DMF as an amine source: iron-catalyzed cyclization of 2H-azirines to imidazoles.

A novel method has been developed for the synthesis of 1-methyl-4,5-diaryl-1H-imidazoles through Fe(II)-catalyzed cyclization of 2H-azirines and N,N-dimethylformamide (DMF) as an amine source. This transformation involves the cleavage of C-N and CN double bonds and the construction of new C-N and CN double bonds. The reaction has readily available starting materials, a wide range of substrates and mild reaction conditions. In addition, the reaction also facilitated the convenient synthesis of 1-methyl-2,4,5-triaryl-1H-imidazoles.

[Response of Soil Nitrifier and Denitrifier Community and Activity to Elevated Atmospheric CO2 Concentration and Temperature].

Elevated atmospheric CO2 concentration and temperature may affect nitrifiers and denitrifiers which are related to soil N turnover. A climate change experiment was conducted in the rice-wheat rotation ecosystem. This study was used to investigate effects of elevated CO2 and temperature on soil microbial community structure, as well as abundance and activity of nitrifiers and denitrifiers. The results showed that no change in the abundance of ammonia-oxidizing bacteria (AOB) and denitrifier was observed at the tillering stage, however at the later stages, elevated CO2 alone significantly increased the abundance of ammonia-oxidizing archaea (AOA) and denitrifier but there were no changes under CW treatment. The analysis of T-RFLP profiles showed that elevated CO2 and temperature had no obvious effect on community structure of AOA, AOB or denitrifier, but altered diversity index (H') of AOA and denitrifier. Moreover, elevated CO2 alone significantly increased nitrifying rate at the ripening stage. Elevated CO2 and temperature did not result in significant change in denitrifying rate at each single stage. These results suggested that effects of elevated CO2 and temperature on microbial community were different among the tillering, heading and ripening stages, and functional microorganism responded differently to multiple climate change treatments.

A novel rosamine based fluorescent sensor for Ag(+) recognition.

Rosamine derivative, N-(9-(4-(bis(2-(ethylthio)ethyl)amino)phenyl)-6-(diethylamino)-3H-xanthen-3-ylidene)-N-ethylethanaminium hexafluorophosphate, L, bearing an NS2 group as receptor, was synthesized as a turn on chemosensor for silver ion in ethanol solution. Sensor L exhibited high selectivity toward Ag(+) in comparison to other metal cations (Cd(2+), Cu(2+), Hg(2+), Na(+), Mg(2+), Ni(2+), Pb(2+), Fe(3+), and Zn(2+)). The detection limit for Ag(+) was in 10(-7) level. The binding properties between silver ion and L were further studied by (1)HNMR titration experiments. The chemosensor L can be used as a potential material for silver recognition.

Novel rhodamine derivate as high selective detection lead sensor.

A novel rhodamine based sensor 1 has been synthesized and characterized by NMR, FT-IR and mass. The binding properties of sensor 1 were investigated in the presence of various metal ions by UV-Vis spectroscopy and fluorescence spectroscopy. Sensor 1 showed colorimetric and high emission intensity enhancement in the presence of Pb(2+) in chloroform-THF (7:3).

A Selective Fluorescent Sensor for Hg(2+).

A novel rhodamine based fluorescent chemosensor RQP was prepared and characterized by (1)HNMR, (13)CNMR and HR-MS. The properties of RQP were studied through UV-Vis spectroscopy and fluorescence spectroscopy. RQP showed highly selectivity toward Hg(2+) over other metal ions, including Ag(+), Cd(2+), Cu(2+), Na(+), Mg(2+), Ni(2+), Pb(2+), Fe(3+), and Zn(2+) in aqueous solutions. The recognition process is reversible and confirmed by EDTA experiment.

[Screening of the binding peptides of Mycobacterium tuberculosis H(37)Rv].

OBJECTIVE: To screen the Mycobacterium tuberculosis H(37)Rv binding peptide using phage-displayed random peptide libraries, and to analyze the binding capacity of the peptide with Mycobacterium tuberculosis. METHODS: Inactive Mycobacterium tuberculosis H(37)Rv was used for screening of the binding peptide from the Ph.D.-7 peptide library, and Mycobacterium smegmatis was used for reverse screening during the 2(nd) to 4(th) rounds of screening. After 4 rounds of screening, single phages were randomly selected for DNA sequencing. The selected clones were tested by indirect enzyme linked immunosorbent assay (ELISA). The peptide of positive clone, which showed the highest affinity, was synthesized in vitro with fluorescent markers. The specific combination of the peptide with 16 mycobacterium standard strains and 3 other microbes (Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans) were observed by fluorescence microscopy. RESULTS: After 4 rounds of biopanning, remarkable enrichment of the phages that specifically bind with target molecules were observed. Single phages were randomly selected for sequencing analysis and 5 sequences were obtained. Five phages with different sequences were detected using indirect ELISA and all of them were found to be positive clones. Phage 8 showed the highest affinity with target molecule. The peptide of phage H8 was synthesized in vitro with fluorescent markers, and it was confirmed that the peptide could bind with H(37)Rv and other 15 mycobacterium including Mycobacterium smegmatis, but not with 3 other microbes. CONCLUSIONS: By using phage-displayed random peptide libraries, we obtained the binding peptide of H(37)Rv. It was shown that the peptide could bind with Mycobacterium tuberculosis specifically, which provided a new way for the detection of Mycobacterium tuberculosis in vitro.

[Fine root biomass and its nutrient storage in karst ecosystems under different vegetations in Central Guizhou, China].

The degeneration of karst ecosystem is closely associated with the reduction of soil nutrients and fine root biomass, and the retention of soil nutrients is of significance in sustaining ecosystem functioning. To understand the changes in the fine root biomass and soil nutrient retention in degenerated karst ecosystems, a comparative study was conducted with three typical vegetation stands (forest, shrub, and shrub-grass) in Central Guizhou of Southwest China. Soil samples with fine roots were collected from the depths 0-5 cm, 5-10 cm, and 10-15 cm, with the related indices of fine roots and nutrients measured. In the three stands, fine roots dominantly distributed in 0 -10 cm soil layer, and decreased sharply with soil depth. The living fine root biomass in 0-10 cm soil layer under forest, shrub, and shrub-grass occupied 83.36%, 86.91%, and 93.79% of the total fine root biomass, and 42.78%, 56.75%, and 53.38% of the total living fine root biomass within the 0-15 cm soil layer, respectively. The fine root biomass of predominant plant species varied with vegetation types. The N and P storage of the living fine roots in 0-5 cm soil layer under forest stand was significantly higher than those under shrub stand and shrub-grass stand, and no significant differences were observed between the latter two stands. However, the N and P storage of the living fine roots in 5-10 cm soil layer under different stands decreased in the order of forest > shrub > shrub-grass (P < 0.05). There was a significant positive correlation between the plant aboveground biomass and the living fine root biomass in 0-10 cm soil layer, and a significant negative correlation between the N and P contents of plant leaves and the specific length of living fine roots, illustrating that the nutrient uptake and retention by the living fine roots could have particular importance in the aboveground biomass establishment and ecosystem functioning.

Two-step scheme for rapid identification and differentiation of Legionella pneumophila and non-Legionella pneumophila species.

A rapid two-step scheme based on PCR amplification and enzymatic digestion analysis of a 226-bp fragment of the 16S rRNA gene was developed to identify the Legionella genus by PCR amplification and to differentiate the Legionella pneumophila and non-Legionella pneumophila species by enzymatic digestion analysis. Among 42 ATCC strains (16 strains of L. pneumophila and 26 strains of non-L. pneumophila) and 200 Legionella isolates from environmental water samples, including pools, rivers, lakes, and cooling towers in Guangdong province, 99.59% of L. pneumophila and non-L. pneumophila strains were correctly identified and differentiated by this scheme. The procedure of this two-step identification and differentiation scheme is simple and takes only about 4 h. These results suggest that this two-step scheme provides a simple and convenient method for the rapid identification and differentiation of L. pneumophila and non-L. pneumophila species.

[Responses of enzyme activities in different particle-size aggregates of paddy soil in Taihu Lake region of China to long-term fertilization].

Taking a long-term fertilized paddy soil in Taihu Lake region as research object, the enzyme activities in <2, 2-20, 20-200, and 200-2000 microm aggregates under no fertilization (NF), chemical fertilization (CF), chemical fertilization plus straw return (CFS), and chemical fertilization plus pig manure (CFM) were investigated. Fertilization promoted the formation of 200-2000 microm aggregates significantly. The enzyme activities differed with aggregates' particle-size. Urease and invertase activities were the highest in <2 microm aggregates, whereas the activities of cellulase, polyphenoloxidase and FDA hydrolase were the highest in 200-2000 microm aggregates. Fertilization, especially the combined fertilization of inorganic and organic fertilizers, increased the activities of urease, invertase, cellulase and FDA hydrolase in 200-2000 microm aggregates significantly. With the geometric mean (GMea) of the five test enzyme activities as the integrative index of soil enzyme activities, it was found that under fertilization, the GMea was significantly higher in 200-2000 microm aggregates, suggesting the high sensitivity of enzyme activities in larger particle-size aggregates to fertilization practices. Long-term inorganic plus organic fertilization could enhance the soil bio-function via the promotion of the formation of larger particle-size aggregates and the enzyme activities in these aggregates.

[Variation of Cd, Zn and Se contents of polished rice and the potential health risk for subsistence-diet farmers from typical areas of South China].

In this study, a total of 70 polished rice samples were randomly collected at agro-product markets from some typical regions of South China. Their contents of Cd, Zn and Se were determined by atomic adsorption spectrophotometers (AAS) and atomic fluorescence spectrometry (AES) respectively. The variation of the contents with rice areas was described in terms of soil conditions and the potential health risk by food exposure to these rice rains for subsistence-diet fanners is discussed. Over 70% of the total samples have Cd contents exceeding the State Food Security Standards (0.2 mg x kg(-1)) with Cd/Zn ratios exceeding the suggested critical threshold of 0.015. Widest variation was found for Cd and smallest for Zn, showing rice Cd prone to environmental stress. The extent to which the contents of the analyzed elements varied with rice areas was rater for Cd and Se than for Zn, though the contents followed in the same order: polluted area > acid paddy area and neutral paddy area. This further evidenced a determinacy of chemical availability in rice Cd uptake. Taking the reference dose values by WHO and USEPA, the health risk by Cd exposure to the rice diet from different areas was estimated. The consumption of rice from polluted area and acid paddy area may impose serious health risks for subsistence diet farmers though those from neutral paddy area may be still safe under the WHO guideline. It is demanded that the problem of the rice rains high in Cd and low in Zn and Se, and serious potential risk should be taken into account while developing high-yielding rice in acid and polluted rice ares of South China. Technology for depressing Cd uptake and low-Cd cultivar breeding should he pursued in rice production sector in the future.

[Effects of heavy metals pollution on paddy soil aggregates composition and heavy metals distribution].

Topsoil samples were collected from a polluted and an adjacent non-polluted paddy field in the Taihu Lake region of China. Different particle size fractions of soil aggregates were separated by low-energy dispersion procedure, and their mass composition and Pb, Cd, Hg, and As concentrations were determined. Under heavy metals pollution, the mass composition of sand-sized fractions reduced, while that of clay-sized fractions increased. The concentrations of test metals in different particle size fractions differed, with the highest in < 0.002 mm fraction, followed by in 2-0.2 mm fraction. In 0.02-0.002 mm and 0.2-0.02 mm fractions, all the test metals were relatively deficient, with an enrichment index of 0.56-0.96. The present study showed that the aggregation of fine particles could be depressed by heavy metals pollution, which in turn, led to a relative increase in the mass composition of fine particles and the associated allocation of heavy metals in weakly aggregated silt particles, and further, increased the risks of heavy metals translocation from polluted farmland into water and atmosphere. Further studies should be made on the impacts of heavy metals pollution on soil biophysical and biochemical processes and related mechanisms.

Evolutional selection of a combinatorial phage library displaying randomly-rearranged various single domains of immunoglobulin (Ig)-binding proteins (IBPs) with four kinds of Ig molecules.

BACKGROUND: Protein A, protein G and protein L are three well-defined immunoglobulin (Ig)-binding proteins (IBPs), which show affinity for specific sites on Ig of mammalian hosts. Although the precise functions of these molecules are not fully understood, it is thought that they play an important role in pathogenicity of bacteria. The single domains of protein A, protein G and protein L were all demonstrated to have function to bind to Ig. Whether combinations of Ig-binding domains of various IBPs could exhibit useful novel binding is interesting. RESULTS: We used a combinatorial phage library which displayed randomly-rearranged various-peptide-linked molecules of D and A domains of protein A, designated PA(D) and PA(A) respectively, B2 domain of protein G (PG) and B3 domain of protein L (PL) for affinity selection with human IgG (hIgG), human IgM (hIgM), human IgA (hIgA) and recombinant hIgG1-Fc as bait respectively. Two kinds of novel combinatorial molecules with characteristic structure of PA(A)-PG and PA(A)-PL were obtained in hIgG (hIgG1-Fc) and hIgM (hIgA) post-selection populations respectively. In addition, the linking peptides among all PA(A)-PG and PA(A)-PL structures was strongly selected, and showed interestingly divergent and convergent distribution. The phage binding assays and competitive inhibition experiments demonstrated that PA(A)-PG and PA(A)-PL combinations possess comparable binding advantages with hIgG/hIgG1-Fc and hIgM/hIgA respectively. CONCLUSION: In this work, a combinatorial phage library displaying Ig-binding domains of protein A, protein G, or protein L joined by various random linking peptides was used to conducted evolutional selection in vitro with four kinds of Ig molecules. Two kinds of novel combinations of Ig-binding domains, PA(A)-PG and PA(A)-PL, were obtained, and demonstrate the novel Ig binding properties.

Topsoil organic carbon mineralization and CO2 evolution of three paddy soils from South China and the temperature dependence.

Carbon mineralization and its response to climatic warming have been receiving global attention for the last decade. Although the virtual influence of temperature effect is still in great debate, little is known on the mineralization of organic carbon (SOC) of paddy soils of China under warming. SOC mineralization of three major types of China's paddy soils is studied through laboratory incubation for 114 d under soil moisture regime of 70% water holding capacity at 20 degrees C and 25 degrees C respectively. The carbon that mineralized as CO2 evolved was measured every day in the first 32 d and every two days in the following days. Carbon mineralized during the 114 d incubation ranged from 3.51 to 9.22 mg CO2-C/gC at 20 degrees C and from 4.24 to 11.35 mg CO2-C/gC at 25 degrees C respectively; and a mineralizable C pool in the range of 0.24 to 0.59 gC/kg, varying with different soils. The whole course of C mineralization in the 114 d incubation could be divided into three stages of varying rates, representing the three subpools of the total mineralizable C: very actively mineralized C at 1-23 d, actively mineralized C at 24-74 d and a slowly mineralized pool with low and more or less stabilized C mineralization rate at 75-114 d. The calculated Q10 values ranged from 1.0 to 2.4, varying with the soil types and N status. Neither the total SOC pool nor the labile C pool could account for the total mineralization potential of the soils studied, despite a well correlation of labile C with the shortly and actively mineralized C, which were shown in sensitive response to soil warming. However, the portion of microbial C pool and the soil C/N ratio controlled the C mineralization and the temperature dependence. Therefore, C sequestration may not result in an increase of C mineralization proportionally. The relative control of C bioavailability and microbial metabolic activity on C mineralization with respect to stabilization of sequestered C in the paddy soils of China is to be further studied.

[Detection of diarrheagenic escherichia coil harboring genomic O island 28 isolated from children diarrhea in Taiyuan].

OBJECTIVE: To investigate the etiologic value of diarrheagenic E. coil harboring genomic O island 28(OI-28) containing five putative virulence genes (Z0608, Z0609, Z0615, Z0634 and Z0635), which were related to RTX (Repeat in toxin) toxin family isolated from children with diarrheal disease in Taiyuan. METHODS: In the study, 257 fecal samples from children with diarrheal disease collected in Shanxi Children's Hospital. Diarrheagenic E. coli and enteropathogenic bacteria were isolated and identified by conventional bacterial culture and typing specific diarrheagenic E. coli (EPEC, EIEC, ETEC and EHEC) diagnostic serum, while diarrheagenic E. coli harboring genomic 01-28 containing five putative virulence genes (Z0608, Z0609, Z0615, Z0634 and Z0635) were detected by PCR and DNA southern blot hybridization. RESULTS: 206 strains (80.16%) of enteropathogenic bacteria were detected from 257 children with diarrhea disease, containing 149 strains (57.98%) of diarrheagenic E. coli and 57 strains(22.18%) of other entero-pathogenic bacteria. Among 3 strains (2.01%) of EPEC, 2 strains (1.34%) of ETEC, 2 strains (1.34%) EHEC were detected by typing specific serum, while all of the 142 strains (95.30%) isolated were suspected to be diarrheagenic E. coli. 21 strains (14.09%) of diarrheagenic E. coil harboring genomic O1-28 containing five putative virulence genes (Z0608, Z0609, Z0615, Z0634 and Z0635) were detected by polymerase chain reaction and DNA southen blot hybridization, 8 strains (5.37%) of diarrheagenic E. coli containing only one genomic OI-28 virulence gene, 2 strains (1.34%) of diarrheagenic E. coli containing two genomic OI-28 virulence gene. 21 children with diarrhea diseases caused OI-28-harboring E. coli containing five important putative virulence genes were among 0 to 3 years old (80.95%). These children correlating with OI-28-harboring E. coli did not present special clinical symptoms or signs. CONCLUSION: The diarrheagenic E. coil harboring genomic OI-28 was one of the important etiology for children with diarrheal disease in summer season.

[Cd uptake and accumulation in grains by hybrid rice in two paddy soils: interactive effect of soil type and cultivars].

Cd translocation through soil-food crop-diet is considered as one of most important pathway for human Cd exposure. Rice is considered as a particular crop with high Cd uptake and accumulation in grains among the main food crops. In this study, a pot experiment was conducted to elucidate mutual interaction of soil and cultivars on uptake and grain accumulation of Cd by hybrid rice with or without Cd spiking at 2.5 mg x kg(-1) under continuous submerging condition. Two hybrid rice cultivars (Shanyou 63, a common hybrid rice and II Youming 86, a super-rice) and two paddy soils (a Wushantu, Gleyic Stagnic Anthrosols and a Hongshanitian, Ultic Stagnic Anthrosols) were used. The results show significant differences in Cd uptake and grain partitioning between soils, cultivars and the soil-cultivar interactions. The cultivars effect on uptake of indigenous soil Cd seems stronger than the soil effect while soil effect turns significant over that of cultivars on spiked Cd. However, intense Cd accumulation in grains is found under the positive interaction of soil with high Cd availability and cultivar with high Cd affinity (super rice on acidic paddy soil). This study demonstrates a phenomenon of intense Cd uptake and grain accumulation by super rice and, thus, imposing a very high Cd exposure risk (as several times as the acceptable daily intake, ADI) to subsistence-diet farmers. The low Cd cultivar Shanyou 63 tends to hamper the up-taken Cd in root while the super rice II Youming 86 promotes higher partitioning to grain. Furthermore, the difference in total biomass between the two cultivars is small compared to that in total Cd uptake under Cd spiking. It is suggested that the Cd uptake behavior should be taken into account in super rice breeding and practical measures should be taken while spread of super rice cultivars in rice areas with acidic soils and under Cd pollution in order to control the human Cd exposure by diet.

[Effect of submerging and wetting-redrying on Cd speciation and uptake by Sorghum hybrid Sudangrass in two paddy soils under spiked Cd].

Effect of continuous submerging and wetting-redrying on cadmium speciation and uptake by Sorghum hybrid Sudangrass in a Ferric-accumulic Stagnic Anthrosol and a Tipical Hapludult collected from the Taihu Lake region and the rolling downs of Yingtan, Jiangxi, China respectively, was studied by pot experiment with Cd spike in 2003. Compared to that under wetting-redrying treatment, the MgCl2-extracted pool of Cd in Huangnitu with spiked Cd of 5mg x kg(-1) and 10mg x kg(-1) was decreased from 21.8% and 28.5% to 8.0% and 16.9% while NH2OH x HCl-extracted pool increased from 17.7% and 17.3% to28.1% and 37.5% under continuous submerging. However, in the Typical Halpudult, NaAC-extracted pool of Cd decreased from 20.8% and 29.6% to 11.6% and 12.6%. Cd uptake by Sorghum hybrid Sudangrass was found in negative correlation with the MgCl2 extracted pool of Cd. Total Cd uptake was significantly reduced by the pretreatment of continuously submerging in Huangnitu.

Two new borates containing the first examples of large isolated polyborate anions: chain [B7O9(OH)5]2- and ring [B14O20(OH)6]4-.

Two novel hydrated borates were synthesized under mild solvothermal conditions. One is hydrated rubidium borate, Rb2B7O9(OH)5, which contains the first example of the isolated chain heptaborate anion, [B7O9(OH)5]2-. The other is hydrated diethylenetriamine borate, [(C4H15N3)]2[B14O20(OH)6], which contains the first example of the largest isolated ring tetradecaborate anion, [B14O20(OH)6]4-.

Distribution of Cu and Pb in particle size fractions of urban soils from different city zones of Nanjing, China.

Soil samples from 4 defined city zones of Nanjing were randomly collected at 0-5 cm and 5-20 cm intervals and size fractions of soil particles were separated from undisturbed bulk soils by low energy dispersion procedure. The total contents of Cu and Pb in the different particle size fractions of the urban soils were analyzed by HNO3-HF-HClO4 digestion and flame atomic absorption spectrophotometer determination. The total content of Cu and Pb in soil particle size fractions varied with their size and with city zones as well. Both the content and variation with the size fractions of Pb was bigger than of Cu supporting our previous finding that there was Pb pollution to different degrees in the urban soils although the two elements were generally enriched in clay-sized fraction. Contaminated Pb tended to be preferentially enriched in the size fraction of 2000-250 microm and clay-sized fraction. While the size fractions of the soils from newly developed and preserved area contained smaller amount of Cu and Pb, the partitioning of them in coarse and fine particle size fractions were insignificant compared to that from inner residence and commercial area. The very high Pb level over 150 mg/kg of the fine particle fractions from the soils of the inner city could be a cause of high blood Pb level reported of children from the city as acute exposure to Pb of fine particles of the urban soil might occur by soil ingestion and inhalation by young children. Thus, much attention should be paid to the partitioning of toxic metals in fine soil particles of the urban soils and countermeasures against high health risk of Pb exposure by soil ingestion and dust inhalation should be practiced against the health problem of blood Pb for young children from the cities.