Ten Years of the Relative Risk Model and Regional Scale Ecological Risk Assessment

It has been 10 years since the publication of the relative risk model (RRM) for regional scale ecological risk assessment. The approach has since been used successfully for a variety of freshwater, marine, and terrestrial environments in North America, South America, and Australia. During this period the types of stressors have been expanded to include more than contaminants. Invasive species, habitat loss, stream alteration and blockage, temperature, change in land use, and climate have been incorporated into the assessments. Major developments in the RRM have included the extensive use of geographical information systems, uncertainty analysis using Monte Carlo techniques, and its application to retrospective assessments to determine causation. The future uses of the RRM include assessments for forestry and conservation management, an increasing use in invasive species evaluation, and in sustainability. Developments in risk communication, the use of Bayesian approaches, and in uncertainty analyses are on the horizon.

黄土丘陵区流域生物量和气体调节服务功能价值动态变化及评价

文章研究纸坊沟流域内草地、农地、林地、灌丛四种不同生态系统类型植被生产力及逐年生物量,估算各生态系统类型固定CO2和释放O2的能力,并根据生态学原理和生态经济学方法,运用碳税法、造林成本法和影子价格法,推算出各生态类型固定CO2和释放O2气体的生态、调节服务功能价值。研究表明,1985～2001年流域总生物量年均生物量和总体呈线性增加趋势。由于各种治理措施的实施和退耕还林(草)政策的正确导向,纸坊沟流域土地利用趋于合理,CO2/O2气体调节服务功能价值逐步增强,流域生态经济系统向良性演变。不同生态系统类型气体调节功能价值的估算为退耕还林(草)年限及生态补偿提供了科学决策依据。

Considerable effects of diversity indices and spatial scales on conclusions relating to ecological diversity

The relationships between ecological diversity and ecosystem functions such as stability and productivity have long been debated and have no final conclusion until now. It is ignored that the debate should be firstly based on the same diversity index, which should be theoretically complete, and on same observation scale. For the issue on the scale of ecotope observation, ecosystems should be distinguished according to intensity of human disturbance. For the issue on the scale of species observation, either number diversity or biomass diversity should be identified. This paper takes grassland ecosystems located within the Bayin Xile grassland of Xilin Gol League of Inner Mongolia Autonomous Region as an example to analyze effects of different diversity indices and spatial scales on the conclusions of ecological diversity and its relationships with ecosystem functions. The analysis results both on the scale of ecotope observation and on the scale of species observation show that different diversity indices might give different conclusions and spatial resolution has a great effect on the relative conclusions. (c) 2005 Elsevier B.V. All rights reserved.

Method for calculating ecological water storage and ecological water requirement of marsh

As one of the most typical wetlands, marsh plays an important role in hydrological and economic aspects, especially in keeping biological diversity. In this study, the definition and connotation of the ecological water storage of marsh is discussed for the first time, and its distinction and relationship with ecological water requirement are also analyzed. Furthermore, the gist and method of calculating ecological water storage and ecological water requirement have been provided, and Momoge wetland has been given as an example of calculation of the two variables. Ecological water use of marsh can be ascertained according to ecological water storage and ecological water requirement. For reasonably spatial and temporal variation of water storage and rational water resources planning, the suitable quantity of water supply to marsh can be calculated according to the hydrological conditions, ecological demand and actual water resources.

Fabrication, characterization of spherical CaWO4:Ln@MCM-41(Ln=Eu3+, Dy3+, Sm3+, Er3+) composites and their applications as drug release systems

Spherical MCM-41 particles with a diameter of about 150 nm have been successfully coated with CaWO4:Ln (Ln = Eu3+, Dy3+, Sm3+, Er3+) phosphor layers through a simple Pechini sol-gel process. The obtained CaWO4:Ln@MCM-41 composites, which kept the mesoporous structure of MCM-41 and the luminescent properties of phosphors, were investigated as a drug delivery system using aspirin (ASPL) as a model drug.

Layer-by-layer assembly of biologically inert inorganic ions/DNA multilayer films for tunable DNA release by chelation

In this work, we illustrate a simple chelation-based strategy to trigger DNA release from DNA-incorporated multilayer films, which were fabricated through the layer-by-layer (LbL) assembly of DNA and inorganic zirconium (IV) ion (Zr4+). After being incubated in several kinds of chelator solutions, the DNA multilayer films disassembled and released the incorporated DNA. This was most probably due to the cleavage of coordination/electrostatic interactions between Zr4+ and phosphate groups of DNA. Surface plasmon resonance (SPR), UV-vis spectrometry and atomic force microscopy (AFM) were used to characterize the assembly and the disassembly of the films.

Electrodissolution of Inorganic ions/DNA Multilayer Film for Tunable DNA Release

A layer-by-layer film composed of DNA and inorganic zirconium ion (Zr4+) was fabricated on the surface of gold thin film, and an electric field triggered disintegration of the multilayer film was studied by using electrochemical surface plasmon resonance (EC-SPR). EC-SPR results demonstrated that the film was disassembled upon the application of an electric field and the disassembly rate varied with the applied potential, leading to the controlled release of DNA. The electrodissolution could be switched off by removing the electric potential and reactivated by reapplying the potential.

Glutathione-Mediated Release of Functional Plasmid DNA from Positively Charged Quantum Dots

DNA was efficiently bound to water-soluble positively charged CdTe quantum dots (QDs) through complementary electrostatic interaction. These QDs-DNA complexes were disrupted and DNA was released by glutathione (GSH) at intracellular concentrations. Interestingly, there was almost no detectable DNA released by extracellular concentration of GSH. The formation of QDs-DNA complexes and GSH-mediated DNA release from the complexes were confirmed by dye displacement assay, electrophoretic mobility shift assay (EMSA), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) experiments.

Mesoporous silica coated CeF3 : Tb3+ particles for drug release

CeF3:Tb3+ nanoparticles were successfully prepared by a polyol process using diethylene glycol ( DEG) as solvent. After being coated with dense silica, these CeF3:Tb3+ nanoparticles can be coated with mesoporous silica using nonionic triblock copolymer EO20PO70EO20 ( P 123) as structure-directing agent. The composite can load ibuprofen and release the drug in the PBS. The composite was characterized by X-ray diffraction ( XRD), transmission electron microscopy ( TEM), nitrogen absorption/desorption isotherms, fluorescence spectra, and UV/Vis absorption spectra, respectively.

Controlled release of urea encapsulated by starch-g-poly(L-lactide)

This paper presented a new approach for preparing a new type of slow-release membrane-encapsulated urea fertilizer with starch-g-PLLA as biodegradable carrier materials. By solution-casting and washing rapidly with water the urea was individually encapsulated within the starch matrix modified by L-lactide through in situ graft-copolymerization.

The release behavior of doxorubicin hydrochloride from medicated fibers prepared by emulsion-electrospinning

The release behavior of a water-soluble small molecule drug from the drug-loaded nanofibers prepared by emulsion-electrospinning was investigated. Doxorubicin hydrochloride (Dox), a water-soluble anticancer agent, was used as the model drug. The laser scanning confocal microscopic images indicated that the drug was well incorporated into amphiphilic poly(ethylene glycol)-poly(L-lactic acid) (PEG-PLA) diblock copolymer nanofibers, forming "core-sheath" structured drug-loaded nanofibers.

Ion-Responsive Behavior of Ionic-Liquid Surfactant Aggregates with Applications in Controlled Release and Emulsification

We propose a simple but efficient, rapid, and quantitative ion-responsive micelle system based on counter-anion exchange of a surfactant with an imidazolium unit. The ion-exchange reaction results in the amphiphilic-to-hydrophobic transition of the imidazolium salt, leading to the destruction of the micelles, which has been successfully applied to control led release and emulsification.

Magnetic Mesoporous Silica Spheres for Drug Targeting and Controlled Release

Magnetically functionalized mesoporous silica spheres with different size (average diameter, A.D.) from 150 nm to 2 mu m and pore size distribution were synthesized by generating magnetic FexOy nanoparticles onto the mesoporous silica hosts using the sol-gel method. The X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), N-2 adsorption/desorption results show that these composites conserved regular sphere morphology and ordered mesoporous structure after the formation of FexOy nanoparticles. XRD and X-ray photoelectron spectroscopy (XPS) analysis confirmed that the FexOy generated in these mesoporous silica hosts is mainly composed of gamma-Fe2O3. Magnetic measurements reveal that these composites with different gamma-Fe2O3 loading amounts possess super-paramagnetic properties at 300 K, and the saturation magnetization increases with increasing Fe ratio loaded.

Synthesis and characterization of magnetic FexOy@SBA-15 composites with different morphologies for controlled drug release and targeting

Magnetic functionalization of the ordered mesoporous SBA-15 (SiO2) aggregate blocks and rice grain-like particles were realized by using a sol-gel method, resulting in the formation of FexOy@SBA-15 composite materials. The X-ray diffraction (XRD), N-2 adsorption/desorption, and transmission electron microscopy (TEM) results show that these composites conserved ordered mesoporous structure after the formation of FexOy nanoparticles in the pores and on the outer surface of SBA-15. It was confirmed by the XRD and X-ray photoelectron spectroscopy (XPS) analysis that the FexOy generated in these mesoporous silica hosts is mainly composed of gamma-Fe2O3. Magnetic measurements reveal that these composites possess superparamagnetic properties at 300 K. The saturation magnetization of these composites increased with the increasing loading amount of gamma-Fe2O3. These composites, which possess high surface area and high pore volume, show magnetic response sufficient for drug targeting in the presence of an external magnetic field.