Zn2SnO4@Ti ceramic film anode preparation by microarc oxidation for 2e- WOR degradation of unsymmetrical dimethylhydrazine (UDMH).

The main challenge facing the anodic electro-Fenton through the 2e- water oxidation reaction (WOR) for toxics degradation lies in the electrode's stability, because the anodic oxygen evolution (OER) generated O2 will inevitably exfoliate the electro-active components loaded on the electrode substrate. To address this point, two aspects need attention: 1) Identifying a catalyst that exhibits both excellent electrocatalytic activity and selectivity can improve the faradaic efficiency of hydrogen peroxide (H2O2); 2) Employing novel methods for fabricating highly stable electrodes, where active sites can be firmly coated. Consequently, this study utilized microarc oxidation (MAO) to prepare a ceramic film electrode Zn2SnO4@Ti at 300 V. Zn2SnO4 acts as an WOR electrocatalyst and further improved the generation of H2O2 for treating real wastewater containing Unsymmetrical Dimethylhydrazine (UDMH). From the perspective of characterization of electrode structure, Zn2SnO4@Ti forms a stable active coating, the electrochemical yield of H2O2 is high up to 78.4 µmol h-1 cm-2, and the selectivity of H2O2 is over 80% at 3.3 V vs. RHE, which can be fully applied to scenarios where it is inconvenient to transport H2O2 and need in-situ safe production. Additionally, the prepared electrodes exhibit significant stability, suitable for various applications, providing insightful preparation strategies and experiences for constructing highly stable anodes.

The Recycling of Substandard Rocket Fuel N,N-Dimethylhydrazine via the Involvement of Its Hydrazones Derived from Glyoxal, Acrolein, Metacrolein, Crotonaldehyde, and Formaldehyde in Organic Synthesis.

"Heptil" (unsymmetrical dimethylhydrazine-UDMH) is extensively employed worldwide as a propellant for rocket engines. However, UDMH constantly loses its properties as a result of its continuous and uncontrolled absorption of moisture, which cannot be rectified. This situation threatens its long-term usability. UDMH is an exceedingly toxic compound (Hazard Class 1), which complicates its transportation and disposal. Incineration is currently the only method used for its disposal, but this process generates oxidation by-products that are even more toxic than the original UDMH. A more benign approach involves its immediate reaction with a formalin solution to form 1,1-dimethyl-2-methylene hydrazone (MDH), which is significantly less toxic by an order of magnitude. MDH can then be polymerized under acidic conditions, and the resulting product can be burned, yielding substantial amounts of nitrogen oxides. This review seeks to shift the focus of MDH from incineration towards its application in the synthesis of relatively non-toxic and readily available analogs of various pharmaceutical substances. We aim to bring the attention of the international chemical community to the distinctive properties of MDH, as well as other hydrazones (such as glyoxal, acrolein, crotonal, and meta-crolyl), wherein each structural fragment can initiate unique transformations that have potential applications in molecular design, pharmaceutical research, and medicinal chemistry.

EFFECT OF DRY EXTRACT FROM REISHI MUSHROOMS ON THE STATE OF ANTIOXIDANT SYSTEM IN RATS WITH DMH-INDUCED COLON CARCINOGENESIS.

OBJECTIVE: The aim: To study pro- and antioxidant systems indicators in rats with chemically induced colon carcinogenesis on the background of the reishi mushrooms dry extract use. PATIENTS AND METHODS: Materials and methods: The study was performed on 120 white male rats. Chronic oncogenic intoxication was modeled by administering 1,2-dimethyl¬hydrazine (DMH) hydrochloride for 30 weeks (1 time per week). A dry extract from the reishi mushrooms was administered intragastrically daily at a dose of 100 mg/kg of the animal's body weight. Blood and liver samples were taken for research monthly. The state of the pro- and antioxidant systems was studied by the content of oxidative modification of proteins products, superoxide dismutase and catalase activity, contents of reduced glutathione and ceruloplasmin. RESULTS: Results: An increase in the activity of free radical oxidation processes after DMH-induced colon carcinogenesis in rats is evidenced by a decrease in the super-oxide dismutase activity, catalase activity, content of reduced glutathione, an increase in the content of ceruloplasmin and products of oxidative modification of proteins in the blood serum and liver of animals. The effectiveness of the dry extract of reishi mushrooms and its positive effect on the state of pro- and antioxidant systems was experimentally proved. CONCLUSION: Conclusions: The use of the dry extract of reishi mushrooms under conditions of DMH-induced colon carcinogenesis in rats led to normalization of the anti¬oxidant protection system state and the reduction of oxidative stress.

Ficus dubia latex extract prevent DMH-induced rat early colorectal carcinogenesis through the regulation of xenobiotic metabolism, inflammation, cell proliferation and apoptosis.

Ficus dubia latex is recognized as a remedy in Asian traditional medicine with various therapeutic effects. The present study aimed to determine the preventive action of Ficus dubia latex extract (FDLE) on 1,2-dimethylhydrazine (DMH)-induced rat colorectal carcinogenesis and its mechanisms. The experiment included an initiation model in which rats were orally administered with FDLE daily for 1 week before DMH injection until the end of the experiment, while only after DMH injection until the end in the post-initiation model. The results firstly indicated that FDLE treatment could reduce the level of methylazoxymethanol (MAM) in rat colonic lumen by inhibition of the activities of both phase I xenobiotic metabolizing enzymes in the liver and ß-glucuronidase in the colon, leading to reduced DNA methylation in colonic mucosal cells, related to the number of ACF in the initiation stage. Besides, FDLE modulated the inflammation which could suppress the growth and induce apoptosis of aberrant colonic mucosal cells, leading to retardation of ACF multiplicity. Therefore, FDLE showed the ability to suppress the DMH-induced rat ACF formation and inflammation promoted growth of ACF. In conclusion, FDLE had the potential to prevent carcinogens-induced rat colorectal carcinogenesis in the initiation stage.

Rapid Simultaneous Quantification of 1-Formyl-2,2-Dimethylhydrazine and Dimethylurea Isomers in Environmental Samples by Supercritical Fluid Chromatography-Tandem Mass Spectrometry.

When released to the environment, the rocket fuel unsymmetrical dimethylhydrazine (UDMH) undergoes oxidative transformations, resulting in the formation of an extremely large number of nitrogen-containing transformation products, including isomeric compounds which are difficult to discriminate by common chromatography techniques. In the present work, supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS) was proposed for resolving the problem of fast separation and simultaneous quantification of 1-formyl-2,2-dimethylhydrazine (FADMH) as one of the major UDMH transformation products, and its isomers-1,1-dimethylurea (UDMU) and 1,2-dimethylurea (SDMU). 2-Ethylpyridine stationary phase provided baseline separation of analytes in 1.5 min without the distortion of the chromatographic peaks. Optimization of SFC separation and MS/MS detection conditions allowed for the development of rapid, sensitive, and "green" method for the simultaneous determination of FADMH, UDMU, and SDMU in environmental samples with LOQs of 1-10 µg L-1 and linear range covering three orders of magnitude. The method was validated and successfully tested on the real extracts of peaty and sandy soils polluted with rocket fuel and UDMH oxidation products. It was shown that both UDMU and SDMU are formed in noticeable amounts during UDMH oxidation. Despite relatively low toxicity, UDMU can be considered one of the major UDMH transformation products and a potential marker of soil pollution with toxic rocket fuel.

Machine learning-assisted non-target analysis of a highly complex mixture of possible toxic unsymmetrical dimethylhydrazine transformation products with chromatography-mass spectrometry.

Unsymmetrical dimethylhydrazine (UDMH) is a toxic and environmentally hostile compound that was massively introduced to the environment during previous decades due to its use in the space and rocket industry. The compound forms multiple transformation products, and many of them are as dangerous as UDMH or even more dangerous. The danger includes, but is not limited to, acute toxicity, chronic health hazards, carcinogenicity, and environmental damage. UDMH transformation products are poorly investigated. In this work, the mixture formed by long storage of the waste that contained UDMH was studied. Even a preliminary screening of such a mixture is a complex task. It consists of dozens of compounds, and most of them are missing in chemical and spectral databases. The complete preparative separation of such a mixture is very laborious. We applied several methods of gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry, and several machine learning and chemoinformatics methods to make a preliminary but informative screening of the mixture. Machine learning allowed predicting retention indices and mass spectra of candidate structures. The combination of various ion sources and a comparison of the observed with the predicted spectra and retention was used to propose confident structures for 24 compounds. It was demonstrated that neither high-resolution mass spectrometry nor mass spectral library matching is enough to elucidate the structures of unknown UDMH transformation products. At the same time, the use of machine learning and a combination of methods significantly improves the identification power. Finally, machine learning was applied to estimate the acute toxicity of the discovered compounds. It was shown that many of them are comparable to or even more toxic than UDMH itself. Such an extremely wide and still underestimated variety of easily formed derivatives of UDMH can lead to a significant underestimation of the potential hazard of this compound.

1-Methyl-1H-1,2,4-triazole as the main marker of 1,1-dimethylhydrazine exposure in plants.

With their wide application in chemical industry, human health and environmental toxic effects of hydrazines arise extensive concerns. Although hydrazine exposure is known to lead to inhibition of seed germination and seedling growth in plants, there are few reports about the mechanism of oxidation or transformation ways of hydrazines in plant tissue. In this research, garden cress (Lepidium sativum L.) and zucchini (Cucurbita pepo L.) were used as model plant objects to study 1,1-dimethylhydrazine exposure in vitro using the GC-MS system. The seed germination and plant growth experiments were carried out in Petri dishes using an aqueous media. Among the detected 1,1-dimethylhydrazine transformation products in plant tissues, 1-methyl-1H-1,2,4-triazole had the highest intensity and reproducibility. In our research, 1-methyl-1H-1,2,4-triazole formed at all contaminant concentrations in an extremely short period. This preliminary study determined 1,1-dimethylhydrazine environment contamination by detecting 1-methyl-1H-1,2,4-triazole in combination with other transformation products.

Antioxidant and Anticarcinogenic Potentials of Propolis for Dimethylhydrazine-Induced Colorectal Cancer in Wistar Rats.

Propolis is a natural compound with anticarcinogenic properties. The present study aimed to compare the inhibitory effect of ethanolic extract of propolis (EEP) and vitamin E on dimethylhydrazine-induced colon lesions in rats. In this study, 60 rats were randomly categorized into six 10-member groups. After 13 weeks, blood and colon tissue were sampled to examine some factors. The parameters included red (RBC) and white (WBC) blood cell profile, lactate dehydrogenase (LDH), C-reactive protein (CRP), total protein (TP), creatine kinase (CPK), and albumin, as well as the extent of colon histological lesions, protein expression (adenomatous polyposis coli (APC), proliferating cell nuclear antigen (PCNA), carcinoembryonic antigen (CEA), and platelet-derived growth factor (PDGF)), and oxidative stress markers (total antioxidant capacity (TAC), malondialdehyde (MDA), and superoxide dismutase (SOD)) in colon tissue. A significant decrease was observed in congestion, mitotic index, inflammation, and cell destruction in colon tissue in dimethylhydrazine group in comparison with the control group (P < 0.05). The EEP exposed rats exhibited a significant lower oxidative stress than the DMH group (P < 0.05). Furthermore, the extract significantly affected TAC level (P < 0.05). While the expression level of APC rose substantially in the EEP-treated group compared to the DMH group, the level of PCNA, CEA, and PDGF proteins significantly reduced. It seems that the EEP can efficiently prevent DMH-induced colonic lesions. Furthermore, its effectiveness is more than the vitamin E, which is a strong antioxidant.

5-fluorouracil and curcumin with pectin coating as a treatment regimen for titanium dioxide with dimethylhydrazine-induced colon cancer model.

Colorectal cancer was inducted in Wister rats using titanium dioxide nanoparticles (TiO2NPs) and dimethylhydrazine (DMH) and treatment using 5-fluorouracil (5-FU) and curcumin (CUR), individually and following a synergistic approach. Compatibility studies are evaluated by using FT-IR spectra analysis, and Vero cell lines as well as HCT-116 cell lines are used for evaluating the synergistic approach. It was then followed by induction of colorectal cancer in rats for 70 days and treatment using 5-FU and CUR with pectin coating (individually and in combination) for 28 days. The reports state that 5-FU and CUR combination was found to be compatible. The synergistic effect was evaluated for1:1, 1:2, 1:4, and 2:1 ratio of 5-FU:CUR, where 1:4 ratio shows a CI50 value of 0.853, selected further for the animal studies. The 1:4 ratio of 5-FU and CUR (50:200) shows to be effective for the treatment of colorectal cancer within 28 days, proven using histopathology report, bodyweight analysis, and hematological reports. 5-FU and CUR (1:4) ratio with pectin coating was proven effective for the treatment of colorectal cancer induced by TiO2NPs with DMH and was found to produce a synergistic effect.

Unsymmetrical dimethylhydrazine and related compounds in the environment: Recent updates on pretreatment, analysis, and removal techniques.

Unsymmetrical dimethylhydrazine (1,1-Dimethylhydrazine, UDMH) has been widely used as aerospace fuel in many countries. The launch of space vehicles can cause the release and leakage of UDMH into the environment, posing serious threats to ecology system and human population. Even worse, the health risks are also pertinent to its numerous classes of transformation products including N-Nitrosodimethylamine (NDMA), because most of them display carcinogenic and mutagenic properties. Recently, there has been an intense ongoing development of simple, fast, green, and effective techniques for determining and removing these hazardous substances. This review summarizes the latest research progress regarding the sources, fates, pretreatment, analysis, and removal techniques of UDMH and related products in the environment. Sample preparation methods mainly include pressurized liquid extraction, liquid-phase microextraction techniques, solid-phase extraction, headspace-solid-phase microextraction, and supercritical fluid extraction. Detection and identification methods mainly include high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS), gas chromatography coupled with tandem mass spectrometry (GC-MS/MS), and sensors. Removal methods mainly include advanced oxidation processes, adsorption, biodegradation techniques. The advantages/disadvantages, applications, and trends of the proposed approaches are thoroughly discussed to provide a valuable reference for further studies.

Effect of Unsymmetrical Dimethylhydrazine on Isolated Heart and Lymphatic Vessels.

Unsymmetrical dimethylhydrazine (UDMH, heptyl) and its derivatives are used in the rocket and space industry as components of rocket fuel. UDMH is a highly toxic compound exhibiting irritant, hepatotoxic, and neurotoxic properties. In this study, the toxic effect of heptyl on isolated rat heart and lymphatic vessels was demonstrated. Acute exposure to UDMH leads to vasoconstriction of the coronary vessels of the isolated heart and pronounced stimulation of isolated lymphangions starting from the concentration of 10-4 M. The changes are dose-dependent. After exposure to UDMH in high concentrations (10-2 M), the changes in the functional parameters became irreversible. The obtained results provide evidence for the organ-specific effect of UDMH on visceral muscle organs.

Quantification of trace transformation products of rocket fuel unsymmetrical dimethylhydrazine in sand using vacuum-assisted headspace solid-phase microextraction.

Quantification of unsymmetrical dimethylhydrazine transformation products in solid samples is an important stage in monitoring of environmental pollution caused by heavy rockets launches. The new method for simultaneous quantification of unsymmetrical dimethylhydrazine transformation products in sand samples using vacuum-assisted headspace solid-phase microextraction without addition of water followed by gas chromatography-mass spectrometry is proposed. Decreasing air evacuation time from 120 to 20 s at 23 °C resulted in increased responses of analytes by 25-46% and allowed obtaining similar responses as after evacuation at -30 °C. The best combination of responses of analytes and their relative standard deviations (RSDs) was achieved after air evacuation of a sample (m = 1.00 g) for 20 s at 23 °C, incubation for 30 min at 40 °C, and 30-min extraction at 40 °C by Carboxen/polydimethylsiloxane (Car/PDMS) fiber. The method was validated in terms of linearity (R2=0.9912-0.9938), limits of detection (0.035 to 3.6 ng g-1), limits of quantification (0.12-12 ng g-1), recovery (84-97% with RSDs 1-11%), repeatability (RSDs 3-9%), and reproducibility (RSDs 7-11%). It has a number of major advantages over existing methods based on headspace solid-phase microextraction-lower detection limits, better accuracy and precision at similar or lower cost of sample preparation. The developed method was successfully applied for studying losses of analytes from open vials with model sand spiked with unsymmetrical dimethylhydrazine transformation products. It can be recommended for analysis of trace concentrations of unsymmetrical dimethylhydrazine transformation products when studying their transformation, migration and distribution in contaminated sand.

N-nitrosodimethylamine formation during oxidation of N,N-dimethylhydrazine compounds by peroxymonosulfate: Kinetics, reactive species, mechanism and influencing factors.

This study found that peroxymonosulfate (PMS) oxidation without activation has the potential to generate a suspected human carcinogen, N-nitrosodimethylamine (NDMA), in water containing N,N-dimethylhydrazine compounds. Considerable amounts of NDMA formed from three compounds by PMS oxidation were observed. 1,1,1',1'-Tetramethyl-4,4'-(methylene-di-p-phenylene) disemicarbazide (TMDS), which is an industrial antiyellowing agent and light stabilizer, was used as a representative to elucidate the kinetics, transformation products, mechanism and NDMA formation pathways of PMS oxidation. TMDS degradation and NDMA formation involved direct PMS oxidation and singlet oxygen (1O2) oxidation. The oxidation by PMS/1O2 was pH-dependent, which was related to the pH-dependent characteristics of the reactive oxygen species and intermediates. The degradation mechanism of TMDS mainly included the side chain cleavage, dealkylation, and O-addition. NDMA was generated from TMDS mainly via O-addition and 1,1-dimethylhydrazine (UDMH) generation. The cleavage of amide nitrogen in O-addition products and primary amine nitrogen in UDMH are likely the key steps in NDMA generation. The results emphasized that the formation of harmful by-products should be taken into account when assessing the feasibility of PMS oxidation.

NDMA reduction mechanism of UDMH by O3/PMS technology.

Carcinogenic N, N-Dimethylnitrosamine (NDMA) has been reported to generate significantly during ozonation of fuel additive unsymmetrical dimethylhydrazine (UDMH), the combined ozone/Peroxy-Monosulfate (O3/PMS) technology was tried for reducing its formation in this study. The influence of PMS dosages, ozone concentrations, pH, Br- and humic acid (HA) on NDMA formation from UDMH were investigated. In addition, the reduction mechanisms were explored by intermediates identification and Gaussian calculation. The results demonstrated that O3/PMS technology was effective on NDMA reduction, reaching an efficiency of 81% with 80 µM PMS. Higher NDMA reduction rates were achieved by O3/PMS with increasing pH within the scope of research (from 5 to 9), achieving a maximum of 69.9% at pH 9. The presence of bromide ion facilitated NDMA generation during ozonation, but the reduction efficiency by O3/PMS slightly improved from 66.3% to 70.6%. The presence of HA reduced NDMA formation in O3/PMS system. The contribution of SO4•- on NDMA reduction accounted for ~64%, which was higher than that of •OH (41.4%); however, its promotion role on conversing UDMH to NDMA was lower than O3. Therefore, the technology could reduce NDMA formation effectively. In addition, the results of Gaussian calculation manifested that the N atom in -NH2 group of UDMH was easily attacked not only by •OH but also by O3, so it is the key path that determines final NDMA formation. This study would provide reference for reducing NDMA formation during ozonation of UDMH-containing water matrixes.

Validation of the promotion mechanism between bromide and UDMH to form NDMA during ozonation.

Unsymmetrical dimethylhydrazine (UDMH) is found to generate substantial carcinogenic nitroso-dimethylamine (NDMA) during ozonation, moreover, its formation is promoted by ubiquitous bromide ions (Br-) in water matrixes, but the mechanism is still unclear. In this study, effects of Br- on NDMA formation during ozonation of UDMH were studied, meanwhile, its promotion pathways were also determined. The results demonstrated that Br- promoted NDMA formation from UDMH during ozonation, the formation rate constant with Br- is over 7 times of that without Br-. NDMA amount raised from 142.5 to 327.5 µg/L when Br- dosages increased from 0 to 100 µM. No matter with or without Br-, the augment of O3 dosages facilitated NDMA formation; the maximum value was achieved at pH 8. NDMA decreased dramatically from 173.8 to 123.5 µg/L with HCO3- raising from 0 to 160 µM, while increasing remarkably to 222.5 µg/L with SO42- dosing. In addition, NOM inhibited NDMA formation from UDMH during ozonation. The mass spectrum of LC-MS/MS verified that the generation of Br-UDMH was main cause for promoting NDMA formation. Moreover, hypobromous acid (HBrO) was confirmed to be responsible for Br-UDMH formation. In addition, the position that oxidants and Br- attacked was demonstrated based on Gaussian calculation. The results of this study could provide theoretical basis for the application of ozonation in bromine-containing water matrixes.

A novel simple and sensitive approach for determination of 1,1-dimethylhydrazine in aqueous samples by high performance liquid chromatography with ultraviolet and tandem mass spectrometric detection after derivatization with unsubstituted aromatic aldehydes.

In this work, simple, rapid and highly sensitive method of hazardous chemical 1,1-dimethylhydrazine (unsymmetrical dimethylhydrazine, UDMH) determination based on pre-column derivatization with unsubstituted aromatic aldehydes and reversed-phase high performance liquid chromatography-ultraviolet-tandem mass spectrometry (RP HPLC-UV-MS/MS) has been developed. Along with benzaldehyde, commercially available aromatic aldehydes, namely: 2-naphthaldehyde, 2-pyridinecarboxaldehyde, and 2-quinolinecarboxaldehyde, were used as derivatizing reagents in the analysis of hydrazines for the first time. The reactions were studied in a wide pH range by varying reaction time and other conditions. A slightly alkaline pH 9 was shown to be optimal for the derivatization of UDMH by aromatic aldehydes. The quantitative yield of derivatization products under the established conditions was confirmed by HPLC analysis with amperometric detection. For all studied reagents, wide linear ranges of concentrations (0.01-1000 µg/L) in natural water samples were observed. The limits of detection for UDMH in natural water were in the 3.7-130 ng/L range. 2-Quinolinecarboxaldehyde was selected as the most appropriate reagent for HPLC-UV-MS/MS determination of UDMH. In case of using this reagent, the accuracy was in the range of 97-102%, and precision, expressed as RSD was less than 8%. The developed approach does not require laborious stages of pre-concentration and isolation of UDMH from natural water components.

Styrax camporum, a typical species of the Brazilian cerrado, attenuates DNA damage, preneoplastic lesions and oxidative stress in experimental rat colon carcinogenesis.

Styrax camporum Pohl, a typical species from the Brazilian cerrado, commonly known as "benjoeiro", is used to treat gastroduodenal diseases. In previous studies carried out by our research group, hydroalcoholic extract of S. camporum stems (SCHE) exhibited antigenotoxic and antiproliferative effects. For a comparative analysis of the chemopreventive effect of SCHE, the aim of this study was to investigate the influence of SCHE against carcinogen 1,2-dimethylhydrazine (DMH)-induced DNA damage and pre-neoplastic lesions in Wistar rat colon. Animals were treated orally with SCHE at 250, 500 or 1000 mg/kg body weight in conjunction with a subcutaneous injection of DMH. DNA damage was assessed using the comet assay while tpre-neoplastic lesions by aberrant crypt foci (ACF) assay. The following hepatic oxidative stress markers were determined including activities of catalase (CAT) and glutathione S-transferase (GST) as well as levels of reduced glutathione (GSH) and malondialdehyde (MDA). Treatment with SCHE was not genotoxic or carcinogenic at the highest dose tested (1000 mg/kg b.w.). The extract effectively inhibited DNA damage and pre-neoplastic lesions induced by DMH administration at all concentrations tested. Measurement of CAT, and GST activities and levels of GSH showed that SCHE did not reduce oxidative processes. In contrast, treatment with SCHE (1000 mg/kg b.w.) decreased liver MDA levels. Taken together, these findings suggested the chemopreventive effect attributed to SCHE in colon carcinogenesis, may be related to its capacity to inhibit DNA damage as well as an antioxidant action associated with its chemical constituents egonol and homoegonol.

Major products and their formation and transformation mechanism through degrading UDMH wastewater via DBD low temperature plasma.

Unsymmetrical dimethylhydrazine (UDMH) is a liquid propellant widely used in aviation and aerospace. It produces a large amount of dimethyl hydrazine wastewater during long-term storage, testing, and reinjection. Traditional treatments produce numerous secondary contaminants such as residual high carcinogens, including N-nitrosodimethylamine (NDMA) and formaldehyde dimethylhydrazone (FDMH). In this paper, the dielectric barrier discharge (DBD) low temperature plasma technology is used to degrade the dimethyl hydrazine wastewater. Aiming at the problem of secondary pollutants in the degradation process, we used qualitative and quantitative methods to study the changes of NDMA and FDMH during the degradation of dimethyl hydrazine wastewater by DBD low temperature plasma. The kinetics of these two products showed that the degradation process of NDMA was consistent with the first-order reaction kinetics. Using density functional theory, we established molecular models of UDMH, NDMA and FDMH. According to the molecular orbital theory, the formation mechanism of NDMA and FDMH was calculated from three aspects: reaction structure, reaction path and energy change. We found that during the degradation of dimethyl hydrazine, the dimethyl hydrazine oxidation product was initiated by hydrogen abstraction on methyl (-CH3) and amine (-NH2). NDMA is produced by the oxidation of -NH2, whereas FDMH is mainly produced from dimethyl hydrazine and formaldehyde.

A novel CWPO/H2O2/VUV synergistic treatment for the degradation of unsymmetrical dimethylhydrazine in wastewater.

In this paper, the catalytic wet peroxide oxidation (CWPO) combined with vacuum ultraviolet (VUV) irradiation was developed to mineralize the wastewater with high concentration of unsymmetrical dimethylhydrazine (UDMH), especially to decompose the main byproduct of UDMH decomposition, N-nitrosodimethylamine (NDMA). CuO-NiO-MgO/γ-Al2O3 was used as the catalyst and H2O2 as the resources of ⋅ O H . Fourier Transform Infrared spectroscopy (FT-IR), X-ray Powder Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray spectroscopy (EDX) were employed to evaluate the structure of the catalyst. The treatment performances such as the UDMH degradation efficiency, chemical oxygen demand (COD) removal efficiency, and the concentration of N-nitrosodimethylamine (NDMA) were investigated in the treating process. The optimal conditions were obtained based on the results of single-factor experiments including parameters such as the initial UDMH concentration, catalyst dosage, initial pH, H2O2 dosage and temperature. The comprehensive results indicated that CWPO/H2O2/VUV process presented remarkable treatment performance to the reaction conditions with about 100% UDMH conversion efficiency, 95.02% COD removal efficiency and approximately 100% UDMH removal within 30 min.

Oncopreventive effects of theanine and theobromine on dimethylhydrazine-induced colon cancer model.

Theanine and theobromine are abundantly present in tea and cocoa, respectively. This study was performed to assess the chemopreventive effects of these phytochemicals, alone or together, on dimethylhydrazine (DMH)-induced colon cancer. Thirty male Wistar rats were divided into five groups and subcutaneously injected with saline (negative control group) or 30 mg/kg DMH (the other groups) two times/week for 12 weeks. The negative and positive control animals were orally treated with drinking water, and the other groups were gavaged with theanine (400 mg/kg), theobromine (100 mg/kg), or their mixture for two weeks before and throughout the injection period. At the end of the study, the morphological and histopathological features, Ki-67 proliferation marker, and the expression of Akt/mTOR, JAK2/STAT3, MAPK/ERK, and TGF-ß/Smad pathways were investigated. Theanine and theobromine, alone or together, reduced the number of cancerous and precancerous lesions, the volume of tumors, the Ki-67 immunostaining, and the expression of Akt/mTOR and JAK2/STAT3 oncogenic pathways. The simultaneous treatment was more effective in the down-regulation of Akt and mTOR compared to either theanine or theobromine alone. Theobromine administration also caused more inhibitory effects on the Ki-67 and Akt/mTOR expression than theanine. Besides, all dietary interventions increased the mRNA and protein expression of Smad2. In conclusion, theanine and theobromine, alone and in combination, inhibited tumorigenesis through down-regulation of the Akt/mTOR and JAK2/STAT3 pathways and an increment of the Smad2 tumor suppressor. The inhibition of the Akt/mTOR pathway was more pronounced by simultaneous treatment.