scholarly journals Two-wavelength thermo-optical determination of Light Absorbing Carbon in atmospheric aerosols

2019 ◽  
Author(s):  
Dario Massabò ◽  
Alessandro Altomari ◽  
Virginia Vernocchi ◽  
Paolo Prati
Keyword(s):  
Laser Diode ◽  
Atmospheric Aerosols ◽  
Direct Determination ◽  
Optical Transmittance ◽  
Carbonaceous Aerosol ◽  
Electromagnetic Spectrum ◽  
Multi Wavelength ◽  
Set Up ◽  
Physics Department

Abstract. Thermo-optical analysis is widely adopted for the quantitative determination of Total, TC, Organic, OC, and Elemental, EC, Carbon in atmospheric aerosol sampled by suitable filters. Nevertheless, the methodology suffers of several uncertainties and artefacts as the well-known issue of charring affecting the OC-EC separation. In the standard approach, the effect of the possible presence of Brown Carbon, BrC, in the sample is neglected. BrC is a fraction of OC, usually produced by biomass burning with a thermic behaviour intermediate between OC and EC. BrC is optically active: it shows an increasing absorbance when the wavelength moves to the blue/UV region of the electromagnetic spectrum. Definitively, the thermo-optical characterization of carbonaceous aerosol should be reconsidered to address the possible BrC content in the sample under analysis. We introduce here a modified Sunset Lab Inc. EC/OC Analyzer. Starting from a standard commercial set-up, the unit has been modified at the Physics Department of the University of Genoa (IT), making possible the alternative use of the standard laser diode at λ = 635 nm and of a new laser diode at λ = 405 nm. In this way, the optical transmittance through the sample can be monitored at both the wavelengths. Since at shorter wavelengths the BrC absorbance is higher, a better sensitivity to this species is gained. The modified set-up also gives the possibility to quantify the BrC concentration in the sample at both the wavelengths. The new unit has been thoroughly tested, with both artificial and real-world samples: the first experiment, in conjunction with the Multi Wavelength Absorbance Analyzer (MWAA, Massabò et al., 2013 and 2015), resulted in the first direct determination of the BrC Mass Absorption Coefficient (MAC) at λ = 405 nm: MAC = 23 ± 1 m2 g−1.

scholarly journals Two-wavelength thermal–optical determination of light-absorbing carbon in atmospheric aerosols

2019 ◽  
Vol 12 (6) ◽  
pp. 3173-3182 ◽  
Author(s):  
Dario Massabò ◽  
Alessandro Altomari ◽  
Virginia Vernocchi ◽  
Paolo Prati
Keyword(s):  
Laser Diode ◽  
Atmospheric Aerosols ◽  
Direct Determination ◽  
Optical Transmittance ◽  
Carbonaceous Aerosol ◽  
Electromagnetic Spectrum ◽  
Multi Wavelength ◽  
Physics Department ◽  
The University

Abstract. Thermal–optical analysis is widely adopted for the quantitative determination of total (TC), organic (OC), and elemental (EC) carbon in atmospheric aerosol sampled by suitable filters. Nevertheless, the methodology suffers from several uncertainties and artifacts such as the well-known issue of charring affecting the OC–EC separation. In the standard approach, the effect of the possible presence of brown carbon, BrC, in the sample is neglected. BrC is a fraction of OC, usually produced by biomass burning with a thermic behavior intermediate between OC and EC. BrC is optically active: it shows an increasing absorbance when the wavelength moves to the blue–UV region of the electromagnetic spectrum. Definitively, the thermal–optical characterization of carbonaceous aerosol should be reconsidered to address the possible BrC content in the sample under analysis. We introduce here a modified Sunset Lab Inc. EC–OC analyzer. Starting from a standard commercial instrument, the unit has been modified at the physics department of the University of Genoa (Italy), making possible the alternative use of the standard laser diode at λ=635 nm and of a new laser diode at λ=405 nm. In this way, the optical transmittance through the sample can be monitored at both wavelengths. Since at shorter wavelengths the BrC absorbance is higher, a better sensitivity to this species is gained. The modified instrument also gives the possibility to quantify the BrC concentration in the sample at both wavelengths. The new unit has been thoroughly tested, with both artificial and real-world aerosol samples: the first experiment, in conjunction with the multi-wavelength absorbance analyzer (MWAA; Massabò et al., 2013, 2015), resulted in the first direct determination of the BrC mass absorption coefficient (MAC) at λ=405 nm: MAC =23±1 m2 g−1.

Multi-wavelength optical determination of black and brown carbon in atmospheric aerosols

2015 ◽  
Vol 108 ◽  
pp. 1-12 ◽  
Author(s):  
D. Massabò ◽  
L. Caponi ◽  
V. Bernardoni ◽  
M.C. Bove ◽  
P. Brotto ◽  
...  
Keyword(s):  
Atmospheric Aerosols ◽  
Brown Carbon ◽  
Multi Wavelength ◽  
Optical Determination

scholarly journals X. A method of measuring the pressure produced in the detonation of high, explosives or by the impact of bullets

1914 ◽  
Vol 213 (497-508) ◽  
pp. 437-456 ◽  
Keyword(s):  
Practical Interest ◽  
Direct Determination ◽  
High Explosives ◽  
Time Curve ◽  
Considerable Difficulty ◽  
Cylindrical Steel ◽  
Set Up ◽  
The Right ◽  
The Impact

The determination of the actual pressures produced by a blow such as that of a rifle bullet or by the detonation of high explosives is a problem of much scientific and practical interest but of considerable difficulty. It is easy to measure the transfer of momentum associated with the blow, which is equal to the average pressure developed, multiplied by the time during which it acts, but the separation of these two factors has not hitherto been effected. The direct determination of a force acting for a few hundred-thousandths of a second presents difficulties which may perhaps be called insuperable, but the measurement of the other factor, the duration of the blow, is more feasible. In the case of impacts such as those of spheres or rods moving at moderate velocities the time of contact can be determined electrically with considerable accuracy.* The present paper contains an account of a method of analysing experimentally more violent blows and of measuring their duration and the pressures developed. If a rifle bullet be fired against the end of a cylindrical steel rod there is a definite pressure applied on the end of the rod at each instant of time during the period of impact and the pressure can be plotted as a function of the time. The pressure-time curve is a perfectly definite thing, though the ordinates are expressed in tons and the abscissae in millionths of a second; the pressure starts when the nose of the bullet first strikes the end of the rod and it continues until the bullet has been completely set up or stopped by the impact. Subject to qualifications, which will be considered later, the result of applying this varying pressure to the end is to send along the rod a wave of pressure which, so long as the elasticity is perfect, travels without change of type. If the pressure in different sections of the rod be plotted at any instant (fig. l) then at a later time the same curve shifted to the right by a distance proportional to the time will represent the then distribution of pressure. The velocity with which the wave travels in steel is approximately 17,000 feet per second. As the wave travels over any section of the rod, that section successively experiences pressures represented by the successive ordinates of the curve as they pass over it. Thus the curve also represents the relation between the pressure at any point of the rod and the time, the scale being such that one inch represents the time taken by the wave to travel that distance which is very nearly 1/200,000 of a second. In particular the curve giving the distribution of pressure in the rod along its length is, assuming perfect elasticity, the same as the curve connecting the pressure applied at the end and the time, the scale of time being that just given.

scholarly journals Chemical Analysis through CL-Detection Assisted by Periodate Oxidation

2007 ◽  
Vol 2007 ◽  
pp. 1-10 ◽  
Author(s):  
Nicholaos P. Evmiridis ◽  
Athanasios G. Vlessidis ◽  
Nicholas C. Thanasoulias
Keyword(s):  
Chemical Analysis ◽  
Flow Injection ◽  
Research Work ◽  
Periodate Oxidation ◽  
Direct Determination ◽  
Good Reproducibility ◽  
Through Flow ◽  
Set Up ◽  
Simple Flow

The progress of the research work of the author and his colleagues on the field of CL-emission generated by pyrogallol oxidation and further application for the direct determination of periodate and indirect or direct determination of other compounds through flow-injection manifold/CL-detection set up is described. The instrumentation used for these studies was a simple flow-injection manifold that provides good reproducibility, coupled to a red sensitive photomultiplier that gives sensitive CL-detection. In addition, recent reports on studies and analytical methods based on CL-emission generated by periodate oxidation by other authors are included.

scholarly journals Age determination and authentication of ceramics: advancements in the thermoluminescence dating laboratory in Torino (Italy)

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 32
Author(s):  
Laura Guidorzi ◽  
Fulvio Fantino ◽  
Elisabetta Durisi ◽  
Marco Ferrero ◽  
Alessandro Re ◽  
...  
Keyword(s):  
Nuclear Physics ◽  
Age Determination ◽  
Ceramic Materials ◽  
Absolute Dating ◽  
Dating Method ◽  
Pre Treatment ◽  
Set Up ◽  
Physics Department ◽  
The University

Classified as an absolute dating method, thermoluminescence (TL) is a well-established radiation-based technique for the age determination and authentication of ceramic materials. Specifically, this method allows the determination of the time elapsed since kiln firing (or later fire events) by evaluating the luminescent emission of ceramics under heating at high temperatures. This paper provides a comprehensive presentation of the TL laboratory developed over the last decade at the Physics Department of the University of Torino. The laboratory was set up in collaboration with TecnArt S.r.l. and is also currently operating within the cultural heritage network of the National Institute of Nuclear Physics (INFN-CHNet). More than 10 years of experience in the field has resulted in improvements in procedures, with the development of customised alpha- and beta-irradiation systems and the optimisation of sampling approaches and chemical pre-treatment. Thanks to TecnArt S.r.l., the laboratory has been employed for dating and authenticating hundreds of archaeological sites and artworks, some of which are discussed in this work and compared, when possible, with radiocarbon dating.

The Direct Determination of I131 in Heterogeneous Fecal Specimens

1961 ◽  
Vol 41 (4) ◽  
pp. 380-384 ◽  
Author(s):  
Arthur F. Dratz ◽  
James C. Coberly
Keyword(s):  
Direct Determination

A New Method for Direct Determination of the Recoilless Fraction with Application to Magnetic Nanoparticles

2002 ◽  
Vol 721 ◽  
Author(s):  
Monica Sorescu
Keyword(s):  
Room Temperature ◽  
Average Particle Size ◽  
Direct Determination ◽  
Average Particle ◽  
Lattice Method ◽  
Recoilless Fraction ◽  
Single Room ◽  
Magnetite Particles ◽  
Physical Mixtures

AbstractWe propose a two-lattice method for direct determination of the recoilless fraction using a single room-temperature transmission Mössbauer measurement. The method is first demonstrated for the case of iron and metallic glass two-foil system and is next generalized for the case of physical mixtures of two powders. We further apply this method to determine the recoilless fraction of hematite and magnetite particles. Finally, we provide direct measurement of the recoilless fraction in nanohematite and nanomagnetite with an average particle size of 19 nm.

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