Differential Mobility Particle Sizers for Nanoparticle Characterization

2014 ◽  
Vol 5 (2) ◽  
Author(s):  
Jingjie Zhang ◽  
Daren Chen
Keyword(s):  
Particle Concentration ◽  
State Of The Art ◽  
Differential Mobility Analyzer ◽  
Differential Mobility ◽  
Nanoparticle Characterization ◽  
The Past ◽  
Essential Components ◽  
Size Limits ◽  
Aerosol Charger

Differential mobility particle sizers (DMPSs) are instruments for online sizing gas-borne particles in submicrometer and nanometer diameter ranges. The aerosol charger, the differential mobility analyzer (DMA), and the particle concentration detector are three essential components in DMPSs. In the past four decades, the design of DMAs has evolved into a variety of modern versions to extend their sizing limits, especially in lower detectable size limits. The DMAs are now capable of classifying or sizing particles in the diameters down to 1.0 nm. This article gives a brief overview of state-of-the-art DMAs particularly designed for classifying particles with sizes down to sub-10 nm.

scholarly journals Development of a new Nano-particle sizer equipped with a 12 channel multi-port differential mobility analyzer and multi-condensation particle counters

2019 ◽  
Author(s):  
Hong Ku Lee ◽  
Handol Lee ◽  
Kang-Ho Ahn
Keyword(s):  
Particle Size ◽  
Steady State ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Particle Concentration ◽  
Size Distributions ◽  
Nano Particle ◽  
Differential Mobility Analyzer ◽  
Differential Mobility ◽  
Particle Sizer

Abstract. Measuring particle size distributions precisely is an important concern in addressing environmental and human health-related issues. To measure particle size distribution, a scanning mobility particle sizer (SMPS) is often used. However, it is difficult to analyze particle size distribution under fast-changing concentration conditions because the SMPS cannot respond fast enough to reflect current conditions due to the time necessary for voltage scanning. In this research, we developed a new Nano-particle sizer (NPS), which consists of a multi-port differential mobility analyzer (MP-DMA) with 12 sampling ports and multi-condensation particle counters (M-CPCs) that simultaneously measure concentrations of particles classified by the sampling ports. The M-CPC can completely condense particles larger than 10 nm, and the total particle concentrations measured by each homemade CPC in the M-CPCs and an electrometer were in agreement up to 20,000 # cm−3. For particle classification tests on the MP-DMA, geometric standard deviations of the size distributions of classified particles were estimated in the range of 1.035–1.066. We conducted size distribution measurements under steady-state conditions using an aerosol generator and under unsteady conditions by switching the aerosol supply on/off. The data obtained by the NPS corresponded closely with the SMPS measurement data for the steady-state particle concentration case. In addition, the NPS could successfully capture the changes in particle size distribution under fast-changing particle concentration conditions. For the last, we presented the NPS measurement results of size distributions in common situation (cooking) as an exemplary real-world application.

scholarly journals Development of a new nanoparticle sizer equipped with a 12-channel multi-port differential mobility analyzer and multi-condensation particle counters

2020 ◽  
Vol 13 (3) ◽  
pp. 1551-1562
Author(s):  
Hong Ku Lee ◽  
Handol Lee ◽  
Kang-Ho Ahn
Keyword(s):  
Particle Size ◽  
Steady State ◽  
Size Distribution ◽  
Particle Concentration ◽  
Measurement Data ◽  
Size Distributions ◽  
Differential Mobility Analyzer ◽  
Particle Size Distributions ◽  
Scanning Mobility Particle Sizer ◽  
Differential Mobility

Abstract. Measuring particle size distributions precisely is an important concern in addressing environmental and human health-related issues. To measure particle size distributions, a scanning mobility particle sizer (SMPS) is often used. However, it is difficult to analyze particle size distributions under fast-changing concentration conditions because the SMPS cannot respond fast enough to reflect current conditions due to the time necessary for voltage scanning. In this research, we developed a new nanoparticle sizer (NPS), which consists of a multi-port differential mobility analyzer (MP-DMA) with 12 sampling ports and multi-condensation particle counters (M-CPCs) that simultaneously measure concentrations of particles classified by the sampling ports. The M-CPC can completely condense particles larger than 10 nm, and the total particle concentrations measured by each CPC in the M-CPCs and an electrometer were in agreement up to 20 000 no.cm-3. We conducted size distribution measurements under steady-state conditions using an aerosol generator and under unsteady conditions by switching the aerosol supply on or off. The data obtained by the NPS corresponded closely to the SMPS measurement data for the steady-state particle concentration case. In addition, the NPS could successfully capture the changes in particle size distribution under fast-changing particle concentration conditions. Finally, we present NPS measurement results of size distributions in a common situation (cooking) as an exemplary real-world application.

A Macintosh Interface for the Cameca Camebax-Micro Electron Microprobe

1990 ◽  
Vol 48 (1) ◽  
pp. 438-439
Author(s):  
Carl E. Henderson
Keyword(s):  
Electron Microprobe ◽  
Processing Speed ◽  
Word Processing ◽  
State Of The Art ◽  
Computer Control ◽  
Third Party ◽  
Disk Storage ◽  
The Past ◽  
User Facility ◽  
Instrument Control

Over the past few years it has become apparent in our multi-user facility that the computer system and software supplied in 1985 with our CAMECA CAMEBAX-MICRO electron microprobe analyzer has the greatest potential for improvement and updating of any component of the instrument. While the standard CAMECA software running on a DEC PDP-11/23+ computer under the RSX-11M operating system can perform almost any task required of the instrument, the commands are not always intuitive and can be difficult to remember for the casual user (of which our laboratory has many). Given the widespread and growing use of other microcomputers (such as PC’s and Macintoshes) by users of the microprobe, the PDP has become the “oddball” and has also fallen behind the state-of-the-art in terms of processing speed and disk storage capabilities. Upgrade paths within products available from DEC are considered to be too expensive for the benefits received. After using a Macintosh for other tasks in the laboratory, such as instrument use and billing records, word processing, and graphics display, its unique and “friendly” user interface suggested an easier-to-use system for computer control of the electron microprobe automation. Specifically a Macintosh IIx was chosen for its capacity for third-party add-on cards used in instrument control.

scholarly journals Inflammation, epigenetics, and metabolism converge to cell senescence and ageing: the regulation and intervention

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Xudong Zhu ◽  
Zhiyang Chen ◽  
Weiyan Shen ◽  
Gang Huang ◽  
John M. Sedivy ◽  
...  
Keyword(s):  
Cell Fate ◽  
Cellular Response ◽  
State Of The Art ◽  
Cell Senescence ◽  
Therapeutic Interventions ◽  
Cell Fate Decision ◽  
The Past ◽  
Fate Decision ◽  
The Individual ◽  
Remarkable Progress

AbstractRemarkable progress in ageing research has been achieved over the past decades. General perceptions and experimental evidence pinpoint that the decline of physical function often initiates by cell senescence and organ ageing. Epigenetic dynamics and immunometabolic reprogramming link to the alterations of cellular response to intrinsic and extrinsic stimuli, representing current hotspots as they not only (re-)shape the individual cell identity, but also involve in cell fate decision. This review focuses on the present findings and emerging concepts in epigenetic, inflammatory, and metabolic regulations and the consequences of the ageing process. Potential therapeutic interventions targeting cell senescence and regulatory mechanisms, using state-of-the-art techniques are also discussed.

scholarly journals Security assurance cases—state of the art of an emerging approach

2021 ◽  
Vol 26 (4) ◽  
Author(s):  
Mazen Mohamad ◽  
Jan-Philipp Steghöfer ◽  
Riccardo Scandariato
Keyword(s):  
State Of The Art ◽  
Tool Support ◽  
Security Assurance ◽  
The Past ◽  
Depth Analysis ◽  
Structured Argumentation ◽  
Security Properties ◽  
Standards And Regulations ◽  
Assurance Cases ◽  
Security Standards

AbstractSecurity Assurance Cases (SAC) are a form of structured argumentation used to reason about the security properties of a system. After the successful adoption of assurance cases for safety, SAC are getting significant traction in recent years, especially in safety-critical industries (e.g., automotive), where there is an increasing pressure to be compliant with several security standards and regulations. Accordingly, research in the field of SAC has flourished in the past decade, with different approaches being investigated. In an effort to systematize this active field of research, we conducted a systematic literature review (SLR) of the existing academic studies on SAC. Our review resulted in an in-depth analysis and comparison of 51 papers. Our results indicate that, while there are numerous papers discussing the importance of SAC and their usage scenarios, the literature is still immature with respect to concrete support for practitioners on how to build and maintain a SAC. More importantly, even though some methodologies are available, their validation and tool support is still lacking.

scholarly journals The state of the art in soybean transcriptomics resources and gene coexpression networks

2021 ◽  
Author(s):  
Fabricio Almeida-Silva ◽  
Kanhu C Moharana ◽  
Thiago M Venancio
Keyword(s):  
State Of The Art ◽  
The State ◽  
Gene Coexpression Network ◽  
Rna Seq ◽  
Transcriptomic Data ◽  
The Past ◽  
Gene Coexpression ◽  
Genomics Research ◽  
Public Repositories ◽  
Coexpression Networks

Abstract In the past decade, over 3000 samples of soybean transcriptomic data have accumulated in public repositories. Here, we review the state of the art in soybean transcriptomics, highlighting the major microarray and RNA-seq studies that investigated soybean transcriptional programs in different tissues and conditions. Further, we propose approaches for integrating such big data using gene coexpression network and outline important web resources that may facilitate soybean data acquisition and analysis, contributing to the acceleration of soybean breeding and functional genomics research.

scholarly journals Beyond Mindfulness

Open Theology ◽  
2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Thomas G. Plante
Keyword(s):  
Research Evidence ◽  
State Of The Art ◽  
Empirical Studies ◽  
Religion And Spirituality ◽  
Spiritual Values ◽  
Quality Research ◽  
The Past ◽  
Enormous Amount ◽  
Consulting Psychology ◽  
Areas Of Interest

AbstractSince the publication of Bergin’s classic 1980 paper “Psychotherapy and Religious Values” in the Journal of Clinical and Consulting Psychology, an enormous amount of quality research has been conducted on the integration of religious and spiritual values and perspectives into the psychotherapy endeavor. Numerous empirical studies, chapters, books, blogs, and specialty organizations have emerged in the past 35 years that have helped researchers and clinicians alike come to appreciate the value of religion and spirituality in the psychotherapeutic process. While so much has been accomplished in this area of integration, so much more needs to occur in order for the psychotherapeutic world to benefit from the wisdom of the great religious and spiritual traditions and values. While state-of-the-art quality research has and continues to demonstrate how religious and spiritual practices and values can be used effectively to enhance the benefits of behavioral and psychological interventions, too often the field either gets overly focused on particular and perhaps trendy areas of interest (e.g., mindfulness) or fails to appreciate and incorporate the research evidence supporting (or not supporting) the use of certain religiously or spiritually informed assessments and interventions. The purpose of this article is to reflect on where the field integrating religion, spirituality and psychotherapy has evolved through the present and where it still needs to go in the future. In doing so I hope to reflect on the call for integration that Bergin highlights in his classic 1980 paper.

scholarly journals A novel tandem differential mobility analyzer with organic vapor treatment of aerosol particles

2001 ◽  
Vol 1 (1) ◽  
pp. 51-60 ◽  
Author(s):  
J. Joutsensaari ◽  
P. Vaattovaara ◽  
M. Vesterinen ◽  
K. Hämeri ◽  
A. Laaksonen
Keyword(s):  
Water Vapor ◽  
Sodium Chloride ◽  
Citric Acid ◽  
Ammonium Sulfate ◽  
Adipic Acid ◽  
Aerosol Particles ◽  
Ethanol Vapor ◽  
Differential Mobility Analyzer ◽  
Differential Mobility ◽  
Organic Vapor

Abstract. A novel method to characterize the organic composition of aerosol particles has been developed. The method is based on organic vapor interaction with aerosol particles and it has been named an Organic Tandem Differential Mobility Analyzer (OTDMA). The OTDMA method has been tested for inorganic (sodium chloride and ammonium sulfate) and organic (citric acid and adipic acid) particles. Growth curves of the particles have been measured in ethanol vapor and as a comparison in water vapor as a function of saturation ratio. Measurements in water vapor show that sodium chloride and ammonium sulfate as well as citric acid particles grow at water saturation ratios (S) of 0.8 and above, whereas adipic acid particles do not grow at S <  0.96. For sodium chloride and ammonium sulfate particles, a deliquescence point is observed at S = 0.75 and S = 0.79, respectively. Citric acid particles grow monotonously with increasing saturation ratios already at low saturation ratios and no clear deliquescence point is found. For sodium chloride and ammonium sulfate particles, no growth can be seen in ethanol vapor at saturation ratios below 0.93. In contrast, for adipic acid particles, the deliquescence takes place at around S = 0.95 in the ethanol vapor. The recrystallization of adipic acid takes place at S < 0.4. Citric acid particles grow in ethanol vapor similarly as in water vapor; the particles grow monotonously with increasing saturation ratios and no stepwise deliquescence is observed. The results show that the working principles of the OTDMA are operational for single-component aerosols. Furthermore, the results indicate that the OTDMA method may prove useful in determining whether aerosol particles contain organic substances, especially if the OTDMA is operated in parallel with a hygroscopicity TDMA, as the growth of many substances is different in ethanol and water vapors.

Newly developed instrumentation for measuring highly oxidized molecules at atmospheric pressure

2021 ◽  
Author(s):  
Paap Koemets ◽  
Sander Mirme ◽  
Kuno Kooser ◽  
Heikki Junninen
Keyword(s):  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Atmospheric Pressure ◽  
Chemical Ionization ◽  
Measurement Technology ◽  
Differential Mobility Analyzer ◽  
Neutral Cluster ◽  
Differential Mobility ◽  
Alpha Pinene ◽  
Ambient Measurements

&lt;p&gt;The Highly Oxidized Molecule Ion Spectrometer (HOMIS) is a novel instrument for measuring the total concentration of highly oxidized molecules (HOM-s) (Bianchi et al., 2019) at atmospheric pressure. The device combines a chemical ionization charger with a multi-channel differential mobility analyzer. The chemical ionization charger is based on the principles outlined by Eisele and Tanner (1993). The charger is attached to a parallel differential mobility analyzer identical to the ones used in the Neutral cluster and Air Ion Spectrometer (NAIS, Mirme 2011), but with modified sample and sheath air flow rates to improve the mobility resolution of the device. The complete mobility distribution in the range from 3.2 to 0.056 cm&lt;sup&gt;2&lt;/sup&gt;/V/s is measured simultaneously by 25 electrometers. The range captures the charger ions, monomers, dimers, trimers but also extends far towards larger particles to possibly detect larger HOM-s that have not been measured with existing instrumentation. The maximum time resolution of the device is 1 second allowing it to detect rapid changes in the sample. The device has been designed to be easy to use, require little maintenance and work reliably in various environments during long term measurements.&lt;/p&gt;&lt;p&gt;First results of the prototype were acquired from laboratory experiments and ambient measurements. Experiments were conducted at the Laboratory of Environmental Physics, University of Tartu. The sample was drawn from a reaction chamber where alpha-pinene and ozone were introduced. Initial results show a good response when concentrations of alpha-pinene and ozone were changed.&amp;#160;&lt;/p&gt;&lt;p&gt;Ambient measurements were conducted at the SMEAR Estonia measurement station in a hemiboreal forest for 10 days in the spring and two months in the winter of 2020. The HOMIS measurements were performed together with a CI-APi-TOF (Jokinen et al., 2012).&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Bianchi, F., Kurt&amp;#233;n, T., Riva, M., Mohr, C., Rissanen, M. P., Roldin, P., Berndt, T., Crounse, J. D., Wennberg, P. O., Mentel, T. F., Wildt, J., Junninen, H., Jokinen, T., Kulmala, M., Worsnop, D. R., Thornton, J. A., Donahue, N., Kjaergaard, H. G. and Ehn, M. (2019), &amp;#8220;Highly Oxygenated Organic Molecules (HOM) from Gas-Phase Autoxidation Involving Peroxy Radicals: A Key Contributor to Atmospheric Aerosol&amp;#8221;, Chemical Reviews, 119, 6, 3472&amp;#8211;3509&lt;/p&gt;&lt;p&gt;Eisele, F. L., Tanner D. J. (1993), &amp;#8220;Measurement of the gas phase concentration of H2SO4 and methane sulfonic acid and estimates of H2SO4 production and loss in the atmosphere&amp;#8221;, JGR: Atmospheres, 98, 9001-9010&lt;/p&gt;&lt;p&gt;Jokinen T., Sipil&amp;#228; M., Junninen H., Ehn M., L&amp;#246;nn G., Hakala J., Pet&amp;#228;j&amp;#228; T., Mauldin III R. L., Kulmala M., and Worsnop D. R. (2012), &amp;#8220;Atmospheric sulphuric acid and neutral cluster measurements using CI-APi-TOF&amp;#8221;, Atmospheric Chemistry and Physics, 12, 4117&amp;#8211;4125&lt;/p&gt;&lt;p&gt;Mirme, S. (2011), &amp;#8220;Development of nanometer aerosol measurement technology&amp;#8221;, Doctoral thesis, University of Tartu&lt;/p&gt;

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