Effects of soil metal(loid)s pollution on microbial activities and environmental risks in an abandoned chemical smelting site

Abandoned chemical smelting sites containing toxic substances can seriously threaten and pose a risk to the surrounding ecological environment.Soil samples were collected from different depths(0 to 13 m)and analyzed for metal(loid)s content and fractionation,as well as microbial activities.The potential ecological risk indices for the different soil depths(ordered from high to low)were:1 m(D-1)>surface(S-0)>5 m(D-5)>13 m(D-13)>9 m(D-9),ranging between 1840.65-13,089.62,and representing extremely high environmental risks,of which Cd(and probably not arsenic)contributed to the highest environmental risk.A modified combined pollution risk index(MCR)combining total content and mobile proportion of metal(loid)s,and relative toxicities,was used to evaluate the degree of contamination and potential environmental risks.For the near-surface samples(S-0 and D-1 layers),the MCR considered that As,Cd,Pb,Sb,and Zn achieved high and alarming degrees of contamination,whereas Fe,Mn,and Ti were negligible or low to moderate pollution degrees.Combined microcalorimetry and enzymatic activity measurements of contaminated soil samples were used to assess the microbial metabolic activity characteristics.Correlation analysis elucidated the relationship between metal(loid)s exchangeable fraction or content and microbial activity characteristics(p<0.05).The microbial metabolic activity in the D-1 layer was low presumably due to heavy metal stress.Enzyme activity indicators and microcalorimetric growth rate(k)measurements were considered sensitive indicators to reflect the soil microbial activities in abandoned chemical smelting sites.

Luminescence Studies on Interaction of an Isoquinoline Alkaloid with Calf Thymus DNA in Aqueous Medium and on Solid Substrate

The interaction of calf thymus DNA（ctDNA） with berberine（Ber） was systematically investigated via UV-Vis,fluorescence and phosphorescence spectroscopies in aqueous solution and on solid substrate.The very weak fluorescence intensity of Ber at 525 nm in aqueous solution can be greatly enhanced by ctDNA.The UV-Vis spectrum shows that Ber could bind with DNA by intercalation.In addition,strong fluorescence of Ber alone could be observed on filter paper substrate and can be quenched by ctDNA effectively,and the increase of fluorescence polarization of Ber on the filter paper implies the intercalation binding.Ber emits phosphorescence at 619 nm in the presence of thallium（I） acetate.The lifetime of Ber increased from 38.4 ms to 43.4 ms with the increase of ctDNA.The increase of lifetime is possibly attributed to the increase of rigidity of Ber after its intercalating into the ctDNA base pairs.This explanation is also augmented by the anionic quenching results.Ber behaves as a typical intercalating agent into ctDNA.The intrinsic binding constant between Ber and ctDNA is（1.84±0.12）×10^4 L/mol and n=0.16.

Synthesis and Characterization of Fe₃O₄Coated on APTES as Carriers for Morin-Anticancer Drug

Morin (MR) is an anticancer drug present in fruits and Chinese herbs. Fe3O4 magnetic nanoparticles (MNPs) coated on 3-aminopropyl triethoxysilane (APTES) were synthesized (MNPs-APTES) as carriers for MR. The characterization of drug delivery system was confirmed by Fourier Transform Infrared (FTIR), Transmission Electron Microscope (TEM), X-Ray Diffraction (XRD), dynamic light scattering (DLS), and vibrating sample magnetometer (VSM). The adsorbed APTES on the magnetite surface (MNPs-APTES) was examined by FTIR. The TEM image showed that the average particle size is obtained to be about 26.7 nm for MNPs-APTES. The MR loading and release behavior of MNPs-APTES were studied and the results showed that up to 60% of the adsorbed drug was released within 4 h. In summary, the MNPs-APTES nanocarriers are based on the results, promising for targeted morin drug delivery.

磷添加剂对Bacillus spp.修复铀尾矿过程中细菌群落演替的驱动作用

铀尾矿库中堆积的铀尾矿会产生环境污染问题。生物矿化可以有效降低铀尾矿中铀的浸出,降低铀尾矿的环境风险。然而,目前尚不清楚磷添加剂如何影响生物矿化过程中铀尾矿的微生物群落结构。在本研究中,评估了羟基磷灰石(HS)和β-甘油磷酸五水合物(GP)作为添加剂对Bacillus spp.修复铀尾矿过程中的微生物群落演替的影响。结果表明,磷添加剂有效地改变铀尾矿浸出液的pH值和铀浸出浓度,显著提高了微生物多样性,促进了微生物群落中门类微生物从actinobacteria向firmicutes和proteobacteria的演替。两种添加剂对细菌群落演替模式的影响不同,其中GP的促进作用较大。GP促进了微生物群落结构中核心物种尤其是Firmicutes的生长,在GP处理中,Bacillus,Pseudomonas,Desulfotomaculum,和Clostridium_sensu_stricto_12的丰度较高,表明这些属类微生物在微生物群落中发挥了重要作用。研究结果为磷添加剂参与生物修复和细菌群落演替提供了证据,从而为铀尾矿的生物矿化技术提供理论支撑。

Protein surface recognition of the novel tetra-carboxylphenyl calix[4]arene to cytochrome c

The interaction of the novel tetra-carboxylphenyl calix[4]arene （TCPC） with the bovine heart cytochrome c （Cc） was first investigated by fluorescence spectroscopy and molecular modeling methods. The formation of a stable 1：1 complex was monitored by fluorescence titration, and its binding constant is 1.916 ×10^7 L mol^-1. Molecular modeling reveals the recognition mechanism of TCPC to the Cc surface, that is, the electrostatic interaction drives TCPC to the Cc surface, and the van der Waals interaction orientates TCPC parallel to the cleft of Cc.

A novel sensor of potassium ions based on mode-filtered light detection

A novel potassium ions sensor based on mode-filtered light detection was reported. The analyzer was consisting of an optical fiber immobilized with a dye of bromocresol green and a fused-silica capillary. It was found that mode-filtered light intensity decreased with the concentration of potassium ions and a linear detection range of 0.25-20 mmol/L （R^2 = 0.9977） was obtained with a detection limit of 9 ×10^-5 mol/L as well as fast response, good reproducibility and reversibility in the working concentration range.

Study on mode-filtered light sensor for methane detection

A novel mode-filtered light gas sensor has been reported. It was constructed by inserting an optical fiber deposited by a thin silicone cladding of cryptophane A into a fused-silica capillary. When different concentration of methane gas was introduced to the sensor, the phenomenon that mode-filtered light intensity decreased with the increasing concentration of methane was observed. And a linear relationship was obtained within the methane concentration range of 0.0-16.0% （v/v）. The detection limit was 0.06% （v/v）. The mode-filtered light sensor has been exploited to respond to various concentrations of methane gas at room temperature.

Methane sensor based on palladium/MWNT nanocomposites

Methane gas sensor was fabricated based on electrocatalytic properties of the Pd/MWNT nanocomposites on indium tin oxide （ITO） glass substrates. A linear response for methane was obtained in the range of 0-16% （v/v） with a detection limit of 0.167% （v/ v） and R.S.D. of 4.1%. After 100 times sensing or stable stored more than 12 months in atmosphere, unconspicuous measurable decrease was observed. The response time was less than 60 s at room temperature and ambient pressure. Some common potential interferents in samples such as N2, CO, CO2, ethane, propane, pentane, methanol, ethanol, H2 and NH3 were investigated and all the effects were less than 5% on the response for 3.0% （v/v） methane. The sensor was applied to methane determinations in man-made gas samples, the results are satisfied.

Synthesis of a new ratiometric emission Ca^(2+) indicator for in vivo bioimaging

Received 4 November 2012 Received in revised form 29 November 2012 Accepted 5 December 2012 Available online 18 January 2013

An ethanol biosensor based on a bacterial cell-immobilized eggshell membrane

An ethanol biosensor was fabricated based on a Methylobacterium organophilium-immobilized eggshell membrane and an oxygen（O2） electrode.A linear response for ethanol was obtained in the range of 0.050-7.5 mmol/L with a detection limit of 0.025 mmol/L（S/N= 3） and a R.S.D.of 2.1%.The response time was less than 100 s at room temperature and ambient pressure. The optimal loading of bacterial cells on the biosensor membrane is 40 mg（wet weight）.The optimal working conditions for the microbial biosensor are pH 7.0 phosphate buffer（50 mmol/L） at 20-25℃.The interference test,operational and storage stability of the biosensor are studied in detail.Finally,the biosensor is applied to determine the ethanol contents in various alcohol samples and the results are comparable to that obtained by gas chromatographic method and the results are satisfactory.Our proposed biosensor provides a convenient,simple and reliable method to determine ethanol content in alcoholic drinks.