Is it possible to stabilize the hexaazabenzene cyclic system?

1987 ◽  
Vol 36 (7) ◽  
pp. 1552-1552
Author(s):  
E. G. Gal'pern ◽  
I. V. Stankevich ◽  
A. L. Chistyakov ◽  
V. B. Shur ◽  
M. E. Vol'pin
Keyword(s):  
Cyclic System

scholarly journals A Biologically Active Insulin Analog with an Enlarged Intrachain Cyclic System

1973 ◽  
Vol 248 (21) ◽  
pp. 7304-7309
Author(s):  
Alexandros Cosmatos ◽  
Panayotis G. Katsoyannis
Keyword(s):  
Biologically Active ◽  
Insulin Analog ◽  
Cyclic System

Mathematics and beauty: Time-discrete phase planes associated with the cyclic system, (t) = −f(y(t)), ẏ(t) = f(x(t))}

1987 ◽  
Vol 11 (2) ◽  
pp. 217-226 ◽  
Author(s):  
Clifford A. Pickover
Keyword(s):  
Cyclic System ◽  
Discrete Phase

A fundamental study of CO2 capture and CH4 production in a rapid cyclic system using nickel-lithium-silicate as a catal-sorbent

Fuel ◽  
2021 ◽  
pp. 122602
Author(s):  
Seongbin Jo ◽  
Jong Heon Lee ◽  
Tae Young Kim ◽  
Jin Hyeok Woo ◽  
Ho-Jung Ryu ◽  
...  
Keyword(s):  
Co2 Capture ◽  
Lithium Silicate ◽  
Fundamental Study ◽  
Cyclic System ◽  
Ch4 Production

scholarly journals Versatility of the Cyano Group in Intermolecular Interactions

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4495
Author(s):  
Steve Scheiner
Keyword(s):  
Intermolecular Interactions ◽  
Lewis Acid ◽  
Electrostatic Potential ◽  
Cyano Group ◽  
Acid Molecule ◽  
Cyclic System ◽  
Precise Nature ◽  
Noncovalent Bond ◽  
Positive Region ◽  
Cyano Groups

Several cyano groups are added to an alkane, alkene, and alkyne group so as to construct a Lewis acid molecule with a positive region of electrostatic potential in the area adjoining these substituents. Although each individual cyano group produces only a weak π-hole, when two or more such groups are properly situated, they can pool their π-holes into one much more intense positive region that is located midway between them. A NH3 base is attracted to this site, where it forms a strong noncovalent bond to the Lewis acid, amounting to as much as 13.6 kcal/mol. The precise nature of the bonding varies a bit from one complex to the next but typically contains a tetrel bond to the C atoms of the cyano groups or the C atoms of the linkage connecting the C≡N substituents. The placement of the cyano groups on a cyclic system like cyclopropane or cyclobutane has a mild weakening effect upon the binding. Although F is comparable to C≡N in terms of electron-withdrawing power, the replacement of cyano by F substituents substantially weakens the binding with NH3.

scholarly journals SUSTAINABILITY VALUE CHAIN IN BIOECONOMICS

2020 ◽  
Vol 18 (Suppl.1) ◽  
pp. 614-618
Author(s):  
N. Penev ◽  
Y. Andreev
Keyword(s):  
Value Chain ◽  
Renewable Resources ◽  
Fossil Fuels ◽  
Value Chains ◽  
Processing Industry ◽  
Cyclic System ◽  
Microbiological Processes ◽  
Sustainable Value ◽  
Textile Industries ◽  
Processed Products

The concept of bioeconomics covers all sectors of the economy, including agriculture, which supplies renewable resources: plants, animals, microorganisms and their processed products. The goal is a transition to an economy that is independent of fossil fuels and non-renewable resources. Agriculture and forestry, fisheries and aquaculture, as well as the conversion of biotechnological biomass and biological waste, are central to the multilateral new value chain. The processing industry uses renewable resources in various products, in particular, due to the industrial application of biotechnological and microbiological processes, especially in the chemical industry. This also applies to the food, woodworking, paper, construction, leather, and textile industries, as well as parts of the pharmaceutical and energy industries. Thus, the cyclic system and the storage of reusable waste are also included in the bioeconomic system. The aim of our study is to study the degree of development of sustainable value chains in bioeconomics.

scholarly journals V Plenum of the Central Bureau of the Medical Section

1929 ◽  
Vol 25 (2) ◽  
pp. 241-243
Author(s):  
A. Ya. Pleschitser
Keyword(s):  
Complex System ◽  
Central Bureau ◽  
Obstetrics And Gynecology ◽  
Advanced Training ◽  
Cyclic System ◽  
Medical Section ◽  
Leningrad Institute ◽  
Near Future ◽  
First Time

On January 10-15 with. For the first time the reports of the institutes for advanced training of doctors (Leningrad and Kazan) were heard in the Plenum of Ts. B. for the first time. In both in-tah the cyclic system is practiced, however in its content it differs from each other. The cyclic system of the Kazan Institute is a complex system of a number of disciplines (internal diseases, nervous, physical, children's make up a therapeutic cycle, surgery, obstetrics and gynecology and orthopedics a surgical cycle, and an eye cycle). Listening to the subjects of these cycles is mandatory for students during the semester, only a bias in one discipline or another is allowed. The cycles at the Leningrad Institute cover a number of courses in one discipline: a separate cycle of internal diseases, a cycle of nervous diseases, etc .; a visiting physician has the opportunity to freely define himself for two cycles at his own discretion. The debate on this issue revealed that each of these systems has its own advantages and the regulations adopted on the reports will preserve these systems for the near future. The proposal to unify systems for both institutes did not meet with support.

The crystal and molecular structure of 4-Bromo-1,1,3,3,5,7,7,9,9-nonamethylbicyclo[4,4,0]pentaborophane

1975 ◽  
Vol 28 (6) ◽  
pp. 1187 ◽  
Author(s):  
GR Clark ◽  
GJ Palenik
Keyword(s):  
Molecular Structure ◽  
Bond Length ◽  
Crystal And Molecular Structure ◽  
Bromine Atom ◽  
Chair Conformation ◽  
Ring System ◽  
Intensity Data ◽  
Internal Ring ◽  
Charge Delocalization ◽  
Cyclic System

Crystals of 4-bromo-1,1,3,3,5,7,7,9,9- nonamethylbicyclo[4,4,0]pentaborophane, C9H35B5P5Br, are monoclinic, with a = 9.502(3), b = 20.185(15), c = 13.604(4) Ǻ, β = 116.49(2)�. The space group is P21/c, with four molecules in the cell. Intensity data were collected by means of an automated diffractometer. The atomic positions have been determined by least-squares refinement of 2859 observed reflections. The final residual, R, is 0.077. The molecule contains a framework of alternat- ing boron and phosphorus atoms constituting a decalin-like ring system. The two cis-fused cyclo- hexane type rings are both in the chair conformation. The bromine atom is equatorially bonded to the boron atom in the 4-position. The Br-B bond length is 2.039(10) Ǻ. The average P-B and P-C distances are 1.943 and 1.828 Ǻ respectively. Average internal ring angles are 112.2� for P-B-P, and 113.6� for B-P-B. This geometry indicates only very slight charge delocalization in the cyclic system.

Photosystem I-abhängige Phosphorylierung isolierter Chloroplasten mit Ascorbat/2.6-Dichlorphenolindophenol als Elektronendonator und Methylviologen als Elektronenakzeptor / Photosystem I Dependent Phosphorylation of Isolated Chloroplasts with Ascorbate/2,6-Dichlorophenolindophenol as Electron Donor and Methylviologen as Electron Acceptor

1972 ◽  
Vol 27 (4) ◽  
pp. 445-455 ◽  
Author(s):  
Heinrich Strotmann ◽  
Christa Von Gösseln
Keyword(s):  
Electron Transport ◽  
Linear System ◽  
Photosystem I ◽  
Electron Acceptor ◽  
Electron Flow ◽  
Phosphorylation Site ◽  
Cyclic System ◽  
Atp Production ◽  
Proton Uptake ◽  
Isolated Chloroplasts

Photosystem I related phosphorylation of isolated chloroplasts was investigated with special reference to the stoichiometry between ATP production and electron transprt (ATP: 2e⊖). The system studied contained DCMU to inhibit electron flow from photosystem II, ascorbate and DPIP to supply electrons to photosystem I, and methylviologen as electron acceptor. The following results were obtained:1. Basal electron transport is stimulated by the addition of the phosphorylating system, indicating that phosphorylation is really coupled to non-cyclic electron flow. The ratio ATP: 2e⊖ is 1, when the increase of electron flow obtained by the addition of ADP and phosphate is correlated to phosphorylation. This ratio is constant upon varying several parameters including DPIP concentration and light intensity.2. In the absence of methylviologen a DPIP catalyzed cyclic phosphorylation takes place (cf. I. c.7, 11, 12). Phosphorylation is not increased by the addition of methylviologen, indicating that both, the cyclic DPIP mediated and the non-cyclic system are coupled to the same phosphorylation site and limited by the same reaction step.3. In the absence of oxygen a methylviologen supported cyclic phosphorylation occurs. Comparing optimum rates, phosphorylation under these conditions is about twice as high as in the noncyclic system. Therefore we conclude that two phosphorylation sites are involved in methylviologen catalyzed cyclic electron transport. This system is sensitive against trypsin treatment of the chloroplasts, whereas the linear system is not.4. The two cyclic systems as well as the non-cyclic system are coupled to reversible proton uptake. Furthermore the linear system exhibits an irreversible uptake of hydrogen ions, which is stoichiometric to electron flow. From the reversible and the irreversible components of the pH changes the ratio of the proton pump to electron transprt can be calculated. Under steady state conditions the ration H⨁ : e⊖ approaches 1.

ChemInform Abstract: Synthesis of a Cyclic System from a Linear Azatriquinane by Three Cascade Radical Cyclizations

ChemInform ◽  
2010 ◽  
Vol 25 (2) ◽  
pp. no-no
Author(s):  
D. BOATE ◽  
C. FONTAINE ◽  
E. GUITTET ◽  
L. STELLA
Keyword(s):  
Radical Cyclizations ◽  
Cyclic System

On strongly decreasing solutions of cyclic systems of second-order nonlinear differential equations

2015 ◽  
Vol 145 (5) ◽  
pp. 1007-1028 ◽  
Author(s):  
Jaroslav Jaroš ◽  
Kusano Takaŝi
Keyword(s):  
Differential Equations ◽  
Asymptotic Behaviour ◽  
Nonlinear Differential Equations ◽  
Radial Symmetry ◽  
Second Order ◽  
Accurate Information ◽  
Regularly Varying Functions ◽  
Cyclic System ◽  
Regularly Varying ◽  
Image Position

The n-dimensional cyclic system of second-order nonlinear differential equationsis analysed in the framework of regular variation. Under the assumption that αi and βi are positive constants such that α1 … αn > β1 … βn and pi and qi are regularly varying functions, it is shown that the situation in which the system possesses decreasing regularly varying solutions of negative indices can be completely characterized, and moreover that the asymptotic behaviour of such solutions is governed by a unique formula describing their order of decay precisely. Examples are presented to demonstrate that the main results for the system can be applied effectively to some classes of partial differential equations with radial symmetry to provide new accurate information about the existence and the asymptotic behaviour of their radial positive strongly decreasing solutions.

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