[Effects of water-nitrogen interactions on NH3 and N2O emissions and yield in winter wheat cropland]. / 水氮互作对冬小麦农田NH3和N2O排放及产量的影响.

To investigate the effects of different irrigation and nitrogen application modes on nitrogen gaseous loss in winter wheat farmland, we conducted a field experiment at Changqing Irrigation Experiment Station in Shandong Province, with two irrigation levels (80%-90% θf(I1) and 70%-80% θf(I2)) and three nitrogen application levels (conventional nitrogen application of 240 kg·hm-2(N1), nitrogen reduction of 12.5% (N2), and nitrogen reduction of 25% (N3)). The results showed that ammonia volatilization and nitrous oxide emission rate peak appeared within 2-4 days after fertilization or irrigation. The ammonia volatilization rate during the chasing fertilizer period was significantly higher than that during the basal fertilizer period. Compared with other treatments, the ave-rage ammonia volatilization rate of I2N2 treatment during the chasing fertilizer period was reduced by 10.1%-51.6%, and the average nitrous oxide emission rate over the whole growth period was reduced by 15.4%-52.2%. The ammonia volatilization rate was significantly positively associated with surface soil pH value and ammonium nitrogen content, while the nitrous oxide emission rate was significantly positively associated with nitrate content in topsoil. The accumulation amount of soil ammonia volatilization and nitrous oxide emission ranged from 0.83-1.42 and 0.11-0.33 kg·hm-2, respectively. Moderate reduction of irrigation water and nitrogen input could effectively reduce cumulative amounts of ammonia volatilization and nitrous oxide emission from winter wheat farmland. The cumulative amounts of ammonia volatilization and nitrous oxide emission under I1N3 and I2N2 treatments were signi-ficantly lower than those under other treatments. The highest winter wheat yield (5615.6 kg·hm-2) appeared in I2N2 treatment. The irrigation water utilization efficiency of I2 was significantly higher than that of I1, with the maximum increase rate of 45.2%. Compared with N1 and N3 treatments, the maximum increase rate of nitrogen fertilizer productivity and agricultural utilization efficiency in N2 reached 15.2% and 31.8%, respectively. In conclusion, the treatment with 70%-80% θf irrigation level and 210 kg·hm-2 nitrogen input could effectively improve the utilization efficiency of irrigation water and nitrogen fertilization and reduce gaseous loss from winter wheat farmland.

DNA intercalating studies of [Ru(bpy)2dmt]2+ with two vacant nitrogen atoms by introducing copper(II) ions.

A novel, yet effective method for identifying DNA-binding modes of [Ru(bpy)(2)dmt](2+) (where bpy = 2,2'-bipyridine and dmt = 2,3-dimethyl-1,4,8,9-tetra-aza-triphenylene) on an indium tin oxide electrode has been successfully developed by introducing Cu(2+) ion and ethylenediaminetetraacetic acid. The results from emission spectra and fluorescence microscopic images suggested that [Ru(bpy)(2)dmt](2+) not only associates with Cu(2+) ion in both the absence and presence of DNA but also shows strong affinity with DNA in the presence of Cu(2+). Evidence for the strong binding of [Ru(bpy)(2)dmt](2+) to DNA was determined from the interface studies using electrochemical methods. The present study suggests that a combination of photoluminescence measurement with electrochemical methods identifies the DNA-binding behavior of luminescent molecules with redox activities. [Ru(bpy)(2)dmt](2+) binds to DNA via an intercalative mode.

Electrochemical detection of bisphenol A mediated by [Ru(bpy)(3)](2+) on an ITO electrode.

A simple strategy for the direct and indirect detections of bisphenol A (BPA) at an ITO electrode is described. The direct determination of BPA in buffer solution of pH 7.2 is accomplished by the application of differential pulse voltammograms with the anodic peak at 0.546 V. The indirect approach is based on the mediation of [Ru(bpy)(3)](2+) (where bpy=2,2'-bipyridine), which is served as an excellent catalyst to induce the oxidation of BPA. By monitoring the peak current of [Ru(bpy)(3)](2+)-BPA complex, the mediated detection of BPA is successfully carried out. The response current exhibits a linear range between 5 and 120 micromol L(-1) with a high sensitivity (0.22 microA micromol(-1) L). The detection limit of BPA is 0.29 micromol L(-1) (S/N=3), which is larger than that analyzed by gas chromatography-mass spectrometry, however this detection method not only has the advantages of low cost and simple operation, but also provides a powerful basis for removing BPA. In addition, according to the effects of pH, scan rate and mediator concentrations on the voltammetric responses of BPA oxidation, the oxidized mechanism of BPA in the presence of [Ru(bpy)(3)](2+) on the ITO electrode is discussed in detail.

DNA-binding and cleavage studies of novel copper(II) complex with L-phenylalaninate and 1,4,8,9-tetra-aza-triphenylene ligands.

DNA-binding properties of novel copper(II) complex [Cu(l-Phe)(TATP)(H(2)O)](+), where L-Phe=L-phenylalaninate and TATP=1,4,8,9-tetra-aza-triphenylene are investigated using electronic absorption spectroscopy, fluorescence spectroscopy, voltammetry and viscosity measurement. It is found that the presence of calf thymus DNA results in a hypochromism and red shift in the electronic absorption, a quenching effect on fluorescence nature of ethidium bromide-DNA system, an enhanced response on voltammograms of [Co(phen)(3)](3+/2+)-DNA system, and an obvious change in viscosity of DNA. From absorption titration, fluorescence analysis and voltammetric measurement, the binding constant of the complex with DNA is calculated. The latter two methods reveal the stronger binding of [Cu(l-Phe)(TATP)(H(2)O)](+) complex to double strand DNA by the moderate intercalation than [Co(phen)(3)](3+). Such a binding induces the cleavage of plasmid pBR322 DNA in the presence of H(2)O(2).