Copper-catalyzed [2+3]-annulation of N–H imines with vinyl azides: access to polyaryl 2H-imidazoles

2020 ◽  
Vol 56 (42) ◽  
pp. 5621-5624
Author(s):  
Zhongzhi Zhu ◽  
Hanze Lin ◽  
Baihui Liang ◽  
Junjie Huang ◽  
Wanyi Liang ◽  
...  
Keyword(s):  
Vinyl Azides ◽  
By Products

A copper-catalyzed [2+3] annulation of N–H imines with vinyl azides to generate polyaryl 2H-imidazoles with N2 and H2O as the only by-products has been developed.

Hydrogen Cyanide Polymers from the Impact of Comet P/Shoemaker-Levy 9 on Jupiter

1997 ◽  
Vol 161 ◽  
pp. 179-187
Author(s):  
Clifford N. Matthews ◽  
Rose A. Pesce-Rodriguez ◽  
Shirley A. Liebman
Keyword(s):  
Amino Acids ◽  
Solar System ◽  
Hydrogen Cyanide ◽  
Nitrogen Heterocycles ◽  
Laboratory Studies ◽  
Heterogeneous Solids ◽  
The Many ◽  
Comet Halley ◽  
The Impact ◽  
By Products

AbstractHydrogen cyanide polymers – heterogeneous solids ranging in color from yellow to orange to brown to black – may be among the organic macromolecules most readily formed within the Solar System. The non-volatile black crust of comet Halley, for example, as well as the extensive orangebrown streaks in the atmosphere of Jupiter, might consist largely of such polymers synthesized from HCN formed by photolysis of methane and ammonia, the color observed depending on the concentration of HCN involved. Laboratory studies of these ubiquitous compounds point to the presence of polyamidine structures synthesized directly from hydrogen cyanide. These would be converted by water to polypeptides which can be further hydrolyzed to α-amino acids. Black polymers and multimers with conjugated ladder structures derived from HCN could also be formed and might well be the source of the many nitrogen heterocycles, adenine included, observed after pyrolysis. The dark brown color arising from the impacts of comet P/Shoemaker-Levy 9 on Jupiter might therefore be mainly caused by the presence of HCN polymers, whether originally present, deposited by the impactor or synthesized directly from HCN. Spectroscopic detection of these predicted macromolecules and their hydrolytic and pyrolytic by-products would strengthen significantly the hypothesis that cyanide polymerization is a preferred pathway for prebiotic and extraterrestrial chemistry.

Bright-Field Images (Ctem) of Phase Objects at High Resolution

1976 ◽  
Vol 34 ◽  
pp. 490-491 ◽  
Author(s):  
Sumio Iijima
Keyword(s):  
High Resolution ◽  
Electron Beam Irradiation ◽  
Fine Particles ◽  
High Resolution Electron Microscopy ◽  
Good Test ◽  
Resolution Electron ◽  
Single Crystal Films ◽  
Crystal Films ◽  
By Products ◽  
Test Objects

We have developed a technique to prepare thin single crystal films of graphite for use as supporting films for high resolution electron microscopy. As we showed elsewhere (1), these films are completely noiseless and therefore can be used in the observation of phase objects by CTEM, such as single atoms or molecules as a means for overcoming the difficulties because of the background noise which appears with amorphous carbon supporting films, even though they are prepared so as to be less than 20Å thick. Since the graphite films are thinned by reaction with WO3 crystals under electron beam irradiation in the microscope, some small crystallites of WC or WC2 are inevitably left on the films as by-products. These particles are usually found to be over 10-20Å diameter but very fine particles are also formed on the film and these can serve as good test objects for studying the image formation of phase objects.

On the rational use of slaughter by-products in sausage production

2020 ◽  
Vol 3 (1) ◽  
pp. 20-25
Author(s):  
A.I. Zharinov ◽  
O.V. Kuznetsova ◽  
L.A. Tekutieva
Keyword(s):  
Rational Use ◽  
By Products

A history of some fruit models in wax and other materials: scientific teaching aids and courtly table decorations

2003 ◽  
Vol 30 (2) ◽  
pp. 299-316 ◽  
Author(s):  
Hans-JüRgen Lechtreck
Keyword(s):  
Nineteenth Century ◽  
Fruit Trees ◽  
Visual Aids ◽  
Early Nineteenth Century ◽  
Teaching Aids ◽  
Scientific Teaching ◽  
Glass Marble ◽  
History Of ◽  
By Products ◽  
Wax Models

Two early nineteenth century texts treating the production and use of wax models of fruit reveal the history of these objects in the context of courtly decoration. Both sources emphasise the models' decorative qualities and their suitability for display, properties which were not simply by-products of the realism that the use of wax allowed. Thus, such models were not regarded merely as visual aids for educational purposes. The artists who created them sought to entice collectors of art and natural history objects, as well as teachers and scientists. Wax models of fruits are known to have been collected and displayed as early as the seventeenth century, although only one such collection is extant. Before the early nineteenth century models of fruits made from wax or other materials (glass, marble, faience) were considered worthy of display because contemporaries attached great importance to mastery of the cultivation and grafting of fruit trees. This skill could only be demonstrated by actually showing the fruits themselves. Therefore, wax models made before the early nineteenth century may also be regarded as attempts to preserve natural products beyond the point of decay.

Valorisation of by-Products/Waste of Agro-Food Industry by the Pyrolysis Process

2016 ◽  
Vol 3 (1) ◽  
pp. 1-11 ◽  
Author(s):  
D. Fino ◽  
◽  
Y.S. Camacho ◽  
S Bensaid ◽  
B. Ruggeri ◽  
...  
Keyword(s):  
Food Industry ◽  
Pyrolysis Process ◽  
By Products
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