scholarly journals Ring-Forming Polymerization toward Perfluorocyclobutyl and Ortho-Diynylarene-Derived Materials: From Synthesis to Practical Applications

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1486
Author(s):  
Eugene B. Caldona ◽  
Ernesto I. Borrego ◽  
Ketki E. Shelar ◽  
Karl M. Mukeba ◽  
Dennis W. Smith
Keyword(s):  
Chemical Resistance ◽  
Structural Features ◽  
Review Article ◽  
Aryl Ether ◽  
Aromatic Rings ◽  
Practical Applications ◽  
Repeat Units ◽  
Wide Range ◽  
Synthetic Routes ◽  
The Cost

Many desirable characteristics of polymers arise from the method of polymerization and structural features of their repeat units, which typically are responsible for the polymer’s performance at the cost of processability. While linear alternatives are popular, polymers composed of cyclic repeat units across their backbones have generally been shown to exhibit higher optical transparency, lower water absorption, and higher glass transition temperatures. These specifically include polymers built with either substituted alicyclic structures or aromatic rings, or both. In this review article, we highlight two useful ring-forming polymer groups, perfluorocyclobutyl (PFCB) aryl ether polymers and ortho-diynylarene- (ODA) based thermosets, both demonstrating outstanding thermal stability, chemical resistance, mechanical integrity, and improved processability. Different synthetic routes (with emphasis on ring-forming polymerization) and properties for these polymers are discussed, followed by their relevant applications in a wide range of aspects.

scholarly journals Unprecedented Coumarin-Pyronin Hybrid Dyes: Synthesis, Fluorescence Properties and Theoretical Calculations

2021 ◽  
Author(s):  
Kevin Renault ◽  
Arnaud Chevalier ◽  
Jérôme Bignon ◽  
Denis Jacquemin ◽  
Jean-Alexandre Richard ◽  
...  
Keyword(s):  
Intramolecular Charge Transfer ◽  
Knoevenagel Condensation ◽  
Theoretical Calculations ◽  
A549 Cells ◽  
Hybrid Structures ◽  
Aryl Ether ◽  
Xanthene Dyes ◽  
Wide Range ◽  
Synthetic Routes ◽  
Nucleophilic Center

A novel class of rosamine dyes bearing a 7-substituted 4-hydroxycoumarin unit as <i>meso</i>-heteroaryl ring is presented. The latent <i>C</i>-nucleophilic character of 4-hydroxycoumarin derivatives (<i>i.e.</i>, their C-3 position as nucleophilic center) has been drawn on in the designing of two unprecedented synthetic routes towards these atypical xanthene dyes. They are based on an effective formal Knoevenagel condensation with either pyronin derivatives or a mixed bis-aryl ether bearing both an aldehyde and a masked phenylogous amine, possibly applicable to a wide range of latent cyclic <i>C</i>-nucleophiles. We also report experimental and theoretical photophysical investigations of these unique coumarin-pyronin hybrid structures and particularly their form low-lying quenching states, some of dark twisted intramolecular charge transfer (TICT) nature, depending on the medium (CHCl<sub>3</sub> and water). Furthermore, two fluorophore compounds <b>9</b> and <b>11</b> have been applied for imaging in paraformaldehyde-fixed A549 cells to gain insights into their permeation and localization.

scholarly journals Unprecedented Coumarin-Pyronin Hybrid Dyes: Synthesis, Fluorescence Properties and Theoretical Calculations

2021 ◽  
Author(s):  
Kevin Renault ◽  
Arnaud Chevalier ◽  
Jérôme Bignon ◽  
Denis Jacquemin ◽  
Jean-Alexandre Richard ◽  
...  
Keyword(s):  
Intramolecular Charge Transfer ◽  
Knoevenagel Condensation ◽  
Theoretical Calculations ◽  
A549 Cells ◽  
Hybrid Structures ◽  
Aryl Ether ◽  
Xanthene Dyes ◽  
Wide Range ◽  
Synthetic Routes ◽  
Nucleophilic Center

A novel class of rosamine dyes bearing a 7-substituted 4-hydroxycoumarin unit as <i>meso</i>-heteroaryl ring is presented. The latent <i>C</i>-nucleophilic character of 4-hydroxycoumarin derivatives (<i>i.e.</i>, their C-3 position as nucleophilic center) has been drawn on in the designing of two unprecedented synthetic routes towards these atypical xanthene dyes. They are based on an effective formal Knoevenagel condensation with either pyronin derivatives or a mixed bis-aryl ether bearing both an aldehyde and a masked phenylogous amine, possibly applicable to a wide range of latent cyclic <i>C</i>-nucleophiles. We also report experimental and theoretical photophysical investigations of these unique coumarin-pyronin hybrid structures and particularly their form low-lying quenching states, some of dark twisted intramolecular charge transfer (TICT) nature, depending on the medium (CHCl<sub>3</sub> and water). Furthermore, two fluorophore compounds <b>9</b> and <b>11</b> have been applied for imaging in paraformaldehyde-fixed A549 cells to gain insights into their permeation and localization.

A New Detector System For The HB5 Stem Instrument

1985 ◽  
Vol 43 ◽  
pp. 134-135
Author(s):  
J.M. Cowley
Keyword(s):  
Dark Field ◽  
Detector System ◽  
Electron Holography ◽  
Small Specimen ◽  
Bright Field ◽  
Multiple Images ◽  
Practical Applications ◽  
Wide Range ◽  
Diffraction Patterns ◽  
Operational Modes

The HB5 STEM instrument at ASU has been modified previously to include an efficient two-dimensional detector incorporating an optical analyser device and also a digital system for the recording of multiple images. The detector system was built to explore a wide range of possibilities including in-line electron holography, the observation and recording of diffraction patterns from very small specimen regions (having diameters as small as 3Å) and the formation of both bright field and dark field images by detection of various portions of the diffraction pattern. Experience in the use of this system has shown that sane of its capabilities are unique and valuable. For other purposes it appears that, while the principles of the operational modes may be verified, the practical applications are limited by the details of the initial design.

IMPROVEMENT OF INNOVATIVE ACTIVITY OF THE ENTERPRISE

2017 ◽  
Author(s):  
Nataliya Stoyanets ◽  
◽  
Mathias Onuh Aboyi ◽  
Keyword(s):  
Value Chain ◽  
Net Present Value ◽  
Successful Implementation ◽  
Innovative Development ◽  
Technological Equipment ◽  
Alliance Partner ◽  
Innovation Potential ◽  
Wide Range ◽  
Technological Platform ◽  
The Cost

The article defines that for the successful implementation of an innovative project and the introduction of a new product into production it is necessary to use advanced technologies and modern software, which is an integral part of successful innovation by taking into account the life cycle of innovations. It is proposed to consider the general potential of the enterprise through its main components, namely: production and technological, scientific and technical, financial and economic, personnel and actual innovation potential. Base for the introduction of technological innovations LLC "ALLIANCE- PARTNER", which provides a wide range of support and consulting services, services in the employment market, tourism, insurance, translation and more. To form a model of innovative development of the enterprise, it is advisable to establish the following key aspects: the system of value creation through the model of cooperation with partners and suppliers; creating a value chain; technological platform; infrastructure, determine the cost of supply, the cost of activities for customers and for the enterprise as a whole. The system of factors of influence on formation of model of strategic innovative development of the enterprise is offered. The expediency of the cost of the complex of technological equipment, which is 6800.0 thousand UAH, is economically calculated. Given the fact that the company plans to receive funds under the program of socio-economic development of Sumy region, the evaluation of the effectiveness of the innovation project, the purchase of technological equipment, it is determined that the payback period of the project is 3 years 10 months. In terms of net present value (NPV), the project under study is profitable. The project profitability index (PI) meets the requirements for a positive decision on project implementation> 1.0. The internal rate of return of the project (IRR) also has a positive value of 22% because it exceeds the discount rate.

pH-Dependent Thermal Stability of Vibrio cholerae L-asparaginase

2019 ◽  
Vol 26 (10) ◽  
pp. 743-750 ◽  
Author(s):  
Remya Radha ◽  
Sathyanarayana N. Gummadi
Keyword(s):  
Vibrio Cholerae ◽  
Conformational Changes ◽  
Kinetic Studies ◽  
Structural Features ◽  
Structure Stability ◽  
Kcal Mole ◽  
Scanning Calorimetry ◽  
Wide Range ◽  
Ph Dependent ◽  
Ph Range

Background:pH is one of the decisive macromolecular properties of proteins that significantly affects enzyme structure, stability and reaction rate. Change in pH may protonate or deprotonate the side group of aminoacid residues in the protein, thereby resulting in changes in chemical and structural features. Hence studies on the kinetics of enzyme deactivation by pH are important for assessing the bio-functionality of industrial enzymes. L-asparaginase is one such important enzyme that has potent applications in cancer therapy and food industry.Objective:The objective of the study is to understand and analyze the influence of pH on deactivation and stability of Vibrio cholerae L-asparaginase.Methods:Kinetic studies were conducted to analyze the effect of pH on stability and deactivation of Vibrio cholerae L-asparaginase. Circular Dichroism (CD) and Differential Scanning Calorimetry (DSC) studies have been carried out to understand the pH-dependent conformational changes in the secondary structure of V. cholerae L-asparaginase.Results:The enzyme was found to be least stable at extreme acidic conditions (pH< 4.5) and exhibited a gradual increase in melting temperature from 40 to 81 °C within pH range of 4.0 to 7.0. Thermodynamic properties of protein were estimated and at pH 7.0 the protein exhibited ΔG37of 26.31 kcal mole-1, ΔH of 204.27 kcal mole-1 and ΔS of 574.06 cal mole-1 K-1.Conclusion:The stability and thermodynamic analysis revealed that V. cholerae L-asparaginase was highly stable over a wide range of pH, with the highest stability in the pH range of 5.0–7.0.

Synthetic Routes to 2-Iminothiazolidines: State-of-the-Art 2006-2020

2020 ◽  
Vol 24 (24) ◽  
pp. 2823-2844
Author(s):  
Aditya Bhattacharyya
Keyword(s):  
State Of The Art ◽  
Biological Significance ◽  
Review Article ◽  
Synthetic Methods ◽  
Pharmacological Properties ◽  
Cyclic Molecules ◽  
Synthetic Routes

: Multiheteroatom-containing small-sized cyclic molecules such as 2- iminothiazolidines are often found to possess beneficial pharmacological properties. In this review article, the biological significance of 2-iminothiazolidines is discussed and the literature reports published in the last 15 years spanning from 2006 to 2020 describing various preparative routes to access 2-iminothiazolidine derivatives have been categorically and chronologically described. The notable synthetic methods discussed here involve ringexpansion transformations of nonactivated and activated aziridines, thiiranes, epoxides, and other miscellaneous reactions.

1,4-Diazepines: A Review on Synthesis, Reactions and Biological Significance

2019 ◽  
Vol 16 (5) ◽  
pp. 709-729 ◽  
Author(s):  
Muhammad A. Rashid ◽  
Aisha Ashraf ◽  
Sahibzada S. Rehman ◽  
Shaukat A. Shahid ◽  
Adeel Mahmood ◽  
...  
Keyword(s):  
Biological Activities ◽  
Biological Significance ◽  
Biological Evaluation ◽  
Wide Range ◽  
Pharmaceutical Industries ◽  
Biological Aspects ◽  
Synthetic Routes ◽  
Biological Attributes ◽  
Synthesis Reactions ◽  
Potential Use

Background:1,4-Diazepines are two nitrogen containing seven membered heterocyclic compounds and associated with a wide range of biological activities. Due to its medicinal importance, scientists are actively involved in the synthesis, reactions and biological evaluation of 1,4-diazepines since number of decades.Objective:The primary purpose of this review is to discuss the synthetic schemes and reactivity of 1,4- diazepines. This article also describes biological aspects of 1,4-diazepine derivatives, that can be usefully exploited for the pharmaceutical sector.Conclusion:This review summarizes the abundant literature on synthetic routes, chemical reactions and biological attributes of 1,4-diazepine derivatives. We concluded that 1,4-diazepines have significant importance due to their biological activities like antipsychotic, anxiolytic, anthelmintic, anticonvulsant, antibacterial, antifungal and anticancer. 1,4-diazepine derivatives with significant biological activities could be explored for potential use in the pharmaceutical industries.

Application of Nitrogen Heterocyclic Carbenes in Organocatalysis

2020 ◽  
Vol 09 ◽  
Author(s):  
Minita Ojha ◽  
R. K. Bansal
Keyword(s):  
Asymmetric Catalysis ◽  
Building Blocks ◽  
Structural Features ◽  
Heterocyclic Carbenes ◽  
Stetter Reaction ◽  
Metal Pollutants ◽  
Synthetic Strategy ◽  
Wide Range ◽  
Benzoin Condensation ◽  
Nitrogen Heterocyclic

Background: During the last two decades, horizon of research in the field of Nitrogen Heterocyclic Carbenes (NHC) has widened remarkably. NHCs have emerged as ubiquitous species having applications in a broad range of fields, including organocatalysis and organometallic chemistry. The NHC-induced non-asymmetric catalysis has turned out to be a really fruitful area of research in recent years. Methods: By manipulating structural features and selecting appropriate substituent groups, it has been possible to control the kinetic and thermodynamic stability of a wide range of NHCs, which can be tolerant to a variety of functional groups and can be used under mild conditions. NHCs are produced by different methods, such as deprotonation of Nalkylhetrocyclic salt, transmetallation, decarboxylation and electrochemical reduction. Results: The NHCs have been used successfully as catalysts for a wide range of reactions making a large number of building blocks and other useful compounds accessible. Some of these reactions are: benzoin condensation, Stetter reaction, Michael reaction, esterification, activation of esters, activation of isocyanides, polymerization, different cycloaddition reactions, isomerization, etc. The present review includes all these examples published during the last 10 years, i.e. from 2010 till date. Conclusion: The NHCs have emerged as versatile and powerful organocatalysts in synthetic organic chemistry. They provide the synthetic strategy which does not burden the environment with metal pollutants and thus fit in the Green Chemistry.

scholarly journals The Location of Magnetic Reconnection at Earth’s Magnetopause

2021 ◽  
Vol 217 (3) ◽  
Author(s):  
K. J. Trattner ◽  
S. M. Petrinec ◽  
S. A. Fuselier
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Ion Beams ◽  
Review Article ◽  
Observational Evidence ◽  
Magnetic Shear ◽  
General Direction ◽  
Shear Model ◽  
Wide Range

AbstractOne of the major questions about magnetic reconnection is how specific solar wind and interplanetary magnetic field conditions influence where reconnection occurs at the Earth’s magnetopause. There are two reconnection scenarios discussed in the literature: a) anti-parallel reconnection and b) component reconnection. Early spacecraft observations were limited to the detection of accelerated ion beams in the magnetopause boundary layer to determine the general direction of the reconnection X-line location with respect to the spacecraft. An improved view of the reconnection location at the magnetopause evolved from ionospheric emissions observed by polar-orbiting imagers. These observations and the observations of accelerated ion beams revealed that both scenarios occur at the magnetopause. Improved methodology using the time-of-flight effect of precipitating ions in the cusp regions and the cutoff velocity of the precipitating and mirroring ion populations was used to pinpoint magnetopause reconnection locations for a wide range of solar wind conditions. The results from these methodologies have been used to construct an empirical reconnection X-line model known as the Maximum Magnetic Shear model. Since this model’s inception, several tests have confirmed its validity and have resulted in modifications to the model for certain solar wind conditions. This review article summarizes the observational evidence for the location of magnetic reconnection at the Earth’s magnetopause, emphasizing the properties and efficacy of the Maximum Magnetic Shear Model.

scholarly journals Sensuator: A Hybrid Sensor–Actuator Approach to Soft Robotic Proprioception Using Recurrent Neural Networks

Actuators ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 30
Author(s):  
Pornthep Preechayasomboon ◽  
Eric Rombokas
Keyword(s):  
Neural Networks ◽  
Recurrent Neural Networks ◽  
Linear Models ◽  
Open Loop ◽  
Proof Of Concept ◽  
State Estimator ◽  
Loop Control ◽  
Practical Applications ◽  
Soft Actuator ◽  
The Cost

Soft robotic actuators are now being used in practical applications; however, they are often limited to open-loop control that relies on the inherent compliance of the actuator. Achieving human-like manipulation and grasping with soft robotic actuators requires at least some form of sensing, which often comes at the cost of complex fabrication and purposefully built sensor structures. In this paper, we utilize the actuating fluid itself as a sensing medium to achieve high-fidelity proprioception in a soft actuator. As our sensors are somewhat unstructured, their readings are difficult to interpret using linear models. We therefore present a proof of concept of a method for deriving the pose of the soft actuator using recurrent neural networks. We present the experimental setup and our learned state estimator to show that our method is viable for achieving proprioception and is also robust to common sensor failures.

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