Oxidation inhibition of sulfite in dual alkali flue gas desulfurization system

A laboratory-scale well-mixed thermostatic reactor with continuously blasting air was used to investigate the oxidation inhibition of sulfite in dual alkali flue gas desulfurization （FGD） system. The effects of operating parameters such as pH value and catalyst concentration on the oxidation were studied. Sodium thiosulfate was used in the system, and was found that it significantly inhabited the sulfite oxidation. In the absence of catalyst, sodium thiosulfate at 12.67 mmol/L had an inhibition efficiency of approximately 98%. While in the presence of catalyst, sodium thiosulfate at 26.72 mmol/L had an inhibition efficiency less than 85.0%. The oxidation reaction order of sulfite in the sodium thiosulfate was determined to be -1.90 and 4）.55 in the absence and presence of the catalyst, respectively. Apparent activation energy of oxidation inhibition was calculated to be 53.9 kJ/mol. Pilot tests showed that the consumption rate of thiosulfate agreed well with the laboratory-scale experimental results.

Neuroprotective effects of ganoderma lucidum polysaccharides against oxidative stress-induced neuronal apoptosis

Ganoderma lucidum polysaccharides have protective effects against apoptosis in neurons exposed to ischemia/reperfusion injury, but the mechanisms are unclear. The goal of this study was to investigate the underlying mechanisms of the effects of ganoderma lucidum polysaccharides against oxidative stress-induced neuronal apoptosis. Hydrogen peroxide（H_2O_2） was used to induce apoptosis in cultured cerebellar granule cells. In these cells, ganoderma lucidum polysaccharides remarkably suppressed H_2O_2-induced apoptosis, decreased expression of caspase-3, Bax and Bim and increased that of Bcl-2. These findings suggested that ganoderma lucidum polysaccharides regulate expression of apoptosis-associated proteins, inhibit oxidative stress-induced neuronal apoptosis and, therefore, have significant neuroprotective effects.

Synthesis and NO production inhibition of novel Mannich base derivatives of irisolidone

Five new C-8 Mannich base derivatives of irisolidone 2a-2e were synthesized and their nitric oxide（NO）production inhibitory activity was evaluated.Compounds 2a,2b,2c and 2e displayed stronger activities in vitro than the parent compound irisolidone.

Growth inhibition and oxidative damage of Microcystis aeruginosa induced by crude extract of Sagittaria trifolia tubers

Aquatic macrophytes are considered to be promising in controlling harmful cyanobacterial blooms. In this research, an aqueous extract of Sagittaria trifolia tubers was prepared to study its inhibitory effect on Microcystis aeruginosa in the laboratory. Several physiological indices of M. aeruginosa, in response to the environmental stress, were analyzed. Results showed that S. trifolia tuber aqueous extract significantly inhibited the growth of M. aeruginosa in a concentration-dependent way. The highest inhibition rate reached 90% after 6 day treatment. The Chlorophyll-a concentration of M. aeruginosa cells decreased from 343.1 to314.2 μg/L in the treatment group. The activities of superoxide dismutase and peroxidase and the content of reduced glutathione in M. aeruginosa cells initially increased as a response to the oxidative stress posed by S. trifolia tuber aqueous extract, but then decreased as time prolonged. The lipid peroxidation damage of the cyanobacterial cell membranes was reflected by the malondialdehyde level, which was notably higher in the treatment group compared with the controls. It was concluded that the oxidative damage of M. aeruginosa induced by S.trifolia tuber aqueous extract might be one of the mechanisms for the inhibitory effects.

Steroidal saponins with anti-inflammatory activity from Tribulus terrestris L.

Objective:Tribulus terrestris L.(T.terrestris)is a highly valuable traditional Chinese medicine used to treat stroke,inflammation,pulmonary fibrosis,liver cancer,and urolithiasis.To identify the basic substance responsible for the anti-inflammatory effect of TST(total saponins of Tribulus),its chemical composition was systematically studied,and its effect of inhibiting nitric oxide generation and the expression of related inflammatory factors were determined.Methods:To separate chemical constituents from T.terrestris by column chromatography.Spectroscopic methods,including 1D and 2D nuclear magnetic resonance spectroscopy(NMR)and mass spectrometry(MS)techniques,were used to elucidate the isolated compounds.The anti-inflammatory activities of TST and several compounds were evaluated in vitro.Results:Fifteen steroidal saponins,including 9 furostanol steroidal saponins(1,2,3,4,5,6,7,8,and 15)and 6 isospirostanol steroidal saponins(9,10,11,12,13,and 14),were isolated from T.terrestris.TST significantly decreased the expression of tumor necrosis factor-a(TNF-a)and interleukin-6(IL-6)in RAW 264.7 cells stimulated by lipopolysaccharides.Compounds 13 and 15 evidently reduced TNF-a expression.Compounds 6,10,12,13,and 15 markedly reduced IL-6 expression.Conclusions:Compounds 1 was a novel furostanol steroidal saponin,named 26-O-b-D-glucopyranosyl-(25R)-5afurostan-12-carbonyl-20(22)-en-3b,26-diol-3-O-{b-D-xylopyranosyl-(1→2)-[b-D-xylopyranosyl-(1→3)]-b-D-glucopyranosyl-(1→4)-[a-L-rhamnopyranosyl-(1→2)]-b-D-galactopyranoside}.Compounds 2 was isolated from the family Zygophyllaceae for the first time,and 5 and 6 were isolated from the Tribulus genus.TST and compounds 6,10,12,13,and 15 exerts antiinflammatory activity.

Ashless Multi-Functional Friction Modifier for Modern Engine Oils

Automotive manufacturers are currently under pressure to improve fuel efficiency,and at the same time,reduce exhaust gas emission.To meet new emission requirements,modern vehicles are equipped with exhaust gas after-treatment devices.However,as sulfated ash,phosphorus and sulfur(SAPS) have a detrimental impact on these after-treatment devices,the use of low-or zero-SAPS additives is favored.Irgalube F 10 A is an additive that does not contain any metal,phosphorus or sulfur.It enables formulators to develop ...

INHIBITION OF NITRIC OXIDE SYNTHESIS INCREASES THE SECRETION OF ENDOTHELIN-1 IN VIVO AND IN CULTURED ENDOTHELIAL CELLS

The aim of this study is to investigate the effects of nitric oxide, formed from L-arginine, on the production of endothelin?1 in vivo and in cultured endothelial cells. In mechanically ventilated anesthetized dogs (n = 5), mean pulmonary arterial pressure (PAPm) and pulmonary vascular resistance (PVR) during hypoxic ventilation (FIO2 = 0.10) was 25 ?3.1 kPa and 68.7 ?10.2 kPa.s / L respectively. IG-nitro-L-arginine methylester (L-NAME), an inhibitor of nitric oxide synthase, increased the peak value of PAPm and PVR during hypoxic ventilation to 36.6 ?4.7 kPa and 158.4 ?25 kPa.s / L and its effect lasted for 2-3 hours. Meanwhile, plasma endothelin? level in the femoral artery increased by 20.9+ 7.1, 25.6?7.7, 28.6?7.9 pg / ml at the 60 th, 120th, 180th minute after the injection of L-NAME respectively (P<0.05 vs hypoxic control before the injection). In cultured endothelial cells from umbilical veins, endothelin-1 level of culture medium in control group was 35.1 ?.9 pg / 105 cells /ml (n=9). L-NAME increased endothelin-1 level to 42.8 ?4.9pg / 105 cells / ml (n = 9, P < 0.05) in case of 10-11 mol / L and to 43.0+ 4.7 pg / 105 cells / ml in case of 10 -7 mol/L (n=9, F<0.05). These findings indicate that endogenous nitric oxide is an inhibitory modulator of hypoxic pulmonary vasoconstriction and that nitric oxide inhibits the production of endothelin? in vivo and in cultured vascular endothelial cells.

Triterpenoid saponins from the roots of Cyathula officinalis and their inhibitory effects on nitric oxide production

The present study was designed to investigate the chemical constituents of the roots of Cyathula officinalis. Compounds were isolated by silica gel, Sephadex LH-20, ODS column chromatography, and preparative HPLC. Their structures were determined on the basis of 1D and 2D NMR techniques, mass spectrometry, and chemical methods. One new oleanane-type triterpenoid saponin, 28-O-[α-L-rhamnopyranosyl-(1→3)-β-D-glucuronopyranosyl-(1→3)-β-D-glucopyranosyl] hederagenin(1), was isolated from the roots of Cyathula officinalis. The anti-inflammatory activities of the isolates were evaluated for their inhibitory effects against LPS-induced nitric oxide(NO) production in RAW 264.7 macrophages cells. Compounds 2, 4, and 6 exhibited moderate anti-inflammatory activities.

Enhanced simultaneous absorption of NO_(x) and SO_(2) in oxidation-reduction-absorption process with a compounded system based on Na_(2)SO_(3)

Oxidation of sulfite and competitive absorption existed in Na_(2)SO_(3) solution for simultaneous removal of NO_(x) and SO_(2),inhibited the long-term high-efficiency when used for practical applications.A matching strategy was developed to solve these problems.Antioxidants combination was used to retard the oxidation of antioxidant and enhance inhibition of S(IV)(tetravalent sulfur)oxidation.Hydroquinone(HQ)and sodium thiosulfate(ST)showed a positive synergistic effect on inhibition of S(IV)oxidation.When SO_(2) concentration was 500 and 2000 ppmV,the addition of 0.1 wt.%HQ and 1 wt.%ST decreased the percentage of S(IV)oxidized by oxygen by over 30%and 40%,respectively.Alkali(Na_(2)CO_(3))alleviated the competitive absorption between NO_(x) and SO_(2).Moreover,Na_(2)CO_(3) exhibited an enhancement effect on the absorption of NO_(x) and SO_(2) when coupled with anti-oxidants.While the increase of oxygen pressure accelerated the oxidation of S(IV),the anti-oxidants can retard the oxidation.The measurement of pH suggested the removal efficiency of NO_(x) highly depended on SO_(3)^(2-) concentration rather than pH.The further investigation of the mechanism suggested the match effect was related to the interaction between ST and the intermediate product of HQ.The match strategy holds a potential for application of SO_(3)^(2-) to denitration.

In-situ surface transformation of magnesium to protect against oxidation at elevated temperatures

The native oxide thin scale on magnesium(Mg)surface appears continuous and crack-free,but cannot protect the Mg matrix from further oxidation,especially at elevated temperatures.This thermal oxidation process is witnessed in its entirety using a home-made in-situ heating device inside an environmental electron transmission microscope.We proposed,and verified with real-time experimental evidence,that transforming the native oxide scale into a thin continuous surface layer with high vacancy formation energy(low vacancy concentration),for example MgCO3,can effectively protect Mg from high-temperature oxidation and raise the threshold oxidation temperature by at least two hundred degrees.

Camganoids A and B,two new sesquiterpenes with different carbon skeletons isolated from fruits of Cinnamomum migao

Objective:To isolate and identify the undescribed compounds from the fruits of Cinnamomum migao and evaluate its nitric oxide inhibition potential.Methods:The chromatographic techniques of silica gel,Sephadex,and HPLC were used for isolation and purification of the compounds,while HR-ESI-MS,1D NMR,2D NMR,ECD,and X-ray diffraction techniques were used to characterize and confirm the isolated compounds.Moreover,the antiinflammatory activity of the isolated compounds was carried out to check inhibitory potential against the production of nitric oxide with RAW264.7 cells stimulated by LPS.Results:Camganoid A(1),a novel sesquiterpene possessing an unprecedented skeleton,and camganoid B(2),containing a unique eight-membered sesquiterpene moiety with a new carbon skeleton,were isolated and identified from the fruits of C.migao.The absolute configurations of 1 and 2 were confirmed by single crystal X-ray diffraction and electronic circular dichroism(ECD)calculations.Among these compounds,compound 1 exhibited potent inhibitory activity against the production of nitric oxide with IC50value of 4.59μmol/L in RAW264.7 cells stimulated by LPS.Conclusion:The isolation of two new skeletons from the fruits part of C.migao possessed unique skeletons which have not been reported before.

Erythrocyte membrane Ca^(2+)-ATPase inhibited by oxidized low density lipoprotein

Oxidized low density lipoprotein (LDL) has been shown to inhibit the activity of platelet plasma mambrane Ca^2+ ATPase, and induce changes of factin in endothelial cells. Since the deformability of human erythrocytes are closely related to the calcium metabolism and the stability of cytoskeleton, the influence of oxidized LDL on plasma membrane Ca^2+ ATPase and plasma membrane fluidity were studied in human erythrocytes. Our in vitro experiments demonstrated that oxidized LDL, but not native LDL, inhibits the activity of Platelet Research Unit, Institute of Anatomy, University of Münster, Germany (Zhao B, Filler TJ and Dierichs R) Shanghai Fourth People's Hospital, Shanghai, China (Yu H) Department of Biochemistry, University of Louisville, Kentucky, USA (Dean W)Ca^2+ ATPase in purified erythrocyte plasma membrane (P<0.01). Since no change in the membrane fluidity was detected in the erythrocyte plasma membrane exposed to native LDL and oxidized LDL as estimated by steady state by trimthylammonium diphenylhexatriene (TMA DPH) anisotropy, oxidized LDL did not affect the Ca^2+ ATPase by grossly changing the erythrocyte deformability probably by interfering the cytosolic calcium and then altering the cytoskeleton. The deformability of erythrocytes is important in microcirculation. A better understanding of the interactions between oxidized LDL, erythrocytes, platelets and endothelial cells can prevent cardiovascular diseases.