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2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Hee Jeong Im ◽  
Yong Joon Park

AbstractLithia (Li2O)-based cathodes, utilizing oxygen redox reactions for obtaining capacity, exhibit higher capacity than commercial cathodes. However, they are highly reactive owing to superoxides formed during charging, and they enable more active parasitic (side) reactions at the cathode/electrolyte and cathode/binder interfaces than conventional cathodes. This causes deterioration of the electrochemical performance limiting commercialization. To address these issues, the binder and salt for electrolyte were replaced in this study to reduce the side reaction of the cells containing lithia-based cathodes. The commercially used polyvinylidene fluoride (PVDF) binder and LiPF6 salt in the electrolyte easily generate such reactions, and the subsequent reaction between PVDF and LiOH (from decomposition of lithia) causes slurry gelation and agglomeration of particles in the electrode. Moreover, the fluoride ions from PVDF promote side reactions, and LiPF6 salt forms POF3 and HF, which cause side reactions owing to hydrolysis in organic solvents containing water. However, the polyacrylonitrile (PAN) binder and LiTFSI salt decrease these side reactions owing to their high stability with lithia-based cathode. Further, thickness of the interfacial layer was reduced, resulting in decreased impedance value of cells containing lithia-based cathodes. Consequently, for the same lithia-based cathodes, available capacity and cyclic performance were increased owing to the effects of PAN binder and LiTFSI salt in the electrolyte.


Author(s):  
И.А. Крупнова ◽  
Г.Т. Суханов ◽  
К.К. Босов ◽  
А.Г. Суханова ◽  
Ю.В. Филиппова ◽  
...  

Изучен процесс взаимодействия 1-метил-5-нитро-1,2,4-триазола с многоцентровым бифункциональным О-нуклеофилом – диаминоглиоксимом. Показано, что исходный субстрат вступает в реакцию SNipso-замещения нитрогруппы с гидроксильными группами О-нуклеофила с образованием биологически активного соединения, объединяющего в единой молекуле фармакофорные фрагменты различного типа – 1,2,4-триазоловые гетероциклы и NH2-группы. Процесс сопровождается конкурентными реакциями образования триазолона и продукта его дальнейшего взаимодействия с исходным субстратом. С помощью веб-ресурса PASS Online осуществлен компьютерный скрининг, показано, что исходный субстрат и продукты реакции могут выступать потенциальными фармацевтическими субстанциями. The reaction between 1-methyl-5-nitro-1,2,4-triazome and a concerted bifunctional О-nucleophile – diaminoglyoxime was explored herein. The starting substrate was shown to engage into the SNipso-substitution of the nitro group by the О-nucleophile hydroxyls to furnish a bioactive compound whose single molecule combines different-type pharmacophoric moieties – 1,2,4-triazole heterocycles and NH2groups. The process came amid competitive reactions to form triazolone and a product from its subsequent reaction with the starting substrate. The PASS Online web-resource was used to perform computer-aided screening, demonstrating that the starting substrate and the reaction products can serve as potential pharmaceutical substances.


2021 ◽  
Vol 3 (12) ◽  
Author(s):  
Ayotomi Olokun ◽  
Tyler Dillard ◽  
Abhijeet Dhiman ◽  
Vikas Tomar

AbstractFor energetic crystals such as HMX, the sensitivity of the material to shock, the possibility of initiation, and the subsequent reaction is known to be controlled by processes occurring at the crystal level. The anisotropic nature of β-HMX can be critical in determining the performance of HMX based polymer bonded explosives, which are widely used across multiple industries as propellant or explosives. In this work, we experimentally obtain constitutive parameters for characterizing the response of multiple crystalline planes of β-HMX crystals to external loading. Nanoindentation and small-scale dynamic impact experiments were performed on multiple planes of β-HMX crystals to comparatively measure the indentation moduli in multiple orientation directions. Anisotropic material behavior, involving constitutive elastic and non-elastic parameters, was measured and studied. Findings regarding material properties for the (100), (010), (001), {110}, and {011} planes of β-HMX are presented and compared with literature data.


2021 ◽  
Author(s):  
Hee Jeong Im ◽  
Yong Joon Park

Abstract Lithia (Li2O)-based cathodes, utilizing oxygen redox reactions for obtaining capacity, exhibit higher capacity than commercial cathodes. However, they are highly reactive owing to superoxides formed during charging, and they enable more active parasitic (side) reactions at the cathode/electrolyte and cathode/binder interfaces than conventional cathodes. This causes deterioration of the electrochemical performance limiting commercialization. To address these issues, the binder and salt for electrolyte were replaced in this study to reduce the side reaction of the cells containing lithia-based cathodes. The commercially used polyvinylidene fluoride (PVDF) binder and LiPF6 salt in the electrolyte easily generate such reactions, and the subsequent reaction between PVDF and LiOH (from decomposition of lithia) causes slurry gelation and agglomeration of particles in the electrode. Moreover, the fluoride ions from PVDF promote side reactions, and LiPF6 salt forms POF3 and HF, which cause side reactions owing to hydrolysis in organic solvents containing water. However, the polyacrylonitrile (PAN) binder and LiTFSI salt decrease these side reactions owing to their high stability with lithia-based cathode. Further, thickness of the interfacial layer was reduced, resulting in decreased impedance value of cells containing lithia-based cathodes. Consequently, for the same lithia-based cathodes, available capacity and cyclic performance were increased owing to the effects of PAN binder and LiTFSI salt in the electrolyte.


Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5940
Author(s):  
Julia Modrzejewska ◽  
Marcin Szala ◽  
Aleksandra Grzelakowska ◽  
Małgorzata Zakłos-Szyda ◽  
Jacek Zielonka ◽  
...  

Derivatives of coumarin, containing oxidant-sensitive boronate group, were recently developed for fluorescent detection of inflammatory oxidants. Here, we report the synthesis and the characterization of 3-(2-benzothiazolyl)-7-coumarin boronic acid pinacol ester (BC-BE) as a fluorescent probe for the detection of peroxynitrite (ONOO–), with high stability and a fast response time. The BC-BE probe hydrolyzes in phosphate buffer to 3-(2-benzothiazolyl)-7-coumarin boronic acid (BC-BA) which is stable in the solution even after a prolonged incubation time (24 h). BC-BA is slowly oxidized by H2O2 to form the phenolic product, 3-benzothiazol-2-yl-7-hydroxy-chromen-2-one (BC-OH). On the other hand, the BC-BA probe reacts rapidly with ONOO−. The ability of the BC-BA probe to detect ONOO– was measured using both authentic ONOO– and the system co-generating steady-state fluxes of O2•– and •NO. BC-BA is oxidized by ONOO– to BC-OH. However, in this reaction 3-benzothiazol-2-yl-chromen-2-one (BC-H) is formed in the minor pathway, as a peroxynitrite-specific product. BC-OH is also formed in the reaction of BC-BA with HOCl, and subsequent reaction of BC-OH with HOCl leads to the formation of a chlorinated phenolic product, which could be used as a specific product for HOCl. We conclude that BC-BA shows potential as an improved fluorescent probe for the detection of peroxynitrite and hypochlorite in biological settings. Complementation of the fluorescence measurements by HPLC-based identification of oxidant-specific products will help to identify the oxidants detected.


2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Fahrudin Kurniawan ◽  
Wawan Trisnadi Putra ◽  
Munaji Munaji ◽  
Rizal Arifin

This study aims to determine the inner surface morphology of pipes and to identify pipe corrosion products using stereo microsocope and X-ray diffraction (XRD) observations. In this study, the sample used was a piece of Blacksteel gas pipe that had been used for 107 days and 570 days with dimensions of 3 cm in length and 4 cm in diameter. The sample was taken from the Air heater Unit of the Pagotan Madiun sugar factory, East Java, Indonesia. Morphology the inside of the tube was observed with a CARL ZEISS Stemi DV4 stereo microscope (32x magnification). Furthermore, the rust material powder on the sample pipe was taken to determine the corrosion product using the XRD X'Pert PRO instrument. The results of observation by using a stereo microscope on the inner surface of air heater pipe that had been used for 107 days and 570 days indicated that the pipe surface experienced corrosion and peeling. From the results of X-ray diffraction (XRD) observations, FeOOH layer were formed from Fe2+ and OH- ions produced from O2 and H2O molecules in the smoke gas from burning bagasse. At the bottom of FeOOH layer, Fe3O4 was formed from the subsequent reaction between FeOOH and Fe2+ ions.Keywords: pipe, air heater, corrosion, smoke gas.


Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3808
Author(s):  
Gita Matulevičiūtė ◽  
Eglė Arbačiauskienė ◽  
Neringa Kleizienė ◽  
Vilija Kederienė ◽  
Greta Ragaitė ◽  
...  

Series of methyl 3- and 5-(N-Boc-piperidinyl)-1H-pyrazole-4-carboxylates were developed and regioselectively synthesized as novel heterocyclic amino acids in their N-Boc protected ester form for achiral and chiral building blocks. In the first stage of the synthesis, piperidine-4-carboxylic and (R)- and (S)-piperidine-3-carboxylic acids were converted to the corresponding β-keto esters, which were then treated with N,N-dimethylformamide dimethyl acetal. The subsequent reaction of β-enamine diketones with various N-mono-substituted hydrazines afforded the target 5-(N-Boc-piperidinyl)-1H-pyrazole-4-carboxylates as major products, and tautomeric NH-pyrazoles prepared from hydrazine hydrate were further N-alkylated with alkyl halides to give 3-(N-Boc-piperidinyl)-1H-pyrazole-4-carboxylates. The structures of the novel heterocyclic compounds were confirmed by 1H-, 13C-, and 15N-NMR spectroscopy and HRMS investigation.


2021 ◽  
Author(s):  
Feng Tang ◽  
Yuqi Jin ◽  
Yong Chi ◽  
Zhongxu Zhu ◽  
Jie Cai ◽  
...  

Abstract The co-pyrolysis tar formed from microcrystalline cellulose (MCC) and polyethylene (PE) was used to study their further conversion path under the effect of steam. This paper addressed the yield and transformation of tar with different steam/feedstock mass ratios (S/F= 0.8, 1.6) in a two-stage fixed-bed when the two stages furnace temperature was set at 600℃ and 800℃, separately. Compared with pyrolysis, steam promoted tar cracking effectively, the tar yield decreased at least 1/3. However, with the addition of steam, the cracking effect of tar is not further improved. The tar yield depended more on the PE content in the mixture, which was enhanced with PE increment. Besides, the H/C atom ratio was related to the conversion path of tar. Steam was beneficial to the cracking of compounds, but the generated hydrogen radicals affected the direction of the subsequent reaction. The steam mainly promotes the cracking of long-chain hydrocarbons, accompanied by cyclization and aromatization when the steam was limited. Nevertheless, these reactions were hindered when the steam was excessive due to the apparent effect of hydrogenation. In this process, the short-chain hydrocarbons come to recombine instead of cyclization and aromatization.


Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 605
Author(s):  
Gonzalo de Gonzalo ◽  
Andrés R. Alcántara

Baeyer–Villiger monooxygenases (BVMOs) are flavin-dependent oxidative enzymes capable of catalyzing the insertion of an oxygen atom between a carbonylic Csp2 and the Csp3 at the alpha position, therefore transforming linear and cyclic ketones into esters and lactones. These enzymes are dependent on nicotinamides (NAD(P)H) for the flavin reduction and subsequent reaction with molecular oxygen. BVMOs can be included in cascade reactions, coupled to other redox enzymes, such as alcohol dehydrogenases (ADHs) or ene-reductases (EREDs), so that the direct conversion of alcohols or α,β-unsaturated carbonylic compounds to the corresponding esters can be achieved. In the present review, the different synthetic methodologies that have been performed by employing multienzymatic strategies with BVMOs combining whole cells or isolated enzymes, through sequential or parallel methods, are described, with the aim of highlighting the advantages of performing multienzymatic systems, and show the recent advances for overcoming the drawbacks of using BVMOs in these techniques.


2021 ◽  
Vol 47 (3) ◽  
pp. 197-208
Author(s):  
V. Ya. Shevchenko ◽  
S. N. Perevislov ◽  
V. L. Ugolkov

Abstract The chemical processes occurring during the interaction of carbon (diamond) with silicon are experimentally investigated. Thermal analysis of the interaction of diamond with silicon is carried out. This made it possible to determine the mechanism of the synthesis of silicon carbide and subsequent reaction sintering of diamond particles based on Turing’s reaction-diffusion process and the formation of a microstructure consisting of triple periodic surfaces of the minimal energy.


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