Low-molecular-weight fucoidan: Chemical modification, synthesis of its oligomeric fragments and mimetics

2019 ◽  
Vol 485 ◽  
pp. 107806 ◽  
Author(s):  
Viktoria Evgenievna Suprunchuk
RSC Advances ◽  
2015 ◽  
Vol 5 (30) ◽  
pp. 23202-23209 ◽  
Author(s):  
Ruijuan Li ◽  
Xiaolin Su ◽  
Zheng Chen ◽  
Wanxu Huang ◽  
Yali Wang ◽  
...  

Novel PAK4 inhibitors were discovered using structure-based virtual screening approach for further chemical modification.


2013 ◽  
Vol 749 ◽  
pp. 461-465
Author(s):  
De Jun Shen ◽  
Chang Hai Yu ◽  
Zhen Xing

This topic is considered to modify the fast-growing Poplar to improve the properties, in order to fully meet the performance requirements for the structural material. This study aims to improve the dimensional stability and some other mechanical properties through impregnated with the low-molecular-weight PF resin. Through design orthogonal test in different mole ratio of Formaldehyde and Phenol, different amount of NaOH and PVA, we make PF resin to impregnate Poplar and pressing into laminated timber to measure bonding strength, MOR, MOE. The study indicated that: the optimum conditions of the low molecular weight PF resin for modify Poplar are: mole ratio of Formaldehyde and Phenol is 2.4, mole ratio of NaOH and phenol is 0.05, amount of PVA is 3% of the phenol. Under this condition Poplar specimen got the biggest increase in various properties and it can satisfy the requirements of the outdoor wood structure.


2021 ◽  
Vol 4 ◽  
pp. 21-27
Author(s):  
V.М. Gunka ◽  
Yu.V. Prysiazhnyi ◽  
Yu.Ya. Demchuk ◽  
Yu.M. Hrynchuk ◽  
Yu.V. Sidun ◽  
...  

PRODUCTION OF ROAD OIL BITUMENS BY THE METHOD OF CHEMICAL MODIFICATION OF OIL RESIDUES © V.М. Gunka, PhD in technical sciences, Yu.V. Prysiazhnyi, PhD in technical sciences, Yu.Ya. Demchuk, PhD in technical sciences, Yu.M. Hrynchuk, PhD in technical sciences, Yu.V. Sidun, PhD in technical sciences, M.M. Bratychak, Doctor of Chemical Sciences (Lviv Polytechnic Naional University, 12 Stepan Bandera Str., 79013, Lviv, Ukraine) The article is devoted to obtaining road oil bitumen from oil residues by modifying them with relatively cheap low molecular weight organic substances. The proposed method relates to a chemical modification, which, in case of its industrial implementation, will allow avoiding the use of expensive physical modifiers. A 37 % aqueous solution of formaldehyde was used as low molecular weight organic substances (modifier / chemical reagent of the process) for chemical modification of tar; concentrated sulfuric acid (H2SO4) was used as a catalyst for the chemical modification of tar. As a feedstock for chemical modification, we used an oil residue - tar, selected at PJSC “Ukrtatnafta” (Kremenchug, Ukraine). The chemical modification with formaldehyde was carried out in hermetic stationary containers capable of operating under excess pressure. The photographs of the equipment are given. Since the ultimate goal of the work was to obtain road oil bitumen, then, analyzing the results of experimental studies, we focused on the quality characteristics of this particular product. At the same time, the most important quality indicators were determined, namely: the depth of needle penetration, softening temperature, ductility (extensibility), adhesion to glass (adhesion to glass), Fraas brittle temperature, penetration index. For tar, the following characteristics such as density, flash point in an open crucible, and a boiling point were additionally determined. As a result of the experiments, the fundamental possibility of obtaining road oil bitumen by the method of chemical modification of tar with formaldehyde was established. It was revealed that the process factors (formaldehyde content in the reaction mixture, catalyst content in the reaction mixture, temperature and duration) have a significant effect on the quality of the resulting product. Changing their values allows you to adjust the values of the quality characteristics of the resulting bitumen. Keywords: binders, bitumen, oil residue, modification. Corresponding author V.М. Gunka, e-mail: [email protected]


Author(s):  
Dmitry G. Tovbin ◽  
Dmitry N. Tarasov ◽  
Dmitry V. Malakhov ◽  
Natalia A. Tserkovnikova ◽  
Arseniy V. Aybush ◽  
...  

Background: Despite the introduction of direct oral anticoagulants, the search for new oral anticoagulants remains an urgent task. Objective: Using the docking and scoring, based on physical methods, simple chemical rules, methods of synthesis and activity measurement, to develop new low-molecular-weight inhibitors of factor Xa, which are potential anticoagulants. Method: The development of leads was based on chemical synthesis and the structure-based drug design methods. The basic idea is to combine the two approaches: one based on predictive modeling, and the other – on the experimental data. Results: In frame of our concept we developed some nanomolar leads. Further chemical modification improved the inhibition constant by more than one order. Discussion: The method proposed in this paper, as well as other methods, includes virtual screening, screening, chemical synthesis and activity measurement. However, the most time – consuming process in this method (chemical synthesis) was decided to simplify and reduce the cost to the extent that it could be allowed: a very simple chemical reaction was chosen - the formation of an amide bond. Conclusion: In this work, we demonstrated how, using simple chemical rules, based on the structure-based drug design, substances with a nanomolar concentration of activity can be developed. Using our method, we developed substances with nanomolar concentration of activity. Further chemical modification of this leads improved the inhibition constant by more than one order.


Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.


1998 ◽  
Vol 1 (5) ◽  
pp. 166-174 ◽  
Author(s):  
Evelyn R Hermes De Santis ◽  
Betsy S Laumeister ◽  
Vidhu Bansal ◽  
Vandana Kataria ◽  
Preeti Loomba ◽  
...  

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