Vaporisation dEcomposition thermique de dimethylhydrazine,d'hydrate d'hydrazine de leur melange UH25

Engine Viking of Ariane 4 is supplied with asymmetrical dimethylhydrazine (UDMH) (CH₃)₂NNH₂. An addition of a small amount of hydrazine hydrate N₂H₄×H₂O was proposed to increase the thermal stability of UDMH. The mixture where the mass ratio (CH₃)₂NNH₂/N₂H₄×H₂O is equals to 75/25, is called UH25. These propelling agents are unstable when they are heated and the optimisation of burning conditions requires a good knowledge of their vaporisation and of their thermal decomposition kinetics. This revised version was published online in August 2006 with corrections to the Cover Date.     

Determination of picomole amounts of formaldehyde in air and bio-fluids based on its enhanced myoglobin-luminol chemiluminescence reaction

Abstract

The aim of this study was to assess the performance of selected destruction methods for the determination of heavy metals (Cd, Cu, Pb and Zn) in woodlouse (Oniscus asellus). A vigorous total analysis involving microwave destruction with HF, HCl and HNO₃ (method 1) was used as a reference method. Consistently low values for the dry ashing method may indicate incomplete dissolution of the elements and/or losses through volatilisation. Method 3 (concentrated HNO₃) that frequently is used in literature, produced erroneous values for Cd, Cu and Pb. Results were consistent with the microwave digestion, provided H₂O₂ was used during digestion (method 4, HNO₃/H₂O₂). Method 5 (HNO₃/HCIO₄, one destruction step) yielded low recoveries when only one destruction step was applied. Applying two destruction steps (method 6) resulted in values consistent with the microwave method, but was at the expense of reproducibility and rendered the method more lengthy and laborious. Because of the very good performance combined with speed and simplicity, destruction with HNO₃/H₂O₂ (method 4) emerged as the most convenient method.     

基于柠康酸构筑的三个配合物的合成、结构与性能

在水热条件下,制备出3个配位聚合物,即{[Zn（ca）（iimb）]·0.75H₂O}_n（1）,{[Cd（ca）（iimb）（H₂O）]·0.75H₂O}_n（2）和{[Zn（ca）（bpe）_0.5（H₂O）]·H₂O}_n（3）（H₂ca=柠康酸,iimb=1-（1-咪唑基）-4-（咪唑基-1''-甲基）苯,bpe=1,2-二（4-吡啶基）乙烯）,并通过单晶X射线衍射、红外光谱和元素分析进行结构表征。配合物1是含有一维金属羧酸链的二维网状层。2是具有羧酸桥连双核的一维准梯形链状结构。3是二维波浪层。其中2和3的三维超分子结构由丰富的氢键相互作用形成;而1的三维超分子结构通过范德华力堆积而成。研究了3个配合物的热重分析（TGA）,粉末X射线衍射（PXRD）和荧光性质。固态荧光光谱表明3个配合物的发射光谱与相应的辅助配体相似。此外,配合物3在紫外光照射下,在H₂O₂存在时对亚甲基蓝（MB）的降解表现出良好的光催化活性。     

Dual roles of substituted thiourea as reductant and ligand in CuAAC reaction

A highly efficient catalytic system, CuSO₄·5H₂O/1-(4-methoxyphenyl)-3-phenylthiourea, for the copper(I)-catalyzed azide–alkyne cycloaddition reaction (CuAAC) was discovered. In the above catalytic system, substituted thiourea acts both as a reductant and a ligand. CuSO₄·5H₂O/1-(4-methoxyphenyl)-3-phenylthiourea is both an economical and efficient catalyst for the CuAAC reaction. In addition, the new catalytic system has advantageous features including mild and green reaction conditions, and broad substrate compatibility. A variety of 1,4-disubstituted 1,2,3-triazoles have been prepared with good to excellent yields with the CuSO₄·5H₂O/1-(4-methoxyphenyl)-3-phenylthiourea catalytic system in aqueous solution.     

Synthesis of β-ketophosphonates with electron rich β-aryl groups as useful organophosphorus reagents in lignans synthesis

Investigation of the oxidation reaction of electron rich alkoxy substituted β-aryl β-hydroxyphosphonates to corresponding β-ketophosphonates, which may be utilized in syntheses of lignans with various oxidizing agents (PCC, PDC, SIBX, CAN, Oxone^®, KMNO₄/SiO₂, KMnO₄/MS 4 Å, KMnO₄/CuSO₄, KMnO₄/CuSO₄/Al₂O₃, MnO₂, CrO₃/SiO₂, H₂O₂/salen) is described. The effect of oxidants and reaction conditions on the reaction efficiency and yield was also investigated.     

Synthesis,crystal structure and characterization of a series of complexes constructed from coordinated Lanthanides(III) and the heteropolyanion [SiMo12O40]4−

The reaction of α-[SiMo₁₂O₄₀]^4? with trivalent cations Ln³⁺ and N-methyl-2-pyrrolidone leads to a series of complexes of formula [Ln(NMP)₄(H₂O) _n ]H[SiMo₁₂O₄₀]?·?2NMP?·?mH₂O [where Ln?=?La (1), Pr (2), Nd (3), Sm (4), Gd (5), n?=?4, Ln?=?Dy (6), Er (7), n?=?3. NMP?=?N-methyl-2-pyrrolidone]. The syntheses, X-ray crystal structures, IR, and ESR spectra and thermal properties of the complexes 1, 2, 4, 6, 7 have been reported previously. Here, we report X-ray crystal structures, IR, UV, ESR spectra and thermal properties of the complexes [Nd(NMP)₄(H₂O)₄]H[SiMo₁₂O₄₀]?·?2NMP?·?1.5H₂O (3), and [Gd(NMP)₄(H₂O)₄]H[SiMo₁₂O₄₀]?·?2NMP?·?H₂O (5). In addition, the electrochemical behaviour of this series of complexes in aqueous solution and aqueous-organic solution has been investigated and systematic comparisons have been made. All these complexes exhibit successive reduction process of the Mo atoms.     

Dependence of kinetics of copper sulfate pentahydrate dehydration on water vapor pressure

The dependence of the growth rate v_g of nuclei during CuSO₄·5H₂O dehydration upon water vapor pressure P_H2O has been investigated. At small P_H2O (less than 1 Torr at 50°C), v_g falls rapidly with decreasing P_H2O, and simultaneously v_g anisotropy disappears. At P_H2O = 1–9 Torr, v_g for elliptic and round nuclei is constant and independent of P_H2O. The influence of initially keeping the samples in water vapor upon the kinetics of the following dehydration has been studied. Treatment by water vapor leads to slowing of dehydration and increasing its degree of transformation. On the basis of data obtained a kinetic interpretation of the Topley-Smith effect has been proposed.     

DSC study of melting and solidification of salt hydrates

Most salt hydrates, especially those proposed for thermal-energy-storage applications, melt incongruently. In static systems, this property often leads to differences between the enthalpy of fusion and enthalpy of solidification. By means of differential scanning calorimetry (DSC), these differences have been determined for several salt hydrates. For Na₂SO₄ · 10 H₂O, the enthalpy of solidification at or near the peritectic temperature is never more than 60% of the enthalpy of fusion; further cooling leads to a second phase transition at a temperature corresponding to eutectic melting of mixtures of ice and this hydrate. This asymmetrical melting and freezing behavior of Na₂SO₄ · 10 H₂O decreases its potential as an energy-storing medium and also limits its usefulness for temperature calibration of DSC instruments. Sodium pyrophosphate decahydrate, Na₄P₂O₇ · 10 H₂O, although in some ways a higher temperature analog of Na₂SO₄ · 10 H₂O, exhibited a smaller discrepancy between the enthalpies of fusion and of solidification; its relatively high transition temperature permits a more rapid solidification reaction than is the case for Na₂SO₄ · 10 H₂O. For Mg(NO₃)₂ · 6 H₂O, a congruently melting compound, the magnitude of ΔH of crystallization equalled ΔH of fusion, even when supercooling occurred; a solid-state transition at 73°C, with ΔH = 2.9 cal g^?1, was detected for this hydrate. MgCl₂ · 6 H₂O, which melts almost congruently, exhibited no disparity between ΔH of crystallization and ΔH of fusion. CuSO₄ · 5 H₂O and Na₂B₄O₇ · 10 H₂O exhibited marked disparities. Na₂B₄O₇ · 10 H₂O formed metastable Na₂B₄O₇sd 5 H₂O at the phase transition; this was derived from the transition temperature and verified by relating the observed ΔH of transition to heats of hydration. Peritectic solidification of hydrates can be viewed as a dual process: crystallization from the liquid solution and reaction of the lower hydrate (or anhydrate) with the solution; where ΔH of solidification appears to be less in magnitude than the ΔH of fusion, the difference can be attributed to slower reaction rate between solution and the lower hydrate. New or previously unreported values for ΔH of fusion obtained in this study were, in cal g^?1: Mg(NO₃)₂ · 6 H₂O, 36; Na₄P₂O₇ · 10 H₂O, 59; CuSO₄ · 5 H₂O, 32; Na₂B₄O₇ · 10 H₂O, 33.     

2‐Azido‐2‐deoxycellulose: Synthesis and 1,3‐Dipolar Cycloaddition

Chitosan ( 1 ) was prepared by basic hydrolysis of chitin of an average molecular weight of 70000 Da, ¹H‐NMR spectra indicating almost complete deacetylation. N‐Phthaloylation of 1 yielded the known N‐phthaloylchitosan ( 2 ), which was tritylated to provide 3a and methoxytritylated to 3b . Dephthaloylation of 3a with NH₂NH₂?H₂O gave the 6‐O‐tritylated chitosan 4a . Similarly, 3b gave the 6‐O‐methoxytritylated 4b . CuSO₄‐Catalyzed diazo transfer to 4a yielded 95% of the azide 5a , and uncatalyzed diazo transfer to 4b gave 82% of azide 5b . Further treatment of 5a with CuSO₄ produced 2‐azido‐2‐deoxycellulose ( 7 ). Demethoxytritylation of 5b in HCOOH gave 2‐azido‐2‐deoxy‐3,6‐di‐O‐formylcellulose ( 6 ), which was deformylated to 7 . The 1,3‐dipolar cycloaddition of 7 to a range of phenyl‐, (phenyl)alkyl‐, and alkyl‐monosubstituted alkynes in DMSO in the presence of CuI gave the 1,2,3‐triazoles 8 – 15 in high yields.     

The relationship between the structures of Cu(II) complexes and their chemical transformations

The paper reports an attempt to correlate the structures of hydrates of copper(II) sulphate with some characteristic features of the kinetics of their thermal decompositions. Non-isothermal thermogravimetric measurements were employed to obtain values of experimental activation energy and entropy for the dehydration of CuSO₄ · 5 H₂O, CuSO₄ · 3 H₂O and CuSO₄ · H₂O. The values ofE ^* andΔS ^* for the dehydration of CuSO₄ · 3 H₂O were found to be only little affected by the mode of preparation of this compound. On the other hand, the values ofE ^* andΔS ^* for the dehydration of CuSO₄ · ·H₂O are strongly dependent on whether this compound was prepared by thermal decomposition of CuSO₄ · 5 H₂O or CuSO₄ · 3 H₂O, or by crystallization from solution. As regards the crystalline hydrates of copper(II) sulphate, the greatest energetic hindrance for dehydration was observed for CuSO₄ · 3 H₂O. The experimental results are also discussed with respect to the present opinions concerning the possibilities of using thermal analyses to obtain information on the relationship between the structures and reactivities of solids.     

Tetra(μ3-hydroxo) bridged copper(II) tetranuclear cubane complexes: synthesis,crystal structure,and DNA binding studies

The tridentate Schiff base H₂L was synthesized by the condensation of equimolar amount of 1-amino-2-propanol and salicylaldehyde. The reaction of H₂L with an equimolar amount of Cu(CH₃COO)₂·H₂O in methanol leads to the formation of the tetranuclear Cu₄L₄, 1. However, reaction of equimolar amount of H₂L, copper(II) acetate, and 2,4,6-trimethylaniline in methanol forms a mixture of products which includes a discrete mononuclear complex Cu(L′)₂, 2m (where HL′ is a bidentate ligand), in addition to the tetranuclear Cu₄L₄ species, 2c. In both tetranuclear cubane species, the tridentate H₂L is both a chelating and a bridging ligand, after deprotonation of the enolic and the phenolic OH. The copper(II) centers are five-coordinate with a [N, O₄] donor set from the ligands. The coordination geometry about each copper is distorted square pyramidal with one nitrogen and two oxygen from one ligand and two oxygen from adjacent ligands in the next unit of the cubane. In mononuclear 2m, the ligand is bidentate and the coordination geometry around copper(II) is square planar. The absorption spectra strongly suggest that tetranuclear 1 interacts with CT-DNA.     

Experimental Study on Demercurization Performance of Wet Flue Gas Desulfurization System

The demercurization performance of wet flue gas desulfurization (WFGD) system was investigated by measuring mercury concentrations at the inlet and outlet of WFGD system with a QM201H mercury analyzer. The selected desulfurizer included NH₃·H₂O, NaOH, Na₂CO₃, Ca(OH)₂ and CaCO₃. The influences of adding oxidant and coagulant such as KMnO₄, Fenton reagent, K₂S₂O₈/CuSO₄ and Na₂S into desulfurization solutions were also studied. The results show that elemental mercury is the main component of gaseous mercury in coal‐fired flue gas, and the proportion of oxidized mercury is less than 36%. Oxidized mercury could be removed by WFGD system efficiently, and the removal efficiency could amount to 81.1%–92.6%. However, the concentration of elemental mercury slightly increased at the outlet of WFGD as a result of its insolubility and re‐emission. Therefore, the removal efficiency of gaseous mercury is only 13.3%–18.3%. The mercury removal efficiency of WFGD system increased with increasing the liquid‐gas ratio. In addition, adding KMnO₄, Fenton reagent, K₂S₂O₈/CuSO₄ and Na₂S into desulfurization solutions could increase the mercury removal efficiency obviously. Various additives have different effects, and Na₂S is demonstrated to be the most efficient, in which a mercury removal efficiency of 67.2% can be reached.     

Zur Kenntnis der Reaktionsfähigkeit alkylsubstituierter Thiomorpholine, 2. Mitt.

Zusammenfassung Die Oxydation des 2-Methyl-3-äthylthiomorpholins (1) bzw. seines Hydrochlorids (1·HCl) mit 30proz. H₂O₂ liefert bei 0°C 87 bzw. 84% 2-Methyl-3-äthylthiomorpholin-1-oxid (4), bei 50°C 41 bzw. 46% 2-Methyl-3-äthylthiomorpholin-1,1-dioxid (7). Aus 2-Methyl-3-äthyl-4-formylthiomorpholin (2) bzw. 2-Methyl-3-äthyl-4-acetylthiomorpholin (3) erhält man die entspr. Sulfoxide (5 83%] bzw.6 [80%]), wenn man mit 30proz. H₂O₂ bei 0°C in Wasser bzw. Eisessig oxydiert, dagegen die entspr. Sulfone (8 [93%] bzw.9 [73%]), wenn in Ameisensäure bzw. Eisessig mit überschüss. 85proz. H₂O₂ bei 100°C oxydiert wird.8 und9 lassen sich mit verd. HCl glatt (ca. 90%) zu7 verseifen.Auf Basis von4 und7 werden zahlreiche s-Triazin-Derivate (10–26) und durch Addition von4 und7 an Isocyanate und Senföle einige Harnstoff- (27–31, 35–38) und Thioharnstoff-Derivate (32–34) dargestellt.

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On the reactivity of alkyl substituted thiomorpholines, II¹ (Joint action of elemental sulfur and gaseous ammonia upon ketones, LXXXI²)

Oxidation of 2-methyl-3-ethyl-thiomorpholine (1) and the corresponding hydrochloride (1·HCl) with 30% H₂O₂ leads to the 2-methyl-3-ethyl-thiomorpholine-1-oxide (4) at 0°C in a yield of 87 and 84%, resp.; at 50°C 2-methyl-3-ethyl-thiomorpholine-1.1-dioxide (7) is formed in a yield of 41 and 46%, resp. By oxidation of 2-methyl-3-ethyl-4-formyl-thiomorpholine (2) and 2-methyl-3-ethyl-4-acetyl-thiomorpholine (3) with a 30% solution of H₂O₂ at 0°C in water or acetic acid, resp., the corresponding sulfoxides (5 [83%] and6 [80%]) are obtained; with an excess of 85% H₂O₂ in formic or acetic acid at 100°C the respective sulfones (8 [93%] and9 [73%]) are formed.8 and9 are easily saponified with dilute HCl to7 in a yield of about 90%.A large number of s-triazine derivatives (10–26) are prepared from4 and7; by addition of isocyanates and thio isocyanates to4 and7 urea- (27–31, 35–38) and thiourea derivatives (32–34) are obtained.

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1. Mitt.:F. Asinger, H. Offermanns, A. Saus, C. Dudeck, D. Neuray undE. Wilms, Mh. Chem.104, 118 (1973).

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80. Mitt.:F. Asinger, A. Saus undD. Neuray, Ann. Chem. (im Druck).

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Teil der DiplomarbeitE. Wilms, Techn. Hochschule Aachen, 1969; Teil der DissertationE. Wilms, Techn. Hochschule Aachen 1971.     

Solvothermal synthesis and characterization of coordination polymers of cobalt(II) and zinc(II) with succinic acid

The complexes [Co(C₄H₄O₄)]_n (1) and [Zn(im)₂(C₄H₄O₄)]_n (2) (C₄H₄O₄ = succinate dianion, suc; im = imidazole) have been synthesized solvothermally and characterized by elemental analysis, IR, TG–DTA, and single-crystal X-ray diffraction techniques. Complex 1 is the first anhydrous member of the cobalt succinate family and has high thermal stability under a static air atmosphere, up to 425 °C, and complex 2 is a 1D coordination polymer. In addition, a new synthesis method and some properties of the known [Co(HCOO)₂·2H₂O]_n (3) complex are reported. After in situ synthesis of 3 via decomposition of DMF at 140 °C, it was found that complex 3 can adsorb some solvents repeatedly and is selective for H₂O.     

One-dimensional zinc(II) fumarate coordination polymers

A new procedure developed for the synthesis and crystallization of various zinc(II) fumarate hydrate coordination polymers is described. In the first step, anhydrous Zn(II) fumarate, [Zn(C₄H₂O₄)] (1), is synthesized from Zn(II) acetate and fumaric acid in methanol. Subsequently, this product is used as a starting material for growing small crystals of bis–aqua Zn(II) fumarate, [Zn(H₂O)₂(C₄H₂O₄)] (2), triaqua Zn(II) fumarate monohydrate, [Zn(H₂O)₃(C₄H₂O₄)]·H₂O (3), tetraaqua Zn(II) fumarate, [Zn(H₂O)₄(C₄H₂O₄)] (4), and tetraaqua Zn(II) fumarate monohydrate, [Zn(H₂O)₄(C₄H₂O₄)]·H₂O (5). All structures were determined or redetermined by X-ray structure analyses. The hitherto unknown compound 3 exhibits a zig-zag chain structure with five-coordinate Zn(II) ions.     

Optimized synthesis of selected 4-oxybenzaldehyde and 2,2-dioxybiphenyl cyclotriphosphazene derivatives

Abstract

Selected 4-oxybenzaldehyde and 2,2-dioxybiphenyl cyclotriphosphazene derivatives were synthesized via substitution reactions through tailored control. The reactions of cyclotriphosphazene with 4-oxybenzaldehyde and 2,2-dioxybiphenyl gave the following synthesized derivatives: one mono-substituted open-chain compound, N₃P₃Cl₅(O₂C₇H₅) (1, 69%); mono spiro, N₃P₃Cl₄(O₂C1₂H₈) (2, 91.1%); non-gem tri-substituted, N₃P₃Cl₃ (O₆C₂₁H₁₅) (3, 17%); dispiro, N₃P₃Cl₂(O₄C₂₄H₁₆) (4, 92.3%); penta-substituted, N₃P₃Cl(O₁₀C₃₅H₂₅) (5, 92%);hexa-substituted, N₃P₃(O₁₂C₄₂H₃₀). Most of these derivatives (1–6) are obtained with good yield (up to 97%), This work provides a simple and available approach to obtain versatile cyclotriphosphazene derivatives, which is expected to further promote the use of HCCP as phosphorus platform for the construction of multi-functional materials.     

Titanium-Substituted Heteropolytungstates as Model Catalysts for Studying the Mechanisms of Selective Oxidation by Hydrogen Peroxide

The ³¹P NMR method shows that four forms of titanium(IV)-monosubstituted Keggin-type heteropolytungstate (Ti–HPA) exist in MeCN: the dimer (Bu₄N)₇[{PTiW₁₁O₃₉}₂OH] (in the abbreviated form, (PW₁₁Ti)₂OH or H1), its conjugate base (PW₁₁Ti)₂O (1), and two monomers, PW₁₁TiO (2) and PW₁₁TiOH (H2). The ratio between the forms depends on the concentrations of H⁺and H₂O. Dimer H1is produced from 2in MeCN when H⁺(1.5 mol) is added, and monomer H2is the key intermediate in this process. The catalytic activity of Ti–HPA in the oxidation of thioethers by H₂O₂correlates with their activity in peroxo complex formation and decreases in the order H2> H1> 2. The reaction of 2with H₂O₂in MeCN occurs slowly to form the inactive peroxo complex PW₁₁TiO₂(A). The addition of H₂O₂to H1and H2most likely results in the formation of the active hydroperoxo complex PW₁₁TiOOH (B). Complexes Aand Btransform into each other when H⁺or OH^–(1 mol) is added per 1 mol of Aor B, respectively. The activity of Btoward thioethers in the stoichiometric reaction is proven by ³¹PNMR and optical spectroscopy.     

Synthesis,spectra and crystal structure of a dinuclear manganese(χ) complex [(NTB)Mn(μ-O)]2(ClO4)4 · 2H2O

A novel dinuclear manganese(χ) complex [(NTB)Mn(μ-O)]₂(ClO₄)₄?·?2H₂O (1) (NTB?=?tris(2-benzimidazolylmethyl) amine) has been synthesized and characterized. The crystal structure is determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic system, space group C2/c with a?=?18.3461(1), b?=?15.4170(1), c?=?21.0141(1)?Å, β?=?90.5290(1)°, V?=?5943.4(8)?ų, Z?=?4 and R ₁?=?0.0789 for 5729 observed reflections. Two manganese atoms are bridged by two oxygen atoms forming a dinuclear complex. The results of interaction between 1 and H₂O₂ indicated that hydrogen peroxide destroyed the Mn₂O₂ unit of 1.     

Effect of sample preparation conditions on the determination of the total concentrations of unsymmetrical dimethylhydrazine in soils

It is shown that, for a correct determination of the total concentration of unsymmetrical dimethylhydrazine (UDMH) in soil, it is necessary to consider the simultaneous presence of active products of its transformation, capable of hydrolysis to the parent compound, such as formic acid 1,1-dimethylhydrazide (FADMH). A comparative study is performed of the methods known in the literature for sample preparation to select conditions for the quantitative extraction of UDMH bonded by various mechanisms to organic and mineral fractions of soil, as well as FADMH as one of the most common active transformation products. It is found that the distillation with a 40% NaOH solution with an addition of Na₂S enables the quantitative recovery of UDMH and FADMH from soils of all types and the determination of the maximum concentration of UDMH in the analysis of real samples of contaminated soils, which allows us to recommend this option to determine the total concentration of UDMH.     

Influence of modified atmosphere treatment on post-harvest reactive oxygen metabolism of pomegranate peels

Abstract

Modified atmosphere storage can regulate the reactive oxygen metabolism of fruits and vegetables, reduce the accumulation of hazardous free radicals, and mitigate the peroxidation degree of fruit membrane lipids. In this study, different gas matching ratios were adopted for the modified atmosphere treatment of pomegranate fruits. Up to 120 d of storage, compared with the control treatment, the H₂O₂ and malonaldehyde (MDA) contents in treatment 2 decreased by 8.88% and 18.28%, respectively, when the activities of superoxide dismutase (SOD), catalase (CAT) and ascorbic acid peroxidase (APX) in treatment 2 increased by 21.44%, 117.38% and 114.95%, the ascorbic acid (ASA) and glutathione (GSH) contents in treatment 2 also increased by 116.83% and 50%, these results showed that treatment 2 (6.0% O₂, 6.0% CO₂) could effectively regulate various indexes of the reactive oxygen metabolism of pomegranate peels, maintain the normal physiological actions of the fruits, and postpone the ripening and senescence of histocytes. Under treatment 4 (10.0% O₂, 10.0% CO₂), H₂O₂ contents in the pomegranate peel significantly increased, and the activities of SOD, CAT and APX significantly reduced. ASA and GSH were degraded, the MDA content abruptly increased, the membrane lipid peroxidation accelerated, and the cytomembrane structure was destroyed.