direct reaction
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Biomimetics ◽  
2022 ◽  
Vol 7 (1) ◽  
pp. 10
Author(s):  
Alexander Pestov ◽  
Yuliya Privar ◽  
Arseny Slobodyuk ◽  
Andrey Boroda ◽  
Svetlana Bratskaya

Here we demonstrate the possibility of using acyclic diethylacetal of acetaldehyde (ADA) with low cytotoxicity for the fabrication of hydrogels via Schiff bases formation between chitosan and acetaldehyde generated in situ from acetals in chitosan acetate solution. This approach is more convenient than a direct reaction between chitosan and acetaldehyde due to the better commercial availability and higher boiling point of the acetals. Rheological data confirmed the formation of intermolecular bonds in chitosan solution after the addition of acetaldehyde diethyl acetal at an equimolar NH2: acetal ratio. The chemical structure of the reaction products was determined using elemental analysis and 13C NMR and FT-IR spectroscopy. The formed chitosan-acetylimine underwent further irreversible redox transformations yielding a mechanically stable hydrogel insoluble in a broad pH range. The reported reaction is an example of when an inappropriate selection of acid type for chitosan dissolution prevents hydrogel formation.


2022 ◽  
Vol 58 (1) ◽  
Author(s):  
M. Avrigeanu ◽  
D. Rochman ◽  
A. J. Koning ◽  
U. Fischer ◽  
D. Leichtle ◽  
...  

AbstractFollowing the EUROfusion PPPT-programme action for an advanced modeling approach of deuteron-induced reaction cross sections, as well as specific data evaluations in addition of the TENDL files, an assessment of the details and corresponding outcome for the latter option of TALYS for the breakup model has been carried out. The breakup enhancement obtained in the meantime within computer code TALYS, by using the evaluated nucleon-induced reaction data of TENDL-2019, is particularly concerned. Discussion of the corresponding results, for deuteron-induced reactions on $$^{58}$$ 58 Ni, $$^{96}$$ 96 Zr, and $$^{231}$$ 231 Pa target nuclei up to 200 MeV incident energy, includes limitations still existing with reference to the direct-reaction account.


Author(s):  
Durgesh Kumar Soni ◽  
Dr. Arun Maithani ◽  
Dr. P. K. Kamani

Glycidyl acrylate (GA) and Glycidylmethacrylate (GMA) are the reaction products of the epichlorohydrin (ECH) with acrylic acid (AA) and methacrylic acid (MAA) respectively. These monomers were synthesized via two different routes i.e. direct reaction of AA and MAA with ECH and second by reaction of AA and MAA with Sodium hydroxide to form sodium salt of the acid followed by reacting with ECH. The polymerization inhibitor used was tert-butyl hydroquinone (TBHQ) and catalysts used were triethylamine (TEA) and quaternary ammonium salt. Experimental results show that first route is suitable for synthesizing GA and second route is suitable for synthesis of GMA. The catalysts also have drastic effect on the conversion to the respective glycidyl esters. The study of the effect of catalyst and polymerization inhibitor has been carried out via both routes.


Author(s):  
Lalit Kumar Sahoo ◽  
Chinmay Basu

The direct reaction component of the [Formula: see text]F([Formula: see text]) reaction at [Formula: see text][Formula: see text]keV is studied for the data that became very recently available. This component is significant in this work using the direct pickup model in the framework of the DWBA formalism and indicate the strong cluster structure of [Formula: see text]F. The direct component of astrophysical S-factor is calculated for [Formula: see text]F([Formula: see text]).


2021 ◽  
pp. 1-28
Author(s):  
Surong Luo ◽  
Zhen Wang ◽  
Qingnan Gong ◽  
Dehui Wang

To clarify the role of temperature in the thaumasite formation of cement mortar under magnesium sulfate solution at two different temperature, the corrosion products and microstructure of cement-based materials with different amounts and particle sizes of limestone powder (LP) were quantitatively analyzed by Fourier Transform Infra-Red (FTIR), thermogravimetric analysis (TGA), X-ray Diffraction (XRD), Scanning Electronic Microscopy (SEM) and Energy Dispersive Spectrometer (EDS). At 5oC, the main corrosion product of cement mortar was gypsum and thaumasite. At 20°C, the main corrosion products of cement mortar were gypsum and ettringite. When the temperature increased from 5°C to 20°C, the contents of ettringite, thaumasite and gypsum changed from 0.3%, 12.3% and 64.6% to 4.6%, 0% and 57.0%, respectively. The formation of thaumasite was the combination of direct reaction with ettringite transformation. The incorporation of LP accelerated the corrosion of mortars, and the change coefficient of compressive strength of mortars decreased from 100% to 47.3% when its content increased from 0% to 30%. Low temperature and incorporation of finer limestone powder enhanced the corrosion of magnesium sulfate solution.


Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7402
Author(s):  
Katarzyna Sołtys-Brzostek ◽  
Kamil Sokołowski ◽  
Iwona Justyniak ◽  
Michał K. Leszczyński ◽  
Natalia Olejnik-Fehér ◽  
...  

Introduction of photoactive building blocks into mixed-ligand coordination polymers appears to be a promising way to produce new advanced luminescent materials. However, rational design and self-assembly of the multi-component supramolecular systems is challenging from both a conceptual and synthetic perspective. Here, we report exploratory studies that investigate the potential of [Zn(q)2]2[tBuZn(OH)]2 complex (q = deprotonated 8-hydroxyquinoline) as an organozinc precursor as well as a mixed-ligand synthetic strategy for the preparation of new luminescent coordination polymers (CPs). As a result we present three new 2D mixed-ligand Zn(II)-quinolinate coordination polymers which are based on various zinc quinolinate secondary building units interconnected by two different organic linker types, i.e., deprotonated 4,4′-oxybisbenzoic acid (H2obc) as a flexible dicarboxylate linker and/or selected bipyridines (bipy). Remarkably, using the title organozinc precursors in a combination with H2obc and 4,4′-bipyridine, a novel molecular zinc quinolinate building unit, [Zn4(q)6(bipy)2(obc)2], was obtained which self-assembled into a chain-type hydrogen-bonded network. The application of the organometallic precursor allowed for its direct reaction with the selected ligands at ambient temperature, avoiding the use of both solvothermal conditions and additional base reagents. In turn, the reaction involving Zn(NO3)2, as a classical inorganic precursor, in a combination with H2obc and bipy led to a novel 1D coordination polymer [Zn2(q)2(NO3)2(bipy)]. While the presence of H2obc was essential for the formation of this coordination polymer, this ditopic linker was not incorporated into the isolated product, which indicates its templating behavior. The reported compounds were characterized by single-crystal and powder X-ray diffraction, elemental analysis as well as UV-Vis and photoluminescence spectroscopy.


2021 ◽  
Author(s):  
Adarsha Gupta ◽  
Max Worthington ◽  
Munish Puri ◽  
Justin Chalker

There is growing interest in the bio-based production of lipids from algae. These lipids have a range of uses including nutritional supplements and precursors to biodiesel. Single-cell thraustochytrids are especially attractive in this regard in that they can produce over 50% of their weight as triglycerides. Furthermore, the distribution of saturated and unsaturated triglycerides can be modulated by changes in strain variation and modulation of fermentation conditions. Nonetheless, there remains a need for versatile downstream processing to enrich these so-called “single cell oils” into classes based on degree of unsaturation. In this study, we report a novel strategy for enriching saturated triglycerides produced in thraustochytrids. The method features direct reaction of elemental sulfur with the algae oil extract. The sulfur copolymerizes with >90% of the unsaturated triglycerides, providing a new route to a class of materials previously used in environmental remediation, Li-S battery cathodes, slow-release fertilisers, and insulation. The unreacted oil is enriched in saturated triglycerides, which can be isolated by extraction for potential use in biodiesel production. In this way, a single batch of sustainably produced algae oil can be converted into multiple useful products in a single step.


2021 ◽  
Author(s):  
Songyang Liu ◽  
Liping Zhou ◽  
Ci Li ◽  
Tiantian Min ◽  
Changfeng Lu ◽  
...  

Abstract Peripheral nerve injury (PNI) is one of the common clinical injuries which needs to be addressed. Previous studies demonstrated the effectiveness of using biodegradable chitin (CT) conduits small gap tubulization technology as a substitute for traditional epineurial neurorrhaphy. Aiming to improve the effectiveness of CT conduits in repairing PNI, we modified their surface with a DNA-peptide coating. The coating consisted of single strand DNA (ssDNA) and its complementary DNA’-peptide mimics. First, we immobilize ssDNA (DNA1+2) on CT conduits by EDC/NHS method to construct CT/DNA conduits. EDC/NHS was used to activate carboxyl groups of modified ssDNA for direct reaction with primary amines on the chitin via amide bond formation. Then, DNA1’-BDNF+DNA2’-VEGF mimic peptide (RGI+KLT)were bonded to CT/DNA conduits by complementary base pairing principle at room temperature to form CT/RGI+KLT conduits. When the surrounding environment rose to a certain point (37℃), the CT/RGI+KLT conduits achieved sustainable release of DNA’-peptide. In vitro, the CT conduits modified with the DNA-peptide coating promoted the proliferation and secretion of Schwann cells by maintaining their repair state. It also promoted the proliferation of HUVECs and axon outgrowth of DRG explants. In vivo, CT/RGI+KLT conduits promoted regeneration of injured nerves and functional recovery of target muscles, which was facilitated by the synergistic contribution of angiogenesis and neurogenesis. Our research brings DNA and DNA-peptide hybrids into the realm of tissue engineering to repair peripheral nerve injury.


Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 7003
Author(s):  
Dimitrios Tsikas

Carbon dioxide (CO2) and carbonates, which are widely distributed in nature, are constituents of inorganic and organic matter and are essential in vegetable and animal organisms. CO2 is the principal greenhouse gas in the atmosphere. In human blood, CO2/HCO3− is an important buffering system. Inorganic nitrate (ONO2−) and nitrite (ONO−) are major metabolites and abundant reservoirs of nitric oxide (NO), an endogenous multifunctional signaling molecule. Carbonic anhydrase (CA) is involved in the reabsorption of nitrite and nitrate from the primary urine. The measurement of nitrate and nitrite in biological samples is of particular importance. The derivatization of nitrate and nitrite in biological samples alongside their 15N-labeled analogs, which serve as internal standards, is a prerequisite for their analysis by gas chromatography–mass spectrometry (GC-MS). A suitable derivatization reagent is pentafluorobenzyl bromide (PFB-Br). Nitrate and nitrite are converted in aqueous acetone to PFB-ONO2 and PFB-NO2, respectively. PFB-Br is also useful for the GC-MS analysis of carbonate/bicarbonate. This is of particular importance in conditions of pharmacological CA inhibition, for instance by acetazolamide, which is accompanied by elevated concomitant excretion of nitrate, nitrite and bicarbonate, as well as by urine alkalization. We performed a series of experiments with exogenous bicarbonate (NaHCO3) added to human urine samples (range, 0 to 100 mM), as well as with endogenous bicarbonate resulting from the inhibition of CA activity in healthy subjects before and after ingestion of pharmacological acetazolamide. Our results indicate that bicarbonate enhances the derivatization of nitrate with PFB-Br. In contrast, bicarbonate decreases the derivatization of nitrite with PFB-Br. Bicarbonate is not a catalyst, but it enhances PFB-ONO2 formation and inhibits PFB-NO2 formation in a concentration-dependent manner. The effects of bicarbonate are likely to result from its reaction with PFB-Br to generate PFB-OCOOH. Nitrate reacts with concomitantly produced PFB-OCOOH to form PFB-ONO2 in addition to the direct reaction of nitrate with PFB-Br. By contrast, nitrite does not react with PFB-OCOOH to form PFB-NO2. Sample acidification by small volumes of 20 wt.% aqueous acetic acid abolishes the effects of exogenous and endogenous bicarbonate on nitrite measurement.


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