THEORY OF A RESONANCE METHOD TO MEASURE THE ACOUSTIC PROPERTIES OF SEDIMENTS

Geophysics ◽  
1956 ◽  
Vol 21 (2) ◽  
pp. 299-304 ◽  
Author(s):  
W. J. Toulis

The theory of resonance for a pressure release cylindrical chamber is explored and equations are derived for determining absolute values of the velocity of sound and the attenuation constant in sediment samples. The essential measurements that need to be made are the determination of the frequencies of the lower modes of resonance and the associated sharpness of resonance. Corrections are derived also for the finite thickness and the acoustic losses in the chamber walls.

Author(s):  
Silvana M. Álvarez ◽  
Natalia E. Llamas ◽  
Mónica B. Álvarez ◽  
Jorge E. Marcovecchio ◽  
Mariano Garrido ◽  
...  

Author(s):  
Ling Wu ◽  
Qiurong He ◽  
Jing Zhang ◽  
Yongxin Li ◽  
Weiqing Yang ◽  
...  

Abstract Background Polycyclic aromatic hydrocarbons (PAHs) have attracted worldwide attention due to their carcinogenic, teratogenic and mutagenic effects, environmental persistence and bioaccumulation characteristics. Therefore, the sensitive, reliable and rapid detection of PAHs in sediment is of great importance. Objective To develop a high-performance liquid chromatography (HPLC) with fluorescence and ultraviolet detection after QuEChERS treatment for simultaneous determination of 16 U.S. Environmental Protection Agency priority PAHs in sediment samples. Methods The samples were ultrasonically extracted with acetone and then the supernatant was purified with a modified QuEChERS method. After centrifugation, the supernatant was injected into the HPLC system for analysis. The separation was accomplished on a ZORBAX Eclipse PAH column (150 × 4.6 mm, 3.5 μm) and the column temperature was set at 30 °C. The flow rate of the mobile phase consisting of water and acetonitrile in gradient elution mode was fixed at 0.9 mL/min. Detection was conducted on an ultraviolet detector and a fluorescence detector simultaneously. The qualitative analysis was based on retention time and the quantification was based on standard curves. Results Under the optimal conditions, this method showed good linearities in the range of 10–200 μg/L with correlation coefficients greater than 0.9993. The method had the limits of detection (LODs) ranging from 0.00108 to 0.314 ng/g. The mean recoveries ranged from 78.4 to 117% with the intra-day and inter-day relative standard deviations (RSDs) of 0.592–10.7 and 1.01–13.0%, respectively. The proposed method was successfully applied to the detection of 16 PAHs in sediment samples collected from the Funan River in Chengdu, China with the total contents of 431 to 2143 ng/g·dw. Conclusions The established method is simple, rapid, environment-friendly and cost- effective. It can be applied to the analysis of 16 PAHs in sediment samples. Highlights A method of QuEChERS with ultrasound-assisted extraction combined with HPLC has been established for the analysis of 16 PAHs in sediment samples and the proposed method has been successfully applied to the analysis PAHs in real sediment samples.


2018 ◽  
Vol 189 ◽  
pp. 227-235 ◽  
Author(s):  
S. Padilla ◽  
J.M. López-Gutiérrez ◽  
D.M.R. Sampath ◽  
T. Boski ◽  
J.M. Nieto ◽  
...  

1994 ◽  
Vol 129 (2-3) ◽  
pp. 317-321 ◽  
Author(s):  
Stanislav P. Solodovnikov ◽  
Alexander Yu. Vasil'kov ◽  
Andrei Yu. Olenin ◽  
Vladimir A. Sergeev

1872 ◽  
Vol 20 (130-138) ◽  
pp. 34-35

A galvanic current passes from the batteries at the Royal Observatory, Cape Town, at 1 o’clock, and discharges a gun at the Castle, and through relays drops a time-ball at Port Elizabeth. It appeared to the author that a valuable determination of the velocity of sound might be obtained by measuring upon the chronograph of the Observatory the interval between the time of the sound reaching some point near the gun and that of its arrival at the Observatory. As there is only a single wire between the Observatory and Cape Town, some little difficulty was experienced in making the necessary arrangements, without any interference with the 1 o’clock current to Port Elizabeth; but this difficulty was overcome by a plan which the author describes, and which was brought into successful operation on Feb. 27, 1871. The experiments could not have been carried out, on account of the encroachment they would have made on the time of the Observatory staff, had it not been for the assistance of J. Den, Esq., the acting manager of the Cape Telegraph Company, to whom the author is indebted for the preparation of a good earth-connexion near the gun, for permission to Mr. Kirby, a gentleman attached to the telegraph office, to assist in the experiments, and for a general superintendence of the arrangements at Cape Town. The observed times of hearing the sound were recorded on the chronograph by two observers, situated one (Mr. Kirby) at a distance of 641 feet from the gun, the other (Mr. Mann) at the Observatory, at a distance of 15,449 feet from the gun. The former distance was sufficient to allow the connexion of the main wire to be broken at the telegraph office after the gun had been fired, but before the sound reached the first observer.


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