scholarly journals Metal-Free Polymerizations of Microencapsulated Activated Alkynes for Autonomous Damage Visualization of Polymers

2021 ◽  
Author(s):  
Ting Han ◽  
Shusheng Chen ◽  
Xinnan Wang ◽  
Xinyao Fu ◽  
Haifei Wen ◽  
...  
Keyword(s):  
Composite Film ◽  
Polymer Film ◽  
Chemical Reactions ◽  
Mechanical Damage ◽  
Metal Free ◽  
Turn On ◽  
Wide Range ◽  
Additional Protection ◽  
Activated Alkynes ◽  
Damage Visualization

The development of autonomous materials with desired performance and built-in visualizable sensing units is of great academic and industrial significance. Although a wide range of damage indication methods have been reported, the “turn-on” sensing mechanism by damaging events based on microcapsule systems, especially those relying on chemical reactions to elicit a chromogenic response, are still very limited. Herein, a facile and metal-free polymerization route with an interesting reaction-induced coloration effect is demonstrated. Under the catalysis of 1,4-diazabicyclo[2.2.2]octane (DABCO), the polymerizations of difunctional or trifunctional activated alkynes proceed very quickly at 0 oC in air. A series of polymers composed of stereoregular enyne structure (major unit) and divinyl ether structure (minor unit) are obtained. Both the catalyst and monomers are colorless while the polymerized products are deep-colored. This process can be applied for the damage visualization of polymers using the microencapsulation technique. Microcapsules containing the reactive alkyne monomer are prepared and mixed in a DABCO-dispersed polymer film. The mechanical damage of this composite film can be readily visualized once the reaction is initiated from the ruptured microcapsules. Moreover, the newly formed polymer automatically sealed the cracks with an additional protection function.

Microwaves: Application in Electron Microscopy

1990 ◽  
Vol 48 (3) ◽  
pp. 140-141
Author(s):  
Anthony S-Y Leong ◽  
David W Gove
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Chemical Reactions ◽  
Electromagnetic Waves ◽  
Tissue Fixation ◽  
Primary Method ◽  
Dipolar Molecules ◽  
Wide Range ◽  
Time Required ◽  
Cryostat Sections

Microwaves (MW) are electromagnetic waves which are commonly generated at a frequency of 2.45 GHz. When dipolar molecules such as water, the polar side chains of proteins and other molecules with an uneven distribution of electrical charge are exposed to such non-ionizing radiation, they oscillate through 180° at a rate of 2,450 million cycles/s. This rapid kinetic movement results in accelerated chemical reactions and produces instantaneous heat. MWs have recently been applied to a wide range of procedures for light microscopy. MWs generated by domestic ovens have been used as a primary method of tissue fixation, it has been applied to the various stages of tissue processing as well as to a wide variety of staining procedures. This use of MWs has not only resulted in drastic reductions in the time required for tissue fixation, processing and staining, but have also produced better cytologic images in cryostat sections, and more importantly, have resulted in better preservation of cellular antigens.

p-Sulfonic acid calix[n]arene catalyzed synthesis of bioactive heterocycles: A review

2020 ◽  
Vol 24 ◽  
Author(s):  
Bubun Banerjee ◽  
Gurpreet Kaur ◽  
Navdeep Kaur
Keyword(s):  
Supramolecular Chemistry ◽  
Sulfonic Acid ◽  
Catalytic Efficiency ◽  
The Other ◽  
Reaction Conditions ◽  
Metal Free ◽  
Bioactive Scaffolds ◽  
Wide Range ◽  
Efficient Alternative ◽  
Bioactive Heterocycles

: Metal-free organocatalysts are becoming an important tool for the sustainable developments of various bioactive heterocycles. On the other hand, during last two decades, calix[n]arenes have been gaining considerable attention due to their wide range of applicability in the field of supramolecular chemistry. Recently, sulfonic acid functionalized calix[n] arenes are being employed as an efficient alternative catalyst for the synthesis of various bioactive scaffolds. In this review we have summarized the catalytic efficiency of p-sulfonic acid calix[n]arenes for the synthesis of diverse biologically promising scaffolds under various reaction conditions. There is no such review available in the literature showing the catalytic applicability of p-sulfonic acid calix[n]arenes. Therefore, we strongly believe that this review will surely attract those researchers who are interested about this fascinating organocatalyst.

Explanation Beyond Causation

2018 ◽  
Keyword(s):  
Philosophy Of Science ◽  
Case Studies ◽  
Philosophical Study ◽  
Accurate Information ◽  
Contemporary Philosophy ◽  
Causal Information ◽  
Causal Explanations ◽  
Turn On ◽  
Detailed Case ◽  
Wide Range

Explanations are very important to us in many contexts: in science, mathematics, philosophy, and also in everyday and juridical contexts. But what is an explanation? In the philosophical study of explanation, there is long-standing, influential tradition that links explanation intimately to causation: we often explain by providing accurate information about the causes of the phenomenon to be explained. Such causal accounts have been the received view of the nature of explanation, particularly in philosophy of science, since the 1980s. However, philosophers have recently begun to break with this causal tradition by shifting their focus to kinds of explanation that do not turn on causal information. The increasing recognition of the importance of such non-causal explanations in the sciences and elsewhere raises pressing questions for philosophers of explanation. What is the nature of non-causal explanations—and which theory best captures it? How do non-causal explanations relate to causal ones? How are non-causal explanations in the sciences related to those in mathematics and metaphysics? This volume of new essays explores answers to these and other questions at the heart of contemporary philosophy of explanation. The essays address these questions from a variety of perspectives, including general accounts of non-causal and causal explanations, as well as a wide range of detailed case studies of non-causal explanations from the sciences, mathematics and metaphysics.

Metal-Free Cascade Methylation/Cyclization of N-Alkyl-N-methacryloylbenzamides with Dicumyl Peroxide

Synlett ◽  
2017 ◽  
Vol 29 (05) ◽  
pp. 617-620 ◽  
Author(s):  
Yan-Ning Niu ◽  
Xiao-Feng Xia ◽  
Yuan Yuan
Keyword(s):  
Free Radical ◽  
Dicumyl Peroxide ◽  
Metal Free ◽  
Wide Range ◽  
Radical Cascade ◽  
Convenient Access

A metal-free radical cascade methylation/cyclization of a wide range of N-alkyl-N-methacryloylbenzamides by using dicumyl peroxide as the methylating reagent provides a convenient access to a series of methylated isoquinoline-1,3-diones in moderate yields.

Directional freezing of spermatozoa and embryos

2014 ◽  
Vol 26 (1) ◽  
pp. 83 ◽  
Author(s):  
Amir Arav ◽  
Joseph Saragusty
Keyword(s):  
Cooling Rate ◽  
Drop Size ◽  
Mechanical Damage ◽  
Rapid Freezing ◽  
Wild Animals ◽  
Microscope Slide ◽  
Freezing Method ◽  
Wide Range ◽  
Sexed Semen ◽  
Directional Freezing

Directional freezing is based on a simple thermodynamic principle whereby the sample is moved through a predetermined temperature gradient at a velocity that determines the cooling rate. Directional freezing permits a precise and uniform cooling rate in small- and large-volume samples. It avoids supercooling and reduces mechanical damage caused by crystallisation. Directional solidification was used to date for slow and rapid freezing, as well as for vitrification of oocytes and embryos by means of the minimum drop size technique: small drops are placed on a microscope slide that is moved at high velocity from the hot base to the cold base. Sperm samples from a wide range of domestic and wild animals were successfully cryopreserved using the directional freezing method. The bovine sexed semen industry may benefit from the increased survival of spermatozoa after directional freezing.

scholarly journals A General Fitting Function to Estimate Apparent Reaction Orders of Kinetic Profiles

2019 ◽  
Author(s):  
Robert Pollice
Keyword(s):  
Chemical Reactions ◽  
Catalyst Deactivation ◽  
Rapid Development ◽  
Product Inhibition ◽  
Time Profile ◽  
Time Data ◽  
Concentration Time ◽  
Wide Range ◽  
Reaction Orders

The rapid development of analytical methods in recent decades has resulted in a wide range of readily available and accurate reaction-monitoring techniques, which allow for easy determination of high-quality concentration-time data of chemical reactions. However, while the acquisition of kinetic data has become routine in the development of new chemical reactions and the study of their mechanisms, not all the information contained therein is utilized because of a lack of suitable analysis tools which unnecessarily complicates mechanistic studies. Herein, we report on a general method to analyze a single concentration-time profile of chemical reactions and extract information regarding the reaction order with respect to substrates, the presence of multiple kinetic regimes, and the presence of kinetic complexities, such as catalyst deactivation, product inhibition, and substrate decomposition.<br>

scholarly journals An Effective Statistics Approach to Secure Data File through Forbidden Zone Data Hiding Technique

2019 ◽  
Vol 68 (1) ◽  
pp. 01-07
Author(s):  
Tyler Taylor, Justin Rogers
Keyword(s):  
Data Hiding ◽  
Information Hiding ◽  
Data File ◽  
Video Steganography ◽  
Video Information ◽  
Video Record ◽  
Wide Range ◽  
Secure Data ◽  
Additional Protection

Video Steganography is a strategy wherein we can conceal a wide range of documents with any extension into a carrying Video document. Right now, are utilizing two fundamental wording that is have host file and carrier file where host file is a hidden file (any sort of record like content document, picture document, and sound/video document) and carrier file must be a video record. The primary inspiration of this paper is to make sure about moving of information by utilizing steganography and cryptography system. It is worried about implanting data in a harmless spread media in a safe and hearty way. Right now expositions we are utilizing Forbidden Zone Data Hiding strategy where no modification is required in have signal range during information hidden procedure. To safely moving the information record, we use video information covering up and utilizing revision limit of rehash gather code with predominance of taboo zone information stowing away. Utilizing this methodology we can likewise stow away and move the enormous video record whose size is bigger than spread record in secure way. The principle favorable position of utilizing video record sequestered from everything data is the additional protection from of the outsider or unintended beneficiary because of the overall multifaceted nature of video contrasted with picture and sound document. I have effectively actualized the proposed system of video information hiding utilizing forbidden zone datahiding strategy (FZDH) on content document, picture record, sound record and video document. The exceptional element is that we can hide the bigger size video record behind the smaller size cover record.

Synthesis and third-order nonlinear optical properties of novel ethynyl-linked heteropentamer composed of four porphyrins and one pyrene

2009 ◽  
Vol 13 (02) ◽  
pp. 275-282 ◽  
Author(s):  
Ning Sheng ◽  
Jing Sun ◽  
Yongzhong Bian ◽  
Jianzhuang Jiang ◽  
Dong Xu
Keyword(s):  
Optical Properties ◽  
Nonlinear Optical ◽  
Three Dimensional ◽  
Spectroscopic Methods ◽  
Third Order ◽  
Zinc Compounds ◽  
Nlo Properties ◽  
Metal Free ◽  
The Third ◽  
Wide Range

Novel heteropentameric porphyrins-pyrene arrays, in which four meso-tetraphenyl porphyrins are linked to the center unit of pyrene by four acetylenyl bonds, were designed and synthesized. The newly synthesized heteropentameric compounds have been characterized by a wide range of spectroscopic methods. The third-order nonlinear optical (NLO) properties of both the metal-free and zinc compounds of the three-dimensional arrays were investigated by Z-scan experiments, showing enhanced NLO properties compared with that of the porphyrin and pyrene monomers.

A Metal-free and β-Stereoselective Synthesis of 2-Deoxy-C-aryl Glycosides: Synthesis of 5-aza analogues of Aquayamycin

Synlett ◽  
2021 ◽  
Author(s):  
Yuling Mei ◽  
nan jiang ◽  
Yu Yang ◽  
Wan Zhang ◽  
Saifeng Qiu ◽  
...  
Keyword(s):  
Stereoselective Synthesis ◽  
Metal Free ◽  
Wide Range ◽  
One Step ◽  
Aryl Glycosides ◽  
Aryl Glycoside

A convenient protocol for β-stereoselective synthesis of 2-deoxy-C-aryl glycosides has been developed. This reaction takes place in one step by using I2/Et3SiH to activate glycosyl acetate to generate glycosyl iodide intermediate in situ, which was captured by naphthol followed by Fries-like O- → C-glycoside rearrangement to selectively afford β-C-aryl glycoside. The approach is applicable to a wide range of naphthol modules, and its utility was demonstrated in the synthesis of 5-aza analogues of Aquayamycin.

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