Population dynamics and spatial distribution of microbial species in multispecies biofilms under the action of direct electric current

The metabolism, population dynamics and spatial distribution of nitrifying bacteria and heterotrophs in biofilms under the action of direct electric current were investigated by using the micro-slicing technique. The nitrification rate of nitrifying bacteria was severely inhibited by a current over 10 Am^-2 at lower C/N ratios. Compared to heterotrophs, the nitrifying bacteria in the surface biofilms were severely inhibited, resulting in a significant decrease in bacterial density. An increase in current density narrowed the less current-sensitive inner biofilm region, and in addition the density of NO2-oxidizers decreased more significantly than that of NH4-oxidizers in the surface biofilms probably due to electrochemical reactions at the anode. However, the effect of current on both the population dynamics and the spatial distribution of the microbial species was less significant at larger C/N ratios.     

Covalent immobilization of oligoDNA on the surface of magnetic nanoparticles and surface-enhanced Raman scattering study

The DNA magnetic nanoparticles are potentially useful in isolating and purifying DNA or RNA, directing-target-medicines, the development of DNA biosensors and biochips. Surface functionalized magnetic nanoparticles with monodispersed shape and size were prepared by coating nano-sized γ-Fe2O3 with silica in reverse microemuision, and then thioi-compounds were immobilized onto the magnetic nanoparticles. After immobilizing oligoDNA modified with thioi-disuifide on the surface of the fictionalized magnetic nanoparticles, we obtained DNA-magnetic nanoparticles.The efficiency of the single-linking probes loading at the surfaces of magnetic nanoparticles was examined via hybridization experiment. Surface-enhanced Raman scattering methods were also effectively applied to observing the immobilization and hybridization processes mentioned above.The results demonstrated oligoDNA being availably connected to the surface of the magnetic nanoparticles.     

Interaction between PⅡ and NifA in Azospirillum brasilense Sp7

The interaction between PⅡ and NifA in A.brasilense Sp7 was investigated by using the yeast two-hybrid system.Our experimental results showed that PⅡ directly interacted with the entire NifA protein and its N-terminal domain,but did not interact with the central domin and the C-terminal domain of NifA.No interaction happened if glnB coding for PⅡ was frame-shift mutated.Pz,a homolog of PⅡ,had no interation with NifA.     

Surface characteristics of modified carbon nanotubes and its application in lead adsorption from aqueous solution

Carbon nanotubes(CNT) were modified by nitric acid oxidation.Infrared spectroscopy(IR) demonstrated that hydroxyl(-OH) and carbonyl(-C=O)functional groups were introduced to the surface of modified CNT.Micrometrics ASAP 2000 measurement showed that the surface area of modified CNT was slightly increased.Furthermore,the Pb^2 adsorption behavior on the surface of modified CNT has been investigated.The results indicate that the modified CNT has an exceptional adsorption capability for Pb^2 removal.The adsorption isotherms are well described by the Langmuir equation under test temperatures and the kinetics level is three.     

Synthesis of carbon nanotube array using corona discharge plasma-enhanced chemical vapor deposition

A corona discharge phasma-enhanced chemical vapor deposition with the features of atmospheric pressure and low temperature has been developed to synthesize the carbon nanotube array ,The array was synthesized from methane and hydrogen mixture in anodic aluminum oxide template channels in that cobalt was electrodeposited at the bottom.The characterization results by the scanning electron microscopy,transmission electron microscopy,energy dispersive X-ray spectroscopy and Raman spectroscopy indicate that the array consists of carbon nanotubes with the diameter of about 40 nm and the length of more than 4 μm, and the carbon anotubes are mainly restrained within the channels of templates.     

Synthesis,crystal structure of a novel yttrium (Ⅲ) coordination compound supported by typical plenary Dawson cluster

Asarichanddiverseclassofinorganicclustersytems,thepolyoxometalateions,whicharecharacterizedbyfascinatingstructural,electrochemical,catalytic,manetic,medicinal,andphotophysicalproperties,havebeenfoundtobeextremelyversatileinorganicbuildingblocksinthefieldsofdesigningandassemblingmolecule-basedmaterials[1].Basedoncoordinationcapabilityofthesufaceoxygenatoms(bridgingorterminaloxygenatoms)ofthepolyoxoanions,novelcomplexeswithadiscretecluter,1D,2Dor3Dstructurescanbesynthesizedthroughmetalunitsbeing…     

Functional analysis of the larval serum protein gene promoter from silkworm <Emphasis Type="Italic">Bombyx mori.</Emphasis>

The regulation region of larval serum protein gene, Bombyx mori. (BmLSP), consisting of the first intron, the first exon, the central promoter region and 5′-upstream region, is cloned from genomic DNA from the silkworm va-riety of Suju譓inghu. Using PCR and restriction endonu-clease methods, a series of luciferase reporter plasmids, driven by different length of BmLSP promoters, are con-structed. Via the transient expression system in BmN cells, the effects of the regulation elements and foreign insect hor-mones on the BmLSP promoter activity are investigated. The results demonstrate that the promoter activity of BmLSP is 5.8- or 4.4-fold higher than that of BmLSPs whose first in-tron or the element in 5′-upstream region harboring the homologous sequence with the first intron of light-chain fib-roin gene (EHIF) is deleted, respectively, suggesting that both the first intron and EHIF contain the main positive cis-acting elements. However, the inactive mariner transposable ele-ment (MTE) in 5′-upstream region presents a negative effect. Furthermore, the effects of juvenile hormone analogue (JHA) on the BmLSP promoter activity show a typical dose-dependent manner, that is, low concentration treat-ments increase the BmLSP promoter activity and high con-centration treatments decrease it. Meanwhile, insect ecdy-sone (MH) treatments present no significant effect.     

A novel theoretical model for mass transfer of hollow fiber hemodialyzers

A novel theoretical model for mass transfer of hollow fiber bundles in hemodialyzers is presented. In the model, a hemodialyzer is considered as a porous zone which is composed of two non-interpenetrating porous flow zones.Firstly, the dialysate side (shell side) is thought as a porous medium zone. Then by solidifying the dialysate flow zone and the occupied zone by hollow fiber membrane, the rest zone of bemodialyzer (i.e. blood side or lumen side) is considered as a porous medium zone too. Finally, the interface of the two flow zones is the fiber membrane through which mass transfer is performed. The dialysate and blood flows are all described by Navier-Stokes equations with Darcy momentum source terms. Kedem-Katchaisky equations as other source terms are added into Navier-Stokes equations to simulate the permeating flux through the membrane. All equations must be coupled together in the process of computing. The model is validated by the experimental data in literature. The simulative results show that the predicted clearances agree well with the experimental data, and the model in this paper is better than other models for the forecast of clearance.     

Structure properties for the superconductor MgCNi<Subscript>3</Subscript> under high pressure with synchrotron radiation

In situ high pressure energy dispersive X-ray diffraction measurements on cubic-perovskite superconductor MgCNi₃ under pressure up to 22 GPa have been performed by using diamond anvil cell with synchrotron radiation. We have investigated its crystal structure and compressibility. The results show that the structure of MgCNi₃ is stable under pressure up to 22 GPa. According to Birch-Murnaghan state equation, when we assume B ₀′ = 4, we get B₀ = 267.8 ± 7.2 GPa.     

New dynamic model for non-Fickian diffusion of calcium spark in cardiac myocytes

A new dynamic model for non-Fickian diffusion of calcium spark in cardiac myocytes was developed by introducing time lags on the basis of the microscale mass transport theory. Numerical simulation showed that the size of the calcium spark produced by the new dynamic model was larger than that of Fick diffusion and was in more agreement with experimental results. In addition, the time lags of the calcium spark in cardiac myocytes were about 0.1--0.8 ms. These results can be used to understand the mechanism of calcium spark diffusion in cardiac myocytes.