A review on identification, quantification, and transformation of active species in SCR by EPR spectroscopy.

Electron paramagnetic resonance (EPR) is the only technique that provides direct detection of free radicals and samples that contain unpaired electrons. Thus, EPR had an important potential application in the field of selective catalytic reduction of nitrogen oxide (SCR). For the first time, this work reviewed recent developments of EPR in charactering SCR. First, qualitative analysis focused on recognizing Cu, Fe, V, Ti, Mn, and free-radical (oxygen vacancy and superoxide radical) species. Second, quantification of the active species was obtained by a double-integral and calibration method. Third, the active species evolved because of different thermal treatments and redox-thermal processes under reductants (NH3 and NO). The coordination information of the active species in catalysts and their effects on SCR performances were concluded from mechanism viewpoints. Finally, potential perspectives were put forward for EPR developments in characterizing the SCR processes in the future. After all, EPR characterization will help to have a deep understanding of structure-activity relationship in one catalyst.

Reveal of free radicals in manganese-based catalysts and their roles during selective catalytic reduction of nitrogen oxide.

HYPOTHESIS: Manganese-based catalysts attract extensive attentions in low-temperature selective catalytic reduction (SCR) of nitrogen oxide (NOx). However, seldom work focuses on the existence of free radicals and their roles in SCR. EXPERIMENTS: In this work, electron paramagnetic resonance spectrometer and density functional theory are combined to reveal surface characterizations of manganese oxide and Ce/La-doped manganese oxides. FINDINGS: As a result, superoxide radical (O2*) exists on manganese-oxide surface, produces nitrogen-containing free radical, and functions as electron transfer between NOx and NH3 at 100 °C, resulting in good NOx conversion as well as N2 selectivity at the same time. The O2* is born of accepting electrons on adsorbed oxygen through overlapped orbits of Mn-d and O-p. Additional metal doping increases the percentage of O2* among all oxygen species from 2.9 % to 6.9 % (Ce doping) and 5.1 % (La doping). The order of O2* percentage is consistent with the NOx-conversion order at 100 °C, i.e., Ce doping (91.6 %) > La doping (55.7 %) > catalyst without doping (27.5 %). Above result helps to understand interface behaviors of manganese-based catalyst in SCR. This work is also in favor of developing more effective low-temperature catalysts.

Spatial-temporal dynamics and scenario simulation of land ecological security: a case study of Deyang, Sichuan Province, China.

As a means of producing the resources required for human survival and development, land is the cornerstone of social development and an important part of the ecological environmental system. To measure the granularity and spatial differentiation of changes in the ecological security levels of the study area, this paper uses the PSR model. A kilometer grid is used as the evaluation unit, and a relative entropy theory is used to obtain the combined weight. The comprehensive index method is used to calculate the ecological security value of the land. Based on clarifying the dynamics of time and space, the spatial distribution of the ecological security levels in 2020 is simulated by the CA-Markov model. The results show the following: (1) the level of ecological security in the city of Deyang decreases from 0.580 in 2005 to 0.558 in 2015, showing a fluctuating downward trend, and different districts, cities, and counties and show varying trends. (2) During the study period, the area classified with a safe level decreased from 2853.72 km2 in 2005 to 1809.45 km2 in 2015, and the areas with critical safe, less safe, and unsafe levels all increased. The areas of decrease are mainly concentrated in the Jingyang District, Luojiang County, and Zhongjiang County. (3) The results of four proposed scenarios for future economic or environmental development are significantly different. Maintaining the status quo cannot change the declining trend in ecological security in the city of Deyang. A priority of economic development will lead to a significant decline in land ecological security. Establishing environmental protection as a priority can significantly change the ecological security of the land in the city. The results of the "comprehensive" scenario simulation are closest to the actual security values calculated for 2019, reflecting the trade-off between economic development and environmental protection. The research results can provide a reference for the evaluation and prediction of ecological security and provide theoretical guidance for the formulation of sustainable measures.

A catalyst with the better catalytic activity for NO reduction showed bigger reduction capacity and limiting current.

The catalytic activity of a new catalyst for NO reduction is usually obtained by a gas-solid phase experiment. For the first time, a relationship has been established between catalytic performance and electrochemistry property. A bimetallic catalyst showed a low-temperature activity and removed 67.27% of NO at 300 °C, 33.39% bigger than a single-metallic catalyst. The bimetallic catalyst removed 9.770 mmol/g of NO after 1440 min, 5.212 mmol/g bigger than the single-metallic one. At the same time, the bimetallic catalyst showed a reduction capacity of 0.441 mmole/g. In comparison, the single-metallic one only had 0.242 mmole/g. Moreover, the limiting current of bimetallic catalyst (4.020 e-4A) was also bigger than that of single-metallic one (3.698 e-4A). Therefore, a catalyst for NO reduction showed better catalytic activity and electron-transfer ability at the same time. In other words, the catalytic activity of a catalyst can be potentially estimated by detecting its electrochemistry properties.

Recombinant Miro domain-containing protein of Haemonchus contortus (rMiro-1) activates goat peripheral blood mononuclear cells in vitro.

In our previous proteomics study, we identified Miro domain-containing protein (Miro-1), an excretory and secretory product of the pole worm, Haemonchus contortus, binds to goat peripheral blood mononuclear cells (PBMCs) in vivo. However, our understanding of the role of Miro-1and its potential immune impact on goat PBMCs is limited. The aim of the present study was to evaluate the effects of Miro-1 on functions of goat PBMCs in vitro. Recombinant protein (rMiro-1) was expressed in a prokaryote and incubated with goat PBMCs. Western blot analysis showed that rMiro-1 is successfully recognized by goat sera infected with H. contortus. Immunofluorescence analysis using rat antibodies against rMiro-1 indicated that this protein binds to goat PBMCs in vitro. Treatment of goat PBMCs/monocytes with various concentrations of rMiro-1 resulted in the upregulation of IL-2, IL-4, and IL-17, which in turn promoted cell proliferation, migration, the release of NO in PBMCs, and enhancement of phagocytosis of monocytes. These findings suggested that rMiro-1 stimulates PBMCs activity.

Modulation of goat monocyte function by HCcyst-2, a secreted cystatin from Haemonchus contortus.

Modulation and suppression of the host immune response by nematode parasites have been reported extensively and the cysteine protease inhibitor (cystatin) is identified as one of the major immunomodulator. In the present study, we cloned and produced recombinant cystatin protein from nematode parasite Haemonchus contortus (rHCcyst-2) and investigated its immunomodulatory effects on goat monocyte. rHCcyst-2 protein is biologically functional as shown by its ability to inhibit the protease activity of cathepsin L, cathepsin B and papain. Immunohistochemical test demonstrated that the native HCcyst-2 protein was predominantly localized at the body surface and internal surface of the worm's gut. We demonstrated that rHCcyst-2 could be distinguished by antisera from goats experimentally infected with H. contortus and could uptake by goat monocytes. The immunomodulatory effects of HCcyst-2 on cytokine secretion, MHC molecule expression, NO production and phagocytosis were observed by co-incubation of rHCcyst-2 with goat monocytes. The results showed that the interaction of rHCcyst-2 decreased the production of TNF-α, IL-1ß and IL-12p40. However, it significantly increased the secretion of IL-10 in goat monocytes. After rHCcyst-2 exposure, the expression of MHC-II on goat monocytes was inhibited. Moreover, rHCcyst-2 could up-regulate the LPS induced NO production of goat monocytes. Phagocytotic assay by FITC-dextran internalization showed that rHCcyst-2 inhibited the phagocytosis of goat monocytes. Our findings provided potential target as immunoregulator, and will be helpful to illustrate the molecular basis of host-parasite interactions and search for new potential molecule as vaccine and drug target candidate.

Transmembrane protein 147 (TMEM147): another partner protein of Haemonchus contortus galectin on the goat peripheral blood mononuclear cells (PBMC).

BACKGROUND: Recombinant galectins of male and female Haemonchus contortus (rHco-gal-m/f) have been recognized as significant regulators of the functions of goat peripheral blood mononuclear cells (PBMC). In previous research, transmembrane protein 63A (TMEM63A) was identified as a partner protein in the regulation associated with H. contortus infection. However, in the identification of binding partners for galectins of male and female H. contortus (Hco-gal-m/f) by yeast two-hybrid (YTH) screening, it was found that the transmembrane protein 147 (TMEM147) could also bind to Hco-gal-m/f. In this study, the functions of TMEM147 in the regulations of H. contortus galectin on the goat PBMC were investigated. METHODS: To identify Hco-gal-m/f-interacting proteins, a yeast two-hybrid system to detect interactions was used. Co-immunoprecipitation and immunoblotting were used to validate the interaction between recombinant galectins of male H. contortus (rHco-gal-m) and candidate binding protein. The localization of TMEM147 in PBMC was explored by immunofluorescence in confocal imaging studies. Flow cytometry was used to determine the distribution of TMEM147 in T cells, B cells and monocytes in PBMC. The modulatory effects of rHco-gal-m and TMEM147 on cell proliferation, phagocytosis, nitric oxide production, migration, apoptosis and cytokine mRNA transcription were observed by co-incubation of rHco-gal-m and knockdown of the tmem147 gene. RESULTS: In this research, it was demonstrated that TMEM147 could bind to rHco-gal-m/f. Immunofluorescence assays showed that TMEM147 was localized to the cell membrane and within the cell membrane in goat PBMC. Flow cytometric analysis revealed that TMEM147 was expressed in all B cells and monocytes in goat PBMC. However, 3.8 % of T cells did not express this protein. Knockdown of the tmem147 gene using RNA interference (RNAi) showed that the interaction of galectin with TMEM147 mainly mediated cell proliferation, cell apoptosis, transcription of interleukin-10 (IL-10) and transforming growth factor-ß1 (TGF-ß1) of goat PBMC. This membrane protein, together with TMEM63A, was also related to the regulation of galectin on phagocytosis and nitric oxide production of goat PBMC. However, it might not be involved in the regulation of galectin on the migration and interferon-γ (IFN-γ) transcription of goat PBMC. CONCLUSIONS: Our results showed that TMEM147 was a binding partner of Hco-gal-m/f and mediated the immunological regulation of Hco-gal-m/f on goat PBMC in a manner different to that of TMEM63A.

Rotavirus VP7 epitope chimeric proteins elicit cross-immunoreactivity in guinea pigs.

VP7 of group A rotavirus (RVA) contains major neutralizing epitopes. Using the antigenic protein VP6 as the vector, chimeric proteins carrying foreign epitopes have been shown to possess good immunoreactivity and immunogenicity. In the present study, using modified VP6 as the vector, three chimeric proteins carrying epitopes derived from VP7 of RVA were constructed. The results showed that the chimeric proteins reacted with anti-VP6 and with SA11 and Wa virus strains. Antibodies from guinea pigs inoculated with the chimeric proteins recognized VP6 and VP7 of RVA and protected mammalian cells from SA11 and Wa infection in vitro. The neutralizing activities of the antibodies against the chimeric proteins were significantly higher than those against the vector protein VP6F. Thus, development of chimeric vaccines carrying VP7 epitopes using VP6 as a vector could be a promising alternative to enhance immunization against RVAs.

A new rotavirus VP6-based foreign epitope presenting vector and immunoreactivity of VP4 epitope chimeric proteins.

The VP6, the group antigenic rotavirus (RV), is highly conserved and the most abundant, constituting about 39% of the viral structure proteins by weight. The high degree of identity (>87%-99%) in the primary amino acid sequences suggests VP6-based vaccines could potentially provide heterotypic protection. Although some efforts have been made toward producing recombinant rotavirus VP6 vaccines, the native VP6 is still unsatisfactory as an optimal vaccine. The major neutralizing antigenic epitopes that exist on VP4 or VP7 are not on the native VP6, and as a vector the native VP6 lacks insertion sites that can be used for insertion of foreign epitopes. In this study, a new foreign epitope presenting system using VP6 as a vector (VP6F) was constructed on the outer surface of the vector six sites that could be used for insertion of the foreign epitopes created. Using this system, three VP6-based VP4 epitope chimeric proteins were constructed. Results showed that these chimeric proteins reacted with anti-VP6 and -VP4 antibodies, and elicited antibodies against VP6 and VP4 in guinea pigs. Antibodies against VP6F or antibodies against the chimeric proteins neutralized RV Wa and SA11 infection in vitro. It is optimistic that the limitation for using the native VP6 as a vaccine candidate or vector will be solved with our proposed approach. It is expected that this VP6-based epitope presenting system and the VP6-based VP4 epitope chimeric proteins will be valuable for and contribute to the development of novel RV vaccines and vaccine vectors.

[NSP5/NSP6 of rotavirus strain TB-Chen and preliminary genotyping analysis].

Strain TB-Chen is a group A rotavirus (RV) isolated from a Chinese infant suffering from gastroenteritis in hospital. The NSP5 and NSP6 of strain TB-Chen are encoded by the 10th gene segment (816bp in whole length) of the viral genome. The results obtained in this study showed that the NSP5 was encoded in the first open-reading-frame (ORF) of the gene segment (from 22bp to 624bp), and NSP6 was encoded in the second ORF (from 80bp to 355bp). The NSP5 protein consisted of 200 amino acid residues with a putative molecular mass of 21.9 kD, and a putative isoelectric point of 7.86. The NSP6 protein consisted of 92 amino acids with a putative molecular mass of 11 kD, and a putative isoelectric point of 9.65. This study further analyzed phylogenetic relationship of the NSP5/NSP6 ORF nucleotide sequence. The results showed that the NSP5s of group A rotavirus could be at least classified into 7 genotypes (H1-H7), the NSP6s could be at least classified into 8 genotypes (hl-h8); the genotypes of the NSP5 and NSP6 derived from strain TB-Chen was classified as H2 and h2. This was the first report on the genotype classification of the NSP6 of group A RVs, and it was proposed English letter "h" to represent genotype of the NSP6, e. g. strain 69M classified as H7h7, strains Wa and KU classified as H1h8.

Full genomic analysis of human rotavirus strain TB-Chen isolated in China.

A G2P[4]/NSP4[A] rotavirus strain TB-Chen was isolated from a 2-year-old patient hospitalized with acute gastroenteritis in Kunming, China. The strain TB-Chen was demonstrated having group A-specific antigenicity, a "short" (subgroup II) electropherotype. To investigate its overall genomic relatedness and to determine which group it belonged, the complete genome of strain TB-Chen was determined. Genomic comparison based on amino acid sequence identity and phylogenetic analysis revealed that all 11 gene segments of strain TB-Chen were highly identical (>91.80%) with the representative G2P[4]/NSP4[A] human strains DS-1, S2, NR1 and IS2, suggesting that this rotavirus strain was derived from human host. Besides, almost all the available representative rotavirus gene segments among group A were analyzed and identified within 15 G-types, 28 P-types, and 6 NSP4 genotypes. This is the first report of group A rotavirus genomic analyses in China and the findings have important implications for rotavirus vaccine development.

Immunoreactivity of HCV/HBV epitopes displayed in an epitope-presenting system.

It has been demonstrated that the immunodominant region of the HCV core protein and the hepatitis B surface antigen (HBsAg) have high degree of reactivity. In order to construct a chimeric protein that carries HCV and HBV epitopes and possesses immunogenicity to both HCV and HBV, four epitopes derived from residues aa2-21 (epitope C1), aa22-40 (epitope C2) of the core protein, residues aa315-328 (epitope E) of E1 protein of HCV, and residues aa124-147 (epitope S) of HBsAg were chosen to be displayed in a conformation-specific manner on the outer surface of the Flock House virus capsid protein and expressed in E. coli cells. The reactivity of these epitopes with antisera from hepatitis C and hepatitis B patients and induction of immune response in guinea pigs were determined. The results showed that when displayed in this system, the chimeric protein carrying only epitope S could react with anti-HBsAg positive human sera, elicit an anti-HBsAg response in guinea pigs. The chimeric protein carrying epitopes C1, C2 and E could react with antibodies to different HCV genotypes, elicit an anti-HCV response in guinea pigs. The chimeric protein carrying epitopes C1, C2, E, and S could react with antibodies against HCV and HBV, elicit anti-HCV and anti-HBsAg responses in guinea pigs. The results suggested that these epitopes displayed in this form could be considered for development of epitope-based vaccines against HCV/HBV infections.

[Protective efficacy of recombinant rotavirus epitope-based vaccine in mice].

OBJECTIVE: To evaluate in vivo immunological protective efficacy and safety of expressed recombinant rotavirus epitopes in mice. METHODS: Using the Flock House virus capsid protein as a vector, three epitopes derived from rotavirus Vp4 amino acid 223-242 [rotavirus epitope A, (REA)], 243-262 [rotavirus epitope B, (REB)], and 234-251 [rotavirus epitope C, (REC)] were genetically engineered on the surface of the vector protein and expressed in pET-3 (E. coli BL21 [DE3]) system into multiple epitopes, REABC, which comprises REA, REB, and REC. Kunming strain mice were inoculated with the recombinant epitopes REABC, and then challenged perorally by cell culture-adapted rotavirus Wa (type G1P1A) and SA11 (type G3P2). Infection syndrome was observed, and virus antigen in stools of mice and serum neutralizing antibody activities were determined and analyzed. RESULTS: The recombinant epitopes REABC significantly induced rotavirus specific neutralyzing antibodies against WA and SA11, reduced virus reproduction, elicitted immune memory in inoculated mice, and protected inoculated mice from challenge by WA or SA11 (P<0.001). CONCLUSION: The recombinant epitopes have high immunological protective efficacy and mild side effects in mice. It may be used as an epitope-based vaccine candidate in human.