Oxygen Species Research Articles

(Invited) Elucidation of Electrochemical Reactions in Li2MnO3 Using Thin-Film Solid-State Battery

All-solid-state is an ideal form of batteries. The all-solid-state batteries are also suitable system for elucidating battery reaction using spectroscopic methods. The present study focuses on the reaction mechanism study of lithium excess cathode materials using all-solid-state batteries. The lithium manganese oxide, Li2MnO3, is a model system of the lithium excess layered rock-salt structure. In the present study, the epitaxial and polycrystalline films with 30 nm-thick with various compositions and morphologies were fabricated using pulsed laser deposition and sputtering methods. These electrodes showed charge-discharge capacity ranging from 150 to 300 mAh g-1 with different degradation characteristics depending on the compositions and morphologies. The reaction mechanisms were studied by in-situ and operando methods using surface X-ray diffraction and operando HAXPES analyses. The Li2MnO3 shows a transformation to a high-capacity phase after activation process by the first charge and the degradation during subsequent cycling depends on the sample stoichiometry and morphology. The transition to the high capacity phase is related the phase change from O3 to O1 type, together with interlayer cation disordering on the Li/Mn layer. The activation process is related to the oxidation of oxygen and a formation new oxygen species. The activation process and the reversible reactions of the lithium-rich layered rock-salt materials are elucidated.

Highly Active and Stable Palladium Catalysts Supported on Surface‐modified Ceria Nanowires for Lean Methane Combustion

AbstractAn efficient strategy was presented to synthesize highly active palladium catalyst supported on ceria nanowires modified by organosilanes (abbreviated as Pd/CeO2NWs@SiO2) for lean methane combustion. It is found that such a surface‐modified strategy can significantly improve the dispersion of surface palladium species and strengthen the concentration of active surface‐adsorbed oxygen species via reconstructing the surface microenvironment, invoking an efficient performance for methane oxidation. Under the space velocity of 60,000 mLg−1h−1, 0.5 wt% Pd/CeO2NWs@SiO2 displayed extraordinary catalytic activity with 90 % conversion rate at a temperature of around 327 °C, far lower than that of pristine Pd/CeO2NWs (378 °C) under the same conditions. What's more, unexpected stability was observed under high temperature and the presence of water vapor conditions owing to the intense metal support interaction of Pd/CeO2NWs@SiO2 catalyst. The possible reaction mechanism of lean methane oxidation was probed by in situ DRIFT spectra. It is observed that the pivotal intermediate products (carbonate and carbon oxygenates) generated on Pd/CeO2NWs@SiO2 surface are more readily decomposed into CO2. Importantly, the silicon hydroxyl groups (Si−OH) formed during the reaction can efficiently restrict the generation of the stable Pd(OH)x phase and release more active sites to facilitate the catalytic performance. This study provides a convenient method to design the highly reactive and durable palladium‐based catalyst for methane combustion.

CD4+ T cells cause renal and placental mitochondrial oxidative stress as mechanisms of hypertension in response to placental ischemia.

The reduced uterine perfusion pressure (RUPP) rat model and normal pregnant (NP) rat recipients of RUPP CD4+ T cells recapitulate many characteristics of preeclampsia such as hypertension and oxidative stress. We have shown an important hypertensive role for natural killer (NK) cells to cause mitochondrial dysfunction in RUPP rats; however, the role for RUPP CD4+ T cells to stimulate NK cells is unknown. Therefore, we hypothesized that RUPP-induced CD4+ T cells activate NK cells to cause mitochondrial dysfunction/reactive oxygen species (ROS) as mechanisms of hypertension during pregnancy. We tested our hypothesis by adoptive transfer of RUPP CD4+T cells into NP rats or by inhibiting the activation of RUPP CD4+T cells with Orencia (abatacept) and examining hypertension, NK cells, and mitochondrial function. RUPP was performed on gestation day (GD) 14, and splenic CD4+ T cells were isolated on GD 19 and injected into NP rats on GD 13. In a separate group of rats, Orencia was infused and the RUPP procedure was performed. Mean arterial pressure and placental and renal mitochondrial ROS increased in RUPP (n = 7, P < 0.05) and NP+RUPP CD4+ T-cell recipients (n = 13, P < 0.05) compared with control NP (n = 7) and NP+NP CD4+ T-cell recipients (n = 5) but was reduced with Orencia (n = 13, P < 0.05). Placental and renal respiration was reduced in RUPP (n = 6, P < 0.05) and NP+RUPP CD4+ T-cell recipients (n = 6, state 3 P < 0.05) compared with NP (n = 5) and NP+NP CD4+ T-cell recipients (n = 5) but improved with Orencia (n = 9, n = 8 P < 0.05). These data indicate that CD4+ T cells, independent of NK cells, cause mitochondrial dysfunction/ROS contributing to hypertension in response to placental ischemia during pregnancy.

The role of lipids in the signaling mechanisms of toll-like receptors

Toll-like receptors (TLRs) are important players in innate and adaptive immune responses involved in the initiation of the inflammatory process in response to the stimulating influence of endogenous (аllarmine) and exogenous ligands (pathogens viruses, bacteria, fungi). It has now become apparent that not only viral and bacterial infections but non-infectious inflammatory diseases are accompanied by the activation of inflammatory response systems and the development of chronic inflammation associated with disorders in the regulation of the TLRs system. In this regard, the ligand-independent activation of TLRs, which occurs with the participation of lipids, is actively studied. Their signalling functions of TLRs implemented in unique microdomains does membrane lipid rafts that coordinate many cellular processes. The ability to activate TLRs has been found for saturated fatty acids (SFAs), both exogenous and endogenous. On the other hand, TLRs can be inhibited by omega-3 polyunsaturated fatty acids (PUFAs), which can block the inflammatory process. The activation of TLRs triggers a signal cascade that induces the production of reactive oxygen and nitrogen species. The development of oxidative stress is accompanied by the formation of oxidized forms of phospholipids (Ox-PLs), which also induce the development of chronic inflammation. At the same time, Ox-PLs is characterized not only by pro-inflammatory but also anti-inflammatory activity, which necessitates in-depth studies of their role in the implementation of these processes. This review article discusses the mechanisms by which SFAs, PUFAs, and Ox-PLs modulate TLRs activation in lipid rafts. Research into the details of these mechanisms will contribute to the development of a strategy to reduce the risk of chronic diseases caused by inflammatory reactions mediated by TLRs.

A combination of electrochemistry and mass spectrometry to monitor the interaction of reactive species with supported lipid bilayers

Reactive oxygen and nitrogen species (RONS), e.g. generated by cold physical plasma (CPP) or photodynamic therapy, interfere with redox signaling pathways of mammalian cells, inducing downstream consequences spanning from migratory impairment to apoptotic cell death. However, the more austere impact of RONS on cancer cells remains yet to be clarified. In the present study, a combination of electrochemistry and high-resolution mass spectrometry was developed to investigate the resilience of solid-supported lipid bilayers towards plasma-derived reactive species in dependence of their composition. A 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid bilayer was undisturbed by 200 µM H2O2 (control) but showed full permeability after CPP treatment and space-occupying oxidation products such as PoxnoPC, PAzePC, and POPC hydroperoxide were found. Electron paramagnetic resonance spectroscopy demonstrated the presence of hydroxyl radicals and superoxide anion/hydroperoxyl radicals during the treatment. In contrast, small amounts of the intramembrane antioxidant coenzyme Q10 protected the bilayer to 50% and LysoPC was the only POPC derivative found, confirming the membrane protective effect of Q10. Such, the lipid membrane composition including the presence of antioxidants determines the impact of pro-oxidant signals. Given the differences in membrane composition of cancer and healthy cells, this supports the application of cold physical plasma for cancer treatment. In addition, the developed model using the combination of electrochemistry and mass spectrometry could be a promising method to study the effect of reactive species or mixes thereof generated by chemical or physical sources.

Oxygen Content-Controllable Synthesis of Non-Stoichiometric Silicon Suboxide Nanoparticles by Electrochemical Anodization.

A facile route to producing non-stoichiometric silicon suboxide nanoparticles (SiOx NPs, 0 < x < 1) with an adjustable oxygen content is proposed. The process is based on electrochemical anodization involving the application of a strong electric field near the surface of a Si electrode to directly convert the Si electrode into SiOx NPs. The difference in ion mobility between oxygen species (O2− and OH−), formed during anodization, causes the production of non-stoichiometric SiOx on the surface of the Si while, simultaneously, fluoride ions in the electrolyte solution etch the formed SiOx layer, generating NPs under the intense electric field. The adjustment of the applied voltage and anodization temperature alters the oxygen content and the size of the SiOx NPs, respectively, allowing the characteristics of the NPs to be readily controlled. The proposed approach can be applied for mass production of SiOx NPs and is highly promising in the field of batteries and optoelectronics.

Reversible synthesis of GO: Role of differential bond structure transformation in fine-tuning photodetector response

The controlled modification of graphene’s electronic band structure poses serious challenges. In the present work, we study the effect of sp 2 cluster size variation on the electronic band gap and photoconductive properties of reduced graphene oxide (RGO). This is achieved by performing reversible functionalization of RGO with oxygen species. The reversible functionalization of RGO results in its partial transformation to graphene oxide (GO) so that the size of the sp 2 clusters within the sp 3 matrix varies, thereby affecting the π-π* band structure and photoconductive properties. The study reveals: (1) incremental creation/elimination of oxygenated surface bonds’ related energy states within the π-π* band; (2) customized tuning of the sp 2/sp 3 ratio; (3) the presence/absence of oxygenated states impacts the optical transition processes both from band-to-band and oxygenated states; and (4) the incremental addition/depletion of surface states in a tunable manner directly influences the carrier transport in the photoconductive device. Experiments show a two-stage transformation of RGO electronic properties with changing oxygen functionalities: oxidation (Stage I) and decomposition or erosion (Stage II). Sp 2 cluster size variation induced bandgap change was analyzed by Raman and photoluminescence studies, indicating the possibility for photodetection in a specific band encompassing NIR to UV, depending on the sp 2/sp 3 ratio. Energy-dispersive x-ray spectroscopy and Fourier transform infrared studies confirm the surface oxygenation/de-oxygenation during plasma treatment, and XRD confirms partial transformation of RGO to GO and its amorphization at higher plasma exposure times. In addition, the photodetector performance is optimized in terms of carrier generation-recombination and carrier-lattice scattering. Thus, manipulating better photoconductive response is possible through suitable handling of the parameters involved in the plasma treatment process. This is the first study on the influence of the sp 2/sp 3 ratio-induced lattice structure evolution on photodetection.

Thioredoxins: Emerging Players in the Regulation of Protein S-Nitrosation in Plants.

S-nitrosation has been recognized as an important mechanism of ubiquitous posttranslational modification of proteins on the basis of the attachment of the nitroso group to cysteine thiols. Reversible S-nitrosation, similarly to other redox-based modifications of protein thiols, has a profound effect on protein structure and activity and is considered as a convergence of signaling pathways of reactive nitrogen and oxygen species. This review summarizes the current knowledge on the emerging role of the thioredoxin-thioredoxin reductase (TRXR-TRX) system in protein denitrosation. Important advances have been recently achieved on plant thioredoxins (TRXs) and their properties, regulation, and functions in the control of protein S-nitrosation in plant root development, translation of photosynthetic light harvesting proteins, and immune responses. Future studies of plants with down- and upregulated TRXs together with the application of genomics and proteomics approaches will contribute to obtain new insights into plant S-nitrosothiol metabolism and its regulation.

P2X7 receptor deletion attenuates oxidative stress and liver damage in sepsis.

Sepsis is a severe disease characterized by an uncontrolled systemic inflammation and consequent organ dysfunction generated in response to an infection. Extracellular ATP acting through the P2X7 receptor induces the maturation and release of pro-inflammatory cytokines (i.e., IL-1β) and the production of reactive nitrogen and oxygen species that lead to oxidative tissue damage. Here, we investigated the role of the P2X7 receptor in inflammation, oxidative stress, and liver injury in sepsis. Sepsis was induced by cecal ligation and puncture (CLP) in wild-type (WT) and P2X7 knockout (P2X7-/-) mice. The oxidative stress in the liver of septic mice was assessed by 2',7'-dichlorofluorescein oxidation reaction (DCF), thiobarbituric acid-reactive substances (TBARS), and nitrite levels dosage. The status of the endogenous defense system was evaluated through catalase (CAT) and superoxide dismutase (SOD) activities. The inflammation was assessed histologically and by determining the expression of inflammatory cytokines and chemokines by RT-qPCR. We observed an increase in the reactive species and lipid peroxidation in the liver of septic WT mice, but not in the liver from P2X7-/- animals. We found an imbalance SOD/CAT ratio, also only WT septic animals. The number of inflammatory cells and the gene expression of IL-1 β, IL-6, TNF-α, IL-10, CXCL1, and CXCL2 were higher in the liver of WT septic mice in comparison to P2X7-/- septic animals. In summary, our results suggest that the P2X7 receptor might be a therapeutic target to limit oxidative stress damage and liver injury during sepsis.

Application of Celestine Blue B and Gallocyanine for Studying the Effect of Drugs on the Production of Reactive Oxygen and Halogen Species by Neutrophils

We investigated the effect of drugs (dapsone, paracetamol, and isoniazid) on the production of reactive oxygen and halogen species by neutrophils. The standard fluorescent method using scopoletin as well as recently developed fluorescent methods using oxazine dyes, celestine blue B, and gallocyanine were employed for this purpose. Celestine blue B reacts selectively with hypochlorous acid, while gallocyanine reacts mainly with the superoxide radical-anion, which reveals the regulatory effect of anti-inflammatory drugs on neutrophil NADPH-oxidase and myeloperoxidase responsible for the production of reactive oxygen and halogen species, respectively. These results indicate that gallocyanine and celestine blue B hold promise as chemosensors for studying the effect of drugs used in anti-inflammatory therapy for the neutrophil respiratory burst.

Di-(2-ethylhexyl) phthalate limits the pleiotropic effects of statins in chronic kidney disease patients undergoing dialysis and endothelial cells

The level of di-(2-ethylhexyl) phthalate (DEHP) is elevated in chronic kidney disease patients undergoing dialysis. However, statins are unable to reduce the cardiovascular events in chronic dialysis patients. In this study, we investigated the effects of DEHP on statin-conferred pleiotropic effects and the underlying molecular mechanism in peritoneal dialysis (PD) patients and endothelial cells (ECs). In PD patients with serum DEHP level ≥0.0687 μg/mL, statin treatment was not associated with lower risk of cardiovascular disease. In ECs, exposure to DEHP abrogated the simvastatin-induced NO bioavailability and EC-related functions. Additionally, DEHP abolished the anti-inflammatory effect of simvastatin on the tumor necrosis factor α-induced upregulation of adhesion molecules and monocyte adhesion to ECs. Mechanistically, DEHP blunted the activation of transient receptor potential vanilloid type 1 (TRPV1), which is required for NO production by simvastatin in ECs. Notably, DEHP increased the activity and expression of protein phosphatase 2B (PP2B), a negative regulator of TRPV1 activity. The effect of DEHP on PP2B activation was mediated by the activation of the NADPH oxidase/reactive oxygen species (NOX−ROS) pathway. Inhibition of PP2B activity by pharmacological antagonists prevented the inhibitory effects of DEHP on simvastatin-induced Ca2+ influx, NO bioavailability, and EC migration, proliferation, tube formation, and anti-inflammatory action. Collectively, DEHP activates the NOX−ROS−PP2B pathway, which in turns inhibits TRPV1/Ca2+-dependent signaling and abrogates the statin-conferred pleiotropic protection in ECs.

Abstract 5494: How cancer arises from chronic inflammation, based on complexity theory

Abstract Introduction: This paper discusses how cancer arises from chronic inflammation, based on complexity theory. Methods: We reviewed the medical literature to identify cancer types strongly associated with chronic inflammation. We then classified the chronic inflammatory etiologies, determined general mechanisms through which they promote cancer and speculated on network changes involved in transforming cells from physiologic to cancer attractor states. Results: Bacterial and viral infection are a common etiology of chronic inflammation associated cancer and cause 15% of cancer cases worldwide, predominantly Helicobacter pylori, human papillomavirus and hepatitis B and C virus. Other etiologies include parasitic infestations by Opisthorchis viverrini, Clonorchis sinensis and Schistosoma haematobium; autoimmunity in Hashimoto thyroiditis, Sjögren syndrome and celiac disease; local trauma due to gastroesophageal reflux and hot beverages; excess weight; diabetes; Western diet (high fat, low fiber, low consumption of fruit and vegetables); aging and immune system dysfunction. General mechanisms include immune system activation that damages DNA by producing reactive oxygen and nitrogen species and nitrosamines; tumor immune evasion via immune suppression and immune senescence; antigen driven lymphoproliferation; continuous mitotic activity due to repair; synergy with other chronic stressors; creation of a tumor nurturing microenvironment; development of a “runaway” immune system; and microbiome changes that produce carcinogens or activate inflammation. Immune system dysfunction and germ line variations of inflammatory mediators can promote each step. From a network perspective, the usual physiologic state for many cellular processes consists of a delicate balance between stimulating and dampening forces, maintained by inherent network features and evolved control systems. Chronic inflammation may disturb this balance, leading to propagation of network instability throughout the cell, across adjacent tissues and ultimately systemically. This may create identifiable network hierarchies and intermediate states (hyperplasia, metaplasia or dysplasia), but some changes in network and molecular patterns may not alter histology. Ultimately, cells may move to a cancer attractor state. Summary: Chronic inflammation causes cancer by initiating local changes to cellular networks and their microenvironment which facilitate their escape from physiologic states towards intermediate and cancer attractor states. This suggests that early detection and reduction of these inflammatory changes may reduce cancer mortality. Novel treatment options include more diverse treatment combinations, destabilizing existing cancer attractors and their microenvironment, stimulating physiologic pathways that stabilize networks, reducing other chronic stressors and optimizing rational medical care. Citation Format: Nat L. Pernick. How cancer arises from chronic inflammation, based on complexity theory [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5494.

Non-thermal plasma combined with zeolites to remove ammonia nitrogen from wastewater

In this work, non-thermal plasma combined with zeolites was used to remove inorganic pollutant ammonia nitrogen from wastewater. Ammonia nitrogen elimination performances at various operating parameters were investigated. Roles of active species in the removal of ammonia nitrogen were also discussed. The experimental results showed that 69.97% ammonia nitrogen can be removed from the plasma/zeolites synergistic system after 30 min treatment. The removal efficiency was 16.23% and 61.55% higher than that in sole zeolites adsorption system and that in sole discharge plasma system, respectively. Higher applied voltage, lower initial ammonia nitrogen concentration and weak acidic conditions were favorable for ammonia nitrogen removal. After the addition of zeolites, part of O3 and H2O2 generated in the plasma/zeolites system were decomposed into other oxygen species (•OH and 1O2), which improved the oxidation degree of ammonia nitrogen. In addition, the reaction mechanism of ammonia nitrogen in water by plasma/zeolites process was discussed. After repeated use three times, the effect of the zeolites in the plasma/zeolites system remained stable. Characterization of the zeolites after reaction was analyzed through BET, SEM, XRD and FT-IR. The experiments have confirmed the applicability of the plasma/zeolites system for the further treatment of low-concentration ammonia nitrogen wastewater.

Ferromagnetic correlation in hydrogen doped highly oriented pyrolytic graphite

Observation of granular superconductivity in water doped graphite materials has motivated recent research because of the unexplored scenarios in the field of magnetism and spintronics.Diffusion of hydrogen and/or oxygen species has been reported to promote doping within graphitic grains; however, the origin and dynamics of the magnetic phenomena (i.e. superconductive ordering), which arise as a consequence of this doping-process, are still not well understood.In this work, we investigated the relationship between magnetic-ordering and hydrogen/oxygen doping in highly oriented pyrolytic graphite (HOPG). Diamagnetic lamellae exfoliated from HOPG were soaked in water and alcoholic beverages, with a variable ethanol concentration (0–60%). Superconducting quantum interference device (SQUID), electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy were employed for an in-depth characterization of undoped and doped lamellae. Presence of a hydrogen-induced ferromagnetic ordering in the π-electrons is demonstrated.To further enhance infiltration and achieve enhanced ferromagnetic signals, Isostatic-Pressure-Wine-Doping was employed. The application of pressure-induced disruption of the regular mosaic distribution within HOPG layers enhanced 1) the diffusion of the dopant within the layers and 2) the ferromagnetic response of the samples.

Formation of BN-covered silicene on ZrB2/Si(111) by adsorption of NO and thermal processes.

We have investigated the adsorption and thermal reaction processes of NO with silicene spontaneously formed on the ZrB2/Si(111) substrate using synchrotron radiation x-ray photoelectron spectroscopy (XPS) and density-functional theory calculations. NO is dissociatively adsorbed on the silicene surface at 300 K. An atomic nitrogen is bonded to three Si atoms most probably by a substitutional adsorption with a Si atom of silicene (N≡Si3). An atomic oxygen is inserted between two Si atoms of the silicene (Si-O-Si). With increasing NO exposure, the two-dimensional honeycomb silicene structure gets destroyed, judging from the decay of typical Si 2p spectra for silicene. After a large amount of NO exposure, the oxidation state of Si becomes Si4+ predominantly, and the intensity of the XPS peaks of the ZrB2 substrate decreases, indicating that complicated silicon oxinitride species have developed three-dimensionally. By heating above 900 K, the oxide species start to desorb from the surface, but nitrogen-bonded species still exist. After flashing at 1053 K, no oxygen species is observed on the surface; SiN species are temporally formed as a metastable species and BN species also start to develop. In addition, the silicene structure is restored on the ZrB2/Si(111) substrate. After prolonged heating at 1053 K, most of nitrogen atoms are bonded to B atoms to form a BN layer at the topmost surface. Thus, BN-covered silicene is formed on the ZrB2/Si(111) substrate by the adsorption of NO at 300 K and prolonged heating at 1053 K.

In-Vivo Study of Boswellia serrata for Modulating Immune System and Quenching Free Radicals

In several diseased conditions like asthma, allergy, ageing, arthritis, cancer etc., there is a production of reactive nitrogen and oxygen species, as well as our immune system also gets harmed. In order to stop or quench these harmful free radicals, antioxidants, which are the first line of defense, are used. And the immune system can be modulated to work properly by using natural agents like medicinal plants, having antioxidant property. In this context, the present study was undertaken to investigate the immunomodulatory activity and free radical quenching ability of the Boswellia serrata Roxb. (Bs) in murine model. This herb is known to afford protection to human physiological system against diverse stressors. It was tested at three dose levels of 50mg /kg of mice body weight, 100mg /kg of mice body weight, and 150 mg /kg of mice body weight for five consecutive days. Alpha tocopherol (25 mg/ kg, of mice body weight) and Di-methyl Sulphoxide (35mg /kg of mice body weight) were used as the reference standards. The extent of protection against immunosuppression was evaluated after 9 days of respective drug administration, by measuring macrophage phagocytic activity. A statistically significant antioxidant and immunomodulatory activity were shown by the extract of Boswellia serrata as evident by its effect on the activity of non-enzyme antioxidant reduced glutathione (GSH), antioxidant enzyme glutathione peroxidase (GPx), the degree of lipid peroxidation, and increase in the number of peritoneal macrophages.

Evolution of Electrical and Optical Parameters of a Helium Plasma Jet in Interaction With Liquids

A helium-operated atmospheric pressure plasma jet was used to treat biologically relevant liquids, such as ultrapure water and phosphate-buffered saline. The present experiments are focused on the behavior and evolution of selected electrical and optical signals of the helium plasma jet, while in contact with the liquid targets. To that extent, this article presents multiple results extracted from the monitoring of the electrical current over the entire treatment duration, with emphasis on the identification of a minute order long plasma warm-up duration and the differences observed when using the two liquid targets. Moreover, spectral monitoring of the intensity of lines and bands corresponding to helium, oxygen, and nitrogen excited species in the gas phase also points to a similar evolution towards a steady state level. The existence of transient regimes should not be disregarded when plasma jets are used for industrial and life science applications, where the exposure duration of biological targets, liquids, and solid state materials is usually of the order of a few minutes.

Synthesis of monetite micro particles from egg shell waste and study of its environmental applications: Fuel additive and catalyst

Monetite is used in water decontamination and fuel additive due to less toxic, easy and cheap synthesis approach. Egg shell is used as precursor along with disodium phosphate for synthesis of monetite particles. Composition, phase and purity of the product are analyzed by X-ray diffraction spectroscopy. Bond angles and bond lengths of the polyhedra constituted by phosphorus and oxygen species are calculated. The morphology of particles is analyzed, and size is measured with the help of scanning electron microscopy and transmission electron microscopy. Monetite is used as catalyst for degradation of Congo red dye, a carcinogenic dye. Effect of catalyst dosage on apparent rate constant is investigated and results are compared with literature to analyze the catalytic property of monetite particles. Monetite is also used as additive for diesel fuel. Calorific value and other parameters are measured and effect of additive on efficiency of fuel is analyzed. Monetite is a promising catalyst because kapp value is increased from 0.0077 to 0.00114 min−1 by increasing catalyst dosage from 1.0 to 2.5 mg/mL. It is also a good additive because calorific value is increased from 2.55 to 8.902 MJ/kg with increase in additive dosage from 10 to 40 ppm.

The effects of hyperbaric oxygen therapy on the brain with middle cerebral artery occlusion.

Middle cerebral artery occlusion (MCAO) causes focal cerebral hypoperfusion, resulting in cerebral ischemia or ischemic stroke. The main therapeutic approach is to restore an adequate blood flow to the brain via the process of reperfusion. However, rapid reperfusion can itself aggravate brain damage; this adverse effect is known as ischemic/reperfusion (I/R) injury. The pathological conditions that occur after cerebral ischemia and cerebral I/R are microvascular injury, blood-brain barrier dysfunction, post-ischemic inflammation, increased oxidative stress/reactive oxygen species, and a reduction in neuronal survival, leading to brain infarction. Animal and clinical studies on hyperbaric oxygen therapy (HBOT) have recently been carried out, and there is evidence of positive effects on neurological outcomes after cerebral ischemia. However, some evidence has shown that HBOT may not affect the functional recovery after ischemic injury. This review describes the current evidence, both in vivo and clinical data, regarding the potential benefits of HBOT after MCAO and cerebral I/R injury. The contrary data are also discussed to verify the effectiveness of HBOT in stroke outcomes.

ROLE OF THE REACTIVE OXYGEN AND NITROGEN SPECIES IN THE DEVELOPMENT OF FIBROSIS IN THE TESTES OF RATS WITH PROLONGED CENTRAL DEPRIVATION OF TESTOSTERONE SYNTHESIS

Prostate cancer is the second most common diagnosis in oncology and ranks the fifth among the causes of mortality in men around the world. 1,276,106 cases of newly diagnosed prostate cancer were recorded in 2018. Androgens play a large role in the development of prostate cancer. Elimination of androgens and blockade of their synthesis are key pathogenetic steps in the treatment of prostate cancer. Metabolic and morphological changes in the testes under prolonged central deprivation of testosterone synthesis are currently not well understood. The aim of this study was to establish the role of reactive oxygen and nitrogen species in the development of morphological changes in the testes of rats under prolonged central deprivation of testosterone synthesis. Materials and methods. The experiments were conducted on 20 sexually mature male Wistar rats. Animals were divided into 4 groups of 5 animals in each. The first group (control) received a subcutaneous injection of 0.9% sodium chloride for 180 days. The second group received a subcutaneous injection of diphereline (triptoreline) in a dose of 0.3 mg/kg of active agent for 30 days in order to simulate the central deprivation of testosterone synthesis. In the third group, diphereline was administered in a dose of 0.3 mg/kg of the active agent for 90 days. The fourth group received a subcutaneous injection of diphereline in a dose of 0.3 mg/kg of the active agent for 180 days. Small pieces of testes were fixed and enclosed in paraffin blocks; then 4-μm thick sections were made and stained with hematoxylin and eosin. Histological preparations were studied using an optical microscope with a digital microphotographic nozzle Olympus C 3040-ADU with programs adapted for these studies. The total activity of NO synthases (gNOS), the activity of the inducible isoform of NO synthase (iNOS) and constitutive isoforms (cNOS), as well as the production of superoxide anion radical (O2•-) were determined in 10% homogenate of testes. Results. Long-term central deprivation of testosterone synthesis leads to an increase in the interstitial space volume with the development of fibrotic changes in the testes on the 180th day of the experiment. The wall of seminiferous tubules was compacted, swollen, there were a large number of parietal macrophages from the outside compared to previous periods of the experiment. In the structure of some convoluted seminiferous tubules, first there was discompletion and disorientation, and then desquamation of spermatids. The number of spermatogonia type A and B decreased. Hypochromia and pycnosis were noted in the nuclei. The activities of gNOS and iNOS increased until the 90th day and decreased by 180th when compared with 90th day, remaining higher than the activities of the control group. Activity of cNOS was reduced in all experimental groups. O2•- production increased in all experimental groups. Conclusion: an increase in the production of nitric oxide by the inducible isoform of NO synthase leads to destructive changes in the testes of rats with the subsequent development of fibrotic changes on the 180th day of central deprivation of testosterone synthesis by enhancing the production of superoxide anion radical.