Ring opening copolymerization of ε-caprolactone and diselenic macrolide carbonate for well-defined poly(ester-co-carbonate): kinetic evaluation and ROS/GSH responsiveness

2020 ◽  
Vol 11 (9) ◽  
pp. 1597-1605 ◽  
Author(s):  
Jiahao Wang ◽  
Chuanhao Sun ◽  
Jieni Hu ◽  
Yanling Huang ◽  
Yunxiang Lu ◽  
...  
Keyword(s):  
Ring Opening ◽  
Theoretical Calculations ◽  
Experimental Results ◽  
Kinetic Evaluation ◽  
Composition And Structure ◽  
Competitive Mechanism

Theoretical calculations agreed well with the experimental results. The competitive mechanism was proposed to clarify the composition and structure of the copolymers.

An NBO-TS predictive approach for torquoselectivity of ring opening in 3-substituted cyclobutenes

2017 ◽  
Author(s):  
Arpita Yadav ◽  
Dasari L V K Prasad ◽  
Veejendra Yadav
Keyword(s):  
Transition State ◽  
Ring Opening ◽  
Natural Bond Orbital ◽  
Theoretical Calculations ◽  
Lone Pair ◽  
Product Distribution ◽  
Acceptor Substituent ◽  
Important Contributor ◽  
Predictive Approach ◽  
Donor Substituent

<p>The torquoselectivity, the inward or outward ring opening of 3-substituted cyclobutenes, is conventionally guided by the donor and/or acceptor ability of the substituent (S). It is typically predicted by estimating the respective ring opening transition state (TS) barriers. While there is no known dissent in regard to the outward rotation of electron-rich substituents from the approaches of TS calculations, the inward rotation was predicted for some electron-accepting substituents and outward for others. To address this divergence in predicting the torquoselectivity, we have used reliable orbital descriptors through natural bond orbital theoretical calculations and demonstrated that (a) interactions <i>n</i><i><sub>S</sub></i>→s*<sub>C3C4</sub> for a lone pair containing substituent, s<sub>S</sub>→s*<sub>C3C4</sub> for a s-donor substituent, s<sub>C3C4</sub>→p*<sub>S</sub> for a resonance-accepting substituent and s<sub>C3C4</sub>→s*<sub>S</sub> for a s-acceptor substituent constitute the true electronic controls of torquoselectivity, and (b) reversibility of the ring opening event is an additional important contributor to the observed product distribution.</p>

scholarly journals Heck-Type Coupling of Fused Bicyclic Vinylcyclopropanes: Synthesis of 1,2-Dihydropyridines, 2,3-Dihydro-1H-Azepines, 1,4-Cyclohexadienes, 2H-Pyrans, and 1,3-Butadienes

2021 ◽  
Author(s):  
Nikolai Wurzer ◽  
Urszula Klimczak ◽  
Tobias Babl ◽  
Sebastian Fischer ◽  
Ricardo A. Angnes ◽  
...  
Keyword(s):  
Heck Reaction ◽  
Ring Opening ◽  
Theoretical Calculations ◽  
Ring Expansion ◽  
Mechanistic Studies ◽  
Type Coupling ◽  
Hydride Elimination ◽  
Unexpected Behavior

Herein, we report a versatile approach for the endocyclic ring-opening of bicyclic vinylcyclopropanes triggered by Heck arylations. Key step for this transformation is a [1,3]-migratory shift of Pd allowing the ring expansion of cyclopropanated pyrroles, piperidines, furans as well as cyclopentadienes to grant access to the corresponding 1,2-dihydropyridines, 2<i>H</i>-pyrans, 2,3-dihydro-1<i>H</i>-azepines and 1,4-cyclohexadienes, respectively. Additionally, <i>gem</i>-disubstituted cyclopropanated furans showed unexpected behavior by giving diastereoselectively asymmetrically substituted dienes. Mechanistic studies and theoretical calculations point towards a facile [1,3]-migratory shift of Pd along the cyclopropane moiety, which can successfully compete with the usual termination step of a Heck reaction via a <i>syn</i>-b-hydride elimination.<br>

Research of stamping of unequal channel bars. Part 5. Methods for calculating the extrusion of channels. 2. Extrusion of non-strengthening material

2021 ◽  
pp. 46-52
Author(s):  
A.L. Vorontsov
Keyword(s):  
Plane Strain ◽  
Theoretical Calculations ◽  
Experimental Studies ◽  
High Accuracy ◽  
Experimental Results ◽  
Die Forging

The results of experimental studies on the extrusion of channels from non-strengthening material are presented. Comparison of theoretical calculations with experimental results showed the high accuracy of the derived formulas. Keywords: die forging, extrusion, punch, matrix, misalignment, plane strain. [email protected]

Young’s Experiment on Slits with an Angle Between Them

2014 ◽  
Vol 9 (2) ◽  
pp. 173-179
Author(s):  
Anton Bogomyagkov ◽  
Viktor Dorokhov ◽  
Oleg Meshkov ◽  
Aleksandr Polygalov ◽  
Alexey Shcheglov
Keyword(s):  
Experimental Data ◽  
Interference Pattern ◽  
Intensity Distribution ◽  
Mathematical Analysis ◽  
Theoretical Calculations ◽  
Experimental Results ◽  
Digital Data ◽  
Hyperbolic Function ◽  
Standard Laboratory ◽  
Arbitrary Angle

Here are proposed a modified version of Young’s experiment on slits with an arbitrary angle between them. Also here performed mathematical analysis of the proposed scheme, showing that the intensity distribution can be approximated by a hyperbolic function. Experimental data confirm theoretical calculations. Analysis of the experimental results has conducted using two different methods of processing the digital data of the interference pattern. Theoretical calculations and experimental results established a nontrivial fact, that the interference patterns for slits with different, but symmetrical respect to 90° angles have the same intensity distribution. This experiment may be used as a standard laboratory work in University on optics workshop

scholarly journals Wavelength dependent nonlinear optical response of tetraphenylethene aggregation-induced emission luminogens

2018 ◽  
Vol 2 (12) ◽  
pp. 2263-2271 ◽  
Author(s):  
Jianbo Xiong ◽  
Xinyue Li ◽  
Chunqing Yuan ◽  
Sergey Semin ◽  
Zhaoquan Yao ◽  
...  
Keyword(s):  
Optical Properties ◽  
Nonlinear Optical ◽  
Theoretical Calculations ◽  
Experimental Results ◽  
Nlo Properties ◽  
Aggregation Induced Emission ◽  
Non Linear ◽  
Potential Applications ◽  
Linear Optical Properties ◽  
Linear Optical

Studies of the non-linear optical properties of classical AIEgens are rare, despite their important potential applications in organic composite photonic circuits. Here, we present experimental results, supported by theoretical calculations, of the non-linear optical (NLO) properties of TPE and its halogenated derivates.

Thermal intramolecular reactions of Δ1-1,2,4-triazolines with extended exocyclic unsaturation

1988 ◽  
Vol 66 (3) ◽  
pp. 385-390 ◽  
Author(s):  
Adrian L. Schwan ◽  
John Warkentin
Keyword(s):  
Ring Opening ◽  
Hydrolysis Product ◽  
Sigmatropic Rearrangement ◽  
Membered Ring ◽  
Ring Closure ◽  
Experimental Results ◽  
First Order ◽  
Ring Opening Reaction ◽  
Intramolecular Reactions

Fumaratotriazoline (1) and amidotriazoline (3) undergo thermal first-order transformations in solution at 65 °C. The former affords the isomeric pyrrole 5 and its hydrolysis product 6. A mechanism involving opening of the initial five-membered ring to form 8, followed by closure to a new five-membered ring (9), is proposed. Amidotriazoline (3) loses N2 on heating to form 19. The experimental results are best accommodated in terms of a novel mechanism involving an electrocyclic ring closure, a [3 + 2] cycloreversion to form an ylide, a sigmatropic rearrangement of the ylide, and, finally, an electrocyclic ring-opening reaction.

Preparation and Degradation Properties of Hydroxyethyl Chitosan-g-Poly(D,L-Lactide) Copolymers

2012 ◽  
Vol 457-458 ◽  
pp. 308-313
Author(s):  
Bing Hong Luo ◽  
Jian Hua Li ◽  
Wan Xu ◽  
Chang Ren Zhou
Keyword(s):  
Ring Opening ◽  
Ph Value ◽  
Saline Water ◽  
Feed Ratio ◽  
Casting Method ◽  
Composition And Structure ◽  
Solution Casting Method ◽  
Lactide Copolymers ◽  
Degradation Properties

The goal of the present study was to investigate the degradation of hydroxyethyl chitosan-g-poly(D,L-lactide) (HECS-g-PDLLA) copolymers in vitro. For this purpose, HECS-g-PDLLA copolymers were firstly synthesized by bulk ring-opening polymerization with different nD,L-lactide:naminoglucoside feed ratio. Then, a series of poly(D,L-lactide), chitosan and HECS-g-PDLLA copolymers films were prepared by solution casting method, and their degradation were carried out in vitro in saline water at 37 °C. The degradation properties were investigated by measurement of pH value, weight loss, and changes in the composition and structure of the HECS-g-PDLLA copolymers films with time. Results showed that the degradation of the HECS-g-PDLLA copolymers occurred firstly on the poly(D,L-lactide) side chains. The degradation rate of the graft copolymers obviously faster than that of CS, and can be controlled by changing the value of nD,L-lactide:naminoglucoside. Due to the alkalinity of CS, the pH value of saline water for HECS-g-PDLLA copolymers degradation higher than that of PDLLA.

scholarly journals Subsurface imaging of flexible circuits via contact resonance atomic force microscopy

2019 ◽  
Vol 10 ◽  
pp. 1636-1647 ◽  
Author(s):  
Wenting Wang ◽  
Chengfu Ma ◽  
Yuhang Chen ◽  
Lei Zheng ◽  
Huarong Liu ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Theoretical Calculations ◽  
Contact Stiffness ◽  
Metal Layer ◽  
Experimental Results ◽  
Subsurface Imaging ◽  
Force Microscopy ◽  
Atomic Force ◽  
Cover Thickness ◽  
Contact Resonance

Subsurface imaging of Au circuit structures embedded in poly(methyl methacrylate) (PMMA) thin films with a cover thickness ranging from 52 to 653 nm was carried out by using contact resonance atomic force microscopy (CR-AFM). The mechanical difference of the embedded metal layer leads to an obvious CR-AFM frequency shift and therefore its unambiguous differentiation from the polymer matrix. The contact stiffness contrast, determined from the tracked frequency images, was employed for quantitative evaluation. The influence of various parameter settings and sample properties was systematically investigated by combining experimental results with theoretical analysis from finite element simulations. The results show that imaging with a softer cantilever and a lower eigenmode will improve the subsurface contrast. The experimental results and theoretical calculations provide a guide to optimizing parameter settings for the nondestructive diagnosis of flexible circuits. Defect detection of the embedded circuit pattern was also carried out, which indicates the capability of imaging tiny subsurface structures smaller than 100 nm by using CR-AFM.

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