Cycloproparenyl anions: From models to real systems

2005 ◽  
Vol 77 (11) ◽  
pp. 1835-1850 ◽  
Author(s):  
Mirjana Eckert-Maksic ◽  
Zoran Glasovac
Keyword(s):  
Aromatic Ring ◽  
Linear Extension ◽  
Resonance Effect ◽  
Lone Pair ◽  
Membered Ring ◽  
Electron Interaction ◽  
Anionic Center ◽  
Cyano Groups ◽  
Opposing Effects ◽  
The Impact

An overview of our recent work on cycloproparenyl anions is given. Preparation, the electronic structure, and the properties of the progenitor of the series, cyclopropabenzenyl anion, are discussed. It is shown that the cyclopropabenzenyl anion is by ca. 145 kJ mol-1 more stable than the parent cyclopropenyl anion according to results of the MP2/6-31+G(d) calculations. This finding was attributed to a delicate balance of two opposing effects: (a) propensity of the aromatic ring to alleviate unfavorable 4π electron interaction within the three-membered ring by the anionic resonance effect and (b) a pyramidalization of the anionic center, which tends to maximize the s-character of the lone pair. We have also shown that stability of the cyclopropabenzenyl anion could be considerably enhanced by substitution of the aromatic ring with fluorine and cyano groups, as well as by a linear extension of the aromatic backbone. Finally, the impact of the fusion of additional cyclopropenyl ring to the benzene moiety to acidity of the benzylic position in cyclopropabenzene is discussed.

scholarly journals On the diverse and opposing effects of nutrition on pathogen virulence

2019 ◽  
Vol 286 (1906) ◽  
pp. 20191220 ◽  
Author(s):  
Victoria L. Pike ◽  
Katrina A. Lythgoe ◽  
Kayla C. King
Keyword(s):  
Infectious Disease ◽  
Immune System ◽  
Meta Analysis ◽  
Anthropogenic Factors ◽  
Anthropogenic Activity ◽  
Pathogen Virulence ◽  
Disease Outcomes ◽  
Host Nutrition ◽  
Opposing Effects ◽  
The Impact

Climate change and anthropogenic activity are currently driving large changes in nutritional availability across ecosystems, with consequences for infectious disease. An increase in host nutrition could lead to more resources for hosts to expend on the immune system or for pathogens to exploit. In this paper, we report a meta-analysis of studies on host–pathogen systems across the tree of life, to examine the impact of host nutritional quality and quantity on pathogen virulence. We did not find broad support across studies for a one-way effect of nutrient availability on pathogen virulence. We thus discuss a hypothesis that there is a balance between the effect of host nutrition on the immune system and on pathogen resources, with the pivot point of the balance differing for vertebrate and invertebrate hosts. Our results suggest that variation in nutrition, caused by natural or anthropogenic factors, can have diverse effects on infectious disease outcomes across species.

Research on the Influence of Ocean Condition on the Oscillation in Parallel Double-Channel

2010 ◽  
Author(s):  
Linglan Zhou ◽  
Hong Zhang
Keyword(s):  
Resonance Effect ◽  
System Model ◽  
Half Cycle ◽  
Flow Oscillation ◽  
Multichannel System ◽  
Oscillation Cycle ◽  
Parallel Channels ◽  
The Difference ◽  
The Impact ◽  
Double Channel

In this paper, the flow oscillation in the parallel multichannel system has been studied under ocean condition with RELAP5/MC. A double-channel boiling system model is built using the code RELAP5/MC and it is proved to be capable of simulating the instable phenomena. The influences of rolling, heaving and inclination on the flow oscillation have been analyzed. The result shows that the effect of lengthways rolling on the oscillation in parallel channels can be ignored. The influence of athwartships rolling and heaving reveals resonance effect, that is, when the rolling cycle is close to the oscillation cycle and half cycle respectively, the oscillation would happen earlier, when the difference between the cycles is large, the impact of rolling can also be ignored. The influence of inclination on the oscillation in parallel channels is feeble.

scholarly journals Investigating the impact of aromatic ring substitutions on selectivity for a multimodal anion exchange prototype library

2018 ◽  
Vol 1569 ◽  
pp. 101-109 ◽  
Author(s):  
Julie Robinson ◽  
Mark A. Snyder ◽  
Chris Belisle ◽  
Jia-li Liao ◽  
Hong Chen ◽  
...  
Keyword(s):  
Anion Exchange ◽  
Aromatic Ring ◽  
The Impact

scholarly journals The glycocalyx affects force loading-dependent mechanotransductive topography sensing at the nanoscale

2021 ◽  
Author(s):  
Matteo Chighizola ◽  
Tania Dini ◽  
Stefania Marcotti ◽  
Mirko D’Urso ◽  
Claudio Piazzoni ◽  
...  
Keyword(s):  
Flow Speed ◽  
Signal Integration ◽  
Excessive Force ◽  
Cell Microenvironment ◽  
Force Loading ◽  
Flat Substrate ◽  
Starting Point ◽  
Opposing Effects ◽  
The Impact ◽  
Speed Characteristic

ABSTRACTThe cell/microenvironment interface is the starting point of integrin-mediated mechanotransduction, but many details of mechanotransductive signal integration remain elusive due to the complexity of the involved (extra)cellular structures, such as the glycocalyx.We used engineered nano-bio interfaces with extracellular matrix nanotopography-mimicking features to analyse the impact of the glycocalyx on nano-mechanosensing. Our data demonstrates that the glycocalyx configuration affects spatiotemporal nanotopography-sensitive mechanotransductive events at the cell/microenvironment interface. Opposing effects of glycocalyx removal were observed, when comparing flat and specific nanotopographical conditions (i.e., 15 nm root-mean-square (rms) roughness). In fact, the excessive force loading and retrograde actin flow speed, characteristic for the 15 nm rms nanotopography in the presence of native glycocalyx, are strongly reduced in its absence. Conversely, on the flat substrate, these parameters increased upon glycocalyx-targeting enzymatic treatment.Our results highlight the importance of the glycocalyx configuration in a molecular clutch force loading-dependent cellular mechanism for nano-mechanosensing of the topography.

scholarly journals Role of methyl group number on SOA formation from aromatic hydrocarbons photooxidation under low NO<sub><i>x</i></sub> conditions

2015 ◽  
Vol 15 (21) ◽  
pp. 31153-31196 ◽  
Author(s):  
L. Li ◽  
P. Tang ◽  
S. Nakao ◽  
C.-L. Chen ◽  
D. R. Cocker III
Keyword(s):  
Aromatic Hydrocarbon ◽  
Aromatic Ring ◽  
Aromatic Hydrocarbons ◽  
Methyl Groups ◽  
Methyl Group ◽  
Group Number ◽  
The Impact ◽  
First Time ◽  
Linear Trends

Abstract. Substitution of methyl groups onto the aromatic ring determines the SOA formation from the aromatic hydrocarbon precursor. This study links the number of methyl groups on the aromatic ring to SOA formation from aromatic hydrocarbons photooxidation under low NOx conditions (HC / NO > 10 ppb C : ppb). Aromatic hydrocarbons with increasing numbers of methyl groups are systematically studied. SOA formation from pentamethylbenzene and hexamethylbenzene are reported for the first time. A decreasing SOA yield with increasing number of methyl groups is observed. Linear trends are found in both f44 vs. f43 and O / C vs. H / C for SOA from aromatic hydrocarbons with zero to six methyl groups. An SOA oxidation state predictive method based on benzene is used to examine the effect of added methyl groups on aromatic oxidation under low NOx conditions. Further, the impact of methyl group number on density and volatility of SOA from aromatic hydrocarbons is explored. Finally, a mechanism for methyl group impact on SOA formation is suggested. Overall, this work suggests as more methyl groups are attached on the aromatic ring, SOA products from these aromatic hydrocarbons become less oxidized per mass/carbon.

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