Sequence controlled copolymerization of lactide and a functional cyclic carbonate using stereoselective aluminum catalysts

2019 ◽  
Vol 10 (29) ◽  
pp. 4042-4048 ◽  
Author(s):  
Xiufang Hua ◽  
Xinli Liu ◽  
Dongmei Cui
Keyword(s):  
Random Sequence ◽  
Cyclic Carbonate ◽  
Aluminum Complexes ◽  
Sequence Distributions

Stereoselective aluminum complexes were applied for the ROP of LA and MAC producing functional copolyesters with quasi-diblock, tapered, gradient and random sequence distributions.

Bimetallic scorpionate-based helical organoaluminum complexes for efficient carbon dioxide fixation into a variety of cyclic carbonates

2020 ◽  
Vol 10 (10) ◽  
pp. 3265-3278 ◽  
Author(s):  
Marta Navarro ◽  
Luis F. Sánchez-Barba ◽  
Andrés Garcés ◽  
Juan Fernández-Baeza ◽  
Israel Fernández ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Cyclic Carbonate ◽  
Carbon Dioxide Fixation ◽  
Cyclic Carbonates ◽  
Carbonate Formation ◽  
Aluminum Complexes

The binuclear aluminum complexes [AlR2(κ2-NN′;κ2-NN′)AlR2] with TBAB/PPNCl behave as excellent systems for cyclic carbonate formation from CO2 with challenging epoxides.

Aluminum complexes derived from a hexadentate salen-type Schiff base: synthesis, structure, and catalysis for cyclic carbonate synthesis

2017 ◽  
Vol 46 (18) ◽  
pp. 5848-5855 ◽  
Author(s):  
Ya Xu ◽  
Dan Yuan ◽  
Yaorong Wang ◽  
Yingming Yao
Keyword(s):  
Schiff Base ◽  
Atmospheric Pressure ◽  
Cycloaddition Reaction ◽  
Cyclic Carbonate ◽  
Aluminum Complex ◽  
Aluminum Complexes

The unexpected aluminum complex was synthesized and found to be active in the cycloaddition reaction of terminal epoxides and CO2 at atmospheric pressure.

Selective Synthesis of Cyclic Carbonate by Salalen-Aluminum Complexes and Mechanistic Studies

ChemSusChem ◽  
2017 ◽  
Vol 10 (6) ◽  
pp. 1217-1223 ◽  
Author(s):  
Mariachiara Cozzolino ◽  
Tomer Rosen ◽  
Israel Goldberg ◽  
Mina Mazzeo ◽  
Marina Lamberti
Keyword(s):  
Cyclic Carbonate ◽  
Selective Synthesis ◽  
Mechanistic Studies ◽  
Aluminum Complexes

The d-Enantiomer Form of Indobufen Totally Accounts for the Anti-Cyclooxygenase and Antiplatelet Activity Ex Vivo and for the Increase in Bleeding Time by Indobufen in Man

1992 ◽  
Vol 67 (02) ◽  
pp. 258-263 ◽  
Author(s):  
Raffaele De Caterina ◽  
Rosa Sicari ◽  
An Yan ◽  
Walter Bernini ◽  
Daniela Giannessi ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Plasma Levels ◽  
Bleeding Time ◽  
Ex Vivo ◽  
Random Sequence ◽  
Antiplatelet Agent ◽  
Antiplatelet Drug ◽  
Double Blind

SummaryIndobufen is an antiplatelet drug able to inhibit thromboxane production and cyclooxygenase-dependent platelet aggregation by a reversible inhibition of cyclooxygenase. Indobufen exists in two enantiomeric forms, of which only d-indobufen is active in vitro in inhibiting cyclooxygenase. In order to verify that also inhibition of platelet function is totally accounted for by d-indobufen, ten patients with proven coronary artery disease (8 male, 2 female, age, mean ± S.D., 58.7 ± 7.5 years) were given, in random sequence, both 100 mg d-indobufen and 200 mg dl-indobufen as single administrations in a double-blind crossover design study with a washout period between treatments of 72 h. In all patients thromboxane (TX) B2 generation after spontaneous clotting (at 0, 1, 2, 4, 6, 8, 12, 24 h), drug plasma levels (at the same times), platelet aggregation in response to ADP, adrenaline, arachidonic acid, collagen, PAF, and bleeding time (at 0, 2, 12 h) were evaluated after each treatment. Both treatments determined peak inhibition of TXB2 production at 2 h from administration, with no statistical difference between the two treatments (97 ±3% for both treatments). At 12 h inhibition was 87 ± 6% for d-indobufen and 88 ± 6% for dl-indobufen (p = NS). Inhibition of TXB2 production correlated significantly with plasma levels of the drugs. Maximum inhibitory effect on aggregation was seen in response to collagen 1.5 pg/ml (63 ± 44% for d-indobufen and 81 ± 22% for dl-indobufen) and arachidonic acid 0.5-2 mM (78 ± 34% for d-indobufen and 88 ± 24% for dl-indobufen) at 2 h after each administration. An effect of both treatments on platelet aggregation after 12 h was present only for adrenaline 2 μM (55 ± 41% for d-indobufen and 37 ± 54% for dl-indobufen), collagen 1.5 pg/ml (69 ± 30% for d-indobufen and 51 ± 61% for dl-indobufen), arachidonic acid 0.5-2 mM (56 ± 48% for d-indobufen and 35 ± 49% for dl-indobufen). The extent of inhibition of TX production and the extent of residual platelet aggregation were never significantly different between treatments. Bleeding time prolongation was similar in the two treatment groups without showing a pronounced and long lasting effect (from 7.0 ± 2.0 min to 10.0 ± 3.0 min at 2 h and 8.0 ± 2.0 min at 12 h for d-indobufen; from 6.0 ±1.0 min to 8.5 ± 2.0 min at 2 h and 8.0 ± 1.0 min at 12 h for dl-indobufen). These results demonstrate that the biological activity of dl-indobufen as an antiplatelet agent in vivo is totally accounted for by d-indobufen.

Validation of a monetary Taylor Aggression Paradigm: Associations with trait aggression and role of provocation sequence

2020 ◽  
Author(s):  
J Konzok ◽  
L Kreuzpointner ◽  
GI Henze ◽  
L Wagels ◽  
C Kärgel ◽  
...  
Keyword(s):  
Random Sequence ◽  
Reactive Aggression ◽  
Reaction Time Task ◽  
Competitive Reaction ◽  
Experimental Conditions ◽  
Fixed Sequence ◽  
Taylor Aggression Paradigm ◽  
Trait Aggression ◽  
Significant Difference ◽  
In Series

© 2020 Elsevier Inc. The Taylor Aggression Paradigm (TAP) is widely used to measure reactive aggression in laboratory settings. While modified versions (mTAPs) with various stimulus characteristics (shocks, noise, pressure, heat) have already been established, a modified version with monetary stimuli has only been introduced very recently. In this experiment, 209 young healthy participants (104 males, 105 females) completed a mock Competitive Reaction Time Task (CRTT) with a fictional opponent with preprogrammed 40 win and 60 lose trials. In lose trials, participants were provoked by subtracting a low (0–20 euro cents), medium (30–60 cents) or high (70–90 cents) amount of money from their fictitious account. Provocation stimuli were either presented randomly or in a fixed sequence (experimental conditions). In contrast to a random sequence, the fixed sequence was generated by repeating trials from the same provocation category in series of three. Linear mixed models (LMMs) considering aggression trajectories revealed significant effects of provocation (low, medium, high) and trait aggression (K-FAF) on reactive aggression. Men showed significantly higher reactive aggression levels than women. In regard to provocation sequence, we found no significant difference in reactive aggression between the random vs. fixed stimulus sequences. The findings provide new evidence supporting the view that the monetary mTAP is able to induce as well as capture reactive aggression in the laboratory. Additionally, we found no advantage of a fixed sequence as the level of reactive aggression in a given trial appeared to be mainly predicted by the preceding provocation trial.

Modeling a random sequence of extremes of loads for fatigue tests under irregular loading

2020 ◽  
pp. 13-19
Author(s):  
N.A. Mahutov ◽  
I.V. Gadolina ◽  
S.G. Lebedinskiy ◽  
E.S. Oganyan ◽  
A.A. Bautin
Keyword(s):  
Random Sequence ◽  
Fatigue Tests ◽  
Linear Hypothesis ◽  
Resource Estimation ◽  
Transition Matrices ◽  
Random Loading ◽  
Markov Transition ◽  
Random Nature ◽  
Irregular Loading ◽  
Markov Transition Matrices

Methods and approaches to tests under random loading are considered, their role is characterized. To ensure the random nature of loading, a modeling method based on Markov transition matrices and real processes recorded in operation is proposed. Keywords: random loading process, Markov repetition matrices, resource estimation, corrected linear hypothesis, parameter of completeness of the loading spectrum. [email protected]

Sustainable Solid Catalysts for Cyclic Carbonate Synthesis from CO2 and Epoxide

2015 ◽  
Vol 19 (8) ◽  
pp. 681-694 ◽  
Author(s):  
Xian-Dong Lang ◽  
Xiao-Fang Liu ◽  
Liang-Nian He
Keyword(s):  
Cyclic Carbonate ◽  
Solid Catalysts

Participation of 19-ester groups in the cleavage of 2α,3α- and 5α,6α-steroid epoxides. A case of competition between participation and external nucleophile attack

1979 ◽  
Vol 44 (5) ◽  
pp. 1496-1509 ◽  
Author(s):  
Pavel Kočovský ◽  
Václav Černý
Keyword(s):  
Perchloric Acid ◽  
Hydrobromic Acid ◽  
Ester Group ◽  
Carbonyl Oxygen ◽  
Cyclic Carbonate ◽  
Cyclic Ether ◽  
Normal Reaction ◽  
Neighboring Group ◽  
Ether Oxygen ◽  
The Difference

Acid cleavage of the acetoxy epoxide IIIa with aqueous perchloric acid or hydrobromic acid gave two types of products, i.e. the diol Va or the bromohydrin VIa, and the cyclic ether VIII. The latter compound arises by participation of ether oxygen of the ester group. On reaction with perchloric acid the epoxide IVa gave the diol XIIIa as a product of a normal reaction and the isomeric diol Xa as a product arising by intramolecular participation of the carbonyl oxygen of the 19-acetoxy group. Participation of the 19-ester group is confirmed by the formation of the cyclic carbonate XI when the 19-carbonate IVb is treated analogously. On reaction with hydrobromic acid, the epoxide IVa gave solely the bromohydrin XIVa as a product of the normal reaction course. Discussed is the similarity of these reactions with electrophilic additions to the related 19-acetoxy olefins I and II, the mechanism, the difference in behavior of both epoxides III and IV, the dependence of the product ratio on the nucleophility of the attacking species, and the competition between participation of an ambident neighboring group and an external nucleophile attack.

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