Catalyst modification by metal deposition: the deposition of silver on platinum at underpotential and overpotential

1978 ◽  
Vol 56 (15) ◽  
pp. 2029-2033 ◽  
Author(s):  
Remigio Germano Barradas ◽  
Stephen Fletcher ◽  
Sandor Szabo
Keyword(s):  
Platinum Catalysts ◽  
Metal Deposition ◽  
Electrode Kinetics ◽  
Simultaneous Formation ◽  
Platinum Oxides ◽  
Catalyst Modification

It is demonstrated that platinum catalysts can be modified by electrochemical means. The deposition of silver is described at both underpotential and overpotential. Although the deposition reactions can be quantified, the electrode kinetics cannot be investigated because of the simultaneous formation and reduction of platinum oxides.

The automation of electrode kinetics — II. The application to metal deposition

1980 ◽  
Vol 25 (5) ◽  
pp. 657-668 ◽  
Author(s):  
M. Aslam ◽  
J.A. Harrison ◽  
C.E. Small
Keyword(s):  
Metal Deposition ◽  
Electrode Kinetics

Chemical modification of the bacterial wall to determine sites of metal deposition

1978 ◽  
Vol 36 (2) ◽  
pp. 350-351
Author(s):  
T. J. Beveridge
Keyword(s):  
Electron Scattering ◽  
Metal Salt ◽  
Metal Deposition ◽  
Suitable Model ◽  
X Ray Diffraction ◽  
Subtilis Cell ◽  
Thin Sections ◽  
X Ray ◽  
Section Data ◽  
Metal Impregnation

The Bacillus subtilis cell wall provides a protective sacculus about the vital constituents of the bacterium and consists of a collection of anionic hetero- and homopolymers which are mainly polysaccharidic. We recently demonstrated that unfixed walls were able to trap and retain substantial amounts of metal when suspended in aqueous metal salt solutions. These walls were briefly mixed with low concentration metal solutions (5mM for 10 min at 22°C), were well washed with deionized distilled water, and the quantity of metal uptake (atomic absorption and X-ray fluorescence), the type of staining response (electron scattering profile of thin-sections), and the crystallinity of the deposition product (X-ray diffraction of embedded specimens) determined.Since most biological material possesses little electron scattering ability electron microscopists have been forced to depend on heavy metal impregnation of the specimen before obtaining thin-section data. Our experience with these walls suggested that they may provide a suitable model system with which to study the sites of reaction for this metal deposition.

SEM of non-coated hepatocellular cytoskeleton of perfused livers

1984 ◽  
Vol 42 ◽  
pp. 306-307
Author(s):  
S.W. French ◽  
N.C. Benson ◽  
C. Davis-Scibienski
Keyword(s):  
Ambient Temperature ◽  
Critical Point ◽  
Protease Inhibitors ◽  
Metal Deposition ◽  
Heat Damage ◽  
Detergent Extraction ◽  
Cytoskeletal Elements ◽  
Triton X ◽  
Excised Tissue

Previous SEM studies of liver cytoskeletal elements have encountered technical difficulties such as variable metal coating and heat damage which occurs during metal deposition. The majority of studies involving evaluation of the cell cytoskeleton have been limited to cells which could be isolated, maintained in culture as a monolayer and thus easily extracted. Detergent extraction of excised tissue by immersion has often been unsatisfactory beyond the depth of several cells. These disadvantages have been avoided in the present study. Whole C3H mouse livers were perfused in situ with 0.5% Triton X-100 in a modified Jahn's buffer including protease inhibitors. Perfusion was continued for 1 to 2 hours at ambient temperature. The liver was then perfused with a 2% buffered gluteraldehyde solution. Liver samples including spontaneous tumors were then maintained in buffered gluteraldehyde for 2 hours. Samples were processed for SEM and TEM using the modified thicarbohydrazide procedure of Malich and Wilson, cryofractured, and critical point dried (CPD). Some samples were mechanically fractured after CPD.

Divergent beam microanalysis studies of bimetallic platinum catalysts supported on γ-AL2O3

1995 ◽  
Vol 53 ◽  
pp. 428-429
Author(s):  
JR Fryer ◽  
Z Huang ◽  
D Stirling ◽  
G. Webb
Keyword(s):  
Dead Time ◽  
Platinum Catalysts ◽  
Beam Intensity ◽  
Beam Diameter ◽  
Divergent Beam ◽  
Bimetallic Systems ◽  
Reforming Catalyst ◽  
Before And After ◽  
Individual Particles

Platinum dispersed on γ-alumina is used as a reforming catalyst to convert linear hydrocarbons to cyclic aromatic products. To improve selectivity and lifetime of the catalyst, other elements are included, and we have studied the distributions of Pt/Re, and Pt/Sn, bimetallic systems on the support both before and after use in octane reforming. Often, one or both of the components are not resolvable by HREM or microanalysis as individual particles because of small size and lack of contrast on the alumina, and divergent beam microanalysis has been used to establish the presence and relationship between the two elements.In the majority of catalysts the platinum is in the form of small panicles, some of which are large enough to be resolvable in the microscope. The ABT002B microscope with Link windowless Pentafet detector, used in this work, was able to obtain a resolvable signal from particles of 2nm diameter upwards. When the beam was concentrated on to such a particle the signal was at a maximum, and as the beam diameter was diverged - at the same total beam intensity and dead time - the signal decreased as shown in Figure 1.

Integration of pure copper to optimize heat dissipation in injection mould inserts using laser metal deposition

2021 ◽  
Vol 33 (1) ◽  
pp. 012029
Author(s):  
Stefan Polenz ◽  
Christian Kolbe ◽  
Florian Bittner ◽  
Elena López ◽  
Frank Brückner ◽  
...  
Keyword(s):  
Heat Dissipation ◽  
Pure Copper ◽  
Metal Deposition ◽  
Laser Metal Deposition ◽  
Injection Mould
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