排序方式: 共有182条查询结果,搜索用时 15 毫秒
61.
Nuria SanvicensIlaria Mannelli J.-Pablo SalvadorEnrique Valera M.-Pilar Marco 《Trends in analytical chemistry : TRAC》2011,30(3):541-553
The availability of pharmaceuticals to treat and to prevent disease has brought great benefit. Nevertheless, attention is being drawn to the uncontrolled use and careless disposal of medications for humans and animals. These compounds and their metabolites are found in the environment and foodstuffs, with possible adverse risks to human health.Detection of pharmaceuticals and residues in environmental and biological matrices has become a priority for governmental agencies. However, current analytical methods capable of detecting pharmaceuticals at very low levels require time-consuming sample preparation, concentration and/or extraction prior to analysis.Biosensors offer several advantages over existing techniques (e.g., less time, high-throughput screening, improved sensitivity, real-time analysis and the possibility of developing label-free detection methods and devices). Also, incorporation of nanotechnology into biosensor systems may increase the speed and the capability of the diagnostic methods. Moreover, the possibility of using biosensor systems in different configurations allows us envisaging their implementation as point-of-care systems or multiplexed devices.This review provides a general overview of the progress, the limitations and the future challenges of biosensors for detecting pharmaceuticals. 相似文献
62.
黄金材料的新兴工业应用 总被引:1,自引:0,他引:1
黄金作为一种宝贵的战略性资源,在稳定国民经济、抑制通货膨胀、提高国际资信、维护国家安全和防范金融风险方面具有独特的、不可替代的重要作用。近年来,随着纳米技术的扩展开发,纳米级黄金呈现出不同于大块黄金的诸多物理化学性质,从而可在工业催化、先进电子材料、光学装饰和生物医药等领域大显身手,可以说纳米技术使得黄金从左右国家金融的主要功能逐步扩展到影响国计民生的方方面面。新兴黄金纳米技术的发展日新月异,其规模化工业应用已拉开了序幕。本文综述了黄金纳米材料新兴工业应用领域的国内外进展,重点介绍了已工业化和趋于工业化的黄金纳米材料和相关技术,揭示了我国着力加强黄金工业应用研究和开发的必要性和紧迫性。 相似文献
63.
Mössbauer measurements were carried out in order to study the influence of the transition metal substitution TM/Fe (where TM = Co, Ni, Mn, and (TM)xFe3−xO4) ranging from 0.1 to 0.9 on the morphology and magnetic properties of ferrite nanoparticles. Chemically prepared magnetite nanoparticles with 13 nm were used as a reference material. The Mössbauer spectrum of the initial magnetite sample show a well-resolved magnetically split patterns connected with tetrahedral (A) positions and octahedral (B) positions. For low concentrations of TM, the relative intensities of the sextet that comes from the iron B position decrease. This means that the Co, Ni, Mn atoms are located preferentially in the B-site of the magnetite. However, the qualitative analysis of the spectra also suggests that Mn and Ni partially occupy the A-site. The increase of the concentration of the substitution transition metal causes broadening of the magnetic part of the spectra and appearance of a doublet in the central part of spectra for all samples. TEM studies show that the incorporation of the Me atoms into the structure causes a decrease of the average particle size. This is also confirmed by XRD. This also means that the blocking temperature decreases and for about Ni/Fe = 0.8 and TM/Fe = 0.9 (for Mn and Co) reaches room temperature. In the case of the nominal 0.9 substitution by Ni, a pure superparamagnetic state is observed, while for Co and Mn some of the particles are still below the blocking temperature, in agreement with the TEM studies. 相似文献
64.
William H. Fissell Anna Dubnisheva Abigail N. Eldridge Aaron J. Fleischman Andrew L. Zydney Shuvo Roy 《Journal of membrane science》2009
Silicon micromachining provides the precise control of nanoscale features that can be fundamentally enabling for miniaturized, implantable medical devices. Concerns have been raised regarding blood biocompatibility of silicon-based materials and their application to hemodialysis and hemofiltration. A high-performance ultrathin hemofiltration membrane with monodisperse slit-shaped pores was fabricated using a sacrificial oxide technique and then surface-modified with poly(ethylene glycol) (PEG). Fluid and macromolecular transport matched model predictions well. Protein adsorption, fouling, and thrombosis were significantly inhibited by the PEG. The membrane retained hydraulic permeability and molecular selectivity during a 90-h hemofiltration experiment with anticoagulated bovine whole blood. This is the first report of successful prolonged hemofiltration with a silicon nanopore membrane. The results demonstrate feasibility of renal replacement devices based on these membranes and materials. 相似文献
65.
Airborne nanoparticle exposures associated with the manual handling of nanoalumina and nanosilver in fume hoods 总被引:1,自引:1,他引:0
Su-Jung Tsai Earl Ada Jacqueline A. Isaacs Michael J. Ellenbecker 《Journal of nanoparticle research》2009,11(1):147-161
Manual handling of nanoparticles is a fundamental task of most nanomaterial research; such handling may expose workers to
ultrafine or nanoparticles. Recent studies confirm that exposures to ultrafine or nanoparticles produce adverse inflammatory
responses in rodent lungs and such particles may translocate to other areas of the body, including the brain. An important
method for protecting workers handling nanoparticles from exposure to airborne nanoparticles is the laboratory fume hood.
Such hoods rely on the proper face velocity for optimum performance. In addition, several other hood design and operating
factors can affect worker exposure. Handling experiments were performed to measure airborne particle concentration while handling
nanoparticles in three fume hoods located in different buildings under a range of operating conditions. Nanoalumina and nanosilver
were selected to perform handling experiments in the fume hoods. Air samples were also collected on polycarbonate membrane
filters and particles were characterized by scanning electron microscopy. Handling tasks included transferring particles from
beaker to beaker by spatula and by pouring. Measurement locations were the room background, the researcher’s breathing zone
and upstream and downstream from the handling location. Variable factors studied included hood design, transfer method, face
velocity/sash location and material types. Airborne particle concentrations measured at breathing zone locations were analyzed
to characterize exposure level. Statistics were used to test the correlation between data. The test results found that the
handling of dry powders consisting of nano-sized particles inside laboratory fume hoods can result in a significant release
of airborne nanoparticles from the fume hood into the laboratory environment and the researcher’s breathing zone. Many variables
were found to affect the extent of particle release including hood design, hood operation (sash height, face velocity), work
practices, type and quantity of the material being handled, room conditions, and the adequacy of the room exhaust.
相似文献
Su-Jung (Candace) TsaiEmail: |
66.
A hygroscopicity tandem differential mobility analyzer (HTDMA) technique is used to determine size-effect of nanoparticles
(NaCl, (NH4)2SO4, KCl, NH4NO3, MgCl2, CaCl2) on their hygroscopic properties (deliquescence relative humidity (DRH) and hygroscopic growth factor (GF)). The HTDMA system
uses a combination of two nano DMAs and two regular DMAs to measure particle size change in a wide dynamic particle size range.
Particles are subsequently analyzed with a transmission electron microscopy to investigate the potential effect of particle
structure or morphology on the hygroscopic properties. We found that structural properties of NaCl and (NH4)2SO4 particles also play an important role in determination of the DRH and GF and are more pronounced at smaller diameters. Data
show that the DRH of NaCl nanoparticles increased from ~75% up to ~83% RH at 8 nm and that their GF decreased with decreasing
size. The extent to which the GF of NaCl nanoparticles decreased with decreasing size was greater than theoretically predicted
with the Kelvin correction. The GF of furnace-generated NaCl nanoparticles that have pores and aggregate shape was found to
be smaller than that of atomizer-generated particles that are close to perfectly cubic. For the case of atomizer-generated
(NH4)2SO4 nanoparticles, we observed no significant size-effect on their DRH, and the measured GF agreed well with predicted values
using the Kelvin correction. For furnace-generated (NH4)2SO4 nanoparticles, a gradual growth at moderate RH without noticeable deliquescence behavior occurred. Their TEM images showed
that contrary to atomizer-generated (NH4)2SO4 nanoparticles the furnace-generated (NH4)2SO4 nanoparticles are not perfectly spherical and are often aggregates having pores and holes, which may favor holding residual
water even in the dried condition. For atomizer-generated KCl, MgCl2, and CaCl2 nanoparticles, we observed no significant size-effects on their DRH and GF for the mobility size as small as 20 nm. 相似文献
67.
Dustiness test of nanopowders using a standard rotating drum with a modified sampling train 总被引:2,自引:1,他引:1
Chuen-Jinn Tsai Chien-Hsien Wu Ming-Long Leu Sheng-Chieh Chen Cheng-Yu Huang Perng-Jy Tsai Fu-Hsiang Ko 《Journal of nanoparticle research》2009,11(1):121-131
The standard rotating drum tester was used to determine the dustiness of two nanopowders, nano-TiO2 and fine ZnO, in standard 1-min tests. Then, the sampling train was modified to determine the number and mass distributions
of the generated particles in the respirable size range using a Scanning Mobility Particle Sizer (SMPS), an Aerodynamic Particle
Sizer (APS) and a Multi-orifice Uniform Deposit Impactor (MOUDI) in the 30-min tests. It was found that very few particles
below 100 nm were generated and the released rate of particles decreased with increasing rotation time for both nanopowders
in the 30-min tests. Due to the fluffy structure of the released TiO2 agglomerated particles, the mass distributions measured by the MOUDI showed large differences with those determined by the
APS assuming the apparent bulk densities of the powders. The differences were small for the ZnO agglomerates, which were more
compact than the TiO2 agglomerates. 相似文献
68.
Tommi Tervonen Igor Linkov José Rui Figueira Jeffery Steevens Mark Chappell Myriam Merad 《Journal of nanoparticle research》2009,11(4):757-766
Various stakeholders are increasingly interested in the potential toxicity and other risks associated with nanomaterials throughout
the different stages of a product’s life cycle (e.g., development, production, use, disposal). Risk assessment methods and
tools developed and applied to chemical and biological materials may not be readily adaptable for nanomaterials because of
the current uncertainty in identifying the relevant physico-chemical and biological properties that adequately describe the
materials. Such uncertainty is further driven by the substantial variations in the properties of the original material due
to variable manufacturing processes employed in nanomaterial production. To guide scientists and engineers in nanomaterial
research and application as well as to promote the safe handling and use of these materials, we propose a decision support
system for classifying nanomaterials into different risk categories. The classification system is based on a set of performance
metrics that measure both the toxicity and physico-chemical characteristics of the original materials, as well as the expected
environmental impacts through the product life cycle. Stochastic multicriteria acceptability analysis (SMAA-TRI), a formal
decision analysis method, was used as the foundation for this task. This method allowed us to cluster various nanomaterials
in different ecological risk categories based on our current knowledge of nanomaterial physico-chemical characteristics, variation
in produced material, and best professional judgments. SMAA-TRI uses Monte Carlo simulations to explore all feasible values
for weights, criteria measurements, and other model parameters to assess the robustness of nanomaterial grouping for risk
management purposes. 相似文献
69.
Facilitating cross-disciplinary research has attracted much attention in recent years, with special concerns in nanoscience
and nanotechnology. Although policy discourse has emphasized that nanotechnology is substantively integrative, some analysts
have countered that it is really a loose amalgam of relatively traditional pockets of physics, chemistry, and other disciplines
that interrelate only weakly. We are developing empirical measures to gauge and visualize the extent and nature of interdisciplinary
interchange. Such results speak to research organization, funding, and mechanisms to bolster knowledge transfer. In this study,
we address the nature of cross-disciplinary linkages using “science overlay maps” of articles, and their references, that
have been categorized into subject categories. We find signs that the rate of increase in nano research is slowing, and that
its composition is changing (for one, increasing chemistry-related activity). Our results suggest that nanotechnology research
encompasses multiple disciplines that draw knowledge from disciplinarily diverse knowledge sources. Nano research is highly,
and increasingly, integrative—but so is much of science these days. Tabulating and mapping nano research activity show a dominant
core in materials sciences, broadly defined. Additional analyses and maps show that nano research draws extensively upon knowledge
presented in other areas; it is not constricted within narrow silos.
相似文献
Jan YoutieEmail: |
70.
Laura K. Braydich-Stolle Nicole M. Schaeublin Richard C. Murdock Jingkun Jiang Pratim Biswas John J. Schlager Saber M. Hussain 《Journal of nanoparticle research》2009,11(6):1361-1374
Certain properties that nanoparticles possess differentiate them from their bulk counterparts, and these characteristics must
be evaluated prior to nanoparticle studies and include: size, shape, dispersion, physical and chemical properties, surface
area, and surface chemistry. Early nanotoxicity studies evaluating TiO2 have yielded conflicting data which identify either size or crystal structure as the mediating property for nano-TiO2 toxicity. However, it is important to note that none of these studies examined size with the crystal structure composition
controlled for or examined crystal structure while controlling the nanoparticle size. The goal of this study was to evaluate
the role of size and crystal structure in TiO2 nanotoxicity while controlling for as many other nanoproperties as possible using the HEL-30 mouse keratinocyte cell line
as a model for dermal exposure. In the size-dependent studies, all the nanoparticles are 100% anatase, and aggregate sizes
were determined in order to take into account the effect of agglomeration on size-dependent toxicity. In addition, varying
crystal structures were assessed while the size of the nanoparticles was controlled. We were able to identify that both size
and crystal structure contribute to cytotoxicity and that the mechanism of cell death varies based on crystal structure. The
100% anatase TiO2 nanoparticles, regardless of size, induced cell necrosis, while the rutile TiO2 nanoparticles initiated apoptosis through formation of reactive oxygen species (ROS). 相似文献