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1.
While several studies on the public opinion of nanotechnology have pointed to a rather enthusiastic U.S. public, the public
uptake of nanotechnology in Europe is more contained. The results of the Swiss publifocus on nanotechnology reveal a pragmatic attitude of citizens toward the emerging technologies, thus confirming what has been
identified as a “balanced approach” in the NanoJury UK.
相似文献
Regula Valérie BurriEmail: |
2.
Graphs of the total radius (the distance between an anionic nuclei and a cationic nuclei in a crystal) of sodium halides and
alkali metal fluorides versus total limiting equivalent conductivities were plotted. For the hard ions Na+ and F−, whose behaviour approaches a hard spherical model, it was determined that radii values could be obtained using differences
in limiting equivalent conductivities and ionic crystal data. From the determined radii of sodium and fluoride ions and known
crystal data, radii of other alkali metal halides were calculated.
相似文献
Sevda AyataEmail: |
3.
An overview of the special issue of the Journal of Nanoparticle Research on Occupational and Environmental Health of nanotechnology
is presented. Papers published in this special issue show considerable progress in understanding nanoparticle toxicity, monitoring,
generation, dustiness, filtration, and applications of nanoparticles. More research is needed to ensure safe handling of nanomaterials
as nanotechnology continues to develop at an incredible pace.
相似文献
Chuen-Jinn TsaiEmail: |
4.
Refining search terms for nanotechnology 总被引:5,自引:3,他引:2
Alan L. Porter Jan Youtie Philip Shapira David J. Schoeneck 《Journal of nanoparticle research》2008,10(5):715-728
The ability to delineate the boundaries of an emerging technology is central to obtaining an understanding of the technology’s
research paths and commercialization prospects. Nowhere is this more relevant than in the case of nanotechnology (hereafter
identified as “nano”) given its current rapid growth and multidisciplinary nature. (Under the rubric of nanotechnology, we
also include nanoscience and nanoengineering.) Past efforts have utilized several strategies, including simple term search
for the prefix nano, complex lexical and citation-based approaches, and bootstrapping techniques. This research introduces
a modularized Boolean approach to defining nanotechnology which has been applied to several research and patenting databases.
We explain our approach to downloading and cleaning data, and report initial results. Comparisons of this approach with other
nanotechnology search formulations are presented. Implications for search strategy development and profiling of the nanotechnology
field are discussed.
相似文献
Jan YoutieEmail: |
5.
Joseph S. Gardner Endrit Shurdha Chongmin Wang Lisa D. Lau René G. Rodriguez Joshua J. Pak 《Journal of nanoparticle research》2008,10(4):633-641
The properties of CuInS2 semi-conductor nanoparticles make them attractive materials for use in next-generation photovoltaics. We have prepared CuInS2 nanoparticles from single source precursors via microwave irradiation. Microwave irradiation methods have allowed us to increase
the efficiency of preparation of these materials by providing uniform heating and rapid reaction times. The synergistic effect
of varying thiol capping ligand concentrations as well as reaction temperatures and times resulted in fine control of nanoparticle
growth in the 3–5 nm size range. Investigation of the photophysical properties of the colloidal nanoparticles were performed
using electronic absorption and luminescence emission spectroscopy. Qualitative nanoparticles sizes were determined from the
photoluminescence (PLE) data and compared to HRTEM images.
相似文献
Joshua J. PakEmail: |
6.
Expert opinion on nanotechnology: risks,benefits, and regulation 总被引:2,自引:2,他引:0
John C. Besley Victoria L. Kramer Susanna H. Priest 《Journal of nanoparticle research》2008,10(4):549-558
A survey of American (US) nanotechnology researchers (N = 177) suggests a diversity of views about what areas are most important to the burgeoning field, as well as perceptions about
the overall benefits and risks of such research. On average, respondents saw a range of technologies as key and viewed public
health and environmental issues as areas where both risks and the need for regulation are greatest. These areas were also
where respondents said current regulations were least adequate. Factor analyses of the survey questions suggest that, when
considering both risks and regulations, respondents make a distinction between health and environmental risks, and what might
be termed “social risks” (e.g., invasion of privacy, use of nanotechnology in weapons, and economic impacts).
相似文献
John C. BesleyEmail: |
7.
As technology has evolved available guidelines for normal-phase flash chromatography have become less relevant. Years of experience
performing chromatography with disposable columns have been condensed into simple guidelines useful for translating TLC results
into either isocratic- or gradient-flash chromatography. The described studies should provide researchers with a means of
selecting adequate columns and guidelines to reduce the waste of solvents, silica, time, and money.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
William C. Stevens Jr.Email: |
8.
Using the total radius of alkaline fluorides and sodium halides and their experimental total enthalpy values, absolute hydration
enthalpies of sodium and fluoride ions ( and ) were previously calculated. Also, by the help of data of sodium and fluoride ions for all alkaline metal ions and halides
absolute hydration enthalpies were determined.
相似文献
Sevda AyataEmail: |
9.
A. O. Salman D. Dibekci S. Gavrilov A. Alexei Vertiy 《International Journal of Infrared and Millimeter Waves》2008,29(5):465-485
In this paper, investigation of radiation properties of the traveling-wave sinusoidal wire antennas is extended to the millimeter-wave
frequencies (Ka-band) for the antennas whose geometrical dimensions vary in a wide range. Far-field patterns and S-parameters
of composed three antenna sets were measured. A mathematical model was constructed for the structure and a MATLAB code based
on this theoretical approach was written to calculate patterns, phase and attenuation constants of all investigated antennas.
Frequency characteristics and the relation of antenna dimensions with wave parameters were investigated. Measured and calculated
patterns were also compared with the constructed far-field patterns obtained by MoM (method of moments) and the MoM current
distributions were used to explain the loss mechanisms of antennas. A directive, undistorted and smooth radiation can be achieved
only choosing small undulated antennas whose peak-to-peak amplitude to period ratio κ is smaller than 0.4 (κ < 0.4). It is
shown that wavelength of broadside radiation is not equal to antenna period for all antennas, except for very small undulated
antennas (κ < 0.2). This antenna type can be used as a frequency-scan antenna for millimeter wave radars.
相似文献
A. O. SalmanEmail: |
10.
To understand and engineer applications for mixed conducting oxides, it is desirable to have explicit, analytical expressions
for the functional dependence of defect concentration and transport properties on the partial pressure of the external gas
phase. To fulfill this need, general expressions are derived for the functional dependence of defect concentration on the
oxygen partial pressure () for the mixed ionic electronic conductors. The model presented in this paper differs from expressions obtained using the
popular Brouwer approach because they are continuous across multiple Brouwer regions.
相似文献
Eric D. WachsmanEmail: |
11.
This article investigates the development of nanotechnology in Latin America with a particular focus on Argentina, Brazil,
Chile, and Uruguay. Based on data for nanotechnology research publications and patents and suggesting a framework for analyzing
the development of R&D networks, we identify three potential strategies of nanotechnology research collaboration. Then, we
seek to identify the balance of emphasis upon each of the three strategies by mapping the current research profile of those
four countries. In general, we find that they are implementing policies and programs to develop nanotechnologies but differ
in their collaboration strategies, institutional involvement, and level of development. On the other hand, we find that they
coincide in having a modest industry participation in research and a low level of commercialization of nanotechnologies.
相似文献
Philip ShapiraEmail: |
12.
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: |
13.
The effect of co-doping yttria-stabilised zirconia with calcia and scandia has been investigated. Changes in the yttrium ion
local environment have been monitored using solid-state magic angle sample spinning 89Y nuclear magnetic resonance. The effect on the low-temperature (below 320 °C) bulk ionic conductivity has been observed using
AC impedance spectroscopy. It was found that the number of oxygen vacancies in the nearest-neighbour sites to yttrium ions
decreased on co-doping with scandia, correlating with an increase in conductivity, but increased on co-doping with calcia,
correlating with a decrease in conductivity. This behaviour can be explained by proposing the trapping of oxygen vacancies
in the nearest-neighbour yttrium ion sites so that they no longer contribute to the conduction mechanism.
相似文献
R. J. DarbyEmail: |
14.
Alexis D. Ostrowski Tyronne Martin Joseph Conti Indy Hurt Barbara Herr Harthorn 《Journal of nanoparticle research》2009,11(2):251-257
Understanding the toxicity of nanomaterials and nano-enabled products is important for human and environmental health and
safety as well as public acceptance. Assessing the state of knowledge about nanotoxicology is an important step in promoting
comprehensive understanding of the health and environmental implications of these new materials. To this end, we employed
bibliometric techniques to characterize the prevalence and distribution of the current scientific literature. We found that
the nano-toxicological literature is dispersed across a range of disciplines and sub-fields; focused on in vitro testing;
often does not specify an exposure pathway; and tends to emphasize acute toxicity and mortality rather than chronic exposure
and morbidity. Finally, there is very little research on consumer products, particularly on their environmental fate, and
most research is on the toxicity of basic nanomaterials. The implications for toxicologists, regulators and social scientists
studying nanotechnology and society are discussed.
相似文献
Barbara Herr HarthornEmail: |
15.
Pascual Jordan Jürgen Ehlers Wolfgang Kundt 《General Relativity and Gravitation》2009,41(9):2191-2280
This is an English translation of a paper by Pascual Jordan, Jürgen Ehlers and Wolfgang Kundt, first published in 1960. The
original paper was part 1 of a five-part series of articles containing the first summary of knowledge about exact solutions
of Einstein’s equations found until then. (The other parts of the series will be printed as Golden Oldies in the future.)
The paper has been selected by the Editors of General Relativity and Gravitation for re-publication in the Golden Oldies series
of the journal. It is accompanied by an editorial note written by G. F. R. Ellis, and by the biographies of the authors: P.
Jordan (written by A. Krasiński) and W. Kundt (written by himself). The biography of J. Ehlers is contained elsewhere in the
same issue of GRG, which is devoted to his memory.
An editorial note to this paper and a biography can be found in this issue preceding this Golden Oldie and online via doi:.
Original paper: Pascual Jordan, Jürgen Ehlers, Wolfgang Kundt, Strenge L?sungen der Feldgleichungen der Allgemeinen Relativit?tstheorie.
Akademie der Wissenschaften und der Literatur, Abhandlungen der Mathematisch-naturwissenschaftliche Klasse Nr 2S (1960), pp. 21–105. Reprinted with the kind permission of the Academy of Sciences and Literature, Mainz, and of the
authors: Jürgen Ehlers and Wolfgang Kundt. Translated by Anita Ehlers, Anita.Ehlers@t-online.de, and by Manfred Trümper, manfred@truemper.fr,
with ample help from Wolfgang Kundt.
P. Jordan (Deceased July 31, 1980)
J. Ehlers (Deceased May 20, 2008)
相似文献
Wolfgang KundtEmail: |
16.
Dhimiter Bello Brian L. Wardle Namiko Yamamoto Roberto Guzman deVilloria Enrique J. Garcia Anastasios J. Hart Kwangseog Ahn Michael J. Ellenbecker Marilyn Hallock 《Journal of nanoparticle research》2009,11(1):231-249
This study investigated airborne exposures to nanoscale particles and fibers generated during dry and wet abrasive machining
of two three-phase advanced composite systems containing carbon nanotubes (CNTs), micron-diameter continuous fibers (carbon
or alumina), and thermoset polymer matrices. Exposures were evaluated with a suite of complementary instruments, including
real-time particle number concentration and size distribution (0.005–20 μm), electron microscopy, and integrated sampling
for fibers and respirable particulate at the source and breathing zone of the operator. Wet cutting, the usual procedure for
such composites, did not produce exposures significantly different than background whereas dry cutting, without any emissions
controls, provided a worst-case exposure and this article focuses here. Overall particle release levels, peaks in the size
distribution of the particles, and surface area of released particles (including size distribution) were not significantly
different for composites with and without CNTs. The majority of released particle surface area originated from the respirable
(1–10 μm) fraction, whereas the nano fraction contributed ~10% of the surface area. CNTs, either individual or in bundles,
were not observed in extensive electron microscopy of collected samples. The mean number concentration of peaks for dry cutting
was composite dependent and varied over an order of magnitude with highest values for thicker laminates at the source being
>1 × 106 particles cm−3. Concentration of respirable fibers for dry cutting at the source ranged from 2 to 4 fibers cm−3 depending on the composite type. Further investigation is required and underway to determine the effects of various exposure
determinants, such as specimen and tool geometry, on particle release and effectiveness of controls.
相似文献
Dhimiter BelloEmail: |
17.
Farruggia G Iotti S Prodi L Zaccheroni N Montalti M Savage PB Andreani G Trapani V Wolf FI 《Journal of fluorescence》2009,19(1):11-19
The intracellular behaviour of diaza-18-crown-6 appended with two H-substituted hydroxyquinoline groups (DCHQ1) was investigated
to explore its application as a new sensor for the evaluation of cell magnesium content and distribution. We used five cells
lines characterised by different contents of magnesium and different intracellular membrane-defined compartments. The main
result is the definition of the appropriate experimental conditions to quantitatively assess the total cell magnesium by fluorescence
spectroscopy. We showed that disrupting cells by sonication, DCHQ1 was capable to assess total cell magnesium in all cell
types examined, obtaining overlapping results with atomic absorption spectroscopy (AAS). This new analytical approach requires
very small cell samples and a simple fluorimetric technique, and can be a valid alternative to AAS. The fluorescent properties
of DCHQ1 in living cells are: (a) it consistently stains live cells, (b) it discriminates small variations of cell Mg contents,
(c) cell staining is stable for at least 30 min. We also investigated the role of lipophilic environment on DCHQ1 fluorescence
by mimicking cell membranes and described how the composition and structure of lipid vesicles affect Mg-DCHQ1 fluorescence.
Thus, DCHQ1 may offer important information also on magnesium distribution in living cells, providing a novel strategy to
map the intracellular compartmentalization of this cation.
相似文献
Federica I. Wolf (Corresponding author)Email: |
18.
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: |
19.
We construct approximate solutions to the time–dependent Schr?dinger?equation
for small values of ħ. If V satisfies appropriate analyticity and growth hypotheses and , these solutions agree with exact solutions up to errors whose norms are bounded by
for some C and γ>0. Under more restrictive hypotheses, we prove that for sufficiently small T
′, implies the norms of the errors are bounded by
for some C
′, γ′>0, and σ > 0.
Received: 7 January 1999 / Accepted: 30 April 1999 相似文献
20.
Frequency domain (FD) fluorescence lifetime data was collected for a series of 20 crude petroleum oils using a 405 nm excitation
source and over a spectral range of ~426 to ~650 nm. Average fluorescence lifetimes were calculated using three different
models: discrete multi-exponential, Gaussian distribution, and Lorentzian distribution. Fitting the data to extract accurate
average lifetimes using the various models proved easier and less time consuming for the FD data than with Time Correlated
Single Photon Counting (TCSPC) methods however the analysis of confidence intervals to the computed average lifetimes proved
cumbersome for both methods. The uncertainty in the average lifetime was generally larger for the discrete lifetime multi-exponential
model when compared to the distribution-based models. For the lifetime distributions, the data from the light crude oils with
long lifetimes generally fit to a single decay term. Heavier oils with shorter lifetimes required multiple decay terms. The
actual value for the average lifetime is more dependant on the specific fitting model employed than the data acquisition method
used. Correlations between average fluorescence lifetimes and physical and chemical parameters of the crude oils were made
with a view to developing a quantitative model for predicting the gross chemical composition of crude oils. It was found that
there was no significant benefit gained by using FD over TCSPC other than more rapid data analysis in the FD case. For the
FD data the Gaussian distribution model for fluorescence lifetime gave the best correlations with chemical composition allowing
a qualitative correlation to some bulk oil parameters.
相似文献
Alan G. RyderEmail: |