for transmission electron microscopy using a f... more A new method for the preparation of cross sections for transmission electron microscopy using a focused ion beam workstation is presented. The new technique consists of micromachining a freestanding cantilever into which a membrane for transmission electron microscopy is milled. An advantage of this approach over the trench and lift out focused ion beam procedures for the preparation of cross sections for transmission electron microscopy is that the resulting cross sections can be both tilted through large angles ͑ϩ45°͒ without the electron path becoming obstructed and they can be returned to the focused ion beam system for further thinning.

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000

A new method for the preparation of cross sections for transmission electron microscopy using a f... more A new method for the preparation of cross sections for transmission electron microscopy using a focused ion beam workstation is presented. The new technique consists of micromachining a freestanding cantilever into which a membrane for transmission electron microscopy is milled. An advantage of this approach over the trench and lift out focused ion beam procedures for the preparation of cross sections for transmission electron microscopy is that the resulting cross sections can be both tilted through large angles ͑ϩ45°͒ without the electron path becoming obstructed and they can be returned to the focused ion beam system for further thinning.

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000

A new method for the preparation of cross sections for transmission electron microscopy using a f... more A new method for the preparation of cross sections for transmission electron microscopy using a focused ion beam workstation is presented. The new technique consists of micromachining a freestanding cantilever into which a membrane for transmission electron microscopy is milled. An advantage of this approach over the trench and lift out focused ion beam procedures for the preparation of cross sections for transmission electron microscopy is that the resulting cross sections can be both tilted through large angles ͑ϩ45°͒ without the electron path becoming obstructed and they can be returned to the focused ion beam system for further thinning.

Wear, 2008

Friction processes for ice on carbon-black filled styrene butadiene rubber have been investigated... more Friction processes for ice on carbon-black filled styrene butadiene rubber have been investigated by observing wear and debris morphology on wear surfaces using low temperature scanning electron microscopy (LT-SEM) and correlating the features with sliding velocity and temperature. Friction experiments were carried out over a velocity range of 0.003 m s −1 to 2.6 m s −1 and a temperature range of −33 • C to −0.5 • C and the results used to form a friction map. Observation of worn surfaces at high velocity showed melt films that result from frictional heating. At low velocities and low temperatures morphologies indicative of much drier contact were seen. At higher temperatures and low velocity there is evidence of liquid films that we propose arise from the salt content of the ice. High friction (μ ∼ 1) at low velocity and at temperatures around −25 • C was caused by the internal friction associated with the rubber glass transition.

Proceedings of The Institution of Mechanical Engineers Part L-journal of Materials-design and Applications, 2007

ABSTRACT Ice particles containing NaCl were made by spraying 0.043 M salt solution into liquid ni... more ABSTRACT Ice particles containing NaCl were made by spraying 0.043 M salt solution into liquid nitrogen. The ice particles were packed into capsules and annealed at -8 °C for 168 h and -25 °C for 20 h. This material can be considered as a model material for sintered snow containing impurities. The capsules were fractured open inside the low-temperature scanning electron microscope, which minimized the artefacts caused by cryofixation. The morphology of the sintered structure was observed with low-temperature scanning electron microscope. The microstructure of the sintered material consists of ice grains with a liquid meniscus containing NaCl between the grains. This structure is similar to the equilibrium morphology of water-filled veins in polycrystalline ice and liquid phase sintered metallic materials. The combined effect of the surface energies between the solid, liquid, and vapour governs the morphology of the microstructure. A dihedral angle where the brine intersects a grain boundary in ice of 8.0 ± 2.6°, and a contact angle for brine on ice at the interface with vapour of 5.0 ± 1.3° were measured, for samples quenched from -8 °C. Using the dihedral angle measurement, a surface energy value for ice-brine of 32.6 ± 0.1 mJ/m2 was calculated.

New Phytologist, 1993

Soluble polysaccharides, of natural and synthetic origins, are immobilized by nylon, nitrocellulo... more Soluble polysaccharides, of natural and synthetic origins, are immobilized by nylon, nitrocellulose, and polyvinylidene difluoride blotting membranes. Retention of an acid and a neutral polysaccharide, measured using radioactive pectin and xyloglucan-rich hemicellulose, exceeded 90% on some blotting membranes eluted in aqueous media. The two polysaccharides displayed different binding characteristics.Several polyanionic uronic acid polysaccharides, bound strongly to nylon 66 (Hybond N, Amersham) and to positively charge-modified or cationic nylon blotting membranes (Hybond N +, Amersham), but much less strongly to paper, nitrocellulose or polyvinylidene difluoride. Fragments of pectin, including Rhamnogalacturonan I and Rhamnogalacturonan II, and galacturonic acid oligosaccharides as small as the dimer also bind to nylon membranes, and can be detected using cationic dyes or by means of their radioactivity. Xyloglucan-rich hemicellulose in general binds more strongly than pectin to the same substrates. Of the substrates tested charge-modified nylon gave best retention of pectin, and paper gave best retention of xyloglucan during washes in water and solutions of salts, acids and bases.The influence of pH and solutions of mono, di- and trivalent salts on the retention of some pectic polysaccharides by nylon was investigated. A large proportion, in excess of 70% of pectin applied to charge-modified nylon, remained tightly bound at all salt concentrations up to 2 M.Soluble acid polysaccharides immobilized on blotting membranes could be detected by staining with cationic dyes, such as ruthenium red, alcian blue 8GX, and coriphosphine O, providing facile detection and a simple means of characterizing the cytochemical specificity of their staining reactions. Immobilized neutral polysaccharides, which do not react with cationic dyes, could usually be detected by the periodate-Schiff reaction, or, if labelled with radionuclides, by autoradiography or scintillation counting.Soluble polysaccharides, like proteins and nucleic acids, may therefore be immobilized on blotting membranes for investigation with cytochemical, immunocytochemical, and other molecular probing and detection procedures. Quantitative binding data showed marked differences in the affinity of different polysaccharides for blotting substrates. Detailed characterization of the binding behaviour is therefore a prerequisite for optimization and rational application of polysaccharide blotting.

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000

A new method for the preparation of cross sections for transmission electron microscopy using a f... more A new method for the preparation of cross sections for transmission electron microscopy using a focused ion beam workstation is presented. The new technique consists of micromachining a freestanding cantilever into which a membrane for transmission electron microscopy is milled. An advantage of this approach over the trench and lift out focused ion beam procedures for the preparation of cross sections for transmission electron microscopy is that the resulting cross sections can be both tilted through large angles ͑ϩ45°͒ without the electron path becoming obstructed and they can be returned to the focused ion beam system for further thinning.

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000

A new method for the preparation of cross sections for transmission electron microscopy using a f... more A new method for the preparation of cross sections for transmission electron microscopy using a focused ion beam workstation is presented. The new technique consists of micromachining a freestanding cantilever into which a membrane for transmission electron microscopy is milled. An advantage of this approach over the trench and lift out focused ion beam procedures for the preparation of cross sections for transmission electron microscopy is that the resulting cross sections can be both tilted through large angles ͑ϩ45°͒ without the electron path becoming obstructed and they can be returned to the focused ion beam system for further thinning.

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000

A new method for the preparation of cross sections for transmission electron microscopy using a f... more A new method for the preparation of cross sections for transmission electron microscopy using a focused ion beam workstation is presented. The new technique consists of micromachining a freestanding cantilever into which a membrane for transmission electron microscopy is milled. An advantage of this approach over the trench and lift out focused ion beam procedures for the preparation of cross sections for transmission electron microscopy is that the resulting cross sections can be both tilted through large angles ͑ϩ45°͒ without the electron path becoming obstructed and they can be returned to the focused ion beam system for further thinning.

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000

A new method for the preparation of cross sections for transmission electron microscopy using a f... more A new method for the preparation of cross sections for transmission electron microscopy using a focused ion beam workstation is presented. The new technique consists of micromachining a freestanding cantilever into which a membrane for transmission electron microscopy is milled. An advantage of this approach over the trench and lift out focused ion beam procedures for the preparation of cross sections for transmission electron microscopy is that the resulting cross sections can be both tilted through large angles ͑ϩ45°͒ without the electron path becoming obstructed and they can be returned to the focused ion beam system for further thinning.

Wear, 2008

Friction processes for ice on carbon-black filled styrene butadiene rubber have been investigated... more Friction processes for ice on carbon-black filled styrene butadiene rubber have been investigated by observing wear and debris morphology on wear surfaces using low temperature scanning electron microscopy (LT-SEM) and correlating the features with sliding velocity and temperature. Friction experiments were carried out over a velocity range of 0.003 m s −1 to 2.6 m s −1 and a temperature range of −33 • C to −0.5 • C and the results used to form a friction map. Observation of worn surfaces at high velocity showed melt films that result from frictional heating. At low velocities and low temperatures morphologies indicative of much drier contact were seen. At higher temperatures and low velocity there is evidence of liquid films that we propose arise from the salt content of the ice. High friction (μ ∼ 1) at low velocity and at temperatures around −25 • C was caused by the internal friction associated with the rubber glass transition.

Proceedings of The Institution of Mechanical Engineers Part L-journal of Materials-design and Applications, 2007

ABSTRACT Ice particles containing NaCl were made by spraying 0.043 M salt solution into liquid ni... more ABSTRACT Ice particles containing NaCl were made by spraying 0.043 M salt solution into liquid nitrogen. The ice particles were packed into capsules and annealed at -8 °C for 168 h and -25 °C for 20 h. This material can be considered as a model material for sintered snow containing impurities. The capsules were fractured open inside the low-temperature scanning electron microscope, which minimized the artefacts caused by cryofixation. The morphology of the sintered structure was observed with low-temperature scanning electron microscope. The microstructure of the sintered material consists of ice grains with a liquid meniscus containing NaCl between the grains. This structure is similar to the equilibrium morphology of water-filled veins in polycrystalline ice and liquid phase sintered metallic materials. The combined effect of the surface energies between the solid, liquid, and vapour governs the morphology of the microstructure. A dihedral angle where the brine intersects a grain boundary in ice of 8.0 ± 2.6°, and a contact angle for brine on ice at the interface with vapour of 5.0 ± 1.3° were measured, for samples quenched from -8 °C. Using the dihedral angle measurement, a surface energy value for ice-brine of 32.6 ± 0.1 mJ/m2 was calculated.