Dust deposition on vegetation leaves in Shanghai, China.

Urban vegetation can deposit dust to reduce pollution, and dust retention capacity of vegetation has become an important indicator for urban ecological construction. We selected five representative vegetation in Shanghai to explore the regularity of dust deposition on vegetation leaves. Due to the influence of leaf area and surface characteristics, the amount of dust deposition was significantly different to each vegetation; Vegetation shows different dust retention capacity under different pollution intensity, before this capacity reaches its limit, and it will increase with the increase of dust content in the environment; Furthermore, water content of leaves was an important factor affecting dust retention capacity by vegetation. There was a linear positive correlation between the two variables. Our work suggests that the dust retention capacity of vegetation leaves was affected by various factors, but it showed certain regularity, which can provide a scientific basis for the configuration of urban green plant species.

Long-lived phosphorescent iridium(III) complexes conjugated with cationic polyfluorenes for heparin sensing and cellular imaging.

The applications of conjugated polyelectrolytes in biosensing and bioimaging have attracted more and more research interests due to their excellent photophysical properties. In this work, a new series of conjugated polyelectrolytes containing long-lived phosphorescent Ir(III) complexes is designed and synthesized, which can be used for ratiometric and lifetime-based sensing of heparin utilizing the electrostatic interaction between cationic polymers and anionic heparin. By changing the ligand structures of Ir(III) complexes, the sensing performances of phosphorescent-conjugated polyelectrolytes (PCPEs) are optimized. In addition, the application of PCPEs in cellular imaging is carried out. These polymers can be applied for specific staining of cell membrane. Importantly, utilizing the long emission lifetime of phosphorescent signal of Ir(III) complexes, time-gated luminescent imaging is carried out, which can eliminate the short-lived background fluorescence interferences from the environment or biological samples.

Multistage mass spectrometric analysis of human hemoglobin glutathionylation: correlation with cigarette smoking.

Protein glutathionylation is an important protein post-translational modification associated with oxidative stress, in which the thiol groups of cysteine residues react with glutathione and form disulfide bonds. Glutathionylation has been shown to affect protein structure and modulate protein function, and is implicated in the regulation of signaling and metabolic pathways. Glutathionylation of human hemoglobin has been known for decades. However, only glutathionylation on Cys-93 of ß-globin has been characterized. In this study, we used nanoflow liquid chromatography-nanospray ionization multistage mass spectrometry (nanoLC-NSI/MS(n)) under a data-dependent scan mode to identify sites of glutathionylation in human hemoglobin by accurate mass measurement and by their MS(2) and MS(3) spectra. After human hemoglobin was incubated with oxidized glutathione, alkylated and trypsin digested, all three cysteine residues, i.e., α-Cys-104, ß-Cys-93, and ß-Cys-112, were found to be glutathionylated. Glutathionylation at these sites was also detected in hemoglobin freshly isolated from human blood samples by the consecutive reaction monitoring at the MS(3) scan stage, and the extent of modification of each site was quantified relative to the alkylated parent peptide in the selected reaction monitoring (SRM) chromatograms. The peak area ratio of glutathionylated and alkylated parent peptides under MS(3) and MS(2)-SRM, respectively, represents the relative extent of glutathionylation. The extents of glutathionylation at α-Cys-104 and ß-Cys-93 in hemoglobin of 20 smokers were significantly higher than those in 20 nonsmokers with a p value of 0.0008 and <0.0001, respectively. Moreover, there are statistically significant correlations between the extent of glutathionylation at α-Cys-104 and ß-Cys-93 and the number of cigarettes smoked per day as well as smoking index. This assay is highly specific and sensitive as it requires as little as 2 µg of hemoglobin isolated from one drop of blood. These results suggest that this assay might be feasible in measuring the extent of glutathionylation in hemoglobin as a low-invasive biomarker of oxidative stress. To our knowledge, this is the first report identifying all three cysteine residues being glutathionylated in human hemoglobin and quantifying the extent of glutathionylation at the peptide level using multistage mass spectrometry.

Woody vegetation composition and structure in peri-urban Chongming Island, China.

Chongming, the world's largest alluvial island, is located within the municipality of Shanghai, China. Recent projects have now linked peri-urban Chongming to Shanghai's urban core and as a result will soon undergo substantial changes from urbanization. We quantitatively analyzed the structure and composition of woody vegetation across subtropical, peri-urban Chongming as a basis for sustainable management of these rapidly urbanizing subtropical ecosystems elsewhere. We used 178 permanent, random plots to statistically and spatially analyze woody plant composition and tree structure across the 1,041 km(2) of Chongming. A total of 2,251 woody plants were measured comprising 42 species in 37 genera. We statistically and geospatially analyzed field data according to land uses and modeled air pollution removal by trees. Average tree diameter at breast height, total height, and crown widths on transportation land uses were greater than other land uses. These same values were lowest on forest land use and greater tree cover was associated with areas of increased anthropogenic activity. Less than 20 % of the woody vegetation was exotic and a species richness index was significantly different between land uses due to legacy effects. Composition of agriculture and forest land uses were similar to residential and transportation. Tree cover across Chongming was also estimated to annually remove 1,400 tons of air pollutants. We propose that this integrated and quantitative method can be used in other subtropical, peri-urban areas in developing countries to establish baseline trends for future sustainability objectives and to monitor the effects of urbanization and climate change.

A new perspective on the impacts of Spartina alterniflora invasion on Chinese wetlands in the context of climate change: A case study of the Jiuduansha Shoals, Yangtze Estuary.

Spartina alterniflora, an invasive plant, was introduced to the Chinese coastal zone in the early 90s. As an eco-engineering species, S. alterniflora not only alters saltmarsh species distributions, previously described as habitat degradation, but it also plays a vital role in coastal protection, especially for the development of recently emerged intertidal shoals. To provide a reference for coastal management under global change, we quantified the impact of the invasion process on provided ecological and coastal protection functions, exemplified at the emerging Jiuduansha Shoals (JDS) in the Yangtze Estuary. Results obtained by high-precision satellite monitoring and numerical modelling showed that the establishment and growth of S. alterniflora can exert considerable changes on local environment. The invasion of S. alterniflora to JDS wetland can be divided into three distinct phases, (1) establishment 1998-2003, (2) expansion 2003-2009, and (3) dominant 2009-2018 stages according to the changes in saltmarsh composition. Spatially, S. alterniflora continuously replaced Scirpus mariqueter, forcing S. mariqueter and Phragmites australis slowly to the lower and higher intertidal habitats, respectively. Notably, S. alterniflora expansion was the main driver that contributed to over 70 % of recent JDS wetland expansion even under sediment deficit conditions. Established S. alterniflora marsh (directly) dampens more waves because of aboveground stems, but it also causes more accretion and indirectly leads to higher "morphological" wave dampening. Thus, it increases coastal defense provided by the saltmarsh in the context of sea-level rise and strengthening storms. In conclusion, the role of S. alterniflora invasion to the local environment under global changes is controversial. For sustainable coastal management, we need context-dependent S. alterniflora management to maximize the benefit of coastal protection and minimize the impact on local ecology, especially in sediment-starving estuaries with expected coastline retreat.

Identification and characteristic analysis of urban vegetation spectra under different dust deposition.

Urban atmospheric environmental problems have raised increasing attention in recent years. To confirm the impact of plant dust deposition capacity on urban atmosphere and spectral characteristics, this study carried out experiments in Xuhui District and Minhang District of Shanghai, and 4 common greening species were selected as research objects. In order to explore the changes in vegetation spectral characteristics, ASD FieldSpec 3 Spectrometer and 1/10000 electronic balance were used to measure the spectral data and dust data of samples. The results show as follows: (1) 380-680 nm and 750-1350 nm are the best spectral wavelengths to analyze the influence of dust deposition on spectrum. (2) The canopy reflectance spectra of tree species decrease with the increase of dust deposition, especially in the wavelength range of 750-1350 nm. (3) The first derivative and the second derivative are beneficial to observe the spectral changes and judge the position of the red edge. The red edge position of some tree species is easy to move under the interference of dust deposition. (4) Among the four tree species, the spectrum of Osmanthus fragrans is relatively undisturbed by dust deposition, and Osmanthus fragrans is a great tree species for urban greening. The research made a foundation for the future use of spectral information to estimate vegetation dust.

Analysis of ethylated thymidine adducts in human leukocyte DNA by stable isotope dilution nanoflow liquid chromatography-nanospray ionization tandem mass spectrometry.

Studies showed that levels of ethylated DNA adducts in certain tissues and urine are higher in smokers than in nonsmokers. Because cigarette smoking is a major risk factor of various cancers, DNA ethylation might play an important role in cigarette smoke-induced cancer formation. Among the ethylated DNA adducts, O(2)-ethylthymidine (O(2)-edT) and O(4)-ethylthymidine (O(4)-edT) are poorly repaired and are accumulated in the body. In addition, O(4)-edT possesses promutagenic properties. In this study, we have developed a highly sensitive, accurate, and quantitative assay for simultaneous detection and quantification of O(2)-edT, N(3)-edT (N(3)-ethylthymidine), and O(4)-edT adducts by isotope dilution nanoflow liquid chromatography-nanospray ionization tandem mass spectrometry (nanoLC-NSI/MS/MS). Under the highly selected reaction monitoring (H-SRM) mode, the detection limit of O(2)-edT, N(3)-edT, and O(4)-edT injected on-column was 5.0, 10, and 10 fg, respectively. The quantification limit for the entire assay was 50, 100, and 100 fg of O(2)-edT, N(3)-edT, and O(4)-edT, respectively, corresponding to 1.1, 2.3, and 2.3 adducts in 10(9) normal nucleotides, respectively, starting with 50 µg of DNA (from 1.5-2.0 mL of blood). Levels of O(2)-edT, N(3)-edT, and O(4)-edT in 20 smokers' leukocyte DNA were 44.8 ± 52.0, 41.1 ± 43.8, 48.3 ± 53.9 in 10(8) normal nucleotides, while those in 20 nonsmokers were 0.19 ± 0.87, 4.1 ± 13.3, and 1.0 ± 2.9, respectively. Levels of O(2)-edT, N(3)-edT, and O(4)-edT in human leukocyte DNA are all significantly higher in smokers than in nonsmokers, with pvalues of 0.0004, 0.0009, and 0.0004, respectively. Furthermore, levels of O(2)-edT show a statistically significant association (γ = 0.4789, p = 0.0327) with the smoking index in smokers. In the 40 leukocyte DNA samples, the extremely significant statistical correlations (p < 0.0001) are observed between levels of O(2)-edT and O(4)-edT (γ = 0.9896), between levels of O(2)-edT and N(3)-edT (γ = 0.9840), and between levels of N(3)-edT and O(4)-edT (γ = 0.9901). To our knowledge, this is the first mass spectrometry-based assay for ethylated thymidine adducts. Using this assay, the three ethylated thymidine adducts were detected and quantified for the first time. Therefore, this highly sensitive, specific, and accurate assay should be clinically feasible for simultaneous quantification of the three ethylated thymidine adducts as potential biomarkers for exposure to ethylating agents and for cancer risk assessment.

PM2.5 Exposure and Health Risk Assessment Using Remote Sensing Data and GIS.

Assessing personal exposure risk from PM2.5 air pollution poses challenges due to the limited availability of high spatial resolution data for PM2.5 and population density. This study introduced a seasonal spatial-temporal method of modeling PM2.5 distribution characteristics at a 1-km grid level based on remote sensing data and Geographic Information Systems (GIS). The high-accuracy population density data and the relative exposure risk model were used to assess the relationship between exposure to PM2.5 air pollution and public health. The results indicated that the spatial-temporal PM2.5 concentration could be simulated by MODIS images and GIS method and could provide high spatial resolution data sources for exposure risk assessment. PM2.5 air pollution risks were most serious in spring and winter, and high risks of environmental health hazards were mostly concentrated in densely populated areas in Shanghai-Hangzhou Bay, China. Policies to control the total population and pollution discharge need follow the principle of adaptation to local conditions in high-risk areas. Air quality maintenance and ecological maintenance should be carried out in low-risk areas to reduce exposure risk and improve environmental health.

Solar Boosting Pollutant Removal plus Hydrogen Production by Lifting-Heat and Lowering-Potential Chemical Synergy.

Solar-boosted oxidation plus hydrogen production for pollutant removal in wastewater, driven by a high thermal and low-potential electrochemical combination, is facilitated and demonstrated from theory to experiments. One sun fully offers both thermal and electrical energy powered thermo- and electrochemistry for pollutant oxidation. Solar thermal action provides high temperatures for the activation of the pollutant molecules to gear up for solar-driven electrochemical oxidation. Taking wastewater containing phenol as an example, the cyclic voltammetry (CV) curves display two redox processes at less than 100 °C, while only one redox process of single oxidation of phenol appears at more than 100 °C. The oxidation of phenol is accompanied by an efficient evolution of hydrogen, in which the yield of 0.627 mL at 30 °C is increased to 2.294 mL at 210 °C. The phenol removal is enhanced to 80.50% at 210 °C. Tracking the reaction progress shows that small molecular organic acids are detected as the only intermediate at the high temperatures, which suggests the easy realization of full mineralization. The kinetic reaction of the phenol oxidation is fitted to the first order with an increase of the rate constant of 10 times compared with that at low temperatures. Solar engineering of oxidation of organic pollutants not only solves the issue of energy demand for the tough wastewater treatment but also realizes fast and efficient oxidation of organic pollutants. This study opens up new avenues to achieve solar wastewater treatment and simultaneous hydrogen production.

Quantitative analysis of multiple exocyclic DNA adducts in human salivary DNA by stable isotope dilution nanoflow liquid chromatography-nanospray ionization tandem mass spectrometry.

Exocyclic DNA adducts, including 1,N(2)-propano-2'-deoxyguanosine derived from acrolein (AdG) and crotonaldehyde (CdG) and the three lipid peroxidation-related etheno adducts 1,N(6)-etheno-2'-deoxyadenosine (εdAdo), 3,N(4)-etheno-2'-deoxycytidine (εdCyt), and 1,N(2)-etheno-2'-deoxyguanosine (1,N(2)-εdGuo), play an important role in cancer formation and they are associated with oxidative-stress-induced DNA damage. Saliva is an easily accessible and available biological fluid and a potential target of noninvasive biomarkers. In this study, a highly sensitive and specific assay based on isotope dilution nanoflow LC-nanospray ionization tandem mass spectrometry (nanoLC-NSI/MS/MS) is developed for simultaneous detection and quantification of these five adducts in human salivary DNA. The levels of AdG, CdG, εdAdo, εdCyd, and 1,N(2)-εdGuo, measured in 27 human salivary DNA samples from healthy volunteers, were determined as 104 ± 50, 7.6 ± 12, 99 ± 50, 72 ± 49, 391 ± 198 (mean ± SD) in 10(8) normal nucleotides, respectively, starting with 25 µg of DNA isolated from an average of 3 mL of saliva. Statistically significant correlations were found between levels of εdAdo and εdCyd (γ = 0.8007, p < 0.0001), between levels of εdAdo and 1,N(2)-εdGuo (γ = 0.6778, p = 0.0001), between levels of εdCyd and 1,N(2)-εdGuo (γ = 0.5643, p = 0.0022), between levels of AdG and 1,N(2)-εdGuo (γ = 0.5756, p = 0.0017), and between levels of AdG and εdAdo (γ = 0.3969, p = 0.0404). Only 5 µg of DNA sample was analyzed for simultaneous quantification of these adducts. The easy accessibility and availability of saliva and the requirement for the small amount of DNA samples make this nanoLC-NSI/MS/MS assay clinically feasible in assessing the possibility of measuring 1,N(2)-propano-2'-deoxyguanosine and etheno adducts levels in human salivary DNA as noninvasive biomarkers for DNA damage resulting from oxidative stress and for evaluating their roles in cancer formation and prevention.

A Comparative Analysis of Retrieval Algorithms of Land Surface Temperature from Landsat-8 Data: A Case Study of Shanghai, China.

In the trend of global warming and urbanization, frequent extreme weather has a severe impact on the lives of citizens. Land Surface Temperature (LST) is an essential climate variable and a vital parameter for land surface processes at local and global scales. Retrieving LST from global, regional, and city-scale thermal infrared remote sensing data has unparalleled advantages and is one of the most common methods used to study urban heat island effects. Different algorithms have been developed for retrieving LST using satellite imagery, such as the Radiative Transfer Equation (RTE), Mono-Window Algorithm (MWA), Split-Window Algorithm (SWA), and Single-Channel Algorithm (SCA). A case study was performed in Shanghai to evaluate these existing algorithms in the retrieval of LST from Landsat-8 images. To evaluate the estimated LST accurately, measured data from meteorological stations and the MOD11A2 product were used for validation. The results showed that the four algorithms could achieve good results in retrieving LST, and the LST retrieval results were generally consistent within a spatial scale. SWA is more suitable for retrieving LST in Shanghai during the summer, a season when the temperature and the humidity are both very high in Shanghai. Highest retrieval accuracy could be seen in cultivated land, vegetation, wetland, and water body. SWA was more sensitive to the error caused by land surface emissivity (LSE). In low temperature and a dry winter, RTE, SWA, and SCA are relatively more reliable. Both RTE and SCA were sensitive to the error caused by atmospheric water vapor content. These results can provide a reasonable reference for the selection of LST retrieval algorithms for different periods in Shanghai.

Simultaneous quantification of three lipid peroxidation-derived etheno adducts in human DNA by stable isotope dilution nanoflow liquid chromatography nanospray ionization tandem mass spectrometry.

Etheno DNA adducts are promutagenic DNA lesions derived from exogenous industrial chemicals, as well as endogenous sources including lipid peroxidation. Furthermore, levels of etheno adducts in tissue DNA are elevated in cancer-prone tissues. In this study, we have developed a highly sensitive and specific stable isotope dilution nanoflow LC-nanospray ionization tandem mass spectrometry (nanoLC-NSI/MS/MS) assay for simultaneous detection and accurate quantification of 1,N(6)-etheno-2'-deoxyadenosine (epsilondAdo), 3,N(4)-etheno-2'-deoxycytidine (epsilondCyt), and 1,N(2)-etheno-2'-deoxyguanosine (1,N(2)-epsilondGuo) in tissue DNA. Typically, [(13)C(1),(15)N(2)]epsilondAdo, [(15)N(3])epsilondCyd, and [(13)C(1),(15)N(2)]1,N(2)-epsilondGuo were added to calf thymus, human placenta, or human leukocyte DNA as internal standards, and the mixture was subjected to enzyme hydrolysis to form the nucleosides. The etheno adducts in DNA hydrolysate were enriched by a reversed phase solid-phase extraction column before analysis by nanoLC-NSI/MS/MS under the highly selective reaction monitoring (H-SRM) mode. This nanoLC-NSI/MS/MS assay achieved attomole-level sensitivity with the detection limit of 0.73, 160, and 34 amol for the respective standard epsilondAdo, epsilondCyd, and 1,N(2)-epsilondGuo injected on-column, while the quantification limit for the entire assay was 0.18, 4.0, and 3.4 fmol, respectively. The levels of epsilondAdo, epsilondCyd, and 1,N(2)-epsilondGuo in human placental DNA were 28.2, 44.1, and 8.5 adducts in 10(8) normal nucleosides, respectively. The levels of epsilondAdo, epsilondCyd, and 1,N(2)-epsilondGuo in 11 human leukocyte DNA samples were 16.2 +/- 5.2, 11.1 +/- 5.8, and 8.6 +/- 9.1 (mean +/- S.D.) in 10(8) normal nucleotides, respectively, starting from 30 mug of DNA or 1-1.5 mL of blood, and all the relative standard deviations were within 10%. An aliquot equivalent to 6 mug of DNA hydrolysate was used for analysis by this nanoLC-NSI/MS/MS. Thus, this highly sensitive and specific nanoLC-NSI/MS/MS method is suitable for accurate quantification of the three lipid peroxidation-derived etheno DNA adducts as noninvasive biomarkers in clinical studies for cancer risk assessment and for evaluation of preventive agents.

[Analysis on urban vegetations reflectance characteristics in Shanghai].

The spectral features of ground objects are not only the brief contents of mechanism of remote sensing, but also the important basis in remote sensing application. As one of main components of terrestrial ecosystems, urban forest plays a key role in maintaining urban ecosystem balance. In the present paper, the authors adopted FieldSpec 3 portable spectroscope made by American ASD Company, and investigated or examined some spots in the Kangjian park of Shanghai, China. The spectra of euonymus japonicus L. cv, hypericum monogynum, sabina chinensis, ophiopogon japonicus, viburnum awabuki, and buxus sinica were measured. According to the actual conditions, the authors analyzed the data noise characteristic of the spectrum and got rid of the noise with Savitzky Golay method. Meanwhile, differential spectrum technology was used to remove the environmental background influence. Then the authors analyzed their features and variation of these spectral curves from the vegetation canopy and leaf level respectively. The research on spectral reflectance characteristics for urban vegetations is very significant. And the result of this research can be used for the study of physical chemistry performances of urban vegetation, remote sensing retrieval, vegetation classification, vegetation survey and environmental monitoring in urban area.

Simultaneous quantification of 1,N2-propano-2'-deoxyguanosine adducts derived from acrolein and crotonaldehyde in human placenta and leukocytes by isotope dilution nanoflow LC nanospray ionization tandem mass spectrometry.

Humans are exposed to acrolein and crotonaldehyde due to environmental pollution and endogenous lipid peroxidation. These aldehydes react with the 2'-deoxyguanosine moiety of DNA, forming the exocyclic 1,N2-propano-2'-deoxyguanosine adducts AdG and CdG. These adducts are mutagenic lesions, and they play an important role in cancer and neurodegenerative diseases. In this study, a highly sensitive and quantitative assay was developed for simultaneous detection and quantification of AdG and CdG isomers in human placenta and leukocyte DNA by isotope dilution nanoflow LC with nanospray ionization tandem mass spectrometry (nanoLC-NSI/MS/MS). The on-column detection limits (S/N > or = 3) of AdG and CdG were 15 and 8.9 amol, respectively. The quantification limits of AdG and CdG for the entire assay were 619 and 297 amol, respectively, corresponding to 9.8 and 4.7 adducts in 10(9) normal nucleotides, respectively, starting with 20 microg of DNA. Different enzyme hydrolysis methods were compared, and the optimal hydrolysis conditions were employed for the assay. Levels of AdG and CdG in human placental DNA (20 microg) were 108 and 26 in 10(8) normal nucleotides, respectively, with the respective relative standard deviation (RSD) of 2.6% and 3.1% (n = 3). Levels of AdG and CdG in 9 human leukocyte DNA samples were 78 +/- 23 (mean +/- SD) and 6.2 +/- 3.8 (mean +/- SD) in 10(8) normal nucleotides, respectively, starting from 30 microg of DNA. Using this assay, only 4-6 microg of DNA sample was subjected to this nanoLC-NSI/MS/MS system for analysis. Only 1-1.5 mL of blood is needed for measuring AdG and CdG levels in leukocyte DNA. Thus, it is clinically feasible using this highly sensitive assay to investigate the potential of using these adducts as noninvasive biomarkers for DNA damage resulting from acrolein and crotonaldehyde and to study their roles in cancer development and prevention.

Investigation of DNA-protein cross-link formation between lysozyme and oxanine by mass spectrometry.

Reactive nitrogen species are implicated in inflammatory diseases and cancers. Oxanine (Oxa) is a DNA lesion product originating from the guanine base through exposure to nitric oxide, nitrous acid, or N-nitrosoindoles. Oxanine was found to mediate formation of DNA-protein cross-links (DPCs) in the cell extract. We have previously characterized two DNA-protein cross-links from the reaction between Oxa and glutathione: namely, the thioester and the amide. In this study, lysozyme was used to study site-specific modification on protein by Oxa moieties in DNA. With the aid of nanoLC coupled with nanospray ionization tandem mass spectrometry, addition of Oxa was found at Lys13, Lys97, Lys116, Ser85, and Ser86 of lysozyme when it was treated with 2'-deoxyoxanosine (dOxo). Furthermore, incubation of lysozyme with Oxa-containing calf thymus DNA, produced by treating DNA with nitrous acid, led to lysozyme modification at Lys116, Ser85, and Ser86. Interestingly, none of the cysteine residues was modified by dOxo, in contrast with our previous findings that dOxo reacted with oxidized glutathione disulfide, forming the thioester. This might be due to the half-life of the dOxo-derived thioester being 2.2 days at the pH of incubation. Furthermore, the sites of modifications on lysozyme are in good agreement with the solvent accessibility of the residues. Since repair of Oxa-derived DPCs has not been extensively investigated, these results suggest that these stable DPCs might represent important forms of cellular damage caused by reactive nitrogen species involved in inflammationrelated diseases.

H2O2/nitrite-induced post-translational modifications of human hemoglobin determined by mass spectrometry: redox regulation of tyrosine nitration and 3-nitrotyrosine reduction by antioxidants.

Covalent modifications of proteins by endogenous reactive nitrogen oxide species lead to cytotoxic effects that are implicated in diseases associated with chronic infections and inflammation. Tyrosine nitration is a major post-translational modification of proteins by reactive nitrogen oxide species. Recent studies suggest that nitrotyrosine is not a permanent protein modification. We previously demonstrated that lipoyl dehydrogenase is capable of converting 3-nitrotyrosine into 3-aminotyrosine in the presence of certain reducing agents. In this study, we compared the abilities of various hemoproteins, hemin, and the cobalt-containing cofactor cyanocobalamin to mediate H(2)O(2)/nitrite-dependent tyrosine nitration and found that these hemoproteins and metal-containing cofactors also catalyzed the reduction of 3-nitrotyrosine to various extents in the presence of thiol reducing agents or ascorbate. The H(2)O(2)/nitrite-induced post-translational modifications of human hemoglobin identified by nanoLC/nanospray ionization tandem mass spectrometric analysis of the tryptic digest include nitration of tyrosine and tryptophan, as well as oxidation of methionine and cysteine residues. Nitration of human hemoglobin by H(2)O(2)/nitrite was detected on Tyr24 and Tyr42 (alpha-chain) and on Tyr130 and Trp15 (beta-chain) in the alphabeta-dimer. Oxidation of methionine and cysteine residues was also observed. Furthermore, hemoglobin also catalyzed nitro reduction of 3-nitrotyrosine to form 3-aminotyrosine, at Tyr24 in the alpha-chain peptide of human Hb in the presence of ascorbate. The enhanced peroxidase activity of nitrated hemoglobin can be reversed by the antioxidant ascorbate. These results suggest a possible in vivo pathway for hemoglobin contributing to denitration of nitrated proteins through redox regulation.

Wetland ecosystem health assessment through integrating remote sensing and inventory data with an assessment model for the Hangzhou Bay, China.

Due to rapid urbanization, industrialization and population growth, wetland area in China has shrunk rapidly and many wetland ecosystems have been reported to degrade during recent decades. Wetland health assessment could raise the public awareness of the wetland condition and guide policy makers to make reasonable and sustainable policies or strategies to protect and restore wetland ecosystems. This study assessed the health levels of wetland ecosystem at the Hangzhou Bay, China using the pressure-state-response (PSR) model through synthesizing remote sensing and statistical data. Ten ecological and social-economic indicators were selected to build the wetland health assessment system. Weights of these indicators and PSR model components as well as the normalized wetland health score were assigned and calculated based on the analytic hierarchy process (AHP) method. We analyzed the spatio-temporal changes in wetland ecosystem health status during the past 20years (1990-2010) from the perspectives of ecosystem pressure, state and response. The results showed that the overall wetland health score was in a fair health level, but displayed large spatial variability in 2010. The wetland health score declined from good health level to fair health level from 1990 to 2000, then restored slightly from 2000 to 2010. Overall, wetland health levels showed a decline from 1990 to 2010 for most administrative units. The temporal change patterns in wetland ecosystem health varied significantly among administrative units. Our results could help to clarify the administrative responsibilities and obligations and provide scientific guides not only for wetland protection but also for restoration and city development planning at the Hangzhou Bay area.

Polymer-based resistive memory materials and devices.

Due to the advantages of good scalability, flexibility, low cost, ease of processing, 3D-stacking capability, and large capacity for data storage, polymer-based resistive memories have been a promising alternative or supplementary devices to conventional inorganic semiconductor-based memory technology, and attracted significant scientific interest as a new and promising research field. In this review, we first introduced the general characteristics of the device structures and fabrication, memory effects, switching mechanisms, and effects of electrodes on memory properties associated with polymer-based resistive memory devices. Subsequently, the research progress concerning the use of single polymers or polymer composites as active materials for resistive memory devices has been summarized and discussed. In particular, we consider a rational approach to their design and discuss how to realize the excellent memory devices and understand the memory mechanisms. Finally, the current challenges and several possible future research directions in this field have also been discussed.

Smart responsive phosphorescent materials for data recording and security protection.

Smart luminescent materials that are responsive to external stimuli have received considerable interest. Here we report ionic iridium (III) complexes simultaneously exhibiting mechanochromic, vapochromic and electrochromic phosphorescence. These complexes share the same phosphorescent iridium (III) cation with a N-H moiety in the N^N ligand and contain different anions, including hexafluorophosphate, tetrafluoroborate, iodide, bromide and chloride. The anionic counterions cause a variation in the emission colours of the complexes from yellow to green by forming hydrogen bonds with the N-H proton. The electronic effect of the N-H moiety is sensitive towards mechanical grinding, solvent vapour and electric field, resulting in mechanochromic, vapochromic and electrochromic phosphorescence. On the basis of these findings, we construct a data-recording device and demonstrate data encryption and decryption via fluorescence lifetime imaging and time-gated luminescence imaging techniques. Our results suggest that rationally designed phosphorescent complexes may be promising candidates for advanced data recording and security protection.

Single polymer-based ternary electronic memory material and device.

A ternary polymer memory device based on a single polymer with on-chain Ir(III) complexes is fabricated by combining multiple memory mechanisms into one system. Excellent ternary memory performances-low reading, writing, and erasing voltages and good stability for all three states-are achieved.