Vapour phase reactions and the duhem-Margules equation (with some reference to nitric acid)

1954 ◽  
Vol 50 ◽  
pp. 352
Author(s):  
P. A. H. Wyatt
Keyword(s):  
Nitric Acid ◽  
Vapour Phase ◽  
Margules Equation

Electrical properties and phase transformations of graphite nitrates

1968 ◽  
Vol 304 (1476) ◽  
pp. 25-43 ◽  
Keyword(s):  
Nitric Acid ◽  
Phase Transformations ◽  
Electric Power ◽  
Structural Model ◽  
Hysteresis Loops ◽  
Vapour Phase ◽  
Thermo Electric ◽  
Resistivity Measurements ◽  
Electrical Conductivities ◽  
Nitrate Anions

Methods are described for converting pieces of well alined graphite into nitrates of the first and second sequences, using vapour-phase nitration. In general, the more highly pinned starting materials require a higher threshold vapour pressure of nitric acid, before onset of conversion to the nitrates. Measurements of electrical resistivity and of thermo-electric power in the a -axis direction have been made over a range of temperatures, including temperature cycles around the λ point. Electronically, the solid nitrates of both first and second sequences behave as good p -conductors, in accordance with a structural model in which carbon hexagon networks act as macro-cations, with intercalations of nitrate anions, and of molecules of nitric acid. Resistivity measurements down to about 64 °K show that the well ordered graphite nitrates below the λ point have electrical conductivities and temperature coefficients of conductivity comparable with natural elemental conductors such as silver or copper. Resistivity data and thermo-electric power (t. e. p.) measurements both reveal novel features about the order–disorder transformation taking place around –20 °C. Definite hysteresis is found, and details of the hysteresis loops depend on the original texture of the specimen of near-ideal graphite used, as well as on nitration procedures. Furthermore, a large positive excess t. e. p. is observed at the λ peak, flanked by premonitory effects extending on either side of it. Both the hysteresis and the excess t. e. p. at the λ point are interpreted in terms of a general theory of phase transformations, which involve intermediate hybrid structures, with domains of the two forms coexistent in the λ region of temperatures.

Ectodesmata as Revealed By Freeze-Etch Preparations of Plant Epidermal Cell Walls

1973 ◽  
Vol 31 ◽  
pp. 468-469
Author(s):  
N.C. Lyon ◽  
W. C. Mueller
Keyword(s):  
Electron Microscopy ◽  
Acetic Acid ◽  
Nitric Acid ◽  
Oxalic Acid ◽  
Light Microscopy ◽  
Epidermal Cell ◽  
Cell Walls ◽  
Plant Viruses ◽  
Plant Leaves ◽  
Thin Sections

Schumacher and Halbsguth first demonstrated ectodesmata as pores or channels in the epidermal cell walls in haustoria of Cuscuta odorata L. by light microscopy in tissues fixed in a sublimate fixative (30% ethyl alcohol, 30 ml:glacial acetic acid, 10 ml: 65% nitric acid, 1 ml: 40% formaldehyde, 5 ml: oxalic acid, 2 g: mecuric chloride to saturation 2-3 g). Other workers have published electron micrographs of structures transversing the outer epidermal cell in thin sections of plant leaves that have been interpreted as ectodesmata. Such structures are evident following treatment with Hg++ or Ag+ salts and are only rarely observed by electron microscopy. If ectodesmata exist without such treatment, and are not artefacts, they would afford natural pathways of entry for applied foliar solutions and plant viruses.

Characterization of GaAs/AlGaAs quantum wells and quantum wires by chemical lattice imaging

1994 ◽  
Vol 52 ◽  
pp. 736-737
Author(s):  
A. Carlsson ◽  
J.-O. Malm ◽  
A. Gustafsson
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Quantum Wires ◽  
Vapour Phase ◽  
Quantitative Information ◽  
Lattice Imaging ◽  
Vapour Phase Epitaxy ◽  
Metalorganic Vapour Phase Epitaxy ◽  
High Resolution Images

In this study a quantum well/quantum wire (QW/QWR) structure grown on a grating of V-grooves has been characterized by a technique related to chemical lattice imaging. This technique makes it possible to extract quantitative information from high resolution images.The QW/QWR structure was grown on a GaAs substrate patterned with a grating of V-grooves. The growth rate was approximately three monolayers per second without growth interruption at the interfaces. On this substrate a barrier of nominally Al0.35 Ga0.65 As was deposited to a thickness of approximately 300 nm using metalorganic vapour phase epitaxy . On top of the Al0.35Ga0.65As barrier a 3.5 nm GaAs quantum well was deposited and to conclude the structure an additional approximate 300 nm Al0.35Ga0.65 As was deposited. The GaAs QW deposited in this manner turns out to be significantly thicker at the bottom of the grooves giving a QWR running along the grooves. During the growth of the barriers an approximately 30 nm wide Ga-rich region is formed at the bottom of the grooves giving a Ga-rich stripe extending from the bottom of each groove to the surface.

The Action of Nitric Acid on Aluminium

1916 ◽  
Vol 82 (2122supp) ◽  
pp. 150-150
Author(s):  
R. Seligman ◽  
P. Williams
Keyword(s):  
Nitric Acid
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