σ‐Hole Interactions of Tetrahedral Group IV–VIII Lewis Acid Centers with Lewis Bases: A Comparative Study

2021 ◽  
Vol 6 (43) ◽  
pp. 11856-11864
Author(s):  
Mahmoud A. A. Ibrahim ◽  
Yasmeen A. M. Mohamed ◽  
Hassan A. A. Abuelliel ◽  
Al‐shimaa S. M. Rady ◽  
Mahmoud E. S. Soliman ◽  
...  
1991 ◽  
Vol 2 (4) ◽  
pp. 675-681 ◽  
Author(s):  
E. V. Lunina ◽  
G. L. Markaryan ◽  
A. V. Fionov ◽  
A. V. Astashkin ◽  
R. I. Samoilova ◽  
...  

1999 ◽  
Vol 4 (1) ◽  
Author(s):  
SHEILA CANEVESE RAHAL ◽  
MANOEL ÁLVARO GUIMARÃES ◽  
JOSÉ VICENTE FORTES ◽  
HÉLIO LANGONI ◽  
PEDRO HELIO LUCCHIARI

"Linhas de pesca"* em diâmetros de 0,15mm; 0,20mm; 0,25mm; 0,30mm foram divididas em quatro grupos, contendo dez amostras de cada diâmetro: grupo I - controle; grupo II - linhas colocadas em frasco com pastilhas de formalina; grupo III - um ciclo de autoclavagem (30 minutos à 121 C, seguido por 10 minutos de secagem à 37 C em estufa); grupo IV - dois ciclos de autoclavagens. Foram avaliadas quanto: comprimento, calibre, resistência no nó e alongamento. Comparativamente foram examinados fios de náilon cirúrgico nas numerações 0, 1-0, 2-0, 3-0, 4-0 e 5-0 (10 amostras de cada um). Pelos resultados da análise estastística, verificou-se que a esterilização pelo calor úmido exerceu um efeito adverso na resistência da "linha de pesca". Por outro lado não houve diferenças na resistência, calibre e alongamento da "linha de pesca" entre o primeiro e segundo ciclo de autoclavagem. As “linhas” mantidas em pastilhas de formalina mantiveram na sua maioria suas características originais de resistência, comprimento, diâmetro e alongamento quando comparada ao grupo controle, entretanto, cabe lembrar que o formaldeído é considerado irritante para pele e membrana mucosa. Foi possível concluir que a "linha de pesca" apresenta características semelhantes ao fio cirúrgico, podendo ser mantida em pastilhas de formalina ou esterilizada em autoclave, lembrando que a autoclavagem altera algumas de suas propriedades físicas. Abstract A comparative study has been carried out between fishing lines and nylon thread in regard to their applicability as surgical thread. Four groups of 10 fishing lines in each of the following diameters = 0.15, 0.20, 0.25 and 0.30 mm = were subjected to the following treatments: group I, control; group II sterilized with formalin tablets; group III, autoclaved 30 minutes at 121oC; group IV, autoclaved twice 30 minutes at 121oC. The following parameters were then considered: length, caliber, resistance at the knot, and elongation. Ten samples of each surgical 0, 1.0, 2.0, 3.0, 4.0 and 5.0 nylon threads were used in comparatively similar experiments as the ones carried out with the fishing lines. According to the statistical analyses of the experimental results, it has been found that the sterilization by means of the humid heat exerts an adverse effect on the resistance of the fishing line. However, no differences were found between the effect displayed by two cycles sterilization compared with the fishing lines subjected to only one cycle. The threads maintained in formalin kept the majority of their original properties of resistance, length, diameter and elongation when compared with the control group. It is known, however that formaldehyde is an irritant chemical towards the skin and the mucous membranes. It was possible to conclude: a. fishing lines display characteristics similar to that ones of the nylon surgical thread; b. they can be maintained in formalin solution; c. autoclave sterilization alters some of their physical properties.


Author(s):  
Paul H. Kasai

In disk drives of current generation, the thickness of the disk lubricant has been reduced to the level of a sub-monomolecular film. For a mono- or a sub-monomolecular film of a perfluoropolyether terminated with a primary hydroxyl unit at both ends, each lubricant molecular chain is chemically bound to the carbon substrate at both termini, and if it has a hydrocarbon sector inserted at its center, the hydrocarbon sectors would assemble at the top of the film. They are thus poised most aptly to react as a Lewis base (an electron donor) to the Lewis acid centers on the slider thus abating the Lewis acid-catalyzed lubricant degradation.


ChemInform ◽  
1990 ◽  
Vol 21 (40) ◽  
Author(s):  
M. I. COLOMBO ◽  
S. SIGNORELLA ◽  
M. P. MISCHNE ◽  
M. GONZALEZ-SIERRA ◽  
E. A. RUVEDA

ChemPhysChem ◽  
2014 ◽  
Vol 15 (14) ◽  
pp. 2985-2993 ◽  
Author(s):  
Sławomir J. Grabowski
Keyword(s):  

Tetrahedron ◽  
1990 ◽  
Vol 46 (12) ◽  
pp. 4149-4154 ◽  
Author(s):  
Maria I. Colombo ◽  
Sandra Signorella ◽  
Mirta P.Mischne ◽  
Manuel Gonzalez-Sierra ◽  
Edmundo A. Ruveda

Author(s):  
Maxime Ferrer ◽  
Ibon Alkorta ◽  
José Elguero ◽  
Josep M. Oliva-Enrich

High-level quantum-chemical computations (G4MP2) are carried out in the study of complexes featuring tetrel bonding between the carbon atom in the carbenoid CB11H11 - obtained by hydride removal in the C-H bond of the known closo-monocarbadodecaborate anion CB11H12() and acting as Lewis acid (LA) - and Lewis bases (LB) of different type; the electron donor groups in the tetrel bond feature carbon, nitrogen, oxygen, fluorine, silicon, phosphorus, sulphur and chlorine atomic centers in neutral molecules as well as anions H(-), OH(-) and F(-). The empty radial 2pr vacant orbital on the carbon center in CB11H11 , which corresponds to the LUMO, acts as a Lewis acid or electron attractor, as shown by the molecular electrostatic potential (MEP) and electron localization funcion (ELF). The thermochemistry and topological analysis of the complexes {CB11H11:LB} are comprehensively analyzed, and classified according to sharing or closed-shell interactions. ELF analysis shows that the tetrel C···X bond ranges from very polarised bonds, as in H11B11C:F() to very weak interactions as in H11B11C···FH and H11B11C···O=C=O.


ChemPhysChem ◽  
2020 ◽  
Vol 21 (18) ◽  
pp. 2136-2142 ◽  
Author(s):  
Milan R. Milovanović ◽  
Quentin Dherbassy ◽  
Joanna Wencel‐Delord ◽  
Françoise Colobert ◽  
Snežana D. Zarić ◽  
...  
Keyword(s):  

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